TOPLINE:

Older adults who engaged in physical activity (PA) sessions lasting at least 10 minutes at 40 or more steps per minute had lower white matter injury than non-exercisers in new research, highlighting that session frequency and step cadence may be top predictors of brain health outcomes.

METHODOLOGY:

• The analysis included nearly 300 adults aged 40 years or older without dementia (mean age, 72 years; 56% female) from the BrANCH study in San Francisco.
• Participants wore wrist actigraphy devices continuously for 30 days to capture minute-level step count data in their natural environments.
• A novel algorithm identified real-world PA sessions as sustained movement of 10 or more consecutive minutes at 40 or more steps per minute, with participants classified as “exercisers” (more than one session; 79%) or “non-exercisers” (zero sessions).
• Outcomes included neuropsychological assessments of episodic memory, executive function, and information processing speed and changes in neuroimaging measures such as medial temporal lobe volume, white matter hyperintensity (WMH) burden, and global fractional anisotropy.

TAKEAWAY:

• Exercisers who engaged in at least one PA session had lower WMH burden than non-exercisers (P = .005).
• Session frequency and session cadence were the top predictors of executive function (accounting for 50% and 24% of the total coefficient weights, respectively) and WMH burden (accounting for 27% and 38% of total coefficient weights).
• The association between women and session frequency emerged as a top predictor for global fractional anisotropy, accounting for 40% of total coefficient weights and suggesting relatively stronger protective associations in women than in men, the researchers noted.
• In non-exercisers, higher mean daily step counts showed potential protective effects on medial temporal lobe volume (P = .004), WMH burden (P = .003), and global fractional anisotropy (P = .02), suggesting that greater PA may be beneficial even when not sustained for at least 10 minutes.

IN PRACTICE:

“Any physical activity may be better than no activity, but engagement in some physical activity sessions of at least 10 minutes and at least low intensity is associated with lower white matter injury in older adults without dementia,” the investigators of the study wrote.

“Regardless of increasing age, engaging in shorter sessions of at least 10 minutes but at higher frequency and intensity may be optimal,” they added.

SOURCE:

The study was led by Claire J. Cadwallader, PhD, Memory and Aging Center, Weill Institute for Neurosciences, University of California, San Francisco (UCSF). It was published online on March 5 in Alzheimer’s Research & Therapy.

LIMITATIONS:

Wrist-worn step count actigraphy may have underrepresented the true intensity of PA. Additionally, the specific mode of PA (eg, aerobic or resistance training) could not be determined from step count data alone, limiting the ability to provide guidance on clinically meaningful targets.

DISCLOSURES:

The study was funded by the National Institute on Aging, the UCSF Alzheimer’s Disease Research Center, the Alzheimer’s Association, the Larry L. Hillblom Foundation, the New Vision Research Charleston Conference on Alzheimer’s Disease, the American Academy of Neurology, and the Shenandoah Community Foundation. The investigators reported having no relevant conflicts of interest.

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