Cortisol Reactivity to a physical stressor in Patients with Depression and Alzheimer's disease

Some prevalent mental disorders in the elderly, such as Alzheimer's disease (AD) and major depression disorder (MDD), are associated with chronic stress and consequently with possible dysregulation of hypothalamic–pituitary–adrenal (HPA) axis and cortisol levels in basal conditions or in the reactivity of an acute stressor. However, evidence of cortisol behavior after a physical stressor in patients with AD and MDD is scarce. OBJECTIVE: This study aimed to investigate the cortisol reactivity to a single session of physical exercise in patients with MDD and AD and compare it to healthy control (HC) older individuals. METHODS: HC individuals (n=10) and elderly with clinical diagnostic of MDD (n=08) and AD (n=13) were submitted to a single bout of aerobic exercise in a treadmill during 30 minutes of moderate intensity. Salivary cortisol was collected before and after acute stressor. A repeated-measure analysis of variance (ANOVA), spearman correlation, and linear regression were performed. RESULTS: The repeated-measure ANOVA revealed no interaction for cortisol on the moment×group [F(2.000, 28.000)=1.285; p=0.293] and no effect for group (F=0.323; p=0.727). However, a significant effect for moment [F(1.000, 28.000)=4.930; p=0.035] was found, with a decreased cortisol levels in postexercise for all groups. The effect size (ES) of cortisol reduction was small for patients with MDD (d=0.402) and trivial for patients with AD (d=0.166) and HC group (d=0.090). CONCLUSIONS: All participants show a decreased cortisol reactivity to a physical stressor, which can be associated with an impairment in coping with an acute stressor.