Relationship between insomnia phenotype and mild cognitive impairment in young and middle-aged patients with obstructive sleep apnea hypopnea syndrome

Abstract

Objective: To explore the relationship between insomnia phenotype and mild cognitive impairment (MCI) in young and middle-aged patients with obstructive sleep apnea hypopnea syndrome (OSAHS). Methods: Those patients admitted due to snoring and examined by polysomnography (PSG) in the Sleep Center of the Second Affiliated Hospital of Soochow University from January 2014 to January 2019 were screened. They were between 30 and 60 years old, and their cognitive function was assessed by the Montreal cognitive assessment (MoCA) and their sleep quality was assessed by the Pittsburgh sleep quality index (PSQI). According to the sleep apnea hypopnea index (AHI), the patients were divided into three groups: snoring group (AHI<5 times/h), mild/moderate OSAHS group (5≤AHI≤30 times/h) and severe OSAHS group (AHI>30 times/h). According to the results of PSQI score, the patients were further divided into non-insomnia group (PSQI total score<8) and insomnia group (PSQI total score≥8). The differences of parameters in different groups were compared, and the relationship between OSAHS insomnia phenotype and MCI was analyzed by binary logistic regression model. Results: A total of 2 098 patients with the average age of (42.7±8.4) years old and the average BMI of (26.3±3.6) kg/m(2) were enrolled in the study, including 398 cases in snoring group (including 254 cases in non-insomnia group and 144 cases in insomnia group), 754 cases in mild/moderate OSAHS group (including 446 cases in non-insomnia group and 308 cases in insomnia group) and 946 cases in severe OSAHS group (including 722 cases in non-insomnia group and 224 cases in insomnia group). In the mild/moderate OSAHS group, compared with the non-insomnia group, the proportion of women in the insomnia group was higher with lighter degree of obesity, lighter severity of illness and lighter degree of hypoxia (all P<0.05). In the severe OSAHS group, the general characteristics of insomnia patients were similar to those of the mild/moderate OSAHS group, and the MoCA score of the insomnia group was lower than that of the non-insomnia group [(26.3±2.7) vs (25.5±2.9) points] (P=0.001). In the evaluation of each item of PSQI, the total score and daytime dysfunction score of insomnia patients in mild/moderate OSAHS group and severe OSAHS group was higher than those in snoring group [(11.2±1.9) points, (12.8±2.2) points vs (10.9±2.1) points and (1.5±0.4) points, (1.9±0.8) points vs (0.5±0.5) points], but the score in sleep latency was lower than that in snoring group [(1.5±0.5) points, (1.5±0.5) points vs (2.1±0.8) points] (all P<0.05). After correcting the effects of OSAHS disease severity, hypoxia, awake times, education, age, gender, hypnagogue, BMI, smoking and drinking history, the risk of MCI in insomnia group of severe OSAHS patients was significantly higher than that of non-insomnia group by 49% (OR=1.49, 95%CI: 1.05-2.11). Conclusion: Insomnia phenotype is a common clinical phenotype of OSAHS, and it is a risk factor for MCI in young and middle-aged patients with severe OSAHS.