Medium or high physical activity is associated with decreased rates of cognitive decline among older adults, dependent on their serum neurofilament light (NfL) concentrations, according to study findings published in JAMA Network Open.
NfL levels in cerebrospinal fluid tend to be associated with those in the blood, which increase when axons are damaged. Higher serum NfL levels are often associated with neurological diseases, cognitive declines, and sporadic Alzheimer disease (AD). Few studies have evaluated the relationship of NfL and cognitive decline with physical activity, which is inversely associated with cognitive decline. In the current study, researchers assessed this relationship.
The researchers looked at data of 1158 Chicago Health and Aging Project (CHAP) participants older than 65 years (aged 77.4±6.0 years 63% women) who were African American (60%) or White. Participants self-reported physical activity frequency and duration. They completed the East Boston Memory Test: Immediate Recall and Delayed Recall, the Mini-Mental State Examination (MMSE), and the Symbol Digital Modalities Test.
Mean weekly physical activity was 170.78±269.48 minutes. Geometric mean NfL concentrations were 26.1 pg/mL (95% CI 25.2-27.1 pg/mL). Lowest detected values were 0.99 pg/mL.
Global cognitive decline was slower among individuals who exercised compared with their peers who did not.
Participants with NfL concentrations greater than 25 pg/mL who exercised up to 150 minutes per week had a 12% slower rate of global cognitive decline (β, –0.065; 95% CI, −0.099 to −0.032). Those who exercised more than 150 minutes per week had a 36% slower rate of decline (β, –0.048; 95% CI, −0.080 to −0.016) compared with their peers who did not exercise (β, –0.075; 95% CI, −0.108 to −0.041).
Participants with NfL concentrations lower than 25 pg/mL who exercised up to 150 minutes weekly had 43% slower global cognitive decline (β, –0.025; 95% CI, −0.043 to −0.007) and those who exercised even more frequently had 30% slower decline (β, –0.031; 95% CI, −0.048 to −0.014) compared with individuals who did not exercise (β, –0.046; 95% CI, −0.066 to −0.025).
Study limitations included self-reported physical activity, selection bias regarding CHAP sample, lack of evaluation of intensity of physical activity, and lack of adjustment for other trauma or neurological conditions.
NfL concentration may influence the amount of physical activity that’s associated with a reduction in the rate of cognitive decline, according to the researchers. “With respect to slowing the rate of cognitive decline, participating in greater levels of physical activity may be needed more for those with a high NfL concentration than for those with a low NfL concentration,” the researchers concluded.
Disclosure: One study author declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of authors’ disclosures.
Desai P, Dhana K, DeCarli C, et al. Examination of neurofilament light chain serum concentrations, physical activity, and cognitive decline in older adults. JAMA Network Open. Published online March 22, 2022. doi:10.1001/jamanetworkopen.2022.3596