Romain Colle, Delphine de Larminat, Samuel Rotenberg, Franz Hozer, Patrick Hardy, Céline Verstuyft, Bruno Fève, Emmanuelle Corruble

Pioglitazone, a selective agonist of the nuclear transcription factor peroxisome proliferator-activated receptor-gamma (PPAR-γ), prescribed for the treatment of type 2 diabetes, could have antidepressant properties. However, its potential to induce remission of major depressive episodes, the optimal clinical target for an antidepressant drug, is a matter of concern. Indeed, only one out of four double-blind randomized controlled trials show higher remission rates with pioglitazone than with control treatments. Hence, the main aim of this study was to perform a meta-analysis of the efficacy of pioglitazone for the treatment of MDE, focusing on remission rates. Four double-blind randomized controlled trials, comprising 161 patients with an MDE, were included in this meta-analysis. Pioglitazone was studied either alone (one study) or as add-on therapy to conventional treatments (antidepressant drugs or lithium salts). It was compared either to placebo (three studies) or to metformin (one study). Remission was defined by a Hamilton Depression Rating Scale score <8 after treatment. Pioglitazone could induce higher remission rates than control treatments (27% versus 10%, I(2)=17.3%, fixed-effect model: odds ratio [OR] =3.3, 95% confidence interval [95% CI; 1.4; 7.8], P=0.008). The OR was even higher in the subgroup of patients with major depressive disorder (n=80; 23% versus 8%, I(2)=0.0%; fixed-effect model: OR =5.9, 95% CI [1.6; 22.4], P=0.009) and in the subgroup of patients without metabolic comorbidities (n=84; 33% versus 10%, I(2)=0.0%; fixed-effect model: OR =5.1, 95% CI [1.5; 17.9], P=0.01). As compared to control treatments, results suggest six patients would need to be treated with pioglitazone in order to achieve the possibility of one more remission. Pioglitazone, either alone or as add-on therapy to conventional treatments, could induce remission of MDE, suggesting that drugs with PPAR-γ agonist properties may be true and clinically relevant antidepressants, even in patients without metabolic comorbidities.