Targeting the Microbiome to Improve Clinical Outcomes in Bipolar Disorder
Condition: Bipolar Disorder
MeSH terms: Bipolar Disorder
Study type: Interventional

Summary: 
      The objective of this study is to determine how specific dietary control alters the
      microbiome composition to effect clinical outcome measures in a longitudinal study of
      individuals with bipolar disorder. Our central hypothesis is that a low carbohydrate (CHO) /
      high polyunsaturated fat (PUFA) diet will increase the fractional representation of specific
      butyrate producing members of the Firmicutes phylum in the gut microbiome, which will
      attenuate host inflammation, improve sleep quality and reduce anxiety in bipolar patients.
      The rationale for the proposed research is to take the first step in a continuum of studies
      to develop personalized novel approaches to treat mood disorders, including the need to
      address gut dysbiosis, which often co-occurs with mental illness. The investigators will test
      our hypothesis and achieve the objective of this proposal with the following Specific Aims:
      1) Determine the taxonomical change in the stool microbiome following a low CHO / high PUFA
      diet; and 2) Determine the changes in sleep quality, anxiety, and depression following a low
      CHO / high PUFA diet. These aims will be achieved using the unique resources at the
      University of Michigan, including the Nutrition Assessment Laboratory for dietary
      intervention, the Host-Microbiome Laboratory for microbial assays, and the ongoing Prechter
      Longitudinal Study of Bipolar Disorder. At the end of the proposed studies the investigators
      expect to set the stage for future studies to assess neurochemical mechanisms. These data
      will provide a greater understanding of the mechanism by which diet controls the specific
      microbes in the gut microbiome to affect mood disorders and gut dysbiosis and improve
      response to psychiatric treatment paradigms.
    

Detailed description: 
      RECRUITING AND INCENTIVIZING RESEARCH PARTICIPANTS

      For the proposed study, the investigators will recruit research participants from the
      Prechter Longitudinal Study of Bipolar Disorder, housed at the University of Michigan under
      the direction of Dr. Melvin McInnis, mentor on this application. The Prechter study is in its
      10th year with over 1200 participants, including psychiatric and healthy control individuals.
      the investigators have successfully recruited from this study in the past to perform an
      observational dietary study and single point microbiomic analysis described in the Previous
      Work section. The investigators will leverage the infrastructure of the study with 50%
      dedicated time for a research assistant to manage recruitment, scheduling, follow up and data
      entry duties. The investigators will also leverage 5% dedicated time for the study
      coordinator, Gloria Harrington, who oversees all administrative aspects of the Prechter
      Study, including assurance of regulatory compliance.

      The investigators will recruit 20 males and 20 females from the Prechter cohort, aged 25-65
      with a confirmed diagnosis of Bipolar I disorder from a diagnostic interview for genetic
      studies (DIGS), used as the baseline intake instrument for the Prechter study. Eligible
      subjects will be consented and scheduled for an intake interview and assigned a unique
      identification number for tracking with a secure laboratory information management system.
      Subjects will be offered a monetary incentive of $200, paid in installments after completion
      of study milestones activities.

      DETERMINING HABITUAL DIETS

      The investigators will determine the habitual baseline diets of all subjects using a 3 non
      consecutive days over 1 week with an automated online 24-hour diet recall (ASA24 from the
      National Cancer Institute). Subjects will meet with a certified nutritionist from the
      Nutrition Assessment Laboratory in the Nutrition and Obesity Research Center at the
      University of Michigan during the consent visit to explain how to use the recall
      appropriately. After 1 week, subjects will return for to the MCRU for baseline biological
      samples and dietary guidance as detailed below.

      COLLECTING BIOLOGICAL SAMPLES, MORPHOMETRIC DATA AND STANDARD HEALTH MEASURES

      During the baseline visit (following the week involving dietary recalls), all subjects will
      donate baseline fasted blood samples for free fatty acid analysis; a urine sample for
      analysis of oxidative stress markers; and have their height, weight, waist and hip
      circumference, and blood pressure recorded and be asked to complete the interviewer guided
      Hamilton Depression scale questionnaire, the Young Mania Rating Scale questionnaire and the
      Global Physical Activity Questionnaire. Participants will also complete a brief 25-35 minute
      neuropsychological test battery during their baseline and final visit. Subjects will also
      return a stool sample, which will be collected at home with a supplied collection kit.
      Subjects will repeat all procedures at the end of the 1st and 4th week of the dietary
      protocol. These procedures as well as the dietary interviews will occur in the Michigan
      Clinical Research Unit at the University of Michigan, staffed with phlebotomists, nurses,
      nutritionists and technicians with expertise in all proposed procedures; and equipment needed
      to process the samples. Finally, subjects will be asked about all prescription and
      non-prescription medications taken over the previous week.

      DIETARY INTERVENTION

      For the diet intervention, subjects will be guided by a certified nutritionist to achieve a
      target macronutrient composition (by total calorie contribution) of 15% protein, 45%
      carbohydrate, 40% fat, with <10% saturated fat, ~15% PUFA and ~15% monounsaturated fatty
      acids (MUFA). Specific targeted profiles are given in Table 4. For reference, The
      investigators also show the cognate values attained from a 7-day observational study of 91
      individuals with bipolar disorder described above. Comparing the target and previously
      determined habitual values from the same population, the major change to the diet will be a
      near doubling of PUFA intake and a small increase in MUFA intake, at the expense of reducing
      carbohydrates and saturated fat, which is a realistic and achievable goal.

