Body mass index is associated with the antidepressant effects of intravenous ketamine in patients with depression

Jianqiang Tan Limei Gu Yanling Zhou Chengyu Wang Xiaofeng Lan Wei Zheng ^* Yuping Ning ^*

• Guangzhou Brain Hospital, Guangzhou Medical University, Guangzhou, China

Objectives: We aimed to explore the correlation between baseline body mass index (BMI) and the antidepressant properties of intravenous ketamine in patients with depression.Methods: We divided 135 patients diagnosed with either major depressive disorder (n=103) or bipolar disorder (n=32) into lower and higher BMI groups based on their baseline BMI. Patients with a lower BMI (BMI<24 kg/m²; n=92) were included in the lower BMI group, and those with a higher BMI (BMI≥24 kg/m²; n=43) were assigned to the higher BMI group. Each participant received six ketamine infusions. Antidepressant remission was determined using a Montgomery–Åsberg Depression Rating Scale (MADRS; total score of ≤10) within 24 hours after the sixth ketamine infusion on day 13. Antidepressant response was characterized by a ≥50% alleviation in the symptoms of depression at the same time point. Changes in symptoms of depression over time were assessed using a linear mixed model.Results: The antidepressant response rate in the higher BMI group (67.4%, 95% confidence interval [CI]: 53.5%–81.4%) was higher than that in the lower BMI group (51.1%, 95% CI: 41.3%–60.9%). In addition, the remission rate was higher in the higher BMI group (39.5%, 95% CI: 25.6%–55.8%) than in the lower BMI group (31.5%, 95% CI: 21.7%–41.3%). However, these differences were not significant (all P>0.05). The linear mixed models with covariates indicated a significant group-by-time interaction in the MADRS scores (F13, 1729=3.0, P<0.001). A significant correlation was found between baseline BMI level and the change in depressive symptoms on days 13 and 26 (all P<0.05). However, these correlations were not significant after Bonferroni correction or controlling for baseline depressive symptoms (all P>0.05).Conclusion: Our exploratory, post-hoc analysis of an open-label, single-arm study suggests that patients with depression and a higher baseline BMI may experience greater reductions in depressive symptoms compared with those with a lower baseline BMI after receiving six ketamine infusions.