Endocrine Abstracts

Context: The impact of abnormal cortisol secretion on cognitive functions in patients with mild autonomous cortisol secretion (MACS) remains uncertain.

Objective: To assess cognitive functions, determine serum brain-derived neurotrophic factor (BDNF) concentration in patients with MACS, and investigate the possible association between cognitive subdomains and BDNF after minimizing the impact of body mass index (BMI) and visceral adiposity.

Methods: We included 84 participants: 28 patients with MACS, 28 patients with nonfunctional adrenal adenoma (NFAA), and 28 control subjects matched for age, gender, BMI, visceral fat and educational level. The serum BDNF concentration of participants was measured. DSM-5-focused interviews and Montreal Cognitive Assessments (MoCA) were carried out by an experienced psychiatrist.

Results: Patients with MACS had a higher BDNF concentration than the NFAA (P=0.001), while that of patients with NFAA was lower than the controls (P=0.044). There was a positive correlation between BDNF concentration and BMI (r=0.227, P=0.038), waist circumference (r=0.248, P=0.042), abdominal fat (r=0.248, P=0.038), visceral fat (r=0.272, P=0.023), LDL concentration (r=0.486, P<0.001), whereas HDL concentration was negatively correlated with BDNF concentration (r=−0.349, P=0.003) in the whole group. Furthermore, there was a positive relationship between BDNF concentration and the largest adenoma diameter (r=0.311, P=0.020) and cortisol level after 1 mg overnight dexamethasone (DST) (r=0.292, P=0.032) in patients with adrenal adenoma (MACS and NFAA groups). BMI and cortisol level after 1 mg DST were found to be the parameters most associated with BDNF concentration in linear regression analysis. No significant difference was found in total MoCA scores between MACS and NFAA groups (P=0.967), whereas those were lower than the control group (P=0.016, P=0.008 respectively). When the cognitive subdomains were examined seperately, MACS group performed higher memory score than NFAA group, but lower language scores than both the NFAA and control groups (P=0.024, P<0.001). In the whole group, there was a positive correlation between BDNF concentration and memory (r=0.337, P=0.002). DST and language were also negatively correlated (r=−0.355, P=0.008), while DHEA-S level was positively correlated with attention (r=0.310, P=0.043), language (r=0.303, P=0.048), as well as visuospatial and executive functions (r=0.317, P=0.038) in the whole group.

Conclusion: Chronic low-grade hypercortisolism is associated with elevated BDNF concentrations, which might be a protective factor for memory function in patients with MACS compared to NFAA.