Neuroimaging of Tryptophan Challenge in People With Schizophrenia and Healthy Controls
Phase: PHASE2
Conditions: Schizophrenia
Sponsor: University of Maryland, Baltimore

3.28.16 
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Neuroimaging of Tryptophan Challenge in People with Schizophrenia and Healthy  
Controls 
 
 
March 28, 2016 
 
NCT02067975 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

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Neuroimaging of Tryptophan Challenge in People with Schizophrenia and Healthy  
Controls 
 
PI: Robert W. Buchanan , M.D. 
Co-Investigators:  
James Gold, Ph.D. 
 
 
 
 
Deanna Kelly, PharmD. 
 
 
 
 
Robert P. McMahon, Ph.D. 
 
 
 
 
Laura Rowland, Ph.D. 
 
 
 
 
 
Overview of Research Design:  
The study will be a double-blind, placebo-controlled, cross-over, tryptophan (TRYP) challenge 
study to examine the effects of increased kynurenic acid (KYNA) on neuropsychological test 
performance; patterns of fMRI activation and connectivity during the performance of a relational 
memory task; and 1H-MRS measures of medial prefrontal cortex (mPFC) glutamate. The effects 
of increased KYNA on fMRI default network activity and peripheral markers of the kynurenine 
pathway, HPA axis, and inflammatory system will also be explored. Participants will include 
people with DSM-5/DSM-IV-TR schizophrenia or schizoaffective disorder (SRDs) and healthy 
controls. The healthy control group will be used to estimate the normal response parameters to 
the TRYP challenge. Participants will be randomly assigned to either TRYP (6 grams) or 
placebo. They will take the study medication 120 min prior to MRI scanning. TRYP 
administration will be used to increase peripheral kynurenine levels, which will lead to increased 
CNS production of KYNA. 
 
Primary Aims: 
1) To determine if TRYP-induced elevated KYNA levels impair performance on 
neuropsychological measures of attention, processing speed verbal and visual memory, 
and working memory. 
2) To determine if TRYP-induced elevated KYNA levels alter neural circuit activation and 
connectivity between the dorsolateral prefrontal cortex (DLPFC) and hippocampus 
(HPC) during the performance of the Relational and Item-Specific Encoding (RISE; 90) 
task. 
3) To determine if TRYP-induced elevated KYNA levels alter glutamate levels in the medial 
(mPFC), a brain region hypothesized to be important in the performance of cognitive 
tests. 
Secondary Aims: 
1) To examine if TRYP-induced elevated KYNA levels alter resting patterns of default 
network activation and connectivity. 
2) To examine if baseline and/or post-challenge HPA axis and inflammatory indices 
moderate or mediate the response of behavioral or functional measures to TRYP-
induced elevated KYNA levels. 
 
Inclusion/Exclusion Criteria: 
Inclusion Criteria (Participants with Schizophrenia) 
1) Males and females between the ages of 18 and 55 years 
2) Has met DSM-IV-TR criteria for schizophrenia, schizoaffective disorder or 
schizophreniform disorder (documented by SCID) 
3) Prescription of antipsychotic medication for at least 60 days and constant dose for 30 
days prior to study entry (either first or second generation antipsychotics permitted) 
4) Female participants must agree to use a medically accepted means of contraception 

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5) Women must be in the first half of their menstrual cycle at the time of the 2 challenge 
visits. 
Inclusion Criteria (Healthy Controls) 
1) Males and females between the ages of 18 and 55 years 
2) No DSM-IV-TR Axis I Disorder (documented by SCID) 
3) Female participants must agree to use a medically accepted means of contraception 
4) Women must be in the first half of their menstrual cycle at the time of the 2 challenge 
visits. 
Exclusion Criteria (all participants) 
1) DSM-IV-TR substance abuse in the last month or substance dependence in the last 6 
months (documented by SCID) 
2) Calgary Depression Scale total score ≥ 10 at baseline 
3) Current smoker (expired CO ≥ 10 ppm) 
4) Current use of nicotine replacement therapy or other nicotine products 
5) Pregnancy or breast feeding 
6) Excessive self-reported daily caffeine intake, defined as intake exceeding 1000 mg or 
the equivalent of 8 cups of coffee 
7) Active disorders that have been reported to affect tryptophan metabolism or interfere 
with absorption will be excluded (Acute Intermittent Porphyria, Celiac Disease, Crohn’s 
Disease, Irritable Bowel Syndrome 
8) History of an organic brain disorder; mental retardation; or a medical condition, whose 
pathology or treatment could alter cognition 
9) Claustrophobia 
10) Metal in body that will interfere with MR imaging 
11) Treatment with monoamine oxidase inhibitors, migraine headache medications (triptans) 
and dextromethorphan. 
 
Recruitment: 
Healthy Controls: 
Participants will be recruited from the Maryland Psychiatric Research Center (MPRC) Healthy 
Control Pool (HP-00042350), MPRC screening protocol (HP-xxxxx) or by advertisements 
(approved by IRB prior to using). All persons who qualify for this study are referred to the 
recruiter (PI and/or PI staff) and then contacted and asked if they would like to participate in this 
study. Interested persons undergo a brief telephone screening followed by an in-person 
interview. After the initial telephone screen, all potential healthy controls undergo a SCID 
interview. We will use random digit dialing as our primary source for identifying healthy controls. 
For random digit dialing, we will utilize contact information lists purchased from Survey 
Sampling International (SSI), a leading provider of sampling, data collection and data analytic 
solutions for survey-based research. SSI compiles contact information lists based on census 
and market-based research data. 
 
Participants with SRDs: 
Potential participants with SRDs will be recruited from three sources: the Maryland Psychiatric 
Research Center (MPRC) clinical programs: the Outpatient Research Program (ORP), the 
Treatment Research Program (TRP), and the First Episode Clinic (FEC); local outpatient mental 
health centers; and a standing recruitment database, from which we have enrolled participants 
in previous MPRC clinical trials. 
Potential MPRC and community participants will be identified primarily through chart review or 
nomination by their primary clinicians who are aware of study entry criteria and demands, and 
have been asked to identify clinically stable patients who may be interested in research 

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participation. MPRC and community participants may also be self- or peer-referred for this 
study. 
 
Healthy controls will be matched to participants with SRDs by age, gender and parental SES 
level.  The planned total enrollment is 50 participants with SRDs and 50 healthy controls, which, 
under the assumption of 10% attrition, will result in 45 completers in each group. We will enroll 
18 participants per year. In each year, we will plan to recruit an equal number of participants 
with SRDs and healthy controls to avoid potential cohort effects. 
 
 
Assessments: All of the following assessments will be conducted blind to treatment 
assignment. 
 
Clinical Assessments: The following rating scales will be used: Brief Psychiatric Rating Scale 
(BPRS; 98); Scale for the Assessment of Negative Symptoms (SANS; 99); Calgary Depression 
Scale (CDS; 95); and Clinical Global Impression Scale (CGI; 100).  
BPRS: the BPRS total score will be used to measure global psychopathology. The four BPRS 
positive symptom items - conceptual disorganization, suspiciousness, hallucinatory behavior, 
and unusual thought content - will be used to measure positive psychotic symptoms. 
SANS: the SANS total score, minus the global items, inappropriate affect, poverty of content of 
speech, and attention items, will be used to measure negative symptoms. 
CDS: the CDS total score will be used to measure depressive symptoms. The CDS was 
specifically designed to assess depressive symptoms in people with schizophrenia. 
CGI: the CGI severity of illness item will be used to assess global changes. 
 
Cognitive Assessments: The following assessments, drawn from the MATRICS battery (101), 
will be used: Brief Assessment of Cognition in Schizophrenia (BACS): Symbol-Coding, Hopkins 
Verbal Learning Test–Revised (HVLT-R), Brief Visuospatial Memory Test–Revised (BVMT-R), 
Continuous Performance Test-Identical Pairs (CPT-IP), Maryland Letter-Number Sequencing 
(LNS), and WMS®-III Spatial Span. These tests were selected, because they assess cognitive 
processes hypothesized to be under the regulation of α-7 nicotinic or NMDA receptors (34-38).  
BACS Symbol-Coding: is a timed paper-and-pencil test in which the participant uses a key to 
write digits that correspond to nonsense symbols; the total score will be used to asses 
processing speed.  
HVLT-R: is an orally administered test in which a list of 12 words from three taxonomic 
categories is presented and the participant is asked to recall as many as possible after each of 
three learning trials; the total score will be used to assess verbal learning. 
BVMT: is a test that involves reproducing six geometric figures from memory; the total score will 
be used to assess visual learning. 
CPT-IP: is a computer-administered measure of sustained attention in which the respondent 
presses a response button to consecutive matching numbers; the d-prime score will be used to 
assess attention/vigilance. 
LNS: is an orally administered test in which the participant mentally reorders strings of number 
and letters and repeats them to administrator; the total score will be used to assess verbal 
working memory. 
WMS®-III Spatial Span: uses a board on which 10 cubes are irregularly spaced, and the 
respondent taps cubes in the same (or reverse) sequence as the test administrator; the total 
score will be used to assess nonverbal working memory. 
 
