Cognitive impairment and negative symptoms in geriatric chronic schizophrenic patients: a follow-up study

Cognitive impairment is increasingly recognized as an important aspect of schizophrenia. Since cognitive impairment has many features in common with the negative symptoms of the illness, it is possible that some of the characteristics attributed to negative symptoms are due to an association with cognitive impairments. In order to test this hypothesis, 174 chronically hospitalized geriatric schizophrenic patients were examined twice at a 1-year follow-up with ratings of the severity of their symptoms (using the Positive and Negative Syndrome Scale: PANSS) and assessments of cognitive functions with the Mini-Mental State Examination and a brief neuropsychological battery aimed at the typical impairments seen in dementia. Positive symptoms were unassociated with any of the cognitive variables, while negative symptom severity was correlated with each of the cognitive measures. In the cross-temporal analyses, cognitive impairments were more stable over time than negative symptom scores, but cognitive impairment did not predict the severity of any negative symptom over time. At each assessment, however, cognitive impairment was strongly correlated with each of the seven negative symptoms studied. These data indicate that cognitive impairments and negative symptoms are related, but discriminable, features in schizophrenia and that the considerable overlap between some negative symptoms and estimates of cognitive function may suggest a rethinking of the definition of some of these symptoms.