Associations between cognitive function and naturally occurring daily cortisol during middle adulthood: timing is everything.

<p><b>OBJECTIVES: </b>We examined associations between cognitive function (CF) and the naturally occurring daily cortisol levels using data from the Midlife in the United States survey and the National Study of Daily Experiences.</p><p><b>METHODS: </b>A national sample of 1,500 (mean age = 57 years; range = 33-84, 56% female) completed a phone-based battery of cognitive tasks and 3-6 months later provided saliva samples upon waking, 30 min after waking, at lunch time, and at bedtime on 4 consecutive days.</p><p><b>RESULTS: </b>Higher CF, particularly executive function, was associated with healthier daily cortisol profiles, including a steeper diurnal cortisol slope, higher morning cortisol levels, and lower afternoon and evening cortisol levels.</p><p><b>DISCUSSION: </b>The results indicate that better CF is associated with healthier profiles of naturally occurring cortisol and underscore the importance of the timing of cortisol sampling.</p>