Anxiety in Obese Individuals is Associated With Leptin Concentration

Background: Obese individuals suffer from increased incidence of depression and anxiety. Recently research has suggested that appetite regulating hormones may modulate emotions. Although contradictory thus far, some studies suggest that leptin may play a role in mediating anxiety. Obese individuals have higher leptin concentrations primarily due to augmentation of adipose tissue. In addition to leptin’s role in regulating appetite, leptin receptors are also present in non-hypothalamic regions such as the amygdala and hippocampus that modulate emotional function. Obesity is well-known to confer leptin resistance, bringing into question its potential to contribute to emotional dysregulation. Hypothesis: The following hypotheses were examined: (1) Obese subjects (OB) will have higher anxiety than normal weight controls (NW); (2) Leptin will be positively associated with anxiety independent of obesity status. Methods: Bariatric candidates (OB) (n=71) (Mean age = 44.6 years and Mean BMI = 43 kg/m2 ) underwent pre-surgical assessment. Normal weight controls (NW) (n=30) were assessed for comparison. State anxiety was measured using the State-Trait Anxiety Inventory. Fasting blood samples were taken to analyze serum leptin. Difference in anxiety between OB and NW was analyzed using ANOVA. Logistic regressions were performed to ascertain the effects of leptin with and without obesity status on the likelihood that subjects would have high anxiety. Results: There was a significant correlation between anxiety and leptin (r=.202, p=.004). Anxiety was higher for OB compared to NW (F=7.446, p=.008). Logistic regression for fasting leptin was statistically significant (X2=8.600, p=.003); explaining 12% of the variance in anxiety and correctly classifying 65.3% of the cases. Increasing leptin was significantly associated with increasing likelihood of anxiety. The model for leptin and obesity status was statistically significant (X2=9.566, p=.008). When leptin was adjusted for, the association between the anxiety and obesity was no longer significant. This shows that the relationship between obesity, leptin and anxiety was present in the obese, bariatric candidate sample but not in the NM control group. Conclusion: Bariatric candidates have higher anxiety compared to NW counterparts. The association between leptin and anxiety is not independent of obesity status as it was observed in the obese, bariatric candidate group only. While the cause of anxiety is likely multifactorial further, the association between anxiety and leptin should be further explored. Acknowledgements: This study was supported by NIH grants H75/CCH224064, HL04297 and HL64913 and approved by the IRB at the University of North Texas Health Science Center.