Laboratory Assessments: The following laboratory assessments will be collected: 

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Kynurenine, KYNA, and 3-HK: After thawing, serum (100 μl) will be acidified with 50 μl of 6% 
perchloric acid and centrifuged in a microfuge (10 min). The kynurenine pathway metabolites 
will be determined in the supernatant (20 μl) using high performance liquid chromatography 
(HPLC) methods. 
Cytokine Profile: The immune panel consists of 12 cytokines: interferon-γ, IL-1β, IL-1RA, IL-2, 
IL-4, IL-6, IL-10, IL-12, IL-13, CXCL8, GMCSF, and TNF-α. These cytokines are part of the 
Type 1 and Type 2 immune responses, have been previously implicated in schizophrenia (102-
105), and have been linked to changes in KYNA levels (106-109). The cytokine samples will be 
collected in tubes containing EDTA, immediately cooled on and centrifuged under refrigeration 
and stored at -80oC until analyzed. The cytokines will be analyzed by the University of Maryland 
Cytokine Core Laboratory using either Multiplex Luminex technology or ELISA. 
Cortisol and ACTH: The neuroendocrine blood samples will be collected in EDTA-containing 
tubes, immediately placed on ice, centrifuged under refrigeration and stored at -80oC until 
analyzed by LabCorp®. To reduce the possible effect of stress on cortisol levels, participants 
will remain in the same room in a calm environment. To control for menstrual effects, challenge 
studies for females will occur in the first half of the menstrual cycle. If women are 
oligomenorrheic, they will be enrolled between 1-14 days of their last menstrual period, and 
amenorrheic women will be enrolled without regards to hormonal status.  
 
Medical and Safety Assessments: In the 2-week Evaluation Phase, participants will receive a 
complete medical history, including the use of concomitant medications and the use of caffeine, 
alcohol, and illicit substances; and physical examination, including blood pressure, heart and 
respiratory rates, height and weight. We will also baseline EKG; CBC; complete metabolic 
panel, including electrolytes, BUN/Creatinine, LFTs, lipid panel, and TSH); U/A; expired CO, 
and Toxicology screen assessments. Female participants will have a pregnancy test during the 
Evaluation Phase and on each challenge test day.  Female participants will also be asked to 
agree to the use of medically accepted means of birth control.  Participants will given a 
breathalyzer test on the morning of each challenge visit. Menstrual cycle will be assessed by 
patient report of the last day of the previous menstrual cycle. A calendar will be shown for 
participants.  
 
The Side Effect Checklist (SEC) is designed to assess medication side effects commonly 
associated with pharmacological treatments. In addition, if not already assessed, the SEC is 
modified for the purpose of the assessment of specific side effects associated with the particular 
medication under study; in this case TRYP. The SEC version to be used in the proposed study 
rates 32 potential side effects, and comprehensively covers the side effects that have been 
previously reported with TRYP administration, i.e., nausea, vomiting, diarrhea, abdominal pain, 
and sedation. In addition, there are three “other” spaces for idiosyncratic participant complaints, 
which are not usually associated with medication treatment. We will use the self-rated Standford 
Sleepiness Scale (SSS) to supplement our assessment of sedation (110). The SSS is a 7-point 
Likert-type scale.  
 
Assessment Schedule: The clinical assessments will be administered prior to administration of 
the study medication, immediately prior to the MRI scan, upon completion of the MRI scan, and 
at the follow-up safety assessment, which will be conducted 75 min after the completion of the 
MRI scanning. The cognitive assessments will be conducted prior to the administration of the 
study medication and after the MRI scanning is completed and the participant has had lunch. 
The laboratory assessments will be collected at pre-TRYP challenge baseline, and 30 min, 60 
min and 90 min post ingestion. The final laboratory assessment will be collected at the time of 
the second administration of the cognitive battery. The safety assessments will be administered 

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prior to administration of the study medication, every 30 min after medication administration, 
upon completion of the MRI scan, and at the follow-up safety assessment.  
 
Table 1. Assessment Schedule. 
 
Study Lead In  
(up to 2 weeks) 
Challenge 
Visit: 
Estimated 
Time of 
Assessment 
Challenge 
Visit: Actual 
Time of 
Assessment 
Initials 
Informed Consent, ESC 
X 
 
 
 
SCID and diagnostic interview, MRI 
screening 
X 
 
 
 
Medical Screening 
Medical Hx, physical exam, blood draw, 
urinalysis, toxicology screen, pregnancy 
test (females), EKG, medication use 
screening, caffeine use screening, Birth 
Control Selection (females) 
X 
 
 
 
Clinical Stability Determination 
(schizophrenia group only seen on two 
visits, healthy controls one visit) 2 
unchanged CGIs  
X 
 
 
 
Mock scanning session 
X 
 
 
 
Scheduling of 2 challenge visits and NPO 
order for 12 hours in advance of admission 
on challenge study days 
X 
 
 
 
Participant Admission/BSU Arrival 
Review of Study Procedures and 
retrospective recall of food intake (past 12 
hours).  Collect personal items not safe 
during MRI testing.  
 
7:30 am 
 
 
Urine pregnancy (females), expired CO, 
urine toxicology and blood alcohol testing, 
MRI screening 
 
7:45 am 
 
 
Insertion of indwelling IV line, fluids, period 
of relaxation 
 
8:00 am 
 
 
Laboratory Assessments (1): cortisol, 
ACTH, kynurenine, KYNA, 3-HK, 
cytokines  
 
8:15 am 
 
 
Cognitive Measures (1): HVLT-R, BACS 
Symbol Coding, BVMT, CPT-IP, WMS®-
 
8:30 am 
 
 

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III, LNS 
Vital signs, SEC, SSS 
Clinical Assessments (1): BPRS, SANS, 
CDS, CGI 
 
9:15 am 
 
 
Oral Administration of Medication 
(Tryptophan 6 gram/ Placebo) 
 
10:00 am 
 
 
Protein Free Snack 
 
10:15 
 
 
Vital signs, SEC, SSS  
Laboratory Assessments (2) 
 
10:30 
 
 
Vital signs, SEC, SSS  
Laboratory Assessments (3) 
 
11:00 am 
 
 
Clinical Assessments (2; modified version)  
 
11:15 am 
 
 
Vital signs, SEC, SSS  
Laboratory Assessments (4) 
 
11:30 am 
 
 
Arrive at Imaging Center  
 
11:45 am 
 
 
Neuroimaging Studies 
 
12:00 pm 
 
 
Arrive Back at BSU 
Vitals, SEC, SSS 
 
1:40 pm 
 
 
Lunch 
 
1:45 pm 
 
 
Cognitive Measures (2) 
Laboratory Assessments (5) 
 
2:00 pm 
 
 
Clinical Assessments (3; modified version) 
Vital signs, SEC, SSS 
 
2:30 pm 
 
 
Participant discharged.  
If participant has not returned to pre-
 
2:45 pm 
 
 

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tryptophan challenge baseline, they will be 
reassessed every 30 minutes until ready 
 
Neuroimaging Procedures: All MRI data will be acquired using a 3-T Siemens Trio scanner 
equipped with a 32 channel head coil at the University of Maryland Center for Brain Imaging 
Research (CBIR), located at the Maryland Psychiatric Research Center. A T1-weighted 
structural image (MP-RAGE: 1 mm isotropic voxels, 256 X 256 mm FOV, TR/TE/TI = 
1900/3.45/900ms) will be acquired for spectroscopic voxel prescription and anatomical 
reference.  
 
fMRI Studies: the fMRI activation study will use the Relational and Item Specific Encoding 
(RISE) task (89,90) to assess brain activation and connectivity patterns underlying item and 
relational memory. The task, which was developed by the NIMH-funded CNTRACS consortium, 
is comprised of 3 runs: 1) item and relational encoding; 2) item recognition; and 3) relational 
recognition. The encode run will comprise presentation of 54 visual object pairs. Pairs will be 
presented for 4 sec with a variable inter-trial interval of 1-10 sec (4 sec average). Item and 
relational encoding conditions will be administered in blocks, within a run of 9 trials each. For 
item encoding, participants will respond via button press yes or no as to whether both objects 
presented are “living”. During the relational encoding, participants will respond yes or no if one 
of the objects could fit inside the other. For item recognition participants will view one object 
from the pairs presented during encoding along with foils. Objects will be presented for 3 
seconds with a variable inter-trial interval of 0-10 sec (3 sec average). All objects (108 objects) 
presented during encoding will be intermixed with 54 foils. Participants will rate their confidence 
using a 6-point scale as to whether the object is “old” (i.e., previously presented) or “new” (i.e., 
not previously presented). For relational recognition, participants will view 27 intact pairs 
intermixed with 27 re-arranged pairs taken from the encoding task. Objects will each be 
presented for 3 seconds, with a   variable inter-trial interval of 0-10 seconds (3 seconds 
average). Participants will respond “yes” if the pairs were intact from the encoding and “no” if the 
pair was re-arranged. For resting state fMRI, participants will be given a simple instruction to 
rest but hold still and keep their eyes open for 15 minutes (allowing for blinks).  
 
MRS Study: Glutamate (Glu) and glutamine (Gln; the major metabolite of synaptic 
glutamate), will be detected in a 4x3x2 cm mPFC voxel using very short TE phase rotation 
stimulated echo acquisition mode (STEAM: TR/TM/TE= 2000/10/6.5 ms, NEX=256, 2500-Hz 
spectral width, 2048 complex points, and Δφ1 = 135°, Δφ2 = 22.5°, Δφ3 = 112.5°, and ΔφADC 
= 0°) (111). We chose the mPFC voxel placement, because previous studies have 
demonstrated: a) the effect of increased KYNA on glutamate in this region (23); and b) the 
importance of this region in the performance of cognitive tests (112). Water suppression will be 
automated using a water suppression enhanced through T1 effects sequence (WET). For 
measurement of T2*-weighted BOLD effects in whole-brain functional images, we will use echo-
planar image (EPI) pulse sequence (TR=2000 ms, TE = 27 ms, flip angle = 80, slice thickness = 
4.0 mm, interleaved, and FOV = 220 x 220).  
 
