OBJECTIVE: The purpose of this study was to examine the clinical profiles of psychotic patients whose fasting levels of plasma free homovanillic acid (HVA) were elevated on the day after admission to the hospital. METHOD: These 85 subjects with nonorganic psychoses had been previously studied with respect to their response to neuroleptic treatment. They were divided into two groups on the basis of a median split of their pretreatment plasma HVA levels, and the two groups were compared on a number of clinical and demographic variables ascertained during their hospital stay. Fasting levels of plasma free HVA and 3- methoxy-4-hydroxyphenylglycol (MHPG) were measured by gas chromatography-mass spectrometry. RESULTS: The high-HVA group tended to show a better prognostic profile than the low-HVA group; however, the only significant difference between groups was in the greater use of psychotogenic drugs by low-HVA males. Fourteen additional psychotic patients with distinctly elevated HVA levels and normal MHPG values were also diagnostically heterogeneous. CONCLUSIONS: The results suggest that psychotic patients with different diagnoses who have relatively high levels of plasma free HVA before treatment will show a favorable early response to neuroleptic drugs. There may be neurobiological processes linking some patients across the clinical spectrum of the psychotic disorders.Abstract Teaser