Sedentary Behavior Linked to Increased Risk of Dementia in Older Adults: JAMA

A recent study by David Raichlen and team shed light on the relationship between sedentary behavior and the risk of dementia in older adults. The study published in Journal of American Medical Association found that spending more time in sedentary activities is associated with a higher incidence of all-cause dementia.

This retrospective study utilized data collected between February 2013 and December 2015, with follow-up continuing until September 2021 in England, July 2021 in Scotland, and February 2018 in Wales. The participants wore wrist accelerometers to measure their daily sedentary behavior, and the results were striking.

Over the course of the study, 414 individuals were diagnosed with incident all-cause dementia. The data analysis revealed a significant nonlinear association between time spent in sedentary behavior and the incidence of dementia. In fully adjusted models, the hazard ratios (HRs) for dementia were 1.08 for 10 hours of sedentary behavior per day, 1.63 for 12 hours, and a remarkable 3.21 for 15 hours. This means that individuals who spent 15 hours a day in sedentary activities were more than three times as likely to develop dementia compared to those who spent around 9 hours a day being sedentary.

The adjusted incidence rate of dementia per 1000 person-years also followed this trend, with rates increasing from 7.49 for 9.27 hours of sedentary behavior per day to 22.74 for 15 hours.

Furthermore, the study investigated other aspects of sedentary behavior, including the length of sedentary bouts. It found that both mean daily sedentary bout length and maximum daily sedentary bout length were significantly associated with a higher risk of incident dementia. In other words, longer periods of uninterrupted sitting were linked to an increased risk of developing dementia.

Interestingly, the number of sedentary bouts per day did not show a significant association with the risk of dementia when adjusted for overall sedentary time.

The findings highlight the importance of reducing sedentary behavior, especially among older adults. Further research will be needed to determine whether reducing sedentary behavior can indeed lower the risk of dementia.

Source:

Raichlen, D. A., Aslan, D. H., Sayre, M. K., Bharadwaj, P. K., Ally, M., Maltagliati, S., Lai, M. H. C., Wilcox, R. R., Klimentidis, Y. C., & Alexander, G. E. (2023). Sedentary Behavior and Incident Dementia Among Older Adults. In JAMA (Vol. 330, Issue 10, p. 934). American Medical Association (AMA). https://doi.org/10.1001/jama.2023.15231