Obstructive sleep apnea-hypopnea syndrome and cognitive impairments in the elderly

Obstructive sleep apnea-hypopnea syndrome (OSAHS) is a common sleep-related breathing disorder that is associated with significant morbidity and mortality. It has received increasing attention that neurocognitive deficits occur with a high frequency in OSAHS. However, it is rarely known that OSAHS impacts on cognition in the elderly in whom an increased prevalence of OSAHS is present. In this review we consider recent studies in the association between OSAHS and cognitive impairments, with specific interest in the older population. Firstly, we elucidate the characteristics of OSAHS and OSAHS-related cognitive impairments in the older patients. Many studies have showed that the prevalence of OSAHS increases with age and it is higher in the elderly than other population. Moreover, OSAHS is associated with higher incidence of comorbidities and increased risk of clinical deterioration in the elderly, especially the neurocognitive impairments which even can develop dementia. Subsequently, we discuss the possible reasons of cognitive impairments that caused or aggravated by OSAHS in the elderly. The intermittent hypoxia (IH)-related disturbances of homeostasis such as oxidative stress, inflammation, and age-related changes such as the changes of sleep architecture, the declined expression level of anti-aging gene, medical comorbidities and polypharmacy, may be both contribute to the increased risk of cognitive impairments in the older patients with OSAHS.