Neuroimaging Processing and Analyses: fMRI analyses: These analyses will be carried out 
in AFNI, MATLAB, and SPM8. Image preprocessing will include motion correction by 
coregistration to the first image in each series, correction for differences in slice acquisition 
times, normalization to a standard Montreal Neurological Institute template, and smoothing by 
convolution with a Gaussian kernel function (FWHM = 6 mm). Resting state will be low-pass 
filtered (f cutoff = 0.1 Hz). Task: For the task statistical analysis, for each participant, each of the 
conditions (item and relational encoding; item and relational recognition) will be modeled as a 
time series of discrete events that is convolved with a function that accounts for the 

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hemodynamic delay. The condition-specific responses will be assessed by performing 
regression analyses against these functions. Within condition responses, which reflect a 
condition minus baseline contrast, will be assessed for each of the conditions.  Between-
condition differences will be assessed by contrasting the task-specific responses with each 
other. A fixed effects analysis will be performed by entering whole run sequences for all the 
participants into a single analysis and regressing each sequence against all conditions. Random 
effects analysis will be used to assess differences between group fMRI data. For this analysis, 
the contrasts from the first level analysis for each individual will be used to represent mean 
response patterns for that individual, and between-condition or between-group analyses will be 
performed. Due to hypothesis regarding anterior cingulated/medial frontal, dorsolateral frontal 
and hippocampal involvement, between-group differences for BOLD activation within these 
regions will be examined with an ROI mask approach. In addition, the BOLD signal change will 
be extracted from these ROIs for each group to examine the hemodynamic time course. In 
order to obtain the functional connectivity characteristics, we will first manually draw the ROIs 
for each individual based on anatomic landmarks. Manually traced ROIs nicely overcome the 
issue of group structural differences. We will use these ROIs to extract the eigenvariates of time 
series in each participant. The second step will be to elucidate the functional connectivity of 
each ROIs with the whole brain by a seed-voxel analysis (extracting the weighted mean time 
series and then entered as covariates in a whole-brain regression analysis). The individual 
connectivity images created will be taken to a second-level analysis to obtain the connectivity 
characteristics of these 3 regions at the group level. The next step will be to determine if our a 
priori ROIs are correlated to each other by calculating the correlations between eigenvariates of 
each ROI. DMN: For resting state fMRI analysis we will use white matter time course as a 
regressor, assuming it will contain similar spurious fluctuations as in the gray matter. We will 
use SPM segmentation module to segment the whole brain white matter. The time course of 
white matter will be averaged. We will regress out the six head motion parameters and the 
average white matter time course before cross correlation analysis. Cross correlation maps are 
then converted to z score maps using an AFNI built-in function. Correlation analyses will be 
performed by calculating the correlation coefficient between each voxel’s time course and the 
averaging time courses of all the voxels in the defined regions of interest. We will use ROI seed 
based analyses for all hypothesis testing. Manually traced ROIs overcome the issue of group 
structural differences. Independent component analysis (ICA), small-world network, SEM, and 
Granger causality methods can be used to analyze resting state fMRI data. These methods may 
extract additional circuit information. However, there are still challenges in these methods (113). 
We will use ICA primarily for extracting the default mode network component for additional 
exploratory analyses. The Granger causality and small-world brain network methods require 
some a priori definition of brain regions and the resultant topologic properties of brain networks 
are highly dependent on the number of brain regions, which remains to be fully evaluated for 
multiple group x drug comparisons (114,115). A seed-based method is preferred here for testing 
a priori hypotheses that address specific brain regions. It also takes advantage of this method’s 
higher sensitivity and ease of interpretation (116). 4.4.3.2 MRS: Spectra will be analyzed using 
the fully automated, standard curve-fitting software, LCModel. Metabolites will be referenced to 
water and only metabolites of good fits (CRBs< 20) will be included. Voxels will be segmented 
into CSF, gray, and white matter tissue using SPM8 and in house Matlab code; metabolites will 
be corrected according to Gasparovic et al. (117). This method produces excellent reliability for 
glutamate and glutamine as determined by a test-retest reproducibility study in 10 healthy 
controls scanned twice separated by about 1 week. All spectra were of excellent quality (the 
average FWHM was 0.021 ppm and the average SNR was 44). Spectral quantification yielded 
excellent fits as illustrated with Cramer–Rao lower bounds (CRLB) less than 10 for Glu and 
Glu+Gln and 23 for Gln and test-retest coefficients of variation (CVs) of 9.3 for Gln and 4.2 for 

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Glu, absolute percent differences of 13.8 for Gln and 3.8 for Glu, and intra-class correlations 
(ICCs) of 0.82 for Gln and 0.89 for Glu.  
 
Study Design: 
Evaluation Phase: There will be an approximate  2-week Evaluation Phase, during which 
potential participants will undergo baseline assessments to determine whether they meet 
inclusion criteria. Participants will be clinically stable, with clinical stability defined as two 
consecutive CGI ratings with no change in score.  
 
Double-Blind Challenge Phase: The Double-Blind Challenge Phase will utilize a placebo-
controlled, cross-over design. Participants who continue to fulfill entry criteria will be entered into 
the Double-blind Challenge Phase. There will be two Challenge Phase visits. On the day of 
each visit, the participants will arrive at the Brief Stay Unit (BSU) at 7:30AM; all participants will 
have fasted since midnight. At the BSU, an indwelling I.V. will be inserted for the repeated 
laboratory assessments and the initial clinical, cognitive, laboratory, and safety assessments 
(including urine pregnancy test for female participants) will be completed. Upon completion of 
the initial assessments, participants will receive the challenge medication. Participants will be 
randomly assigned to receive TRYP (6 grams) or placebo. They will receive the other study 
medication on the second visit (i.e., placebo or TRYP). The 6 gram dose was chosen based on 
previous work showing cognitive effects to be associated with doses above 5 grams (118) and 
our pilot work, in which we have demonstrated that, in ten healthy controls TRYP (6 grams) 
produces a robust increase in kynurenine. TRYP and placebo will be administered in oral slurry. 
A non-blind pharmacist will dispense all study medications. The blind will be broken only if a 
medical emergency requires this information. If this occurs, the participant will be withdrawn 
from the study. Two hours after ingestion of TRYP or placebo, participants will be transferred to 
the CBIR, which is in a building adjacent to the BSU, where they will undergo the following MRI 
assessments: 1) spectroscopy for the assessment of glutamate, 2) fMRI resting scan; and 3) 
fMRI during relational and item memory tasks. We chose to begin scanning 120 min after study 
medication ingestion, because our preliminary data suggests that serum kynurenine initially 
becomes elevated 30 min after TRYP ingestion, but continues to increase over the next three 
hours; we wanted to ensure sufficient time for kynurenine to cross the BBB and be converted to 
KYNA. Kynurenine levels will remain elevated for at least 3.5 hours, which is sufficient time to 
complete the MRI assessments and post-imaging cognitive assessments. The cognitive 
assessments will be conducted prior to the administration of the study medication and after the 
MRI scanning is completed. The post-baseline clinical, laboratory, and safety assessments will 
be conducted as described above.  
 
Tryptophan Acquisition and Study Dosing: TRYP is a dietary supplement, whose use is 
regulated under the FDA Dietary Supplement Health and Education Act of 1994 (DSHEA). We 
will obtain TRYP powder from Ajinomoto, North American Inc and we have approval under an 
IND for use in this population. On the morning of the challenge studies, TRYP or placebo 
(lactose monohydrate) powder will be diluted in water (250 mL) into a slurry immediately prior to 
oral intake (119). The participant will be instructed to drink the full 250 mL over a one minute 
time period. The unblinded pharmacist, not participating in assessment procedures, will prepare 
and dispense the study medications. 
 
Randomization and Blinding:  
Treatment assignment (placebo and TRYP) will be randomly assigned, with each participant 
receiving each condition on separate occasions. Participants will be randomly assigned using a 
permuted block randomization system with separate randomization sequences for healthy 

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controls and schizophrenia patients. Treatment assignment order is random within each block, 
and an equal number of subjects are assigned to each treatment within a block. The block sizes 
will vary in random sequence and randomization will be matched by age and gender. Thus, it 
will be difficult to ascertain the next treatment assignment, even if a subject becomes unblinded, 
while the imbalance of numbers between the treatment groups is kept within tight limits. 
Randomization requests are sent to the study statistician, who sends a coded treatment 
assignment to an unblinded pharmacist. Separate emergency unblinding envelopes for each 
subject will be kept in a locked cabinet at each dispensing pharmacy. All raters, investigators 
and other staff will be blind to treatment assignment except for the pharmacist. The pharmacist 
does not participate in study assessments and conveys no information about treatment 
assignment to subjects or staff except in a medical emergency.  
 
Payment: 
Participants will be paid $15 per hour for each visit (approximately 3 hours for Evaluation and 
approximately 7 hours for each Challenge visit) as well as $100 for completion of each 
Challenge visit.  The total payment for the study will be approximately $455.   
 
Statistical Analysis: Initially, we will examine responses to TRYP or placebo challenge 
separately in healthy controls and participants with schizophrenia-related disorders (SRD), 
anticipating that different basal states of KYNA metabolism may result in distinct responses to 
TRYP challenge in the two groups. Secondary analyses will compare responses to TRYP 
challenge in the two groups.  
Primary Aims:  
 
1): To determine if TRYP-induced elevated KYNA levels impair performance on 
neuropsychological measures of attention, processing speed verbal and visual memory, 
and working memory. 
Analysis plan: To facilitate comparison of the magnitude of effects across the six 
cognitive tests from the MCCB, we will utilize the MCCB T-scores for each test. For each 
cognitive measure, we will fit a mixed model for repeated measures ANCOVA: post-
study drug score on i-th day = pre-study drug score on i-th day +treatment on i-th day + 
day + treatment x day, where day (=1,2) is an indicator of whether the scores were 
collected on the first or second day of testing. In this model, the treatment effect 
estimates the average TRYP - placebo difference across the two possible orders of 
testing, and the treatment x day effect estimates how much this difference might depend 
on whether TRYP or placebo was administered first. Learning effects from repeated 
cognitive testing could produce diminishing increases across the four repeated 
administrations of each test, resulting in larger pre-post differences in scores on the first 
versus second day of testing; these learning effects could be different following dosing 
with TRYP versus placebo, masking the existence of treatment x day interactions. Since 
the MCCB tests were chosen to have small learning effects (d<0.1; 101), we anticipate 
these learning effects and possible interactions with treatment will be small. To take 
account of multiple testing with six cognitive tests, we will use the Benjamini-Hochberg 
False Discovery Rate (FDR; 120) modification of the Bonferroni method: we will 
compare the six p-values from largest to smallest to successively stricter critical values cj 
= 0.05 x (6-j+1)/6; if the j-th p-value is less than cj, we will reject that null hypothesis and 
all null hypotheses corresponding to smaller p-values. To compare the magnitude of T-
score differences between TRYP and placebo among cognitive tests, we will add terms 
for cognitive test and test x treatment interactions to the model described above.  

