The cumulative effect of cognitive engagement on cognitive function in middle‐aged adults

Background Engagement in cognitively stimulating work and activities is proposed to slow cognitive decline and delay dementia. Few studies have considered the cumulative effect of multiple cognitively engaging factors on cognitive function. In middle‐aged adults, this study aimed to determine the individual and combined associations of four cognitive engagement factors (i.e., educational attainment, occupational complexity, social engagement and cognitively stimulating leisure activities) with objectively measured cognitive performance and subjective ratings of cognitive function. Method A total of 1864 cognitively normal middle‐aged adults (aged 40‐70) enrolled in the Healthy Brain Project, a study with an online remote assessment platform seeking to understand midlife risk factors for dementia. Cognitive engagement factors were measured by online self‐report questionnaires. The Cogstate Brief Battery was used to measure cognitive domains of attention and memory. Subjective ratings of cognitive function were measured using the Cognitive Function Instrument. Result After controlling for age, sex, ethnicity and mood symptomatology, participants with high educational attainment or high occupational complexity performed significantly better on attention and memory tasks and reported less subjective ratings of cognitive concern. Higher participation in cognitively engaging leisure activities was significantly associated with better attention and memory performance, but not with subjective ratings of cognitive function. Social engagement was not associated with any outcome. The magnitude of these effects was small and trivial (Cohen’s d ranging from 0‐0.17). Participants were then classified into five groups based on whether they rated highly in 0‐4 cognitive engagement factors. Compared to participants with no factors, participants scoring highly in 2 or more factors performed significantly better on the memory tasks, with the magnitude of difference moderate (