Associations between cognition and functioning: examining the role of mental health in clinically ascertained and population-based samples

Background Cognitive function is a significant predictor of daily functioning in the population, yet the extent to which common mental health symptoms account for this relationship remains unclear. Aims This study aimed to examine the relationship between cognition, mental health and functioning across two cohorts. Method Participants were recruited from an online population cohort, HealthWise Wales ( N = 3679), and a psychiatric cohort, the National Centre for Mental Health (NCMH, N = 1036), to complete a cognitive battery and the World Health Organization Disability Assessment Schedule (WHODAS). We assessed the associations between cognitive performance and the WHODAS, as well as two measures of life functioning: current employment and cohabitation with a partner. We examined the role of current mood, psychiatric and neurodevelopmental history and lifestyle factors using linear and logistic regression. Results Higher cognitive performance was associated with fewer functional difficulties on the WHODAS (HealthWise Wales: B = −0.12, 95% CI (−0.15,−0.09), P < 0.001; NCMH: B = −0.1, 95% CI (−0.13,−0.08), P < 0.001), being in employment or education (HealthWise Wales: odds ratio 1.22, 95% CI (1.11,1.34), P < 0.001; NCMH: odds ratio 1.31, 95% CI (1.19,1.46), P < 0.001) and living with a partner (HealthWise Wales only: odds ratio 1.19, 95% CI (1.06,1.32), P = 0.003). Higher levels of depression and anxiety symptoms were consistently associated with reduced functioning across all analyses. The relationship between cognition and functioning remained significant but attenuated after accounting for these symptoms. Conclusions Cognitive function was associated with functioning in both clinical and population-derived samples. Current symptoms of depression and anxiety play a key role in this relationship. Both cognitive function and common mental health problems may be potential intervention targets to alleviate daily difficulties.