LONGITUDINAL-STUDY OF BASAL CORTISOL-LEVELS IN HEALTHY ELDERLY SUBJECTS - EVIDENCE FOR SUBGROUPS

A group of 51 healthy elderly volunteer subjects participated in a 3- to 6-year longitudinal study of basal cortisol levels. Once per year b asal cortisol levels were examined using hourly sampling over a 24-h p eriod. Analyses of three cortisol measures (last measure obtained, mea n cortisol levels across years, and the cortisol slope) revealed that the slope of the regression line measuring cortisol levels at each yea r was the most predictive measure of cortisol secretion over the years in this elderly population. Cortisol levels were shown to increase wi th years in one subgroup, to decrease in another, and to remain stable in a third. The age of the subjects was not related to either cortiso l levels or to the pattern of change in cortisol secretion over years. Free and total cortisol levels were highly correlated and the groups did not differ with regard to plasma corticosteroid binding globulin. No group differences were observed for weight, height, body mass index , pulse, blood pressure and glucose. However, significant group differ ences were reported for plasma triglycerides levels as well as high de nsity lipoproteins levels. Positive correlations were reported between the obsession/compulsion subscale of the SCL-90 questionnaire and the cortisol slope of subjects. Finally, previously reported group differ ences in neuropsychological performance are summarized. Thus, there ex ists considerable variation in hypothalamo-pituitary-adrenal function amongst aged humans. These results are consistent with recent animal s tudies showing the existence of subpopulations of aged rats which diff er in hypothalamo-pituitary-adrenal activity and cognitive efficiency.