Is it important to take the co-occurrence of obesity and cigarette smoking into account in brain imaging studies in major depressive disorder?

Objective: To date, a small number of studies have investigated cortical thickness, cortical surface area, and subcortical volume abnormalities in first-episode, untreated patients with Major Depressive Disorder (MDD). The findings of previous studies are not entirely consistent. Previous studies did not match first-episode, untreated patients with MDD to controls regarding body mass index (BMI) and smoking, which could contribute to the inconsistency of results. The aim of the current study was to examine whether morphological abnormalities are present in first-episode and untreated MDD patients in comparison with well-matched controls, particularly concerning BMI and smoking status. Method: Twenty first-episode, untreated patients with MDD were enrolled in the study along with 20 healthy controls (HC) matched for age, education, sex, BMI and smoking status. Thickness and area of the cortex and subcortical volumes were measured using surface-based morphometry implemented with Freesurfer (v5.3.0). Results: There were no significant differences in cortical thickness, surface area, and subcortical volumes between the firstepisode, untreated patients with MDD and HC groups. Conclusion: This study provides evidence that cortical thickness, cortical surface area, and subcortical volumes might be normal in first-episode untreated patients with MDD in comparison with well-matched controls, particularly for BMI and smoking status.