Obstructive sleep apnea is associated with depressive symptoms among patients with mild cognitive impairment

Background Obstructive sleep apnea (OSA) is increasingly recognized as a modifiable risk factor of cognitive decline and dementia. However, the impacts of OSA on mood among patients with mild cognitive impairment (MCI) have remained rarely explored. The aim of this study was to investigate whether OSA is associated with depressive symptoms among patients with MCI. Method The diagnosis of MCI was based on the criteria proposed by Peterson in 2004 after a series of comprehensive work‐up. The over‐night polysomnography (PSG) was performed in hospital for the diagnosis of OSA and the patients with AHI of 10/hour or higher were eligible for enrollment in the OSA group. The group for comparison was composed of the patients without OSA (AHI < 5/hour) by over‐night PSG and the patients with low risk of OSA defined by Berlin Questionnaire. The Center for Epidemiologic Studies Depression Scale (CESD) was administered for assessing depressive symptoms and the Cognitive Abilities Screening Instrument (CASI) with derived Mini‐Mental State Examination (MMSE) score was used for assessing cognitive function. Apolipoprotein E (APOE) genotyping was done in each subject. Result The study sample was composed of 68 MCI patients (age: 67.5 ± 8.83 years; female: 46.8%). As compared to the MCI patients without OSA or with low risk of OSA (n=14), the MCI patients with OSA (AHI ≥ 10/ hour; n=54) had higher CESD score ( 15.8 ± 10.6 versus 7.1 ± 1.9 ; P = 0.011). In the multivariate analysis, the association remained significant after adjusting the confounding factors including age, gender, education years, baseline CASI score, BMI and APOE epsilon 4 genotyping status. (β = 5.54; 95 % CI: 0.63– 10.45, p = 0.028). Conclusion The results of this cross‐sectional study suggest that obstructive sleep apnea is independently associated with depressive symptoms among patients with MCI. The long‐term effects of OSA on the mood among MCI patients warrant longitudinal studies. Our results probably set the horizon for the basic researches for the delineation of pathological mechanisms underlying the association between OSA and depression among MCI patients.