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12 
 
2): To determine if TRYP-induced elevated KYNA levels alter neural circuit activation and 
connectivity between the dorsolateral prefrontal cortex (DLPFC) and hippocampus (HPC) 
during the performance of the Relational and Item-Specific Encoding (RISE; 90) task.  
Analysis Plan: In healthy controls and individuals with SRD, we will compare intensity 
of BOLD signal activation in DLPFC and hippocampus, using the mixed model for 
repeated measures ANOVA: BOLD activation = treatment + ROI + task condition (item 
encoding, relational encode, item/relational recall) + treatment x task condition + 
treatment x ROI + treatment x ROI x task condition + order of treatments + interactions 
with order, with analyses performed separately in each group. A similar model will be 
used to examine functional connectivity or correlations between fluctuations in BOLD 
signal activation between DLPFC and HPC in each task condition, using similar methods 
previously used to test nicotine challenge effect on resting state functional connectivity 
(121). To assist in meeting normality assumptions, Fisher’s z transformation will be 
applied to correlation coefficients measuring task-related connectivity prior to modeling.  
3): To determine if TRYP-induced elevated KYNA levels alter glutamate levels in the medial 
(mPFC), a brain region hypothesized to be important in the performance of cognitive tests.  
Analysis plan: We will estimate the effect of TRYP or placebo on glutamate in healthy 
controls or SRD separately and compare whether it is different in these two groups by 
fitting the mixed model for repeated measures ANOVA: glutamate in mPFC = group + 
treatment + order + treatment x group + interactions with order, where group indicates 
healthy controls or individuals with SRD, treatment indicates receiving TRYP or placebo 
on a given day, and order indicates whether the active treatment is given on the first or 
second session. In the event of significant interactions between order and treatment, we 
will examine treatment effects for each order separately; otherwise, order effects will be 
dropped from the model.  
Secondary Aims: 
1): To examine if TRYP-induced elevated KYNA levels alter resting patterns of default 
network activation and connectivity.  
Analysis Plan: For exploratory analysis of changes in neural activation and functional 
connectivity in the default mode network (i.e., medial temporal lobe, mPFC, posterior 
cingulate cortex, ventral precuneus and medial, lateral and inferior parietal cortex) in 
healthy controls and participants with SRDs given TRYP or placebo, we will use models 
similar to those outlined for Specific Aim 2.  
2): To examine if baseline and/or post-challenge HPA axis and inflammatory indices 
moderate or mediate the response of behavioral or functional measures to TRYP-induced 
elevated KYNA levels.  
Analysis Plan: We will conduct exploratory analyses at unadjusted two-sided alpha = 
0.05. People with SRD have been reported to have higher brain KYNA levels than 
healthy controls, and have major differences in behavioral and functional measures. 
Accordingly, we will analyze mediating and moderating effects of KYNA separately in the 
two groups, following the approach of Kraemer et al (118). To test moderation, we will 
examine the repeated measures models: change (Post-TRYP - Pre-TRYP) in behavioral 
outcome = treatment + pre-TRYP KYNA on test day + treatment x pre-TRYP KYNA, 
where the treatment x pre-TRYP KYNA on test day measures the change of slope for 
pre-treatment KYNA in predicting change in behavioral outcome. If this difference in 
slopes = 0, there is no mediator effect for pre-TRYP KYNA. Similarly, to assess 
mediation, we will fit a similar model to assess the difference between treatments (TRYP 
versus placebo) in slopes predicting change in the behavioral response from change in 
KYNA to whether change in KYNA mediates the treatment effect, noting that this is not 
the same as assessing causality (123).  

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13 
 
 
Risks to Human Subjects 
a. Human Subject Involvement, Characteristics and Design. The proposed project meets 
the definition of a “Clinical Trial.” This challenge study will enroll both healthy controls and 
people with schizophrenia. Following a period of baseline evaluation and assessment, 
participants (healthy controls and schizophrenia patients) will randomly participate in two visits. 
On one of the two visits, the participant will receive L-tryptophan (TRYP), and on the other visit 
the participant will receive placebo as an oral slurry. At each of the two visits, all participants will 
undergo morning baseline assessments followed by medication dosing, assessments and 
imaging procedures.  
 
Potential Risks to Human Subjects:  
This study involves a medication challenge to healthy controls and to people with schizophrenia. 
We have pilot data on the use of TRYP (6 grams) given to healthy controls (n=10; see 
accompanying memo) and have had few side effects reported. On beginning, we will carefully 
monitor for side effects and study risks.  
 
The risks associated with MRI are extremely low. They include the possibility that 
undetected metal in the participant’s body could be displaced by the magnetic field of the MRI 
scanner. Participants could become claustrophobic while in the scanner. Participants could 
experience discomfort in attempting to remain still for up to 90 min in the scanner. The tasks 
could cause boredom or anxiety in some participants. Credit cards, watches or other items 
could be damaged by the magnetic field if they are inadvertently brought into the scan room. 
Headphones and earplugs are provided to the participants to protect from scanner gradient 
noise. There will be no cost to the participant or the participant’s insurance company for the MRI 
scans performed specifically for this study.  
 
There have not been any serious consequences associated with TRYP administration. 
TRYP is sold over the counter (FDA Dietary Supplement Health and Education Act of 1994 
(DSHEA)) and has been available for over 50 years. TRYP is mostly acquired through dietary 
consumption, but increasing tryptophan is possible with using pure TRYP as in this study which 
is intended to produce kynurenine. TRYP loading has been widely used in clinical research. A 
recent review covers 43 studies that assessed TRYP loading. The dosing in these studies 
varied, with many studies using aggressive loading doses (>10 g/day) (126-130), while others 
have used dosing of 5-10 grams (131-136). We propose to use a dose of 6 grams. This 
literature review does not demonstrate any significant side effects other than some minor 
transient effects on cognition, mood and sleep. On the contrary, there have also been 
improvements observed in memory and attention, and worsening of memory, attention, 
executive dysfunction and psychomotor speed generally occurred only at very high 
concentrations of TRYP (118). Similar is true to mood; improvements have been seen in anger, 
depression, vigor and alertness but high concentrations of TRYP have shown minor worsening 
in these domains in a few studies (118). Abnormal sleep behaviors have been improved in 
many studies; however, sleepiness is a reported side effect (118). Occasional side effects have 
been reported at higher TRYP doses (generally >6 grams daily), which include tremor, nausea, 
and dizziness (137). Mild dyspepsia and diaphoresis have occurred in people ingesting TRYP. 
The dose used in this study is lower than that used in most published studies. By giving the 
water and TRYP mixture slowly we will mitigate dyspeptic reactions. A very recent study (138) 
reported on the side effects of up to 5 gram/day of TRYP in healthy volunteers and found no 
changes in laboratory measures, food intake, body weight or mood side effects. In 
schizophrenia, we anticipate only mild, transient effects on cognition. In 1988 and 1989, there 
was an outbreak of eosinophilia-myalgia syndrome (EMS) that was traced to a single 

3.28.16 
14 
 
manufacturer in Canada, leading to a ban in the US for 12 years; however, this is no longer 
considered a risk, and the ban was lifted in the US in 2001 (139). 
 
One potential serious side effect is the serotonin syndrome, which could occur when TRYP 
is administered in combination with other serotonergic agents. The occurrence of the serotonin 
syndrome with TRYP is rare and generally only occurs after routine use of TRYP. The serotonin 
syndrome includes the following symptoms: delirium, myoclonus, hyperthermia and coma. We 
will include these items in the SEC as potential side effects to ensure our ability to detect their 
occurrence.  
 
In summary, side effects with TRYP are mild, even in studies that have used higher doses 
for longer periods of time than will be done in the current study (118).  
 
Adequacy of Protection Against Risks 
Informed consent:  
Schizophrenia-Related Disorders: A partial HIPPA waiver will be obtained to permit the 
identification of potential participants through chart review. In addition, participants will be 
referred by the person’s treatment team for consideration of study participation. No potential 
SRD participant will be approached for recruitment without approval of a primary clinician, who 
will determine suitability of the person for the protocol. A chart review will be completed for all 
potential SRD participants to reduce the likelihood that they will be found ineligible after 
participating in more extensive assessment. The study recruiter will verify with the primary 
clinician that a potential participant is sufficiently stabile to consider participation and has 
capacity to provide consent. This is done prior to the study recruiter approaching a potential 
participant. The study recruiter will be introduced to the person and provide a brief overview of 
the project. Research staff members are trained to recognize symptoms of severe mental illness 
and cognitive impairment that could undermine an individual's ability to provide informed 
consent.  
 
