Distinct Effects of Data Occupational Complexity On Cognitive Aging: Evidence for Dual Brain–Cognitive Reserve Pathways

Introduction : Occupational complexity is a major source of long-term cognitive stimulation across adulthood, yet its multidimensional effects on cognitive aging and their neural mechanisms remain unclear. This study examined how three dimensions of occupational complexity—data, people, and things—shape late-life cognitive performance, and whether brain reserve(BR) and cognitive reserve(CR) mediate these associations. Methods : A total of 3,754 retirees meeting sex-specific age eligibility criteria were recruited from the Beijing Aging Brain Rejuvenation Initiative completed a battery of multidomain neuropsychological assessments and standardized occupational history assessments coded using O*NET-based ratings.. A subsample of 851 participants also underwent structural MRI. Linear models, structural equation modeling, and voxel-/surface-based morphometry were used to test (1) dimension-specific associations with cognitive domains, (2) links to global and regional brain structure, and (3) dual-reserve mediation pathways. Results : Data complexity emerged as the primary protective dimension, independently predicting higher reasoning (β = 0.058), attention (β = 0.041), and reduced mild cognitive impairment(MCI) risk (− 5.7% after adjustment for education, p  < 0.05; −14.3% unadjusted, p  < 0.001). After accounting for data complexity, higher people complexity was associated with poorer working memory and language performance.. Things complexity, referring to demands related to tools and physical objects, showed no direct associations but demonstrated compensation via late-life leisure activities. Neuroimaging showed that data complexity was uniquely associated with larger gray matter volume in frontotemporal–limbic regions and higher CR. Mediation models revealed that data complexity protected cognition via both BR and CR, with mediation effects observed across multiple cognitive domains.. Conclusions : Occupational complexity, particularly data complexity, is associated with enhanced cognitive aging outcomes, including improved reasoning, attention, and reduced mild cognitive impairment (MCI) risk. Neuroimaging revealed that data complexity predicts greater frontotemporal–limbic gray matter volume and higher cognitive reserve. Mediation analyses suggested dual reserve pathways, with cognitive reserve mediating multiple cognitive domains, while brain reserve influenced hippocampal and temporal regions. These findings underscore the role of occupational environments in promoting cognitive health and mitigating late-life MCI risk.