Severe obstructive sleep apnea in patients with chronic obstructive pulmonary disease is associated with an increased prevalence of mild cognitive impairment

Abstract

BackgroundChronic obstructive pulmonary disease (COPD) and obstructive sleep apnea (OSA) are associated with mild cognitive impairment (MCI). However, this association is unclear. This study aimed to assess the prevalence of MCI in patients with overlap syndrome, determine whether OSA increases the risk of MCI in patients with COPD, and investigate the potential mechanisms for this association. MethodsParticipants with stable Global Initiative for Chronic Obstructive Lung Disease (GOLD) stage 2–4 COPD and complaints of snoring in 2016–2018 were enrolled in this cross-sectional observational study. All were free of asthma, acute left-sided congestive heart failure, unstable coronary heart disease, uncontrolled hypertension, diabetes, encephalitis, and epilepsy. They underwent pulmonary function tests and overnight polysomnography and completed the Montreal Cognitive Assessment (MoCA). MCI was defined by an MoCA score of <23, while OSA was defined by an apnea-hypopnea index (AHI) of ≥15 per hour. The association between MCI, demographics, and comorbidities was tested by logistic regression analysis with adjustment for confounders. Sleep-disordered breathing measures were investigated as potential mechanisms underlying this relationship. ResultsMCI was significantly more common in patients with overlap syndrome than in those with COPD (40.6% [43/106] vs 24.6% [42/171]). After adjustment, severe OSA was an independent contributor to MCI (odds ratio, OR 2.27; 95% confidence interval, CI 1.12–4.62). Increased percent of night-time spent with oxygen saturation <90% (TSat90) was associated with increased odds of MCI (odds ratio 4.75, 95% CI 2.73–11.13). ConclusionsMCI is more prevalent in overlap syndrome than in COPD. OSA may contribute to MCI in COPD. The mechanism may involve TSat90.