In the United Kingdom, 14.6 million people reported having a disability in the year 2020–2021. Cognition may be one factor that contributes to disability, as previous studies have shown that cognitive abilities predict later health outcomes and prevalence of disability increases with decreasing cognitive function. Furthermore, studies have demonstrated a link between cognition and common psychiatric disorders, such as depression and anxiety. To our knowledge, no studies have examined the role of current mental health in the association between cognition and disability in a general population sample. The aim of this study was to examine the relationship between cognition, mental health and measures of disability/daily functioning in an online population sample. Our hypotheses were: 1) that lower cognitive performance would be associated with increased reported disability, and 2) that this association would be partly explained by current depression and anxiety symptoms.

The sample consisted of 3679 participants recruited from HealthWise Wales. Participants completed the Cardiff ONline Cognitive Assessment, a web-based battery of five tasks assessing processing speed, working memory, vocabulary, reasoning, and emotion identification. Disability was assessed using the World Health Organisation Disability Assessment Schedule (WHODAS). Real world measures of functioning were also included (currently employed, living with a partner, children and ever married). Current depression and anxiety symptoms were assessed using the Hospital Anxiety and Depression Scale (HADS). Linear and logistic regressions were conducted to assess the associations between cognitive performance and measures of disability/functioning. Structural equation modelling was performed to assess whether these associations could be partially explained by HADS scores, as well as measures of education and health/lifestyle factors.

Higher cognitive performance was associated with lower overall WHODAS scores (B=−0.1, SE = 0.01, P = 1 × 10–13), living with a partner (OR = 1.13, 95% CIs = 1.06–1.21, P = 4.3 × 10–4) and being in employment or education (OR = 1.22, 95% CIs = 1.13–1.33, P = 2.1 × 10-6). HADS scores partially explained the relationship between cognition and: 1) WHODAS (80%), 2) employment (63%) and 3) living with a partner (37%). In addition, smoking status explained 3% of the relationship between cognition and WHODAS.

Current symptoms of depression and anxiety partially explained the relationship between cognition and three measures of disability/functioning. Alleviating these symptoms may improve patients’ daily difficulties. Future research should establish the direction of causality of these associations.