All Participants: Interested people will be provided study information and an informed consent 
form that contains all pertinent details of participation and includes the following: a brief 
explanation of the purpose of the research and a brief explanation of the requirements of the 
participant, including: a) willingness to be randomly assigned to either intervention, b) 
completing a series of interviews about symptoms, c) completing assessment tasks, and d) 
being available for follow-up assessments. The consent form will include an explanation of the 
risks and benefits of participation; assurances of confidentiality; and an explanation that 
participation is entirely voluntary, the decision to participate will in no way influence or restrict 
services at participating sites, and the participant is free to withdraw at any time with no 
negative consequences. Potential participants will be informed that the drug used in this study is 
not known to be effective for any indication under investigation. As some potential participants 
will have poor reading skills, the consent form will be read aloud to all participants in tandem 
with their own silent reading of the document. The individual securing consent will review any 
points about which the participant is unclear, and the participant will be invited to ask questions 
as needed.  
 
Our research staff is carefully trained in strategies for interacting with people with severe 
mental illness, including speaking slowly and clearly, stopping to summarize frequently, and 
providing time for questions. They are all supervised by senior staff members. All participants 
who express willingness to provide consent will be queried about the consent form in order to 
ensure that they have adequate understanding of the study requirements. This questioning is 
performed systematically, and research staff members document that this review has been 
completed. After reading the consent, and before obtaining a signature, a brief questionnaire is 

3.28.16 
15 
 
administered to verify that the participant is competent to provide consent and has 
demonstrated comprehension of the consent document. This questionnaire is attached to the 
informed consent form and is completed immediately after explaining the informed consent form 
and before obtaining the participant's signature on the form. If the participant does not 
understand the consent form, the recruiter will try to explain points of confusion, and administer 
the questionnaire again. Those failing to answer the questions adequately will not be recruited 
into the study. The recruiter will also make a clinical judgment and not recruit participants who 
appear unable to grasp key aspects of the procedure. This approach, which requires a proactive 
demonstration on the part of the participant that they understand what is being requested, has 
been used extensively at the MPRC. Included participants must also be judged competent to 
consent by the Evaluation to Sign Consent (ESC) questionnaire, and provide voluntary informed 
consent. Per University of Maryland School of Medicine IRB regulations, a copy of the signed 
consent form is given to the participant, a copy is placed in the person's medical record, and the 
original is kept in the laboratory. Research assistants obtaining informed consent will be 
experienced clinicians. They will receive detailed and standardized training as to how to obtain 
informed consent from people with serious mental illnesses. They will be observed obtaining 
informed consent from a study participant by senior staff prior to being allowed to recruit on their 
own.   
 
Protections Against Risk:  
We will make every attempt to minimize all study-related risks. Sexually active women of 
childbearing age will agree to the use of medically approved birth control, which includes 
condoms, oral contraceptives, diaphragms, or intrauterine device for 2 weeks after the study. 
Pregnant and lactating females will be excluded. We will test for pregnancy at each visit. In 
addition, the Brief Stay Unit (BSU) is a psychiatric and medical unit with an ACLS-certified nurse 
and physician. The BSU is stocked with an emergency medication supply and crash cart and 
has direct line to the adjacent hospital for emergency support. All BSU staff are trained in 
behavioral and medical emergencies. Because we hypothesize that the kynurenine pathway 
dysregulation may be present in schizophrenia and KYNA level increases may be associated 
with the pathophysiology of the illness, we anticipate slight worsening in neurocognition in the 
schizophrenia group. However we do not anticipate worsening in clinical symptoms. We will be 
carefully monitoring for side effects and distress in a well-staffed medical unit with psychiatric 
and medical coverage. We have a full backup emergency plan and available medications for 
medical and psychiatric emergencies. In order to provide objective criteria for distress and 
symptom worsening and study discontinuation, we have developed the following criteria:  
• 
Participants will be withdrawn from any remaining study assessments if at any time there 
is significant distress reported by the schizophrenia patient or control.  
• 
To be objective in psychiatric symptoms, we will apply a modified battery of psychiatric 
assessments after TRYP administration and prior to imaging. This modified assessment 
allows us to specifically monitor psychotic symptoms, hostile behavior or suicidality.  
• 
Thus, we will look out for an increase in 3 or more points from the premedication BPRS 
in positive symptoms, somatic concern, or hostility on the BPRS, a score of a 3 or more 
on the suicidality item on the Calgary Depression Scale (item 8), or a two or more point 
increase on the CGI. If a participant scores ≥ 6 and this is at least a two point increase 
from baseline, the study procedures will be discontinued.  
• 
At any time, however, a participant can be discontinued from the study.  
 
 
Throughout the challenge, we will closely monitor for side effects, tolerability and any signs 
or symptoms of serotonin syndrome. Heart rate, blood pressure, temperature, diaphoresis, and 

3.28.16 
16 
 
muscle twitching will be monitored continually. With regards to imaging, prior to entry to the 
study, participants are carefully screened for medical illness and to ensure that they will be safe 
in the MR scanner. All participants are screened for contra-indications for magnetic resonance, 
namely severe claustrophobia, pregnancy, cardiac pacemaker, orthodontics, or other non-MR 
compatible ferromagnetic implant. In addition, access to the scan room is strictly controlled to 
ensure that no ferromagnetic materials are introduced. The scanner to be used in the study is 
FDA approved and operates under radiofrequency power monitoring software at all times. All 
scan procedures at magnetic field strengths of 1.5T and 3T are FDA approved and are not 
classified as investigational devices. Some participants may become claustrophobic, bored or 
restless during the testing. The participants have the option of terminating the testing at any 
time without penalty if they so choose. The risks of psychological discomfort will be minimized 
by encouraging participants to let the examiner know if they are feeling any discomfort, and by 
continuous monitoring by experienced operators for participant fatigue, inattention, or 
annoyance. Scanning will be halted if the participant so requests, or if the examiner feels that 
the participant is becoming uncomfortable. The participant will be encouraged to report any 
adverse symptoms during the MRI. The MRI can be stopped by the participant either by 
verbalizing the request to stop (which can be heard through the microphone in the MRI) or by 
pushing a “panic button” provided to him/her. A potential concern with MRI studies is so-called 
radio-frequency heating due to radiofrequency power deposition in the participant. The FDA has 
set strict and very conservative guidelines to guard against this risk. Such power deposition 
increases with the square of the magnetic field strength. To be 100% sure of compliance with 
the FDA guidelines, power deposition is monitored continuously by the software of the 
manufacturers, and scans are not possible if the power deposition exceeds guidelines.  
 
Confidentiality 
All records of the research will be kept in locked files with subjects identified by code only.  A 
separate file will hold the code key.  Subjects will not be personally identified in any publications 
or reports of the study.  All biological specimens collected for research purposes will be 
identified at the laboratory by code only.  Whenever possible, existing clinical laboratory data 
will be used as a source of information for the study, which will minimize testing done on 
subjects.  Any data used will be recopied to research files with the subject identified by code 
only. Computerized records of data are kept in password-protected computers in locked rooms. 
Appropriate firewalls and protections of computerized data are maintained to ensure that entry 
by those other than research personnel is not possible. 
Potential Benefits of the Proposed Research to the Participants and Others There are few 
potential benefits to participating in the study. Participants will have a series of medical and 
laboratory workup prior to study start that may provide new or helpful information on their 
physical and mental health. Mild and transient changes in neurocognition are possible or even 
expected. We feel the importance of the knowledge gained outweighs the risks of the study. 
 
Importance of the Knowledge to be Gained: 
We will be able to examine, for the first time, the connection between the kynurenine pathway, 
cognitive function and neuroimaging in people with schizophrenia. In addition, we will examine 
the role of stress hormones and immune function in the control of kynurenine pathway 
metabolism. This important information could be the first clinical study to link this pathway to 
symptoms and outcomes of people with schizophrenia.  
 

3.28.16 
17 
 
Data and Safety Monitoring Plan: 
A Data Safety Monitoring Board (DSMB) is already established for monitoring studies at the 
MPRC and will be used for this study. The DSMB is comprised of two psychiatrists, a 
pharmacist, a statistician, and a community representative. The psychiatrist will be an expert in 
the clinical treatment of people with schizophrenia. The DSMB will be charged with the following 
responsibilities: 1) to establish a regular meeting schedule; 2) to review the protocol; 3) to 
review the consent form; 4) to monitor the occurrence of side effects/adverse events, and 
serious adverse events throughout the course of the study; and 5) to review with investigators, 
the study data management system; and 6) to establish stop rules for the study as a whole. The 
DSMB will review prior to study enrollment and then receive annual side effect/adverse event 
updates. In addition, all serious adverse events (SAEs) will be reported to the DSMB, PIs, and 
the University of Maryland School of Medicine IRB. The PI will receive all SAE reports within 24 
hours of their occurrence. If the incidence of any side effect/adverse event is 25% or more or 
any SAE occurs in excess in either treatment group, the DSMB will notify the PI. The PI and the 
DSMB will determine whether possible protocol modifications are required to minimize the 
further occurrence of such events. Unexpected adverse events will be reported in accord with 
NIH and Federal requirements. Non-serious and expected adverse events will be reported 
annually to the IRBs. The PI is required to attend the DSMB meeting annually and is asked to 
give a review of the past year with a particular emphasis on safety, side effects, and enrollment. 
The data would remain blinded unless risks to participants justify unblinding. To safeguard 
confidentiality, data are presented in aggregate or are identified only by an ID number. 
 
6. Clinical Trials.Gov Requirements: 
The study will be registered on ClinicalTrials.gov prior to the enrollment of any participants. 
 

