Lack of Efficacy of Simvastatin Adjunctive Therapy for Patients with Schizophrenia: A Meta-Analysis of Randomized Controlled Trials

Junyu Chen,1,* Yupei Yuan,2,* Ying Hu,1 Liang Liang1,3 1Department of Psychology, The Fourth Affiliated Hospital of Xinjiang Medical University, Urumqi, Xinjiang, People’s Republic of China; 2Department of Cardiology, Renmin Hospital of Wuhan University, Wuhan, Hubei, People’s Republic of China; 3Department of Psychiatry, Renmin Hospital of Wuhan University, Wuhan, Hubei, People’s Republic of China*These authors contributed equally to this workCorrespondence: Liang Liang, Department of Psychology, The Fourth Affiliated Hospital of Xinjiang Medical University, Urumqi, Xinjiang, People’s Republic of China, Tel +8609915848029, Email [email protected]: The adjunctive therapeutic potential of simvastatin in schizophrenia treatment has generated interest due to its anti-inflammatory and neuroprotective properties. This meta-analysis aims to assess the efficacy of simvastatin as an adjunct treatment for schizophrenia, synthesizing results from various controlled trials.Methods: We performed a comprehensive search of databases including PubMed, Embase, and the Cochrane Library for randomized controlled trials (RCTs) evaluating the efficacy of simvastatin as an adjunct therapy in patients with schizophrenia. The primary outcome measures were improvements in the Positive and Negative Syndrome Scale (PANSS) scores. Secondary outcomes included changes in overall clinical condition and level of functioning. Data were pooled using random-effects models, and heterogeneity was assessed through I² statistics.Results: The four RCTs included in the analysis represented 425 participants. The combined results demonstrated no significant advantage of simvastatin over placebo in reducing PANSS total scores with a pooled effect size (Standard Mean Difference, SMD) of − 0.36 (95% Confidence Interval, CI: − 0.82 to 0.11) at 1 month, and − 1.80 (95% Confidence Interval, CI: − 4.82 to 1.21) at 3 months, indicating minimal to no effect. Similarly, analyses of secondary outcomes showed no significant improvements in overall clinical condition and level of functioning. The studies exhibited low heterogeneity (I² = 0%).Conclusion: This meta-analysis provides evidence that simvastatin, used as adjunctive therapy, does not significantly improve the symptomatic outcomes of schizophrenia compared to placebo. Although simvastatin is well-tolerated, its role in enhancing antipsychotic treatment efficacy in patients with schizophrenia appears limited. These findings suggest that simvastatin should not be recommended as an adjunctive treatment in the clinical management of schizophrenia. Further research may explore the potential subgroups that could benefit from such treatment or identify the biological reasons for the lack of efficacy.Keywords: schizophrenia, simvastatin, adjunctive therapy, meta-analysis, randomized controlled trials, efficacy