Objective: The prevalence of and morbidity associated with treatment-resistant depression has motivated the exploration of treatment alternatives. In this study, quetiapine was compared with lithium in the augmentation of treatment-resistant depression.
Research design and methods: Open-label, comparative study in 20 patients with major depression who had failed to respond after 4 weeks of treatment with an antidepressant at the maximal recommended dose. Patients were randomised to either lithium or quetiapine in addition to the maximally dosed antidepressant and any other concurrent medications. Lithium was initiated at 600 mg/day; quetiapine was titrated to 400 mg by day 7.
Results: Depression, measured by the Hamilton Depression Rating Scale (HAM-D), significantly improved from baseline in both quetiapine (F(1,90) = 25.11, p < 0.0001) and lithium (F(1,90) = 34.54, p < 0.0001). The difference in improvement between the two groups began at day 14 and was seen at all timepoints thereafter (p < 0.05), with the quetiapine group showing greater improvement than the lithium group. In the Montgomery-Asberg Depression Rating Scale (MADRS) analysis, the difference between the quetiapine and lithium group was significant from day 28 onwards (p < 0.05), with subjects improving more in the quetiapine group than the lithium group. The treatment by week interaction showed a significant difference overall between the two groups (p < 0.0001). The severity of psychomotor retardation showed a significant decrease in the Widlocher Psychomotor Retardation Scale scores in the quetiapine (p < 0.0001) and lithium (p < 0.0001) groups.
Conclusions: In this pilot study, quetiapine was an effective augmenting agent in treatment-resistant depression.