3.28.16 
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Literature Cited: 
1. Schwarcz R, et al (2001) Increased cortical kynurenate content in schizophrenia. Biol 
Psychiatry 50:521- 
530. 
2. Miller CL, Llenos IC, Dulay JR, Weis S (2006) Upregulation of the initiating step of the 
kynurenine 
pathway in postmortem anterior cingulate cortex from individuals with schizophrenia and bipolar 
disorder. 
Brain Res 1073-1074:25-37. 
3. Barry S, Clarke G, Scully P, Dinan TG (2009) Kynurenine pathway in psychosis: evidence of 
increased 
tryptophan degradation. J Psychopharmacol 23(3):287-294. 
4. Sathyasaikumar KV, et al (2011) Impaired kynurenine pathway metabolism in the prefrontal 
cortex of 
individuals with schizophrenia. Schizophr Bull 37(6):1147-1156. 
5. Miller CL, et al (2004) Expression of the kynurenine pathway enzyme tryptophan 2,3-
dioxygenase is 
increased in the frontal cortex of individuals with schizophrenia. Neurobiol Dis 15(3):618-629. 
6. Linderholm KR, et al (2012) Increased levels of kynurenine and kynurenic acid in the CSF of 
patients with 
schizophrenia. Schizophr Bull 38(3):426-432. 
7. Wonodi K, et al (2011) Downregulated kynurenine 3-monooxygenase gene expression and 
enzyme 
activity in schizophrenia and genetic association with schizophrenia endophenotypes. Arch Gen 
Psychiatry 68(7):665-674. 
8. Holtze M, et al (2012) Kynurenine 3-monooxygenase polymorphisms: relevance for kynurenic 
acid 
synthesis in patients with schizophrenia and healthy controls. J Psychiatry Neurosci 37(1):53-
57. 
9. Schwarcz R, Bruno JP, Muchowski PJ, Wu HQ (2012) Kynurenines in the mammalian brain: 
when 
physiology meets pathology. Nat Rev Neurosci 13(7):465-477. 
10. Nuechterlein KH, et al (2004) Identification of separable cognitive factors in schizophrenia. 
Schizophr Res 
72:29-39. 11. Keefe RSE, et al (2007) Neurocognitive Effects of Antipsychotic Medications in 
Patients with Chronic 
Schizophrenia in the CATIE Trial. Arch Gen Psychiatry 64(6):633-647. 
12. Timofeeva OA, Levin ED (2011) Glutamate and nicotinic receptor interactions in working 
memory: 
importance for the cognitive impairment of schizophrenia. Neuroscience 195:21-36. 
13. Parsons CG, et al (1997) Novel systemically active antagonists of the glycine site of the N-
methyl-Daspartate 
receptor: electrophysiological, biochemical and behavioral characterization. J Pharmacol Exp 
Ther 283(3):1264-1275. 
14. Hilmas C, et al (2001) The brain metabolite kynurenic acid inhibits alpha7 nicotinic receptor 
activity and 
increases non-alpha7 nicotinic receptor expression: physiopathological implications. J Neurosci 
21:7463- 

3.28.16 
19 
 
7473. 
15. Wu HQ, et al (2010) The astrocyte-derived α7 nicotinic receptor antagonist kynurenic acid 
controls 
extracellular glutamate levels in the prefrontal cortex. J Mol Neurosci 40:204-210. 16. Stone TW 
(2007) Kyurenic acid blocks nicotinic synaptic transmission to hippocampal interneurons in 
young rats. Eur J Neurosci 25:2656-2665. 
17. Lopes C, et al (2007) Competitive antagonism between the nicotinic allosteric potentiating 
ligand 
galantamine and kynurenic acid at alpha7* nicotinic receptors. J Pharmacol Exp Ther 322:48-
58. 
18. Carpenedo R, et al (2001) Presynaptic kynurenate-sensitive receptors inhibit glutamate 
release. Eur J 
Neurosci 13(11):2141-2147. 
19. Rassoulpour A, Wu HQ, Ferre S, Schwarcz R (2005) Nanomolar concentrations of 
kynurenic acid reduce 
extracellular dopamine levels in the striatum. J Neurochem 93(3):762-765. 
20. Amori L, et al (2009) Specific inhibition of kynurenate synthesis enhances extracellular 
dopamine levels 
in the rodent striatum. Neuroscience 159(1):196-203. 
21. Zmarowski A, etl (2009) Astrocyte-derived kynurenic acid modulates basal and evoked 
cortical 
acetylcholine release. Eur J Neurosci 29(3):529-538. 
22. Konradsson-Geuken A, et al (2010) Cortical kynurenic acid bi-directionally modulates 
prefrontal 
glutamate levels as assessed by microdialysis and rapid electrochemistry. Neuroscience 
169(4):1848- 
1859. 
23. Shepard PD, Joy B, Clerkin L, Schwarcz R (2003) Micromolar brain levels of kynurenic acid 
are 
associated with a disruption of auditory sensory gating in the rat. Neuropsychopharmacology 
28:1454- 
1462. 
24. Erhardt S, Schwieler L, Emanuelsson C, Geyer M (2004) Endogenous kynurenic acid 
disrupts prepulse 
inhibition. Biol Psychiatry 56(4):255-260. 
25. Chess AC, Simoni MK, Alling TE, Bucci DJ (2007) Elevations of endogenous kynurenic acid 
produce 
spatial working memory deficits. Schizophr Bull 33(3):797-804. 26. Potter MC et al (2010) 
Reduction of endogenous kynurenic acid formation enhances extracellular 
glutamate, hippocampal plasticity, and cognitive behavior. Neuropsychopharmacology 34:1734-
1742. 
27. Hardeland R, et al (1999) Indole-3-pyruvic and -propionic acids, kynurenic acid, and related 
metabolites 
as luminophores and free-radical scavengers. Adv Exp Med Biol 467:389-395. 
28. Lugo-Huitrón R, et al (2011) On the antioxidant properties of kynurenic acid: free radical 
scavenging 
activity and inhibition of oxidative stress. Neurotoxicol Teratol 33:538-547. 
29. Salter M, Pogson CI et al (1985) The role of tryptophan 2,3-dioxygenase in the hormonal 
control of 

3.28.16 
20 
 
tryptophan metabolism in isolated rat liver cells. Effects of glucocorticoids and experimental 
diabetes. 
Biochem J 229:499-504. 
30. Saito K, Markey SP, Heyes MP (1992) Effects of immune activation on quinolinic acid and 
neuroactive 
kynurenines in the mouse. Neuroscience 51:25-39. 
31. Saito K, et al (1993) Kynurenine pathway enzymes in brain: responses to ischemic brain 
injury versus 
systemic immune activation. J Neurochem 61:2061-2070. 
32. Joseph MH, Baker HF, Crow TJ, Riley GJ, Risby D (1979) Brain tryptophan metabolism in 
schizophrenia: 
a post mortem study of metabolites of the serotonin and kynurenine pathways in schizophrenic 
and 
control subjects. Psychopharmacology (Berl) 62(3):279-285.  
33.Erhardt S, et al (2001) Kynurenic acid levels are elevated in the cerebrospinal fluid of 
patients with 
schizophrenia. Neurosci Lett 313:96–98. 
34. Levin ED, et al (2009) Nicotinic alpha7- or beta2-containing receptor knockout: effects on 
radial-arm 
maze learning and long-term nicotine consumption in mice. Behav Brain Res 196(2):207-213. 
35. Levin ED (2012) α 7-Nicotinic receptors and cognition. Curr Drug Targets 13:602-606. 
36. Lendvai B, Kassai F, Szájii A, Némethy Z (2013) α7 Nicotinic acetylcholine receptors and 
their role in 
cognition. Brain Res Bull 93:86-96. 
37. Collingridge GL, et al (2013) The NMDA receptor as a target for cognitive enhancement. 
Neuropharmacology 64:13-26. 
38. Javitt DC, Zukin SR, Heresco-Levy U, Umbricht D (2012) Has an angel shown the way? 
Etiological and 
therapeutic implications of the PCP/NMDA model of schizophrenia. Schizophr Bull 38(5):958-
966. 
39. Court J, et al (1993) Neuronal nicotinic receptors in dementia with Lewy bodies and 
schizophrenia: alphabungarotoxin 
and nicotine binding in thalamus. J Neurochem 73:1590-1597. 
40. Freedman R, Hall M, Adler LE, Leonard S (1995) Evidence in postmortem brain tissue for 
decreased 
numbers of hippocampal nicotinic receptors in schizophrenia. Biol Psychiatry 38:22-33. 
41. Guan Z-Z, Zhang X, Blemnow K, Nordberg A (1999) Decreased protein level of nicotinic 
receptor alpha-7 
subunit in the frontal cortex from schizophrenic brain. Neuroreport 10:1779-1782. 
42. Marutle A, et al (2001) Laminar distribution of nicotine receptor subtypes in cortical regions 
in 
schizophrenia. J Chem Neuroanat 22:115-126. 
43. Freedman R, et al (1997) Linkage of a neurophysiological deficit in schizophrenia to a 
chromosome 15 
locus. Proc Natl Acad Sci USA 94:587-592. 44. Leonard S, et al (1998) Further investigation of 
a chromosome 15 locus in schizophrenia: analysis of 
affected subpairs from the NIMH genetics initiative. Am J Med Genet 81:308-312. 
45. Tsuang DW, et al (2001) Examination of genetic linkage of chromosome 15 to schizophrenia 
in a large 
veterans affairs cooperative study sample. Am J Med Genet 105:662-668. 

