Vulnerability to psychosis associated with hallucinogen use.

Ninety-five patients hospitalized for acute psychosis were reviewed with respect to hallucinogen use and family history of mental illness. Sixty-three percent of admissions had used hallucinogens to some degree within 3 years of the index admission. Drug users were predominantly male, although no age or diagnostic differences with the nondrug group were found. The incidence of hospitalized first degree relatives was approximately 30% and equal for both drug and nondrug groups. Male drug users and female nondrug users were more likely to have had first degree relatives hospitalized. For male psychotics only, lower degrees of drug use were associated with a greater number of hospitalized first degree relatives. For female psychotics only, drug use was positively associated with full scale IQ. The findings suggest sex differences in vulnerability to psychoses associated with hallucinogen use.