Sweat it so you don't forget it.
Welcome to installment 3/6 in my brain health series! This series is inspired by 'The Alzheimer's Solution' by Drs. Dean and Ayesha Sherazi. In my first post, I explained that lifestyle choices can prevent up to 90% of Alzheimer's cases. For the 10% of cases that can't be prevented due to very strong genetic risk (such as in those that carry the APOE4 gene), lifestyle changes can delay presentation or progression of the disease by up to 15 years. There are 5 main lifestyle tenets for optimizing brain health that I am covering over the course of this blog series. They include nutrition, exercise, stress management, sleep and regularly engaging in complex cognitive activities. The focus of this post is exercise and its impact on brain health.
One of the most pertinent relationships between exercise and brain health has to do with blood flow. Anything that reduces blood flow throughout the body (such as reduced pliability of arteries, arterial plaques, high cholesterol, and long periods of inactivity) also reduces cognitive function because, well, less blood flow to your brain. Reduced blood flow especially impacts the medial temporal lobe of the brain, which governs short-term memory. It’s no coincidence then that this is often the first noticeable symptom of cognitive decline.
Conversely, anything that facilitates blood circulation throughout the body- like intensive aerobic exercise- maintains the health of the brain AND the rest of the body. A meta-analysis (a statistical procedure that combines data from multiple studies) of 15 studies done in 2010 of 34,000 people (that's a significant sample size!) found that a high level of physical activity could lower the risk of cognitive decline by a whopping 38%!
Throughout the lifespan, exercise is associated with better executive function (multitasking, planning, self-control), increased brain volume, and improved cognitive performance. Aerobic exercise confers the most benefit for your brain, though resistance training and stretching and balance exercises are important too.
Aerobic exercise has the power to:
- Enhance the brain’s connectivity
- Improve the integrity of white matter, which composes the tracts that connect different parts of the brain. Scans of people with cognitive decline often demonstrate damaged white matter.
- Promote growth of brain cells
- Produce brain growth factors, which are proteins that stimulate existing cells, promote brain cell growth and maintain health of mature neurons.
- Reduce inflammatory markers in the blood
- Increase Klotho levels. Klotho is a hormone associated with both longevity and protection against cognitive decline.
Resistance training research has shown that leg strength in particular is correlated with better cognitive function, likely because strong leg muscles help blood circulate up to the brain. Remember, it's all about that blood flow! Other benefits of resistance training include:
- Improvement in white matter
- Increased growth factors
- Improved frontal lobe function. The frontal lobe is where our personality is formed and where we carry out higher mental functions, like planning.
- Better vascular health
Generally, combining strength training with aerobic exercise results in better brain function than an aerobic only program. Doing activities of daily living around the house or walking at a normal pace is not enough. The major conclusion in the literature is that exercise should be aerobic and intensive. This definition is of course individual depending on your baseline health and fitness levels. You should strive for a MINIMUM of 150-minutes of moderate intensity activity, such as brisk walking or jogging, per week. While running shows significant benefits, it’s important to include a variety of activities, particularly ones that challenge balance like yoga, or require hand eye coordination and visuospatial awareness like basketball.
You may have heard the phrase ‘sitting is the new smoking’. We live in an increasingly sedentary society (#cubicleslave) and this is proving to have serious ill consequences on our health. In fact, the number of hours we sit per day is a much better predictor of future cognitive decline (and other chronic diseases like heart disease) than our daily exercise regimen. The benefits of 30-45 minutes of vigorous exercise are negated when you spend the rest of the day on your bum. Our bodies are meant to be active throughout the day. In addition to regular vigorous aerobic exercise it’s important to move throughout the day. You can do this by using a standing desk, getting up every hour for a short walk, using a pedal exerciser (which costs about $40) under your desk or while you watch TV, or do a few reps of resistance exercises like squats, sit ups, push ups or this nitric oxide dump workout a few times throughout the day. Many companies are open to the idea of standing desks if you ask. If you meet resistance, sometimes a note from your healthcare provider will do the trick! Recap: it’s important to incorporate movement every hour, not just a gym session at the end of an otherwise completely sedentary day.
The good news is it's never too late to get moving! People who start exercising early in life seem less likely to experience cognitive decline, but those who pick up exercise later in life fare much better than those that remain inactive. The ultimate goal is to find something that keeps you active, challenges your brain, is convenient (therefore sustainable) and makes you happier in the process! How will you get your movement in today?
Next up in the brain health series: relaxation and brain health. Stay tuned!