Effects of adjunctive antidepressant therapy with quetiapine on clinical outcome, quality of sleep and daytime motor activity in patients with treatment-resistant depression

Objective: To investigate the effects of antidepressant therapy plus quetiapine on major depression, motor activity, daytime sleepiness and quality of sleep. Methods: Patients (N = 27) with major depressive disorder received a standard antidepressant treatment (Venlafaxine, Escitalopram) plus flexible dose of quetiapine. Patients' depression was monitored with HAM-D-21, motor activity was continuously measured with actigraphy and sleep parameters with the Pittsburgh Sleep Quality Index (PSQI) over 4 weeks. Results: Whereas depression, quality of sleep and daytime sleepiness showed a significant improvement over 4 weeks, change of daytime motor activity was significant only between the wash out period and the last 2 days of the study. Repeated measures of variance indicate an independent influence of quetiapine on improved depression, motor activity and sleep. While we found only a mild decrease of daytime sleepiness during the first week of treatment, the further decline of daytime sleepiness got significant after 2 weeks of treatment with quetiapine, even at high mean daily doses and despite the sedative effects of quetiapine. Conclusions: Antidepressant treatment plus quetiapine is possibly a suitable treatment strategy to improve clinical depression, quality of sleep and motor activity. Future research is needed to understand the pharmacological interactions between antidepressants and quetiapine in major depression.