More evidence on proneurocognitive effects of add-on mirtazapine in schizophrenia

Enhancement of neurocognition is essential in the treatment of schizophrenia. In our previously reported six-week Randomized Controlled Trial (RCT) mirtazapine added to conventional antipsychotics improved not only negative, but also positive symptoms and neurocognition in difficult-to-treat schizophrenia. The present study aimed to explore whether a prolonged exposure to mirtazapine could further improve neurocognition.Completers of the RCT who were able and willing to proceed to the extension phase received open label mirtazapine for an additional 6 weeks. During the extension phase, both groups (i.e., patients who previously received mirtazapine and those who received placebo) and the whole population showed improvement on a number of neurocognitive tests. Patients who shifted to open label mirtazapine from placebo achieved in the six following weeks similar results as their initially mirtazapine-treated counterparts did during their first 6 weeks of mirtazapine exposure. Middle-term mirtazapine treatment (12 weeks) demonstrated an advantage over short-term mirtazapine treatment (6 weeks) on Stroop Dots time and Trail Making Test, part B, number of mistakes (t = − 2.562, p = 0.035 and t = − 2.42, p = 0.043, correspondingly).Mirtazapine added to antipsychotics consistently shows desirable effects on neurocognition. Lengthy treatment seems worthwhile. Mirtazapine may become a safe and cost-saving neurocognitive enhancer in schizophrenia, yet more studies are needed.

Research highlights
► Enhancement of neurocognition is essential in the treatment of schizophrenia.
► Mirtazapine added to antipsychotics shows some desired effects on neurocognition.
► Cognitive benefits of mirtazapine may affect mostly attention and executive functions.
► Prolonged treatment with adjunctive mirtazapine may yield additional benefits.