Response variability of salivary cortisol among older adults under psychological stress.

In this study, a quasi-experimental design with repeated measures was used to compare anxious (n = 129) and nonanxious (n = 186) older adults on the cortisol secretion rate attributable to an experimental stressor. Our results support the hypothesis that a first-order longitudinal factor model appropriately describes the cortisol concentration in three saliva samples collected at two experimental times. The model tested explained between 82.6 and 98.0% of the variance in cortisol concentration of the respondent's saliva samples at T1, and between 55.4% and 78.4% at T2. In the nonanxious group ((State-Trait Anxiety Inventory) STAI < 42), the magnitude of the experiment-related cortisol reactivity was, respectively 51 and 33% higher than the respondent's baseline reactivity level at both T1 and T2. By contrast, in the anxious group (STAI ≥ 42), our results showed no significant gradient in the magnitude of the cortisol reactivity at either time. This result was interpreted to be in agreement with the helple...