More about the importance of exercise

Due to a series of unforeseen events this week, both of our children living in Portland needed additional help caring for their children, our four grandchildren. There is nothing I like better than spending time with my grandchildren, but instead of seeing them a few times each week, we have suddenly been spending a lot of time with one or both sets every day.  It’s been great, but what I have missed out on is my daily 10,000 steps of aerobic exercise. I have been lucky on some of these days to get 4,000 steps.  And I can feel the result.  All week I have been more befuddled than usual.  Some of this is doubtless due to the change in schedule, but I think much if not most of my increased confusion has been caused by decreased exercise.

Today we have no child care responsibilities.  It is a beautiful, sunny day in Portland, and Jack and I have already covered 10,566 steps, 4.25 miles, and a total elevation gain of 633 ft. in two walks this morning.  I’m feeling really good. My smartphone cognitive test score just now is 8% better than my average score.

As I discuss in Tattoo, aerobic exercise is good for the brain.  If started in midlife it reduces the chance of getting Alzheimer’s disease.  I don’t think the mechanism for this long-term benefit is fully understood, but it probably is due to a combination of increasing blood flow to the brain, altering release of certain stress hormones, moderating inflammation, improving cardiovascular health, and reducing the occurrence of small strokes. There also is a well-documented acute effect of exercise. Again, the cause is not well understood and has generally been attributed to increased brain blood flow while exercising.  For me this cognitive boost lasts for at least several hours after completing the workout.

A very interesting recent study in older people (average age 65 years) who did not have dementia or MCI suggests a novel mechanism that may play a role in the beneficial cognitive effects of exercise. Half of the subjects underwent a 20-week dance-based aerobic exercise program that met for 60 minutes twice weekly. The other half carried on as usual with no special intervention. Both groups were assessed using a functional MRI (fMRI) method designed to measure the flexibility of neuronal networks, particularly within the medial temporal lobe (MTL), a part of the brain that is home to the hippocampus and is key to learning and memory. At the end of the 20 weeks, the subjects who underwent the exercise regimen had a significant increase in the flexibility of this MTL network suggesting that even in this short period of time there has been an improvement in function of this important network involved in learning and consolidation of memory.  The take home point is that exercise improves the flexibility and efficiency of an important neuronal network thought to be involved in learning and memory, at least in these older subjects who are still cognitively normal.  This has not yet been studied in people who already are cognitively impaired by dementia.

The beneficial effects of exercise on memory are real, and there appear to be several mechanisms involved. Exercise reduces the risk of getting Alzheimer’s, and it slows the progression once it has begun. Exercise also acutely improves cognitive function both in normal people and in those with mild cognitive impairment. The time to start a regular aerobic exercise program is in midlife, not after dementia has taken hold. I can’t stress this enough:  exercise is probably the most effective tool we have now for the prevention and slowing of Alzheimer’s disease.