TOPLINE: 

Older adults who maintained higher levels of physical activity over time, particularly in the years before diagnosis, had a reduced risk of developing dementia.

METHODOLOGY:

• Researchers used data from a prospective cohort to examine whether changes in the levels of daily physical activity over time were linked to the risk for dementia in older adults.
• They included 972 community-dwelling older adults without dementia (mean age, 80.5 years; 77% women) recruited from 24 sites in northeastern Illinois.
• Physical activity levels were measured using sensors worn on the wrist continuously for 10 days, with a mean of 4.9 recordings per participant over a median follow-up duration of 7.0 years.
• Clinicians assessed cognition annually using a standard set of memory and thinking tests, medical history, and a neurologic exam, and diagnosed dementia using accepted criteria.
• In a separate analysis, participants who developed dementia during follow-up were matched to an equal number of those who did not develop the condition, to compare changes in activity levels in the years before diagnosis.

TAKEAWAY:

• A total of 286 participants (29%) developed dementia during the follow-up period. Increased levels of physical activity throughout follow-up were associated with a 22% reduced risk for dementia (P < .0001).
• Higher levels of physical activity at year 6 were linked to a 45% reduced risk for dementia (P = .0021) and at years 2 and 4 were linked to a 39% reduced risk (P < .01 for both); activity at baseline had no such association.
• Levels of physical activity declined by 13.6% per year. Levels started to diverge only 1.8 years before diagnosis, with lower activity levels in those who later developed dementia.
• Impaired cognition at baseline did not predict a faster decline in activity, and genetic analyses found no evidence that higher lifelong activity reduced the risk for Alzheimer's disease.

IN PRACTICE:

"[The study] findings imply that modifiable factors other than physical activity should be sought for prevention of dementia in older adults who are not at an imminent risk of dementia, and confirm that physical activity for prevention of dementia in high-risk older people requires further investigation and consideration of the timing of intervention relative to dementia risk," wrote the researchers.

SOURCE:

The study was led by Shahram Oveisgharan, MD, of Rush University Medical Center in Chicago. It was published online on March 9 in The Lancet Healthy Longevity.

LIMITATIONS: 

The study was observational and could not prove that differences in physical activity caused changes in risk for dementia. Biomarkers of Alzheimer's disease were not considered. 

DISCLOSURES:

The study received funding from the National Institutes of Health. The authors declared having no competing interests.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.