Usefulness of mirtazapine and SSRIs in late-life depression: post hoc analysis of the GUNDAM study

Objective Mirtazapine and SSRIs are widely prescribed as first-line agents for late-life depression. However, evidence for these drugs is mostly based on non-elderly patients. Therefore, we reanalyzed a randomized controlled trial of mirtazapine versus SSRIs for depression in a sub-population of late-life patients. Methods A randomized controlled trial was conducted with 141 patients, of whom 41 were elderly, and 100 were non-elderly. This study compared SSRIs and mirtazapine in late-life depression, examined late-onset and early adult-onset separately and compared elderly and non-elderly patients for each drug. Treatment effects and adverse events were assessed using the Hamilton Depression Rating Scale and the Udvalg for Kliniske Undersøgelser Side Effect Rating Scale, respectively. Results In late-life depression, mirtazapine showed faster HAM-D total score improvement (3.3 points difference, p = 0.021) and higher improvement in insomnia (1.7 points difference, p = 0.001) and appetite (1.2 points difference, p = 0.020). Similar findings were observed for late-onset depression with the HAM-D total score (4.3 points difference, p = 0.007) and appetite (0.9 points difference, p = 0.004), favoring mirtazapine. Depressive symptoms were generally less improved in late-life depression than in non-late-life depression. Regarding the effect of mirtazapine on appetite, late-life depression showed greater improvement (0.7 points difference, p = 0.008). Nausea and micturition disturbances were more common with SSRIs in late-life depression than in non-late-life depression. In contrast, somnolence was less common in late-life depression with mirtazapine. Conclusion The potential usefulness of mirtazapine in elderly patients was demonstrated. The results also showed differences in the treatment response to SSRIs and mirtazapine between elderly and non-elderly patients.