Can low brain-derived neurotrophic factor levels be a marker of the presence of depression in obese women?

OBJECTIVE: Depression is a common condition in obese women that can result in severe impairment of their physical and social functioning. A deficiency of brain-derived neurotrophic factor (BDNF) is involved in the mechanism of depression. The aim of this study is to investigate whether BDNF levels differ between obese female patients and healthy controls and whether BDNF levels alter with affective states in depressive obese women. METHODS: The study group included 40 obese, 40 preobese, and 40 normal weight women. BDNF levels were measured with an enzyme-linked immunosorbent assay in patient and control groups. For identifying the depression and anxiety status, Beck Depression/Anxiety Inventories were used; and for the evaluation of cognitive functions, the mini-mental state examination was used. RESULTS: BDNF levels were significantly lower in obese patients compared to the control group (P<0.01). BDNF levels were significantly lower in obese patients with depression compared to the obese patients without depression (P<0.05). The Beck Depression Inventory showed a negative correlation with BDNF (r=−0.044; P<0.01) and a positive correlation with the Beck Anxiety Inventory (r=0.643; P<0.001), vitamin B12 levels (r=0.023; P<0.001), and insulin levels (r=0.257; P<0.05) in obese patients. When receiver operating characteristic curve analysis was used to analyze the suitability of BDNF to identify depression in obese women, the area under the curve for BDNF, 0.756, was found to be significant (P=0.025). BDNF levels lower than 70.2 pg/mL were associated with a higher prevalence of depressive symptoms. CONCLUSION: The results of our study suggest that the decrease in BDNF levels can be used as a marker for depression diagnosis in obese patients.