CORTISOL SUPPRESSION BY DEXAMETHASONE IN THE HEALTHY ELDERLY - EFFECTS OF AGE, DEXAMETHASONE LEVELS, AND COGNITIVE FUNCTION

The effects of age, cognitive function (measured by Cambridge cognitiv e examination (CAMCOG) score); and dexamethasone (DEX) levels on the d examethasone suppression test were studied in 33 healthy older subject s (age 51-96). Three subjects (9.1%) were nonsuppressors and were olde r and had lower CAMCOG scores than the 30 suppressors. Significant cor relations were observed between natural log-transformed postdexamethas one cortisol (LNCOR) levels and age (r =0.40) and CAMCOG score (r =-0. 45). Multiple regression analysis was used to investigate the relation ship between LNCOR, age, DEX levels, and CAMCOG score. Age and DEX com bined explained 41% of the variance in LNCOR values, whereas CAMCOG sc ore and DEX levels explained 44% variance. As age and CAMCOG were high ly correlated (r =-0.72), both together did not significantly improve the fit of regression equation (47% variance explained). These finding s suggest an association between advancing age, impaired glucocorticoi d feedback, and cognitive dysfunction in healthy human subjects. Altho ugh any causal connection remains to be demonstrated, results would be consistent with the ''glucocorticoid cascade'' hypothesis of human ag ing.