3.28.16 
21 
 
46. Dépatie L, et al (2002) Nicotine and behavioral markers of risk for schizophrenia: a double-
blind, placebocontrolled, 
cross-over study. Neuropsychopharmacology 27:1056-1070. 
47. Sacco KA, et al (2005) Effects of cigarette smoking on spatial working memory and 
attentional deficits in 
schizophrenia. Arch Gen Psychiatry 62:649-659. 
48. AhnAllen CG, Nestor PG, Shenton ME, McCarley RW. Miznikiewicz MA (2008) Early 
nicotine withdrawal 
and transdermal nicotine effects on neurocognitive performance in schizophrenia. Schizophr 
Res 100(1- 
3):261-269. 
49. Barr RS, et al (2008) The effects of transdermial nicotine on cognition in nonsmokers with 
schizophrenia 
and nonpsychiatric controls. Neuropsychopharmcology 33:480-490. 
50. Adler LE, Hoffer LD, Wiser A, Freedman R (1993) Normalization of auditory physiology by 
cigarette 
smoking in schizophrenic patients. Am J Psychiatry 150:1856-1861. 51. Olinicy A, et al (2006) 
An α7-Nicotinic cholinergic agonist enhances cognitive function in schizophrenia. 
Arch Gen Psychiatry 63:630-638. 
52. Buchanan RW, et al (2008) Galantamine for the treatment of cognitive impairments in 
people with 
schizophrenia. Am J Psychiatry 165:82-89. 
53. Freedman R, et al (2008) Initial phase 2 trial of a nicotinic agonist in schizophrenia. Am J 
Psychiatry 
165(8):1040-1047. 
54. Lieberman JA, et al (2013) A randomized exploratory trial of an alpha-7 nicotinic receptor 
agonist (TC- 
5619) for cognitive enhancement in schizophrenia. Neuropsychopharmacology 38:968-975. 
55. Tregellas JR, et al (2011) Effects of an alpha 7-nicotinic agonist on default network activity 
in 
schizophrenia. Biol Psychiatry 69(1):7-11. 
56. Liu J, et al (2009) Combining fMRI and SNP data to investigate connections between brain 
function and 
genetics using parallel CA. Hum Brain Mapp 39:241. 
57. Javitt DC, Zukin SR (1991) Recent advances in the phenocyclidine model of schizophrenia. 
Am J 
Psychiatry 148:1301-1308. 
58. Krystal JH, et al (1994) Subanesthetic effects of the noncompetitive NMDA antagonist, 
ketamine, in 
humans. Psychotomimetic, perceptual cognitive, and neuroendocrine responses. Arch Gen 
Psychiatry 
51(3):199-214. 
59. Malhotra AK, et al (1996) NMDA receptor function and human cognition: the effects of 
ketamine in 
healthy volunteers. Neuropsychopharmacology 14(5):301-307. 
60. Newcomer JW, et al (1999) Ketamine-induced NMDA receptor hypofunction as a model of 
memory 
impairment and psychosis. Neuropsychopharmacoloy 20(2):106-118. 61. Parwani A, et al 
(2005) The effects of a subanesthetic dose of ketamine on verbal memory in normal 
volunteers. Psychopharmacology (Berl) 183(3):265-274. 

3.28.16 
22 
 
62. Rowland LM, et al (2005) Selective cognitive impairments associated with NMDA receptor 
blockade in 
humans. Neuropsychopharmacology 30(3):633-639. 
63. Malhotra AK, et al (1997) Ketamine-induced exacerbation of psychotic symptoms and 
cognitive 
impairment in neuroleptic-free schizophrenics. Neuropsychopharmacology 17(3):141-150. 
64. LaPorte DJ, et al (2005) Subtle effects of ketamine on memory when administered following 
stimulus 
presentation. Psychopharmacology (Berl) 180(3):385-390. 
65. Beneyto M, Meador-Woodruff JH (2008) Lamina-specific abnormalities of NMDA receptor-
associated 
postsynaptic protein transcripts in the prefrontal cortex in schizophrenia and bipolar disorder. 
Neuropsychopharmacology 33(9):2175-2186. 
66. Kristiansen LV, Patel SA, Haroutunian V, Meador-Woodruff JH (2010) Expression of the 
NR2B-NMDA 
receptor subunit and its Tbr-1/CINAP regulatory proteins in postmortem brain suggest altered 
receptor 
processing in schizophrenia. Synapse 64(7):495-502. 
67. Weickert CS, et al (2012) Molecular evidence of N-methyl-D-aspartate receptor 
hypofunction in 
schizophrenia. Mol Psychiatry doi: 10.1038/mp.2012.137. [Epub ahead of print] 68. Amaral DG, 
Witter MP (1989) The three-dimensional organization of the hippocampal formation: a review 
of the anatomical data. Neuroscience 31:571-591. 
69. Tamminga CA, Stan Ad, Wagner AD (2010) The hippocampal formation in schizophrenia. 
Am J 
Psychiatry 167:1-16. 
70. Tamminga CA (1998) Schizophrenia and glutamatergic transmission. Crit Rev Neurobiol 
12:21-36. 
71. Scoville WB, Milner B (2000) Loss of recent memory after bilateral hippocampal lesions. 
1957. J 
Neuropsychiatry Clin Neurosci 12:103-113. 
72. Milner B (1972) Disorders of learning and memory after temporal lobe lesions in man. Clin 
Neurosurg 
19:421-446. 
73. Buchanan RW, et al (2007) The cognitive and negative symptoms in schizophrenia trial 
(CONSIST): the 
efficacy of glutamatergic agents for negative symptoms and cognitive impairments. Am J 
Psychiatry 
164(10):1593-1602. 
74. Goff DC, et al (2008) A placebo-controlled add-on trial of the Ampakine, CX516, for 
cognitive deficits in 
schizophrenia. Neuropsychopharmacology 33(3):465-472. 
75. Wolf H, Brown RR, Arend RA (1980) The kynurenine load test, an adjunct to the tryptophan 
load test. 
Scan J Clin Lab Invest 40(1):9-14. 
76. Perkins MN, Stone TW (1982) An iontophoretic investigation of the actions of convulsant 
kynurenines 
and their interaction with the endogenous excitant quinolinic acid. Brain Res 247:184–187. 
77. Schwarcz R, Pellicciari R (2002) Manipulation of brain kynurenines: glial targets, neuronal 
effects, and 

3.28.16 
23 
 
clinical opportunities. J Pharmacol Exp Ther 303:1–10. 
78. Kita T, Morrison PF, Heyes MP, Markey SP (2002) Effects of systemic and central nervous 
system 
localized inflammation on the contributions of metabolic precursors to the L-kynurenine and 
quinolinic 
acid pools in brain. J Neurochem 82(2):258-268. 79. Pocivavsek A, et al (2011) Fluctuations in 
endogenous kynurenic acid control hippocampal glutamate 
and memory. Neuropsychopharmacology 36(11):2357-2367. 
80. Pocivavsek A, Wu HQ, Elmer GI, Bruno JP, Schwarcz R (2012) Pre- and postnatal 
exposure to 
kynurenine causes cognitive deficits in adulthood. Eur J Neurosci 35(10):1605-1612. 
81. Alexander KS, Wu HQ, Schwarcz R, Bruno JP (2012) Acute elevations of brain kynurenic 
acid impair 
cognitive flexibility: normalization by the alpha7 positive modulator galantamine. 
Psychopharmacology 
(Berl) 220(3):627-637. 
82. Alexander KS, et al (2013) .Early developmental elevations of brain kynurenic acid impair 
cognitive 
flexibility in adults: Reversal with galantamine. Neuroscience 238:9-28. 
83. Rudy JW, Sutherland RJ (1995) Configural association theory and the hippocampal 
formation: an 
appraisal and reconfiguration. Hippocampus 5(5):375-389. 
84. Eichenbaum H (2001) The hippocampus and declarative memory: cognitive mechanisms 
and neural 
codes. Behav Brain Res 127(1-2):199-207. 85. Heckers S, et al (2004) Hippocampal activation 
during transitive inference in humans. Hippocampus 
14(2):153-162. 
86. Ongur D, et al (2006) The neural basis of relational memory deficits in schizophrenia. Arch 
Gen 
Psychiatry 63(4):356-365. 
87. Rowland LM, Griego JA, Spieker EA, Cortes CR, Holcomb HH (2010) Neural changes 
associated with 
relational learning in schizophrenia. Schizophr Bull 36(3):496-503. 
88. Ragland JD, et al (2012) Neural correlates of relational and item-specific encoding during 
working and 
long-term memory in schizophrenia. Neuroimage 59(2):1719-1726. 
89. Ragland JD, et al (2012) CNTRICS imaging biomarkers final task selection: Long-term 
memory and 
reinforcement learning. Schizophr Bull 38(1):62-72. 
90. Ragland JD, et al (2012) Relational and Item-Specific Encoding (RISE): task development 
and 
psychometric characteristics. Schizophr Bull 38(1):114-124. 
91. American Psychiatric Association. Task Force on, D.-I., DSM-IV: diagnostic and statistical 
manual of 
mental disorders. 1994. 
92. First MB, Spitzer RL, Gibbon M, Williams J BW (1996) in Structured Clinical Interview for 
DSM-IV Axis I 
Disorders, Clinician Version (SCID-CV), (American Psychiatric Press, Inc.). 
93. Ceresoli-Borroni G, Rassoulpour A, Wu HQ, Guidetti P, Schwarcz R (2006) Chronic 
neuroleptic treatment 

