Abstract
Background
One of the first regions of the brain to be compromised in AD is the hippocampus, which is located within the medial temporal lobe. Previous research has shown that high cardio-respiratory fitness and participation in aerobic exercise training may attenuate age-related volumetric decline of the hippocampus, medial temporal lobe and grey matter. However, this area of research is yet to be thoroughly investigated and understood. The aim of the current study was to assess the relationship between levels of physical activity and numerous volumetric brain measures calculated from MRIs.
Methods
The current study has investigated the association between habitual physical activity participation and volumetric brain measures in 147 healthy men and women aged sixty years and older. Using region of interest analyses on MRIs; volumes of grey matter, white matter, hippocampi, medial temporal lobes, occipital lobes and temporal lobes were measured. These measures each underwent a correction for intracranial volume (ICV). Furthermore, each individual completed an International Physical Activity Questionnaire (IPAQ), from which a physical activity score (metabolic expenditure) was calculated (met•min•week -1). The physical activity data was not normally distributed, and therefore underwent a square root transformation, which was used as the physical activity variable in all analyses.
Results
Partial Pearson correlations (using age, gender, years of education and Apolipoprotein E -ε4 allele status as covariates) revealed that higher physical activity levels were associated with larger hippocampal volumes (P=0.025). Furthermore, a relationship between physical activity and medial temporal volume, the lobe in which the hippocampus lies, was observed (P=0.016).
Conclusions
These results provide support for the hypothesis that physical activity may play a role in the attenuation of age-related brain atrophy, particularly in areas associated with AD neuropathology. However, as this is a cross sectional analysis, it is not possible to determine the causal direction of this association, and thus longitudinal analyses are necessary to validate these findings.