In Part I of this post, Part 1-The Association we discussed the possible role for physical activity in reducing dementia risk. Part II will delve a bit deeper into that topic and discuss the evidence for this association, and the ways by which physical activity might support brain health.
There are two types of studies that provide support for the notion that physical activity has beneficial effects on cognition and brain health. The first are observational or epidemiological studies – those that follow large groups of individuals over long periods of time (think thousands of people for decades on end). These studies have shown that engagement in physical activity is associated with a reduced risk of Mild Cognitive Impairment and dementia, including Alzheimer’s disease.
Evidence also comes from intervention studies, sometimes designed as randomized control trials, which examine whether physical activity interventions result in more positive outcomes over relatively short periods of time (typically weeks to months, sometimes years). These studies have provided interesting results on the effects of physical activity on the brain. For example, physical activity interventions have been associated with increases in the size in the hippocampus (as well as other regions of the brain), a region that’s critically important for memory and severely affected by many types of dementia. It’s well known that our brain shrinks in size as we age; thus, physical activity may help attenuate these structural changes, providing brain resilience. Physical activity also affects brain health through cardiovascular mechanisms, including a reduced risk of other conditions such as hypertension, diabetes, heart disease, stroke, and obesity – each of which can have negative effects on brain health. Accordingly, management of these conditions is also associated with less decline in brain size, reductions in oxidative stress and inflammation, as well as improved white matter integrity and brain function. An additional mechanism by which physical activity may affect brain health is through the release of brain-derived neurotrophic factor (BDNF), which helps support neural health and growth.
The breadth of scientific evidence – including observational and epidemiological studies, interventions, as well as animal studies (which we didn’t even discuss) – suggests multiple pathways by which physical activity affects dementia risk and brain health, making the benefits of physical activity are hard to ignore. So get out there, find something you enjoy, and get active.
Do more (now), suck less (later), live better (longer).
1. Brown et al. (2013). Multiple effects of physical activity on molecular and cognitive signs of brain aging: Can exercise slow neurodegeneration and delay Alzheimer’s disease? Molecular Psychiatry.
2. Global Council on Brain Health. (2016). The Brain-Body Connection: GCBH Recommendations on Physical Activity and Brain Health. (www.GlobalCouncilOnBrainHealth.org)
3. Institute of Medicine. (2015). Cognitive aging: Progress in understanding and opportunities for action. The National Academies Press.
4. Livingston et al. (2017). Dementia prevention, intervention, and care. Lancet.
5. National Academies of Sciences, Engineering, and Medicine. (2017). Preventing cognitive decline and dementia: A way forward. The National Academies Press.