Quantifying the population-level impact of insomnia on dementia among older adults in the United States.

BACKGROUND: Insomnia has been identified as a plausible modifiable risk factor for dementia. Quantifying its population-level impact may inform strategies to reduce dementia risk among older adults in the United States. METHODS: We used data from the 2022 National Health and Aging Trends Study (NHATS) to classify insomnia as sleep-onset insomnia, sleep-maintenance insomnia, or both, and to identify probable dementia using established algorithms. We obtained relative risks (RRs) from a published meta-analysis. Using these RRs and NHATS prevalence estimates, we estimated the population attributable fraction (PAF) of dementia cases attributable to insomnia overall and stratified by age and sex. RESULTS: Among 5899 participants (44.7% aged ≥80 years; 57.9% females; 77.9% non-Hispanic White), 28.7% (95% CI: 26.9%, 30.5%) reported insomnia symptoms and 6.6% (95% CI: 5.9%, 7.3%) had probable dementia. The estimated PAF of probable dementia due to any insomnia was 12.5% (95% CI: 1.0%, 25.0%), and it was slightly higher among females (13.1%, 95% CI: 1.0%, 26.1%) than males (11.6%, 95% CI: 0.9%, 23.3%). The highest PAF was observed in the 65-69 age group (14.4%, 95% CI: 1.1%, 27.8%) among females and in the 70-74 age group (12.8%, 95% CI: 0.9%, 25.8%) among males. An estimated 449,069 (95% CI: 35 049, 923 082) dementia cases in 2022 could have been prevented if insomnia were eliminated. CONCLUSIONS: Approximately 13% of dementia cases, almost half a million cases, among US older adults may be attributable to insomnia. Addressing insomnia could be a promising target for dementia prevention efforts in aging populations.