Formal thought disorder in offspring of schizophrenic parents

We examined potential early markers of schizophrenia using measures of formal thought disorder in offspring of parents with schizophrenia, other mental illness and no mental illness.

Two blind raters coded formal thought disorder in adolescent/early adult offspring of 42 schizophrenic, 39 other mental illness, and 36 no mental illness parents. In addition to parental diagnosis, we compared the individual offspring diagnosis with severity of formal thought disorder. Within the schizophrenia, other mental illness and no mental illness offspring groups, we examined the relationship between severity of formal thought disorder and performance on cognitive and motor tasks.

There were no statistically significant differences in formal thought disorder by parent or offspring diagnoses. Within the offspring group of parents with schizophrenia, the subjects with higher formal thought disorder scores performed significantly worse on the cognitive battery than those with lower formal thought disorder scores. Offspring of the other mental illness group with higher formal thought disorder scores, however, showed more deficits on motor tasks than those with lower formal thought disorder scores.

Formal thought disorder may reflect underlying cognitive dysfunction in the offspring of parents with schizophrenia. Motor dysfunction in the offspring of parents with other psychiatric illness might be associated with formal thought disorder.