Physical activity and gray mass mediated by changes in insulin and BMI

Data from the Age-Well study (NCT02977819) of elderly people without cognitive impairment show that physical activity is directly associated with glucose metabolism in the brain, whereas that is associated with global gray matter (GM) levels as a cardiovascular risk factor. , More specifically insulin and body mass index (BMI).

The results suggest that the association between physical activity and global GM is mediated by changes in insulin and BMI, but researchers say, “Elderly people practicing physical activity have lower insulin. We conclude that it provides cardiovascular benefits through the maintenance of BMI, which promotes larger structures. Brain integrity. In contrast, its association with global and frontal cerebral insulin metabolism is cardiovascular. Seems to be independent of the risk factors of. “

From November 2016 to March 2018, a total of 134 elderly people aged 65 and over with no cognitive impairment were hired from the general population. Each participant underwent a structural MRI, along with a physical activity questionnaire, blood draws, and clinical trials including: Information on cardiovascular risk factors within 3 months.Measurements of cardiovascular risk factors included insulin, cholesterol (total and high density lipoprotein) [HDL]), Systolic blood pressure (SBP), BMI, and smoking habits.

Senior authors Geraldine Poisnel, PhD, research engineer, Normandy University, and colleagues used multiple regressions to assess the association between physical activity, cardiovascular risk factors, and neuroimaging. As a conclusion of their analysis, they found that higher physical activity was associated with higher GM levels (ß = 0.174; P = .030) and glucose metabolism in the brain (ß = 0.247; P = .019), but there is no amyloid deposition or white matter (WM) high signal or WM microstructure integrity.

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Higher physical activity was also associated with lower insulin and BMI, but not total and HDL cholesterol, SBP, or current smoker status. When insulin and BMI were entered into the same model, they were no longer associated with physical activity. This suggests that the association between physical activity and insulin and BMI is not independent of each other. Through research, researchers have found a consistent correlation between insulin and BMI.

“This study is significant because understanding how physical activity affects brain health may help develop strategies to prevent or delay age-related brain decline. I have it, “writes Poisnel et al.

Both low insulin and BMI correlated with each other when assessing the association between cardiovascular risk factors and global neuroimaging measurements. When BMI and insulin were included in the same model, the correlation between GM levels and insulin was lost, but the association with BMI did not change. This suggests that the association between insulin and GM levels was caused by BMI.

Decreased insulin and BMI were found to correlate with increased GM levels, but neither was associated with cerebral glucose metabolism. When BMI and insulin were included in the same model, the correlation between GM amount and insulin was lost. However, the association with BMI has not changed. This suggests that the association between insulin and GM volume was driven by BMI.

A secondary analysis investigated whether the effects of physical activity, cardiovascular risk factors, and mediation were present in areas specifically associated with Alzheimer’s disease (AD). Analysis replicated in the AD-sensitive region of interest showed that higher physical activity correlated with higher hippocampal volume and glucose metabolism in the precuneus, but not glucose metabolism.

The study was limited, including the fact that physical activity was assessed using a subjective self-reported questionnaire. However, according to research researchers, this approach is widely used in the literature. In addition, participants are not cognitively impaired, so it is unlikely that major recollection issues affected the questionnaire. Third, due to the cross-cutting nature of the design, researchers were unable to infer a causal link between physical activity and GM levels and glucose metabolism.

reference
1. Felisatti F, Gonneaud J, Palix C, and others The role of cardiovascular risk factors in the association between physical activity and brain integrity markers in the elderly. Neurology. Published online April 13, 2022. doi: 10.1212 / WNL.00000000000200270