Schizophrenia: gender, family risk, and plasma homovanillic acid.

Plasma homovanillic acid concentration was assessed in 60 young schizophrenic patients, with and without first-degree relatives with schizophrenia, before treatment, and 3 days after starting haloperidol treatment. The baseline concentration of homovanillic acid in plasma was no different in the two groups before treatment; it was, however, significantly higher in the patients with relatives than in those without relatives diagnosed of schizophrenia after 3 days of haloperidol treatment.