A higher adherence to a is linked to a 7% reduction in dementia risk for each additional point in the healthy sleep score.
Participants with a healthy sleep score of 5 had a 25% lower risk of dementia compared to those with scores of 0-1.
During a median follow-up of 13.8 years, 3,035 new dementia cases were identified, including Alzheimer's and vascular dementia.
The association between healthy sleep patterns and reduced dementia risk was stronger in adults aged 40-55 years than in those aged 56-64 years.
Adherence to a healthy sleep pattern correlated with increased grey matter volume and decreased white matter hyperintensities.
Preservation of grey and white matter integrity may partially explain the relationship between healthy sleep behaviors and reduced dementia risk.
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BACKGROUND: Existing evidence highlights associations between sleep behaviors and dementia risk; however, the impact of adhering to a on dementia risk remains unclear.
METHODS: Of 406,364 UK Biobank participants aged 40-64, we excluded those who had withdrawn, had incomplete sleep data, or had dementia at baseline, yielding a final sample of 333,014. Participants were enrolled between 2006 and 2010, with follow-up extending from recruitment to dementia diagnosis, death, loss to follow-up, or the censoring date (December 2022), whichever came first. Incident dementia was identified using hospital inpatient and death records, along with primary care data, with cases diagnosed at a mean age of 70.0 years (standard deviation [SD]: 5.6). Sleep-related questionnaire items from the UK Biobank were summarized into five sleep behaviors: sleeping 7-8 h daily, early chronotype, absence of frequent insomnia, no snoring, and no frequent daytime sleepiness. Each behavior meeting the healthy criterion was assigned one point, resulting in a total range from 0 to 5, with higher scores indicating better adherence to a healthy sleep pattern. Cox proportional hazards models were used to assess the association between healthy sleep patterns and dementia risk, adjusting for demographics, lifestyle factors, and medical history. A subset of 33,401 participants underwent brain magnetic resonance imaging (MRI) scans during the 9.4-year median period between sleep assessment and imaging. The imaging analysis included total brain volume, gray matter volume, white matter volume, hippocampal volume, and white matter hyperintensities (WMH).
RESULTS: During a median follow-up of 13.8 years, 3,035 incident dementia cases were recorded, including 1,304 Alzheimer's disease (AD) cases and 597 vascular dementia (VD) cases. A higher adherence to a healthy sleep pattern was associated with a lower dementia risk. Each 1-point increase in the healthy sleep score corresponded to a 7% reduction in dementia risk (Hazard Ratio [HR] = 0.93, 95% Confidence Interval [CI]: 0.89-0.96). Compared to participants with a score of 0-1, those with a score of 5 had a significantly lower risk of dementia (HR = 0.75, 95% CI: 0.61-0.92). Benefits were more pronounced in adults aged 40-55 years than those aged 56-64 years (p for interaction < 0.001). Adherence to a healthy sleep pattern was associated with increased grey matter volume and decreased WMH volume (all p < 0.05). Mediation analysis indicates that preserving grey and white matter integrity partially mediated the dementia-risk-lowering benefit (p < 0.05).
CONCLUSIONS: Adherence to a healthy sleep pattern is associated with both a reduced risk of dementia and greater white matter integrity, underscoring the role of improving overall sleep behaviors to support brain structure and lower dementia risk.
Key numbers
7%
Decrease in dementia risk per 1-point increase in sleep score
() = 0.93, 95% CI: 0.89-0.96
0.75
Risk of dementia for highest sleep score
() = 0.75, 95% CI: 0.61-0.92
0.17%
15-year cumulative incidence of dementia
Compared to 0.72% for those with scores of 0-1
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