Correlations Between Endocrine Hormones and Cognitive Function in Patients with Obesity: a Cross-sectional Study.

Background: Obesity not only affects physical and mental conditions, but also influences cognitive function. Endocrine hormones may influence the risk of obesity and severe obesity. Our study investigated the influences of changes in levels of endocrine hormones on cognitive function in patients with obesity and severe obesity.

Methods: We used the MATRICS Consensus Cognitive Battery (MCCB) to evaluate cognitive function in the groups of healthy control (HC), obesity (OB), and severe obesity (SOB). We detected the levels of endocrine hormones and cortisol at 8:00 am in the three groups. We statistically analyzed differences in cognitive function and levels of endocrine hormones among the three groups, and performed linear correlation analysis of cortisol level and cognitive function. Using mediation analysis, we assessed the influences of body mass index (BMI) on endocrine levels and cognitive function.

Results: Our findings revealed that OB and SOB groups exhibited a lower level of cortisol than HC group. Among the three groups, we found significant differences in verbal learning (F = 4.433, P = 0.014), social cognition (F = 4.778, P = 0.010), and total cognition (F = 2.989, P = 0.008). After post hoc Bonferroni correction, we noted that SOB group had worse scores in the above-mentioned three areas than OB and HC groups. Moreover, except for working memory and visual cognition, we identified that the degree of cognitive impairment in SOB group was more severe than that in OB group. In our study, mediation analysis showed a mediating effect of BMI on cortisol level and verbal learning. We also found correlations between cortisol level and attention/alertness (r = 0.277, P = 0.003), between cortisol level and verbal learning (r = 0.205, P = 0.030), and between BMI and verbal learning (r =  - 0.192, P = 0.043).

Conclusion: In our study, patients in both OB and SOB groups experienced a widespread cognitive impairment. We also found that patients with severe obesity had more severe cognitive impairment. Cognitive impairment could be mediated by abnormal cortisol metabolism, and BMI could be a mediating factor in regulation of cortisol level.