3.28.16 
24 
 
reduces endogenous kynurenic acid levels in the rat brain. J Neural Transm 113:1355-1365. 
94. Mackay GM, et al (2009) Kynurenine metabolites and inflammation markers in depressed 
patients treated 
with fluoxetine or counseling. Clin Exp Pharmacol Physiol 36:425-435. 
95. Addington D, Addington J, Matrick-Tyndale E (1993) Assessing depression in 
schizophrenia: the Calgary 
Depression Scale. Br J Psychiatry Suppl 22:39-44. 
96. Brune GG, Oflughaupt KW (1975) Tryptophan metabolism in nervous disease. Acta 
Vitaminol Enzymol 
29:184-189. 97. Torres MI, Lopez-Casado MA, Lorite P, Rios A (2007) Tryptophan metabolism 
and indoleamine2,3- 
dioxygenase expression in celiac disease. Clin Exp Immunol 148:419-424. 
98. Overall JE, Gorham DR (1962) The Brief Psychiatric Rating Scale, Psychol Rep 10(79): p 
812. 
99. Andreasen NC (1983) The Scale for the Assessment ofNegative Symptoms (SANS). 
University of Iowa, 
Iowa City. 
100. Guy W, ed (1976) Clinical Global Impressions. ECDEU Assessment Manual for 
Psychopharmacology, 
Rockville, MD: US Department of Health, Education and Welfare, DHEW Publication No. (ADM) 
76-338. 
101. Neuchterlein KH, et al (2008) The MATRICS Consensus Cognitive Battery, Part 1: Test 
Selection, 
Reliability and Validity. Am J Psychiatry 165:203-213. 
102. Watanabe Y, Someya T, Nawa H (2010) Cytokine hypothesis of schizophrenia 
pathogenesis: evidence 
from human studies and animal models. Psychiatry Clin Neurosci 64:217-230. 103. Dean B 
(2011) Understanding the role of inflammatory-related pathways in the pathophysiologicy and 
treatment of psychiatric disorders: evidence from human peripheral studies and CNS studies. Int 
J 
Neuropscychopharmacol 14:997-1012. 
104. Zuareve OE, Klilmenko VM (2011) Elevation of proinflammatory cytokines level at early 
age as the risk 
factor of neurological and mental pathology development. Ross Fiziol Zh Im I M Scechenova 
97:1048- 
1059. 
105. Richard MD, Brahm NC (2012) Schizophrenia and the immune system: pathophysiology, 
prevention and 
treatment. Am J Health Syst Pharm 69:757-766. 
106. Kim YK, et al (2009) Cytokine changes and typophan metabolites in medication-naïve and 
medication 
free schizophrenic patients. Neuropsychobiology 59:123-129. 
107. DiNatale BC, et al (2010) Kynurenic acid is a potent endogenous aryl hydrocarbon receptor 
ligand tha 
tsyndergistically induces interleukin-6 in the prescence of inflammatory signaling. Toxicol Sci 
115:89-97. 
108. Lee M, Jayathilkake K, Dai J, Meltzer HY (2011) Decreased plasma tryptophan nad 
tryotophan/large 
neutral amino acid ratio in patients with neuroleptic-resistant schizophrenia: relationship to 
plasma 

3.28.16 
25 
 
cortisol concentration. Psychiatry Res 185:328-333. 
109. Zunszain PA, et al (2012) Interleukin-1B: a new regulator of the kyunurenine pathway 
affecting human 
hippocampal neurogenesis. Neuropsychopharmacology 37:939-949. 
110. Hoddes E, Zarcone V, Smythe H, Phillips R, Dement WC (1973) Quantification of 
sleepiness: a new 
approach. Psychophysiology 10:431-436. 
111. Wijtenburg SA, Knight-Scott J (2011) Very short echo time improves the precision of 
glutamate detection 
at 3T in 1H magnetic resonance spectroscopy. J Magn Reson Imaging 34(3):645-652. 
112. Niendam TA, et al (2012) Meta-analytic evidence for a superordinate cognitive control 
network 
subserving diverse executive functions. Cogn Affect Behav Neurosci 12:241-268. 
113. Fox MD, Raichle ME (2007) Spontaneous fluctuations in brain activity observed with 
functional magnetic 
resonance imaging. Nat.Rev.Neurosci 8:700-711. 114. Bassett DS, Bullmore E (2006). Small-
world brain networks. Neuroscientist 12:512-523. 
115. Bassett DS, Bullmore E, Verchinski BA, Mattay VS, Weinberger DR, Meyer-Lindenberg A 
(2008) 
Hierarchical organization of human cortical networks in health and schizophrenia. J Neurosci 
28:9239- 
9248. 
116. Bassett DS, Meyer-Lindenberg A, Achard S, Duke T, Bullmore E (2006) Adaptive 
reconfiguration of fractal 
small-world human brain functional networks. Proc Natl Acad Sci USA 103:19518-19523. 
117. Gasparovic C, et al (2009) Quantitative spectroscopic imaging with in situ measurements 
of tissue water 
T1, T2, and density. Magn Reson Med 62(3):583-590. 
118. Silber BY, Schmitt JA (2010) Effects of tryptophan loading on human cognition, mood, and 
sleep. 
Neurosci Biobehav Rev 34(3):387-407. 
119. Jones HE, et al (2004) Safety and efficacy of L-tryptophan and behavioral incentives for 
treatment of 
cocaine dependence: a randomized clinical trial. Am J Addict 13(5):421-437. 120. Benjamini Y, 
Hochberg Y (1995) Controlling the false discover rate: A new and powerful approach to 
multiple hypothesis testing. J Royal Stat Association, Series B 57:1289-1300. 
121. Hong LE, Gu H, Yang Y, Ross TJ, Salmeron BJ, Buchholz B, Thaker GK, Stein EA (2009). 
Association of 
nicotine addiction and nicotine’s actions with separate cingulated cortex functional circuits. Arch 
Gen 
Psychiatry 66;431-41 
122. Patriat R, et al (2013) The effect of resting condition on resting-state fMRI reliability and 
consistency: A 
comparison between resting with eyes open, closed, and fixated. Neuroimage pii: S1053-
8119(13)00340- 
6. [Epub ahead of print] 
123. Kraemer HC, Wilson GT, Fairburn CG, Agus WS (2002) Mediators and moderators of 
treatment effects in 
randomized clinical trials. Arch Gen Psychiatry 50:877-883. 

3.28.16 
26 
 
124. Brune GG, Pflughaupt KW (1975) Tryptophan metabolism in nervous disease. Acta 
Vitaminol Enzymol 
29:184-9. 
125. Torres MI, Lopez-Casado MA, Lorite P, Rios A (2007) Tryptophan metabolism and 
indoleamine2,3- 
dioxygenase expression in celiac disease. Clin Exp Immunol 148:419-24. 
126. Markus CR, Olivier B, de Haan E (2002). Whey protein rich in alpha-lactalbumin increases 
the ratio of 
plasma tryptophan to the sum of the other large neutral amino acids and improves cognitive 
performance 
in stress-vulnerable individuals. J Clin Nutrition 75:1051-56. 
127. Schmitt JA, Jorissen BL, Dye L, Markus CR, Deutz ME, Riedel WK (2005) Memory 
function in women 
with premenstrual complaints and the effect of serotonergic stimulation by acute administration 
of an 
alpha-lactalbumin protein. J of Psychopharmacology 19:375-84. 
128. Booij L, Merens W, Markus CR, William van der Does AJ (2006) Diet rich in alpha-
lactalbumin improves 
memory in unmedicated recovered depressed patients and matched controls. J of 
Psychopharmacology 
20:526-35. 
129. Markus CR, Olivier B, Panhuysen GEM, Van der Gugten J, Alles MS, Tuiten A, 
Westenburg HGM, 
Fekkes D, Koppeschaar HF, de Haan E (2000) The bovine protein alpha-lactalbumin increase 
the plasma 
ratio of tryptophan to the other large amino acids and in vulnerable subjects raises brain 
serotonin 
activity, reduces cortisol concentration and improves mood under stress. The American J of 
Clinical 
Nutrition 71:1536-44. 130. Merens W, Booij L, Markus R, Zitman FG, Onkenhout W, William van 
der Does AJ (2005) The effects of a 
diet enriched with alpha-lactalbumin on mood and cortisol response in unmedicated recovered 
depressed 
subjects and controls. Brit Journal of Nutrition 94:415-22. 
131. Luciana M, Burgund ED, Berman M, Hanson KL (2001) Effects of tryptophan loading on 
verbal, spatial 
and affective working memory functions in healthy adults. J of Psychopharmacology 15:219-
230. 
132. Winokur A, Lindberg ND, Lucki L, Phillips J, Amsterdam JD (1986). Hormonal and 
behavioral effects 
associated with intravenous l-tryptophan administration. Psychopharmacology 88:213-19. 
133. Dougherty DM, March DM, Mathias CW, Dawes MA, Bradley DM, Morgan CL, Badawy 
AAB (2007). The 
effects of alcohol on laboratory-measured impulsivity after l-typtophan depletion or loading. 
Psychopharmacology 193:137-50. 134. Soczak S, Honig A, Schmitt JAJ, Riedel WK (2003). 
Pronounced cognitive deficits following an 
intravenous l-tryptophan challenge in first degree relative of bipolar patients compared to 
healthy 
controls. Neuropyschopharmacology 28:711-719. 

3.28.16 
27 
 
135. Steinberg S, Annable L, Young SN, Liyanage N (1999). A placebo controlled clinical trial of 
l0trypophan in 
premenstrual dysphoria. Biological Psychiatry 45:313-320. 
136. Wyatt RJ, Engelman K, Kupfer DJ, Fram DH, Sjoerdsma A, Snyder F (1970). Effects of l-
tryptophan (a 
natural sedative) on human sleep. Lancet 2:842-46. 
137. Fernstrom JD (2012). Effects and side effects associated with the non-nutritional use of 
tryptophan by 
humans. J Nutr 142:2236S-2244S. 
138. Hiratsuka C, Fukuwatari T, Sano M, Saito K, Sasaki S, Shibata K (2013). Supplementing 
healthy women 
with up to 5.0 d/d of L-Tryptophan has no adverse effects. J Nutr April 24, epub ahead of print. 
139. Richard DM, Dawes MA, Mathias CW, Acheson A, Hill-Kapturczak, Dougherty DM (2009). 
L-Tryptophan: 
basic metabolic functions, behavioral research and therapeutic indications. Int J Tryptophan Res 
2:45-60.