Objective To analyze the correlations of serum levels of brain-derived neurotrophic factor (BDNF), malondialdehyde (MDA), endothelin-1 (ET-1) and heat shock protein 70 (HSP-70) with cognitive dysfunction in patients with obstructive sleep apnea hypopnea syndrome (OSAHS).

Methods A total of 132 OSAHS patients were selected as the study subjects, and another 90 healthy individuals who underwent physical examination during the same period were chosen as control group. According to the severity of the condition, OSAHS patients were divided into mild group (n=43), moderate group (n=50) and severe group (n=39). Serum levels of BDNF, MDA, ET-1 and HSP-70 were compared among different groups. Cognitive function was assessed using the Montreal Cognitive Assessment (MoCA) scale and Mini-Mental State Examination (MMSE). The correlations of cognitive dysfunction, serum levels of BDNF, MDA, ET-1 as well as HSP-70 with disease severity in OSAHS patients were analyzed. Based on MoCA and MMSE scores, OSAHS patients were categorized into cognitive dysfunction group and non-cognitive dysfunction group. Multivariate Logistic regression analysis was used to screen for risk factors of cognitive dysfunction in OSAHS patients.

Results The serum BDNF level, MMSE score and MoCA score in the severe group were significantly lower than those in the mild and moderate groups, while serum MDA, ET-1 and HSP-70 levels were significantly higher (P < 0.05). In the cognitive dysfunction group, the proportion of low education, severe disease, body mass index, serum levels of MDA, ET-1 and HSP-70 were significantly higher than those in the non-cognitive dysfunction group, while serum BDNF level was significantly lower (P < 0.05). Serum BDNF level was negatively correlated with cognitive dysfunction, whereas serum MDA, ET-1 as well as HSP-70 levels and disease severity were positively correlated (P < 0.05). Low education, high BMI, high levels of MDA, ET-1 as well as HSP-70 and low BDNF level were risk factors for cognitive dysfunction in OSAHS patients (P < 0.05).

Conclusion In OSAHS patients, serum MDA, ET-1 and HSP-70 levels are increased, while serum BDNF level are decreased. Serum levels of MDA, ET-1, HSP-70 and BDNF are closely related to the occurrence of cognitive dysfunction in OSAHS patients.