BMI, sex, and antidepressant response.

BACKGROUND: Investigators have examined potential mechanisms for the observed differences between men and women in antidepressant response. However, to date no studies have measured the impact of body mass index (BMI) on men's and women's response to selective serotonin re-uptake inhibitors or placebo.
METHODS: We evaluated the response to antidepressants and placebo of 274 non-obese (BMI<30) and obese (BMI>30) depressed outpatients participating in Phase II-IV clinical trials. After categorizing men and women into their respective BMI groups, we measured the amount of change each group experienced from baseline to the final visit using the HAM-D-17 and MADRS ratings scales.
RESULTS: Compared to women, men assigned to an antidepressant had a significantly lower mean total change on both the HAM-D-17 [non-obese, F(1,88)=5.292, p=0.024; obese, F(1,39)=7.040; p=0.012] and the MADRS [non-obese, F(1,66)=4.049, p=0.048; obese, F(1,27)=8.631, p=0.007]. In fact, obese men showed the smallest difference in antidepressant-placebo response. The results of the ANCOVAs indicated significant main effects of treatment (placebo vs. antidepressant), sex of the patient, and BMI category as well as a significant interaction between all three variables. LIMITATIONS: Patients participating in clinical trials are not necessarily representative of the entire depressed population. In addition, our results include only SSRIs, not other antidepressants.
CONCLUSION: Compared to the rest of the depressed sample the subgroup of depressed obese men (n=40) showed little or no therapeutic benefit with SSRI antidepressants. Although our findings may have important clinical implications, replication and further research is warranted in order to understand their underlying mechanisms and their pertinence to dosing strategies.