Moderate to high rates of physical activity is associated with slower rates of cognitive decline in older adults with both high and low total tau concentrations, according to study results published in JAMA Network Open.

This is the first study of its kind to evaluate the potential role of physical activity in cognitive function among older adults with high and low tau levels, according to study authors.

Researchers obtained patient data from the population-based Chicago Health and Aging Project cohort study. They collected these data in 3-year cycles between 1993 and 2012. In-home interviews were performed, and study participants underwent clinical evaluations and provided blood samples. The analysis included the participants who had baseline blood samples and had completed 2 or more global cognitive function outcome measurements.


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Total serum tau concentrations were examined in the baseline blood samples, and 1985 US Health Interview Survey items were used to collect data on physical activity levels. In the physical activity assessment, participants reported the number/frequency and duration of physical activities performed in the previous 14 days. Total physical activity was converted into minutes per week and then calculated as hours per week.

“Little” physical activity participation was defined as no participation in 4 or more of the items contained in the physical activity measure. The “medium” activity metric was defined as participation in less than 150 minutes of physical activity each week, while “high” physical activity was defined as participation in 150 minutes or more of physical activity each week.

In-home assessments using the East Boston Tests of Immediate Memory and Delayed Recall (episodic memory), the Mini-Mental State Examination, and the Symbol Digit Modalities Test (modified, oral version; perceptual speed) were used to assess global cognitive function.

The study outcome was global cognitive function.

The majority of the cohort included women (63%) and African American (60%) participants. The average age of participants was 77.4 years, with a mean educational level of 12.6 years.

In the group of participants with high tau concentrations, those with “medium” physical activity levels exhibited a 58% slower rate of cognitive decline vs those with “little” physical activity (estimate, -0.028 standard deviation units [SDU] per year; 95% CI, -0.057 to 0.002 SDU per year; difference, 0.038 SDU per year). Additionally, participants with high tau concentrations and “high” physical activity had a 41% slower cognitive decline rate (estimate, -0.038 SDU per year; 95% CI, -0.068 to -0.009 per year; difference, 0.027 SDU per year).

Among the group of participants with low tau concentrations, those with “medium” physical activity levels had a 2% slower rate of cognitive decline (estimate, -0.050 SDU per year; 95% CI, -0.069 to -0.031 SDU per year; difference, 0.001 SDU per year). In addition, participants with “high” levels of physical activity had a 27% slower cognitive decline rate (estimate, -0.037 SDU per year; 95% CI, -0.055 to -0.019 SDU per year; difference, 0.014 SDU per year).

Study limitations included the reliance on self-reported physical activity data as well as the lack of well-established cutoffs for biomarker measurements. Additionally, the study did not indicate a direction of causation between physical activity levels and Alzheimer disease pathology, suggesting that more research was needed.

To better understand the association between physical activity and cognition, the researchers explained that their “findings may inform the development of prevention trials or interventions that are tailored to individuals with at-risk characteristics with long-term follow-up measurement.”

Overall, the findings suggest assessment of blood biomarkers in older patients may lead to opportunities for earlier physical activity interventions to slow cognitive deterioration.

Reference

Desai P, Evans D, Dhana K, et al. Longitudinal association of total tau concentrations and physical activity with cognitive decline in a population sample. JAMA Netw Open. 2021;4(8):e2120398. doi:10.1001/jamanetworkopen.2021.20398