Is there an association between sedentary behavior and risk of all-cause dementia in older adults?
In this retrospective study of prospectively collected data of 49 841 adults participating in the UK Biobank, more time spent in sedentary behaviors (determined through a machine learning–based analysis of wrist-worn accelerometer data) was significantly associated with higher risk of incident dementia.
Among older adults, more time spent in sedentary behaviors was associated with higher risk of incident all-cause dementia.
Sedentary behavior is associated with cardiometabolic disease and mortality, but its association with dementia is unclear.
To investigate whether accelerometer-assessed sedentary behavior is associated with incident dementia.
Design, Setting, and Participants
A retrospective study of prospectively collected data from the UK Biobank including 49 841 adults aged 60 years or older without a diagnosis of dementia at the time of wearing the wrist accelerometer and living in England, Scotland, or Wales. Follow-up began at the time of wearing the accelerometer (February 2013 to December 2015) and continued until September 2021 in England, July 2021 in Scotland, and February 2018 in Wales.
Mean daily sedentary behavior time (included in the primary analysis) and mean daily sedentary bout length, maximum daily sedentary bout length, and mean number of daily sedentary bouts (included in the secondary analyses) were derived from a machine learning–based analysis of 1 week of wrist-worn accelerometer data.
Main Outcome and Measures
Incident all-cause dementia diagnosis from inpatient hospital records and death registry data. Cox proportional hazard models with linear and cubic spline terms were used to assess associations.
A total of 49 841 older adults (mean age, 67.19 [SD, 4.29] years; 54.7% were female) were followed up for a mean of 6.72 years (SD, 0.95 years). During this time, 414 individuals were diagnosed with incident all-cause dementia. In the fully adjusted models, there was a significant nonlinear association between time spent in sedentary behavior and incident dementia. Relative to a median of 9.27 hours/d for sedentary behavior, the hazard ratios (HRs) for dementia were 1.08 (95% CI, 1.04-1.12, P < .001) for 10 hours/d, 1.63 (95% CI, 1.35-1.97, P < .001) for 12 hours/d, and 3.21 (95% CI, 2.05-5.04, P < .001) for 15 hours/d. The adjusted incidence rate of dementia per 1000 person-years was 7.49 (95% CI, 7.48-7.49) for 9.27 hours/d of sedentary behavior, 8.06 (95% CI, 7.76-8.36) for 10 hours/d, 12.00 (95% CI, 10.00-14.36) for 12 hours/d, and 22.74 (95% CI, 14.92-34.11) for 15 hours/d. Mean daily sedentary bout length (HR, 1.53 [95% CI, 1.03-2.27], P = .04 and 0.65 [95% CI, 0.04-1.57] more dementia cases per 1000 person-years for a 1-hour increase from the mean of 0.48 hours) and maximum daily sedentary bout length (HR, 1.15 [95% CI, 1.02-1.31], P = .02 and 0.19 [95% CI, 0.02-0.38] more dementia cases per 1000 person-years for a 1-hour increase from the mean of 1.95 hours) were significantly associated with higher risk of incident dementia. The number of sedentary bouts per day was not associated with higher risk of incident dementia (HR, 1.00 [95% CI, 0.99-1.01], P = .89). In the sensitivity analyses, after adjustment for time spent in sedentary behavior, the mean daily sedentary bout length and the maximum daily sedentary bout length were no longer significantly associated with incident dementia.
Conclusions and Relevance
Among older adults, more time spent in sedentary behaviors was significantly associated with higher incidence of all-cause dementia. Future research is needed to determine whether the association between sedentary behavior and risk of dementia is causal.
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CME Disclosure Statement: Unless noted, all individuals in control of content reported no relevant financial relationships. If applicable, all relevant financial relationships have been mitigated.
Accepted for Publication: July 22, 2023.
Corresponding Author: David A. Raichlen, PhD, Human and Evolutionary Biology Section, Department of Biological Sciences, University of Southern California, 3616 Trousdale Pkwy, Los Angeles, CA 90089 (firstname.lastname@example.org).
Author Contributions: Dr Raichlen had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.
Concept and design: Raichlen, Maltagliati, Klimentidis, Alexander.
Acquisition, analysis, or interpretation of data: Raichlen, Aslan, Sayre, Bharadwaj, Ally, Lai, Wilcox, Klimentidis, Alexander.
Drafting of the manuscript: Raichlen, Alexander.
Statistical analysis: Raichlen, Lai, Wilcox.
Obtained funding: Raichlen, Klimentidis, Alexander.
Administrative, technical, or material support: Sayre, Bharadwaj.
Supervision: Raichlen, Alexander.
Conflict of Interest Disclosures: None reported.
Funding/Support: This research was supported by grants P30AG072980, P30AG019610, R56AG067200, R01AG064587, and R01AG072445 from the National Institutes of Health and funding from the state of Arizona, the Arizona Department of Health Services, and the McKnight Brain Research Foundation.
Role of the Funder/Sponsor: The funders/sponsors had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication.
Data Sharing Statement: See Supplement 2.
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