Study shows aged individuals who regularly engage in moderate to heavy physical activity have structurally and functionally better brains.
In a study that involved hundred aged individuals, the positive effects of higher physical activity levels on brain functioning and structural integrity were evident. The findings by Agnieszka Z. Burzynska and team were recently published in PLOS ONE.
The physical activity levels were obtained from accelerometers attached to the participants. Initially, the researchers intended to classify the sample population’s physical activity (PA) profile into sedentary (SED), light (LI), moderate (M) and vigorous (V) levels. After analysing the accelerometer data, only 15 individuals performed any vigorous activity during the 7-day trial. Therefore, the scientists combined the moderate and vigorous levels into one moderate-to-vigorous level (MV-PA), along with LI-PA and SED-PA levels. Interestingly, several individuals had inaccurately estimated their levels of physical activity in the pre-trial survey, leading the authors to comment on the difference in information quality between self-reported surveys and objective PA measurements.
The cardiorespiratory fitness (CRF) of the subjects were obtained from testing such as treadmill running. The CRF is measured as maximal oxygen consumption during maximal physical exertion and it depends on several variables. The authors highlight that high CRF does not always imply high levels of PA. CRF has a genetic component which makes it possible for an individual with low or occasionally high PA to have a high CRF value.
The scientists compared the subjects’ CRF and PA values with two brain imaging related measurements; one which reflects brain functionality (SD-BOLD) and another which reflects brain’s structural integrity (FA).
The results indicated that individuals who engage more in LI-PA and MV-PA exhibited higher SD-BOLD in brain regions relevant to integrating segregated functioning. These regions are also the ones that are proven to benefit from higher CRF and PA. SD-BOLD (spontaneous variability in blood oxygenation level dependent signal) is obtained from fMRI data and is increasingly being used as a measure of brain network functionality. Higher SD-BOLD is associated with younger age and better cognitive functioning whereas lower SD-BOLD is associated with older age and poorer cognitive functioning.
The results also indicated a positive relationship between MV-PA and FA. Functional anisotropy (FA) is a score of the brain’s white matter structural integrity. Higher FA indicates greater white matter microstructure which in turn indicates better neural processing by the grey matter.
Interestingly, some of the positive correlations between PA and brain health were not evident with CRF. The authors argue that some aspects of lifestyle behaviours that influence brain function and aging may not be captured by CRF.
The take home message seems to be that if we wish to have a physically and functionally healthy brain even if we are aged, engaging in light to moderate physical activity regularly is a step in the right direction!