The dexamethasone suppression test and sleep electroencephalogram in nonbipolar major depressed inpatients: A multivariate analysis

Background: The present study further examined relationships between postdexamethasone cortisol plasma values and sleep electroencephalogram (EEG) parameters. Methods: The dexamethasone suppression test (DST) and polysomnographic recordings were performed in a sample of 300 inpatients with primary major depressive disorder (MDD) (102 men and 198 women, mean age 44 +/- 12 years, range 20-74 years) consecutively admitted to Erasme Hospital (Brussels, Belgium) between 1981 and 1992. Results: The DST was abnormal in 40% of the sample. Postdexamethasone cortisol plasma values at 4:00 PM were significantly influenced by age, but not by gender. They were also significantly and positively correlated with weight loss, total scares on the Hamilton Depression Rating Scale, total scores on the Newcastle Scale, percentage of awakenings during sleep, and percent of stage 1. They were significantly and negatively correlated with percent of stage 2, slow-wave sleep, and REM sleep. Multiple regression analyses were conducted in two successive steps. First among clinical variables, only age and depressive symptom severity remained correlated with postdexamethasone plasma cortisol values. In the second step, with age and severity held constant, postdexamethasone plasma cortisol values were positively associated with amount of wake time and stage 1, and negatively with amount of slow-wave sleep. Conclusions: These findings provide further indirect support for an overarousal state in MDD with sympathoadrenal system hyperactivity and impaired sleep continuity. They also underline the importance of taking into account various clinical confounding factors in the interpretation of both DST and sleep EEG results. (C) 1998 Society of Biological Psychiatry

TSH RESPONSE TO TRH AND EEG SLEEP IN NON-BIPOLAR MAJOR DEPRESSION - A MULTIVARIATE APPROACH

The TSH response to TRH and selected sleep EEG variables were studied in a homogeneous sample of 280 non-bipolar major depressed inpatients (95 males and 185 females). The TSH response to TRH was blunted in 28% of the sample. Delta max TSH was correlated negatively with age, Hamilton rating scale, Newcastle scale, percentage of wake, and positively with basal TSH, percentage of stage II, slow wave sleep, REM sleep and REM latency. Delta max TSH was also lower in male patients and in patients suffering from an endogenous or a psychotic subtype of major depression. Basal TSH was only correlated negatively with the Newcastle score. In view of intercorrelations between all these variables, and because of the confounding effect of age, gender and severity on both the TSH response to TRH and sleep EEG variables, a multiple regression analysis was performed and demonstrated that basal TSH and gender were the two variables with the highest contribution to the Delta max TSH variance, followed by age and the presence of psychotic symptoms. When controlling strictly for these significant effects, correlation with the severity or with the endogenous character of depression, and with sleep EEG parameters disappeared