Objective: To assess the association of early morning serum cortisol with cognitive performance and brain structural integrity in community-dwelling young and middle-aged adults without dementia. Methods: We evaluated dementia-free Framingham Study (Generation 3) participants (mean age 48.5 years; 46.8% men), who underwent cognitive testing for memory, abstract reasoning, visual perception, attention, and executive function (n= 2231), and brain MRI (n=2018) to assess total white matter, lobar gray matter, and white matter hyperintensity volumes and fractional...