Nithsdale Schizophrenia Surveys. 20. Cognitive function in a catchment-area-based population of patients with schizophrenia.

Abstract

Cognitive deficits are a core aspect of schizophrenia but there has been no study of cognitive function in a catchment-area-based population of patients with schizophrenia. To assess cognitive function in a population of patients with schizophrenia, and relate it to community functioning. All patients with schizophrenia in Nithsdale, south-west Scotland, were identified (n = 182). Measures of assessment were: National Adult Reading Test (NART), Mini-Mental State Examination (MMSE), Rivermead Behavioural Memory Test (RBMT), Executive Interview (EXIT), FAS Verbal Fluency and Health of the Nation Outcome Scales (HoNOS). We assessed 138 patients, mean age 48 years (standard deviation (s.d.) 15). Only 14% were in-patients. The mean premorbid IQ as assessed by NART was 98 (s.d. 14); 15% of patients had significant global cognitive impairment (MMSE); 81% had impaired memory (RBMT); 25% had executive dyscontrol (EXIT); and 49% had impaired verbal fluency (FAS). Scores on the functional impairment sub-scale of HoNOS correlated with all measures of cognitive impairment. Cognitive dysfunction is pervasive in a community-based population of patients with schizophrenia.