A new study finds that obstructive sleep apnea may increase the risk of dementia, with older women showing the greatest vulnerability, underscoring the need for targeted interventions in sleep health and cognitive care.
Study: Gender-specific dementia risk in known or suspected obstructive sleep apnea: a 10-year longitudinal population-based study. Image credits: Andrey Popov / Shutterstock.com
A new study published in SLEEP Progress determines the differential risk of dementia in men and women based on the presence of obstructive sleep apnea (OSA).
Dementia threat in the US
Dementia refers to a progressive and incurable decline in cognitive function that is often accompanied by behavioral changes due to neurodegenerative diseases. Current estimates show that seven million Americans have been diagnosed with dementia; therefore, it is critical to identify modifiable risk factors for targeted interventions.
For example, women have a greater risk of dementia than men. Therefore, environmental and comorbidity-related risk factors that more commonly affect women need to be quantified to determine their role in this context.
OSA is defined as episodes of obstructed breathing in the upper airways leading to interrupted sleep and hypoxia during these episodes. OSA, the prevalence of which increases with age, is an established risk factor for dementia. Nevertheless, prospective sex-stratified studies in a population-based cohort over longer periods are needed.
About the study
The current study included data from 18,815 American men and women aged 50 and older who were part of the Health and Retirement Study (HRS). The average age of the study participants was 60 and 61 years for men and women, respectively.
All study participants were dementia-free at the start of the study. A validated algorithm was used to identify new cases of dementia using objective cognition tests.
Known OSA was recorded if a previous diagnosis of OSA was reported by the participant. Because 80% of people with OSA are never diagnosed, an alternative method was used to identify suspected OSA cases with a positive result on the STOP-Bang OSA screening tool.
These data were analyzed to identify differences in the ten-year cumulative incidence of dementia among men and women, stratified by age and the presence of OSA.
The incidence of dementia
Dementia was reported in 9% and 8% of women and men, respectively, while the prevalence of known or suspected OSA was 48%. OSA was significantly more common in men at 68% than in women at 31%. The mean educational status of OSA participants was lower than that of those without OSA or at low risk for OSA.
Screening for OSA was positive for 29% of men and 30% of women with a previous OSA diagnosis. In comparison, 10% of men and 7% of women were diagnosed with OSA but screened negative with the STOP-Bang OSA screening tool.
The presence of OSA predicted a higher risk of dementia between 60 and 84 years. At age 80, women with OSA had a 4-7% higher cumulative incidence of dementia compared to adults without OSA, regardless of gender, compared to a 2.5% higher cumulative incidence in men.
The difference in risk of dementia increased with age in women, but stabilized after an initial increase in men.
The population attributable hazard rate (PAR%) reflects the proportion of dementia cases attributable to OSA. PAR% was 10.3% and 13.2% in women and men, respectively, reflecting the increased risk of OSA in men.
After adjusting for age, the risk of dementia in OSA became weaker but remained significantly higher compared with non-OSA adults. The cumulative incidence in women with suspected or known OSA was 3.7% higher compared to 2.1% in men with known OSA.
Mechanism of dementia risk in OSA
From any cause, OSA can increase the risk of Alzheimer’s disease (AD) progression and cognitive decline. This association is attributed to the accumulation of tau protein and amyloid β42 (Aβ42) protein.
OSA and sleep disruption can also lead to chronic inflammation, which can subsequently disrupt microglial function with accumulation of Aβ42, increase the risk of atherosclerosis, and lead to increased proinflammatory cytokines associated with brain shrinkage in AD.
OSA in women is likely to cause reduced quality of life, poor sleep, fatigue, depression, risk of cardiovascular disease (CVD), and cognitive decline compared to men with OSA. The risk of OSA increases after menopause, with an older age of onset associated with a reduced risk of dementia.
Conclusions
The current population-based, longitudinal study involved the analysis of objective dementia data to estimate the 10-year risk of dementia in adults with OSA. Taken together, the study results indicate that OSA is a risk factor for dementia in older adults, with women at even higher risk than men.
The value of the observed association is increased by the careful search for undiagnosed OSA, which accounts for 80% of these patients. These findings highlight the importance of identifying and treating OSA as a modifiable risk factor for the development of dementia.
Similar findings have been reported in previous studies, suggesting that positive airway pressure (PAP) could protect OSA patients from mild cognitive impairment, as well as from the onset and progression of AD.
Further research with larger and more diverse cohorts using longitudinal follow-up and objective sleep data and better statistical techniques is needed. These studies could provide important insights into the sex-stratified relationships that develop over time between OSA and dementia. Identification of mediating factors could also lead to the development of targeted interventions to reduce the risk of dementia in older individuals with OSA.
Magazine reference:
- Braley, T.J., Lyu, X., Dunietz, G.L., et al. (2024). Gender-specific dementia risk in known or suspected obstructive sleep apnea: a 10-year longitudinal population-based study. SLEEP Progress. doi:10.1093/sleepadvances/zpae077.