J Neuropsychiatry Clin Neurosci 1997; 9:81-89
Copyright © 1997 by American Neuropsychiatric Association
Cognition, negative symptoms, and diagnosis: a comparison of schizophrenic, bipolar, and control samples
KA Hawkins, RE Hoffman, DM Quinlan, J Rakfeldt, NM Docherty and WH Sledge
Department of Psychiatry, Yale University School of Medicine, New Haven, Connecticut 06519, USA.
Forty-six schizophrenic, 22 bipolar, and 26 normal control subjects were
administered negative and positive symptoms scales and tests of cognitive
function. Test performance was related to diagnosis and to positive and
negative symptom ratings within the schizophrenic group. Bipolar patients
were significantly superior in cognitive status when compared with all
schizophrenic patients, but less so when compared only with those who did
not have key negative symptoms (affective nonresponsivity 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 inferiority of schizophrenic to bipolar
patients. Although the data suggest bipolar patients may also have
cognitive deficiencies, these findings are inconclusive and require
cross-validation.
