Cognitive functions and the brain-derived neurotrophic factor in patients with mild autonomous cortisol secretion

Abstract

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 association between cognitive subdomains and BDNF. Methods We prospectively recruited 84 participants: 28 patients with MACS, 28 patients with nonfunctional adrenal adenoma (NFAA), and 28 control subjects matched for age, gender, body mass index (BMI), visceral adiposity 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 serum BDNF concentration than the NFAA (p = 0.001), while that of patients with NFAA was lower than the controls (p = 0.044). Linear regression analysis revealed BMI and morning cortisol after overnight 1 mg dexamethasone (DST) were mostly associated with BDNF (p < 0.05). No significant difference was found in MoCA scores between MACS and NFAA groups (p = 0.967), whereas those were lower than the control group (p = 0.004). When the cognitive subdomains were examined seperately, MACS group performed higher memory score than NFAA (p = 0.045), but lower language scores than both the NFAA (p = 0.024) and control groups (p < 0.001). In the whole group, BDNF concentration was positively correlated with memory score (r = 0.337, p = 0.002), whereas DST and language score were negatively correlated (r = -0.355, p = 0.008). Conclusion Low-grade hypercortisolism is associated with elevated BDNF concentrations, which may be a protective factor for memory function in patients with MACS relative to those with NFAA.