Serum levels of brain derived neurotrophic factor (BDNF) in severe obstructive sleep apnea syndrome (OSAS): Effects of CPAP treatment

Abstract

Background: OSAS is characterized by a chronic intermittent hypoxia (CIH) and sleep fragmentation. Polysonnography is the standard diagnostic test. New biomarkers have been proposed. The BDNF is a key mediator of neuronal and synaptic plasticity in cognitive functions. Experimental studies demonstrate changes of serum levels of BDNF following CIH Objectives: To determine serum level of BDNF in patients with severe OSAS compared with a control group and its relationship to neurocognitive function. Changes in BDNF serum levels in OSAS patients after CPAP treatment. Methods: Serum BDNF and the Montreal Cognitive Assestment (MoCA) are evaluated in 12 patients with newly diagnosed severe OSAS and in 8 healthy patients (control group). In OSAS patients serum BDNF and MoCA were reassessed after 45 days of CPAP treatment. Results: BDNF in OSAS patients was significantly higher compared to control group (p=0.01) and showed a positive correlation with ODI (p=0.01, r=0.6). Serum BDNF had a decreasing trend after CPAP treatment. Before the treatment, MoCA scores were lower in OSAS patients than controls and are positively correlated with serum BDNF levels (p=0.02, r=0.57). MoCA is normalized by CPAP therapy Conclusions: OSAS patients showed higher serum BDNF levels and lower MoCA scores compared to controls. The positive correlation between BDNF values and MoCA might reveal a peculiar BDNF-mediated neuroprotective mechanism against neuroinflammation induced by hypoxia.