AbstractBackgroundCognitive decline is increasing in prevalence worldwide and poses a heavy burden on society. Sociodemographic factors and health behaviors associated with cognitive decline have been described. While physical exercise has been reported as a protective factor, less education acts as a risk factor. Conversely, work activities associated with lower educational levels are frequently more physically demanding. Few studies have analyzed the impact of work activities on cognition.MethodWe used data from the Brazilian Longitudinal Study of Aging, with a sample of 8,336 complete cases. Linear regression was performed to assess the impact of physical demand at work on cognitive performance, as measured by a global cognitive score composed of temporal orientation, verbal fluency, and memory tests. Work activities were classified by the question “How would you describe physical demand of the job you had most of your life?”, with the following possible answers: “mostly sitting”, “mostly standing or walking”, “some physical effort” and “intense physical effort”. Age, sex, marital status, educational level, household income per capita, number of comorbidities, smoking and alcohol consumption, and level of physical activity were used as covariates.ResultWhen compared to a “mostly sitting” type of work (e.g., office job), a “mostly standing or walking” (e.g., security worker) job did not show any difference in cognitive performance (β = ‐0.03, p = 0.089). On the other hand, a “some physical effort” job (carrying weights or using tools, such as nurse or carpenter) and an “intense physical effort” job (carrying heavy weights, such as miner or construction worker) showed an increasingly worse cognitive performance (respectively, β = ‐0.09, p = 0.000 and β = ‐0.11, p = 0.000).ConclusionAlthough sedentarism has been shown to be associated with a worse cognitive performance and increased dementia risk, physically demanding jobs do not appear to be beneficial. Meanwhile, work stress associated with these activities might exert a negative effect on cognition independent of educational level and physical exercise unrelated to work. Some data suggest mentally demanding jobs, on the contrary, can be beneficial. With development of new technologies, moving from physical work into mental work can potentially reduce dementia risk.