Relationship among selected neuroendocrine and sleep measures in patients with recurrent depression

Relationships among cortisol, TSH, and EEG sleep variables were examined in a group of 23 outpatients with recurrent unipolar depression at initial assessment prior to treatment for an acute major depressive episode. Blunted TSH responses were found in 39% of the sample (criteria of less than or equal to 7 microU/ml); cortisol nadir of greater than 2.5 micrograms% was rated in 41% of the group; and a reduced REM latency (less than or equal to 60 min) was measured in 57% of the group. Although almost all patients demonstrated abnormalities in at least one major neuroendocrine or sleep category, this preliminary analysis failed to find significant associations among these multiple biologic variables. Further studies on this so-called lack of association in a larger group of recurrent depressives is indicated. At this point caution is urged in assuming that biologic measures will identify a homogeneous group of severely depressed patients.