Family characteristics of deficit and nondeficit schizophrenia in the Roscommon Family Study.

Studies of course, treatment response, biological correlates, and environmental risk factors have suggested that the deficit syndrome of schizophrenia defines a meaningful subgroup within schizophrenia. Probands from the Roscommon Family Study who met criteria for schizophrenia or simple schizophrenia were categorized into deficit (N=22) and nondeficit (N=111). Within schizophrenia, the lifetime prevalence of the deficit syndrome was 16.5%; the percentage of males was 91% compared to 63% in the nondeficit group. The first-degree relatives of deficit probands had a significantly greater social isolation than the relatives of nondeficit probands, despite significantly less severe dysphoria and psychotic-like symptoms. The risk of schizophrenia was 1.75 times greater in the families of deficit compared to nondeficit probands. There were no significant differences in the adjusted morbid risk for nonaffective psychosis, affective disorder, or alcoholism. These results provide further evidence that the deficit syndrome is a marker of a group of patients with clinical and neurobiological characteristics that distinguish them from the rest of schizophrenia. The deficit syndrome may be a useful phenotype in genetic linkage studies.