Will Decreased Noradrenergic Activity Normalize Information Processing in Patients With Schizophrenia?

Study Overview
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Brief Summary
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The investigators want to try to improve information processing in schizophrenic patients via pharmacological intervention. The hypothesis is that decreased noradrenergic activity will normalize information processing (PPI, P50 gating, P300, and mismatch negativity) in patients with schizophrenia.

Detailed Description
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A number of reports in literature provide evidence for, among others, an increased central noradrenergic activity in schizophrenia. In addition to this increased noradrenergic activity, patients with schizophrenia often show reduced filtering of sensory information, which is reflected in reduced P50 suppression and reduced prepulse inhibition of the startle reflex (PPI). In two separate initial studies in our laboratory, we found reduced sensory gating following administration of imipramine (a combined noradrenergic and serotonergic agonist) and desipramine (a highly specific noradrenergic agonist) to healthy volunteers. This provides evidence for a direct causal relation between the increased noradrenergic activity and the disturbed gating of sensory information, as both commonly found in patients with schizophrenia. Therefore, in a follow-up study, the effects of a noradrenergic antagonist will be investigated on the sensory gating of patients with schizophrenia. To further extend the data of our initial studies, the patients will additionally be tested for two psychophysiological parameters of attention that are usually found to be disturbed in patients with schizophrenia, i.e. mismatch negativity and selective attention. The design will conform to a double blind, placebo controlled experiment, in which either four doses (0.25 ug, 50 ug, 75 ug or 150 ug)of clonidine or placebo will be added to the current medical treatment of 20 male patients with schizophrenia on five occasions, separated by at least a week, after which they are tested in the Copenhagen Psychophysiological Test Battery (CPTB).In order to test the effects of clonidine in healthy volunteers, 20 healthy males will receive a fixed dose of 0.15 mg clonidine or placebo on two separate occasions separated by at least a week, after which they will be tested in the CPTB as well.

Official Title
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Will Decreased Noradrenergic Activity Normalize Information Processing in Patients With Schizophrenia?

Conditions
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Schizophrenia

Intervention / Treatment
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* Drug: clonidine
* Drug: clonidine


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Patients: Male subjects Meeting the DSM-IV diagnosis of schizophrenia Controls: Male subjects Good Physical and Mental Health meeting criteria never mentally ill, which will be evaluated with a medical history checklist Non smokers Exclusion Criteria: Patients: A P50 suppression or PPI score falling within a range of 10 percent above or below the mean score of the healthy control group Controls: Current use of any medication Any subject who has received any investigational medication within 30 days prior to the start of this study History of neurologic illness History of psychiatric illness in first-degree relatives, evaluated with DSM-IV criteria History of alcohol and drug abuse.

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 45 Years

Sexes Eligible for Study
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Male

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: Triple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: 1<br> | Drug: clonidine<br>* Either placebo or 25 ug, 50 uG 75 ug or 150 ug of clonidine will be added to the current medication of patients with schizophrenia, who are stable on their current medication<br>* Other names: Catapressan;|
| Experimental: 2<br> | Drug: clonidine<br>* 0.15 mg of clonidine will be administered to 20 healthy male volunteers<br>* Other names: Catapressan;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| The following psychophysiological measures: |  | prospective | 
| Prepulse Inhibition og the Startle Response (PPI) |  | Once, 3.5 hrs after intake of capsule | 
| P50 suppression |  | Once, 3.5 hrs after intake of capsule | 
| P300 Event Related Potential |  | Once, 3.5 hrs after intake of capsule | 
| Mismatch negativity |  | Once, 3.5 hrs after intake of capsule | 
| PANSS |  | 5 times hourly after intake of capsule | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Schizophrenia, Information processing, PPI, P50 gating, P300, mismatch negativity, clonidine