Diurnal variation of cortisol in people with dementia: relationship to cognition and illness burden.

Cortisol patterns in nursing home residents with dementia are described and examined in relation to cognition and comorbid illnesses. Saliva was sampled 4 times in a 24-hour period (week 1) and at the same times 1 week later (week 2). In general, cortisol levels decreased from morning to evening, with 50% exhibiting a negative slope. In contrast, 38% of the participants had a relatively flat cortisol diurnal rhythm, and 7% exhibited an afternoon increase. The cortisol pattern was consistent between weeks 1 and 2 for 39% with a negative slope, 13% with a flat profile, and for 2% with an afternoon increase pattern. Cortisol rhythm was not statistically significantly related to cognition or illness burden. While this study contributes to the understanding of differences in the diurnal pattern of cortisol for older adults with dementia, more research is needed to understand the etiology of the differences and the biological mechanisms involved.