REM DENSITY, REM LATENCY AND THE DEXAMETHASONE SUPPRESSION TEST AS PREDICTORS OF TREATMENT RESPONSE IN DEPRESSED OLDER ADULTS.

Abstract

The purpose of this study was to investigate whether biological variables could predict how older adults would respond to different types of treatment for depression. Fifty-six adults over the age of sixty-five, diagnosed with major depression (DSM III criteria) were assigned to one of four treatment conditions: group Cognitive Behavior Therapy with alprazolam or placebo medications, and minimal support therapy with alprazolam or placebo medication. Before and after treatment, REM latency and REM density were measured by polysomnograph in the sleep laboratory and the Dexamethasone Suppression Test (DST) was administered. Depression was measured by weekly by the Hamilton Depression rating Scale and the Beck Depression Inventory. Subjects presented with normal (i.e. nondepressed) values on REM latency and REM density. Thirty five percent of subjects were DST nonsuppressors, a similar percentage to that found in other studies of depressed subjects, but mean DST for the whole group was below the selected cutoff of 4 mcg/dl. The expected correlations among the biological variables and between these variables and baseline depression levels were not found. It was concluded, therefore, that depression in this group of subjects was not characterized by biological abnormalities. Multiple regression analyses of baseline variables and depression scores at mid and end of treatment and at followup indicated that initial depression levels and DST predicted later depression levels for subjects who received Cognitive Behavior Therapy, regardless of medication assignment. Low baseline DST levels were associated with good response to psychotherapy, confirming the findings of previous studies. Sleep variables were not predictive of response to treatment at any time point.