Effect of Curcumin Supplementation on Schizophrenia Treatment: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Abstract

Negative symptoms pose a significant burden in patients with schizophrenia; currently, there are no specific pharmacological therapies available to helping address this problem. Pilot studies suggest a promising role of curcumin as an adjunct to standard treatment for negative symptoms management, but the totality of clinical evidence remains to be comprehensively assessed. We aimed to perform a systematic review and meta-analysis of randomized controlled trials (RCTs) to provide a comprehensive summary of the evidence regarding the effects of curcumin on symptoms in patients with schizophrenia and other psychotic disorders. We performed a systematic search in Pubmed, Scopus, Web of Science, and Cochrane Library from inception to May 2024; no language restriction was applied. Only randomized controlled trials using curcumin as an intervention were included. The certainty of the evidence (CoE) was measured using the GRADE approach. After screening 647 articles and full-text review, four studies were included, all interventions were in patients with schizophrenia. The use of curcumin showed no significant effect on positive (SMD -0.33, 95% CI [-0.76; 0.09], CoE: Low) and total symptoms (SMD -0.47, 95% CI [-1.08; 0.14], CoE: Very low), but a statistically significant decrease on negative symptoms (SMD -0.37, 95% CI [-0.70; -0.03], CoE: Low) and general psychopathology (SMD -0.68, 95% CI [-1.18; -0.17], CoE: Very low) was found. No significant differences were observed for depression (CoE: Very low). Curcumin supplementation as an adjunct to standard treatment may result in a small decrease in negative symptoms in patients with schizophrenia. However, it may have little to no effect on positive symptoms. The evidence for total symptoms, depression and general psychopathology was very uncertain. Due to the low certainty of the evidence, our confidence in these effect estimates is limited, and implementation into clinical practice is not yet recommended. Future studies should be focused on unravelling the molecular targets of negative symptoms regulation to generate specific therapies.

Keywords: Curcumin; Functional food; Schizophrenia; Systematic review.