Efficacy of soy isoflavones for depressive symptoms of the climacteric syndrome

ObjectivesTo evaluate the efficacy of soy isoflavones extract (SIE) in the treatment of depressive symptoms in women with climacteric syndrome.MethodsPlacebo-controlled double-blind randomized study with 84 climacteric outpatients attended in the Lauro Wanderley University Hospital in Joao Pessoa (PB), Brazil. In the assessment of the depressive symptoms, the Brazilian version of the Center of Epidemiologic Studies of Depression (CES-D) scale was used, on the pre-treatment visits (VT1), 8th (VT2) and 16th (VT3) weeks after treatment. The experimental group (EG) received the daily dose of 120 mg SIE and the control group (CG), placebo. The primary efficacy measure was the comparison of the percent reductions in the CES-D scores from VT1 to VT3 between EG and CG (t-test, p < 0.05). The security analysis consisted of laboratory and clinical evaluation of adverse events.ResultsThe CES-D scores in the EG reduced from 12.5 (±4.2) in VT1 to 9.9 (±3.6) in VT2 (VT2 < VT1, p = 0.001) and 8.2 (±3.8) in VT3 (VT3 < VT2, p = 0.007), while the CG, reduced from 13.0 (±4.8) in VT1 to 10.1 (±4.1) in VT2 (VT2 < VT1, p = 0.001) and 9.4 (±4.1) in VT3 (VT2 = VT3, p > 0.05). In the outcome of the 16-week treatment (VT1–VT3), reduction of the CES-D scores did not reach statistical significance between groups. There were no clinically relevant adverse events attributable to the treatment.ConclusionsThe treatment with soy isoflavones did not produce significant reduction on the depressive symptoms of a predominantly affective nature evaluated in this study. The symptomatic reduction initially observed was apparently a nonspecific response to treatment, corroborating evidences from the literature on the placebo phenomenon in treatment of the climacteric syndrome.