COGNITION, NEGATIVE SYMPTOMS, AND DIAGNOSIS - A COMPARISON OF SCHIZOPHRENIC, BIPOLAR, AND CONTROL SAMPLES

Forty-six schizophrenic, 22 bipolar, and 26 normal control subjects we re administered negative and positive symptoms scales and tests of cog nitive function. Test performance was related to diagnosis and to posi tive and negative symptom ratings within the schizophrenic group. Bipo lar patients were significantly superior in cognitive status when comp ared with all schizophrenic patients, but less so when compared only w ith those who did not have key negative symptoms (affective nonrespons ivity and poverty of speech). The schizophrenic patients with negative symptoms displayed severe impairment, performing significantly worse than the control, bipolar, and other schizophrenic subjects. Negative symptoms thus are significantly implicated in the cognitive inferiorit y of schizophrenic to bipolar patients. Although the data suggest bipo lar patients may also have cognitive deficiencies, these findings are inconclusive and require cross-validation.