Minocycline adjunctive treatment to risperidone for negative symptoms in schizophrenia: Association with pro-inflammatory cytokine levels

Abstract Background We attempted to replicate the efficacy of minocycline, a second-generation tetracycline, as adjunctive therapy for the negative symptoms of schizophrenia, and to investigate its association with pro-inflammatory cytokine levels. Methods Seventy-five schizophrenia patients with negative symptoms entered a 3-month, double blind, randomized, placebo-controlled clinical trial. Subjects were assigned low dose (100 mg per day) or high dose minocycline (200 mg per day) or placebo combined with risperidone. The outcomes used the Scale for the Assessment of Negative Symptoms (SANS) and the Positive and Negative Syndrome Scale (PANSS)-negative subscale. We assessed three pro-inflammatory cytokines in serum: interleukin-1β (IL-1β), interleukin-6 (IL-6) and tumor necrosis factor–α (TNF-α). Results Subjects receiving high dose minocycline not only had greater improvements on the SANS total scores and PANSS negative subscale scores ( P P P Conclusions Schizophrenia patients showed a significant improvement in negative symptoms with the addition of minocycline to risperidone. Reducing pro-inflammatory cytokines may play an important role in the potential mechanism for efficacy.