Age-associated differences in cognitive performance in older patients with schizophrenia: a comparison with healthy older adults

Abstract

Background: There are varying results regarding the conjoint influence of aging and schizophrenia on cognitive abilities. Previous studies have been limited by restricted age ranges among schizophrenia and psychiatrically healthy control samples as well as small numbers of control participants.

Objective: To quantify the association between age and cognitive performance in patients with schizophrenia and psychiatrically healthy older adult controls and to determine if age-associated changes in cognitive performance were different in the two groups.

Methods: People with schizophrenia (n = 226) and psychiatrically healthy individuals (n = 834) ranging in age from 40 to older than 80 years were compared on a battery of neuropsychological tests. To directly compare the impact of age on cognitive performance, age was also regressed on performance in the two samples.

Results: The performance of psychiatrically healthy adults age 70 and older was superior to the performance of the youngest patients with schizophrenia (age 40-49) years on measures of working and episodic memory, executive function, and psychomotor speed. Regression analyses indicated that age effects on cognition were significantly greater for schizophrenia patients on measures of verbal learning and speed of processing. Within both the schizophrenia group, and psychiatrically healthy adults, the greatest age-related differences in performance seemed to occur for individuals aged more than 70 years.

Conclusion: In this cross-sectional study, the present findings underscore the fact that schizophrenia is associated with cognitive impairment across all ages and that older schizophrenia patients experience relatively greater age associated differences in cognitive functioning than healthy individuals. These findings have wide-ranging implications regarding the ability of older patients with schizophrenia to function independently and for the development of treatment strategies.