      The investigators will achieve the diet with specific menus, considering personal preferences
      gleaned from the habitual diet analysis described. The investigators will provide subjects
      with specific cooking oils for addition to foods prepared at home, to achieve the oleic
      (OLA), LA and α-linolenic (LNA) targets; and fish-oil supplements to achieve the DHA and EPA
      targets. Subjects will also be provided a list of foods to eat and avoid (tailored from their
      habitual diet records), as well as several menu items from chain restaurants to eat for meals
      unavoidably eaten away from home. Subjects will be trained to report on their diets using the
      ASA24. Records will be reviewed at least weekly by research staff and assessed for deviation
      from the diet outside of threshold ranges (as average daily intake) of at least 12% PUFA and
      no more than 50% carbohydrate. In parallel to this project the investigators will develop
      python scripts to extract data to automate the process, however, the investigators will not
      depend on success of that goal in order to meet the objectives of this project. Values
      falling outside the set thresholds will be brought to the subjects' attention with
      suggestions for correction. Importantly, since plasma LA correlates strongly with dietary
      intake, objective measures of dietary adherence to PUFA intake will be available upon
      completion of free fatty acid analysis from fasting blood samples, which can be leveraged as
      covariates in statistical models. Finally, the investigators will avoid November - January
      for the dietary interventions, as diets tend to be non-habitual during this period.

      Following the 4-week dietary manipulation, subjects will be encouraged to maintain the high
      PUFA diet for 6 months. Due to limited resources, The investigators will not continue to
      collect stool samples following the 4-week period (although other funding will be pursued to
      do so). However, the investigators will continue to encourage subjects to use the ASA24
      weekly. The investigators will also continue to monitor self-report measures as a component
      of the longitudinal study, requiring no additional resources from this application.

      Dr.Evans (Principal Investigator) has established a good relationship with the research staff
      in the Nutrition Assessment Laboratory (NAL) during past studies, described above, and has
      developed the plans for the proposed dietary manipulation with Theresa Han-Markey, RD,
      Bionutrition Manager of the NAL, who's services are budgeted into the proposed study. Dr.
      Evans has also recently completed formal training in nutritional sciences as a component of a
      K01 career development award and will be intimately involved in the dietary studies.
      Furthermore, Dr. Charles Burant, Director of the Nutrition and Obesity Research Center and
      previous mentor for Dr. Evans K01 award, will consult on these studies (see letter of
      support).

      INTERROGATING THE TAXONOMICAL COMPOSITION OF THE STOOL MICROBIOME

      Home OmniGene Gut stool collection kits from DNA Genotek (Ottawa, CA) will be used to collect
      samples at baseline, week 1 and week 4 of the dietary period. These kits were used
      successfully to generate preliminary data describe above, and have the advantage of
      maintaining sample DNA stability for 14 days without freezing. Subjects will return the
      completed kits at the scheduled study visits. Methods for identifying microbial complements
      in the samples have been previously described in a publication by the HMI Laboratory at the
      University of Michigan. Briefly, microbial DNA will be extracted from stool samples and
      processed for 16S ribosomal sequencing using a dual-indexing sequencing strategy. Sequencing
      will be done on the Illumina MiSeq platform, according to the manufacturer's instructions.
      Analysis of the 16S rRNA gene will be done using an SOP (www.mothur.org/wiki/MiSeq_SOP) to
      process the MiSeq data. Sequence classifications will be determined by comparing sequences to
      the Ribosomal Database Project and sequences will be clustered into OTUs.

      COLLECTION OF SELF-REPORTED HEALTH MEASURES

      Longitudinal participants currently complete self-rated questionnaires by mail every 2
      months. For the current study the investigators use average responses previously collected as
      baseline measures and new responses collected at the completion of the diet period as outcome
      measures. These questionnaires include the PHQ-9, the PSQI, the LFQ, the Altman Self-Rating
      Mania Scale (ASRM), the Short Form 12 Health Survey (SF-12), and the Generalized Anxiety
      Disorder Assessment (GAD-7).

      DATA ANALYSIS

      Data analysis has 2 major phases. The first is generating normalized summary scores from the
      various measures. The second is using statistical models to test for main effects of diet.
      Summary of questionnaire scores and anthropomorphic measures are standard and not further
      detailed here. Summary of microbiomic data sets will be done as described above and OTUs
      output in 2 ways: 1) as a fractional representation table, where each OTU is expressed as a
      fraction of the total OTUs per sample; and 2) as total sequence counts, where each OTU is
      represented as total abundance. Both will be tested in statistical analyses.

      For the second phase the investigators will use two main statistical models: 1) regression
      analyses to test for main effects of diet on OTU level microbiome data and self-reported
      burden of disease measures, adjusting for age, sex and BMI; and 2) structured equation
      modeling analysis to test for mediation effects of OTUs on the relationship between diet and
      clinical outcomes. The investigators will achieve the latter approach as diagrammed in Figure
      2. Main effect of diet will be tested on plasma PUFA (primarily LA), microbiome OTUs, and
      self-reported health measures, depicted by the dotted line. The cross-lag model, using SEM,
      will test for statistically significant reciprocal effects, shown by the bold arrows. For
      example, the investigators will test if increase in plasma LA accounts for the effect (fully
      or partially) in changes in microbiome OTUs, and if changes in OTUs account for effects on
      self-reported outcome measures.
    

Intervention name(s): High polyunsaturated fatty acid diet.
Intervention type(s): Other
Intervention description(s): The investigators hypothesize the diet will improve gut health and psychiatric clinical outcomes.
Intervention model: Single Group Assignment
Masking: None (Open Label)
Primary purpose: Supportive Care