A twin study of communication disturbances in schizophrenia.

Relatives of schizophrenia patients have demonstrated several different types of subtle communication disturbances. This study used twin methodology to address the question of whether certain of these disturbances might be reflective of genetic vulnerability. Verbatim interviews from a sample of monozygotic and dizygotic twins in which at least one member of each twin pair had a diagnosis of schizophrenia were rated for three different types of referential communication disturbances. Monozygotic versus dizygotic nonschizophrenic co-twins were compared on each type of disturbance. Associations between the language variables and object sorting test performance also were examined. Differences among subjects in levels of global psychopathology were controlled. Schizophrenic participants showed higher levels of communication disturbance than nonschizophrenic co-twins. One type of communication failure, the "missing information" reference, discriminated monozygotic from dizygotic nonschizophrenic co-twins. This type of failure was associated with specific types of errors on the object sorting test. These findings suggest that missing information references may be an expression of schizophrenia-related genetic vulnerability.