Effects of depression and cognitive impairment on quality of life in older adults with schizophrenia spectrum disorder: Results from a multicenter study

Background: Little is known about the respective effects of depression and cognitive impairment on quality of life among older adults with schizophrenia spectrum disorder. Methods: We used data from the Cohort of individuals with Schizophrenia Aged 55-years or more (CSA) study, a large multicenter sample of older adults with schizophrenia or schizoaffective disorder (N = 353). Quality of life (QoL), depression and cognitive impairment were assessed using the Quality of Life Scale (QLS), the Center of Epidemiologic Studies Depression scale and the Mini-Mental State Examination, respectively. We used structural equation modeling to examine the shared and specific effects of depression and cognitive impairment on QoL, while adjusting for sociodemographic characteristics, general medical conditions, psychotropic medications and the duration of the disorder. Results: Depression and cognitive impairment were positively associated (r = 0.24, p < 0.01) and both independently and negatively impacted on QoL (standardized beta = - 0.41 and beta = - 0.32, both p < 0.01) and on each QLS quality-of-life domains, except for depression on instrumental role and cognitive impairment on interpersonal relations in the sensitivity analyses excluding respondents with any missing data. Effects of depression and cognitive impairment on QoL were not due to specific depressive symptoms or specific cognitive domains, but rather mediated through two broad dimensions representing the shared effects across all depressive symptoms and all cognitive deficits, respectively. Limitations: Because of the cross-sectional design of this study, measures of association do not imply causal associations. Conclusions: Mechanisms underlying these two broad dimensions should be considered as important potential targets to improve quality of life of this vulnerable population.