title: Prediction of changes in memory performance by plasma homovanillic acid levels in clozapine-treated patients with schizophrenia.
abstract: BACKGROUND
  Cognitive dysfunction in schizophrenia has been demonstrated to be dependent, in part, on dopaminergic activity. Clozapine has been found to improve some domains of cognition, including verbal memory, in patients with schizophrenia.
  
  
  OBJECTIVE
  This study tested the hypothesis that plasma homovanillic acid (pHVA) levels, a peripheral measure of central dopaminergic activity, would predict the change in memory performance in patients with schizophrenia treated with clozapine.
  
  
  METHODS
  Twenty-seven male patients with schizophrenia received clozapine treatment for 6 weeks. Verbal list learning (VLL)-Delayed Recall (VLL-DR), a test of secondary verbal memory, was administered before and after clozapine treatment. Blood samples to measure pHVA levels were collected at baseline.
  
  
  RESULTS
  Baseline pHVA levels were negatively correlated with change in performance on VLL-DR; the lower baseline pHVA level was associated with greater improvement in performance on VLL-DR during treatment with clozapine. Baseline pHVA levels in subjects who showed improvement in verbal memory during clozapine treatment ( n=13) were significantly lower than those in subjects whose memory performance did not improve ( n=14).
  
  
  CONCLUSIONS
  The results of this study indicate that baseline pHVA levels predict the ability of clozapine to improve memory performance in patients with schizophrenia.
authors.affiliation: Department of Psychiatry, Vanderbilt University School of Medicine, Nashville, Tenn., USA. sumiyo@ms.toyama-mpu.ac.jp
authors.forename: Tomiki
authors.initials: T
authors.lastname: Sumiyoshi
authors.forename: A
authors.initials: A
authors.lastname: Roy
authors.forename: C-H
authors.initials: CH
authors.lastname: Kim
authors.forename: K
authors.initials: K
authors.lastname: Jayathilake
authors.forename: M A
authors.initials: MA
authors.lastname: Lee
authors.forename: C
authors.initials: C
authors.lastname: Sumiyoshi
authors.forename: H Y
authors.initials: HY
authors.lastname: Meltzer
mesh_terms: D000328:Adult; D003024:Clozapine / Q000494:pharmacology / Q000627:therapeutic use*; D006719:Homovanillic Acid / Q000097:blood*; D006801:Humans; D008297:Male; D008568:Memory / Q000187:drug effects* / Q000502:physiology; D011237:Predictive Value of Tests; D011597:Psychomotor Performance / Q000187:drug effects / Q000502:physiology; D012559:Schizophrenia / Q000097:blood* / Q000188:drug therapy*
chemical_list: D003024:Clozapine; D006719:Homovanillic Acid