Do the generalised cognitive deficits observed in schizophrenia indicate a rapidly-ageing brain?

Background and Objectives: The nature and pattern of cognitive deficits (CD) in schizophrenia and whether the deficits are generalised or domain specific continues to be debated vigorously. We ascertained the pattern of CD in schizophrenia using a novel statistical approach by comparing the similarity of cognitive profiles of patients and healthy individuals. Methods: In a consecutive sample of 78 patients with schizophrenia, performance on six cognitive domains (verbal memory, working memory, motor speed, processing speed, verbal fluency and executive functions) was measured using the Brief Assessment of Cognition in Schizophrenia (BACS). The similarity of cognitive profile between patients and two groups of healthy controls (age-matched and older adults who were in the age group of 70-79) was evaluated using a special purpose-built macro. Results: Cognitive performance profiles in various domains of patients with schizophrenia and age-matched controls were markedly similar in shape, but differed in the overall performance, with patients performing significantly below the healthy controls. However, when the cognitive profiles of patients with schizophrenia were compared to those of older adult controls, the profiles remained similar whilst the overall difference in performance vanished. Conclusions: Cognitive deficit in schizophrenia appears to be generalised. Resemblance of cognitive profiles between patients with schizophrenia and older adult controls provides some support for the accelerated ageing hypothesis of schizophrenia.