With age cognitive abilities slow down. Age related structural changes runs parallel to this. However , huge variation is observed in the population. Why do some individuals preserve the cognitive abilities while others cannot?One factor that might explain is physical activity. increased exercise is associated with better cognitive function in old age or reduced cognitive decline. Researchers at Edinburgh University attempt to bring more clarity to this question.The Lothian Birth Cohort 1936 is a longitudinal study of aging and the current study used 691 participants from this.Previously, same cohort reported that leisure (nonphysical) activity accounted for up to 6% of the variance in cognitive ability at age 70 years. But confounding was a limitations in that study. ie that older adults performing better cognitively and participating in more leisure activities were those who always had higher cognitive function. Small associations were noticed between physical activity and cognitive ability.
This study looked at associations between leisure and physical activities and structural MRI- derived brain biomarkers— computational and visual ratings of tract integrity (Fractional Anisometry) ,White Matter Lesions load (WML) , gray and white matter volumes, and atrophy.
1. Higher level of activity predicted less atrophy, larger Normal Appearing White Matter (NAWM) volumes, lower WML (White Matter Lesions) load, and higher white matter integrity. The associations were almost unaltered by the addition of age 11 IQ and social class in subsequent models. In general these observations remained after inclusion of age, sex, social class, prior cognitive ability, and self- reported health measures.
2.Leisure activity was not associated with any of the assessed structural parameters in the fully adjusted models.
3.The effect of physical activity on tract integrity was attenuated with the inclusion of self-reported hypertension. is physical activity is a proxy for better general health ? is it that physical activity reduces cardiovascular risk profile and this lead to reduced cognitive aging?
Current study also reported that more exercise was associated with fewer WML. This effect survived adjustment for all covariates, which suggested a reduced WML burden might be one advantage of a physically active lifestyle.Physical activity was also associated with less brain atrophy and higher gray and NAWM volumes, generally consistent with the literature.
Are Socio-intellectual activities cognitively protective? Contrary to previous studies,no association between leisure activity and MRI-derived measures were seen. Authors suggest that such associations in previous studies are mostly accounted for by prior ability, i.e., confounding or reverse causation.
This study has a healthy sample size and used both qualitative ratings and computational measures. One limitation to mention is that activities were measured 3 years before MRI was done.
Clinical practice: We already know that physical exercise is good for mind. It is a suggested intervention for depression.Evidence now show that exercise can influence the structure of the brain.
Summary of the article:
Gow AJ, Bastin ME, Muñoz Maniega S, Valdés Hernández MC, Morris Z, Murray C, Royle NA, Starr JM, Deary IJ, Wardlaw JM.Neurology. 2012 Oct 23;79(17):1802-1808.