Schizophrenia and Plasma Homovanillic Acid in Response to Mental Stress Methodological Considerations

Prediction of changes in memory performance by plasma homovanillic acid levels in clozapine-treated patients with schizophrenia

“…Fig. 1 Relationship between baseline pHVA levels and change in the VLL-DR scores (scores at 6 weeks−scores at baseline) in clozapine-treated patients with schizophrenia An association between dopaminergic activity, as reflected by pHVA levels, and cognitive abilities related to learning and memory in the patients who received clozapine, was suggested by the correlation between baseline pHVA levels and changes (6 week vs. baseline) in performance on VLL-DR. Preclinical and clinical studies suggest that subcortical structures, such as nucleus accumbens (NAC), constitute the major component of the brain HVA output (Csernansky et al 1990;Lambert et al 1991;Sumiyoshi et al 2000a). There may also be a contribution of cortical DA neurons, as the ventral tegmentum is the source of the DA neurons projecting to both the cortex and NAC.…”

“…Plasma levels of homovanillic acid (pHVA), the major metabolite of DA, have been studied extensively in subjects with schizophrenia as a peripheral marker of central dopaminergic activity (Bacopoulas et al 1979;Kendler et al 1981Kendler et al , 1982Koreen et al 1994;Sumiyoshi et al 1997bSumiyoshi et al , 1999Sumiyoshi et al , 2000aZhang et al 2001;see Friedhoff and Amin 1997 for review). Although the contribution of the central nervous system to peripheral pHVA concentrations has been reported to be no more than 35% (Kopin et al 1988;Maas et al 1988), pHVA levels have been suggested to be an indicator of several aspects of schizophrenia, including vulnerability to develop the illness (Siever et al 1991;Sumiyoshi et al 2000b).…”