Pd. Harvey et al., COGNITIVE IMPAIRMENT AND NEGATIVE SYMPTOMS IN GERIATRIC CHRONIC-SCHIZOPHRENIC PATIENTS - A FOLLOW-UP-STUDY, Schizophrenia research, 22(3), 1996, pp. 223-231
Cognitive impairment is increasingly recognized as an important aspect
of schizophrenia. Since cognitive impairment has many features in com
mon with the negative symptoms of the illness, it is possible that som
e of the characteristics attributed to negative symptoms are due to an
association with cognitive impairments. In order to test this hypothe
sis, 174 chronically hospitalized geriatric schizophrenic patients wer
e 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 Ex
amination 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 c
orrelated with each of the cognitive measures. In the cross-temporal a
nalyses, cognitive impairments were more stable over time than negativ
e symptom scores, but cognitive impairment did not predict the severit
y of any negative symptom over time. At each assessment, however, cogn
itive impairment was strongly correlated with each of the seven negati
ve symptoms studied. These data indicate that cognitive impairments an
d negative symptoms are related, but discriminable, features in schizo
phrenia and that the considerable overlap between some negative sympto
ms and estimates of cognitive function may suggest a rethinking of the
definition of some of these symptoms.