ADP and arachidonic acid induced platelet aggregation in schizophrenia and atypical psychoses.

Platelet aggregatory responses to adenosine diphosphate (ADP) and arachidonic acid were examined in 6 drug-free schizophrenics, 5 other drug-free psychotics, 8 'acute-on-chronic' schizophrenics (on long-term neuroleptic therapy) and 38 healthy controls. Platelet aggregation and disaggregation following ADP was significantly lower in 'acute-on-chronic' schizophrenics (on drugs) compared with healthy controls, and disaggregation following 1 microM ADP was significantly less in drug-free schizophrenics. The difference between maximum aggregation induced by ADP and that induced by arachidonic acid was significantly greater in schizophrenics (both on drugs and drug-free) than in controls. These findings are related to possible abnormalities of central nervous system function in schizophrenia.