Can Strength Training Protect Against Alzheimer’s?

Exercise can be a protective factor against dementia.

Reviewed by Lybi Ma

Key points

• Nearly seven million American suffer from Alzheimer's disease.
• The cost to caretakers is devastating.
• Several medications are available to treat the disease but come with side effects.
• Exercise interventions show a positive effect in delaying brain aging.

According to the Alzheimer’s Association, nearly seven million Americans are currently suffering from this disease. That means it affects one out of every nine individuals 65 or older. They predict that as the U.S. population ages, more people will be diagnosed with some form of dementia. In terms of mortality, more Americans die of Alzheimer’s or other dementing illnesses than breast and prostate cancer combined. This can take a devastating toll on those caring for Alzheimer’s patients. Compared with non-caretakers, those who care for these patients have twice the incidence of emotional, financial, and physical problems. In addition, the cost of care for patients with dementia is borne mainly by families and can range up to $400,000.

Several medications are currently available to either manage the symptoms or slow the progression of this disease. Most of these medications work best in the early to moderate stages. However, as with all medicines, they come with various side effects. While there are no current ways to prevent Alzheimer’s, researchers have discovered lifestyle changes that can mitigate its onset. This post will address recent studies that discuss the positive effect of exercise on delaying Alzheimer’s onset and progression.

Aerobic exercise is the most extensively studied option for alleviating the negative age-related decline in cognitive function. In the 1970s, research studies reported that middle-aged individuals who exercise regularly respond better to cognitive challenges than those who are sedentary. Even if initiated later in life, exercise interventions positively delay brain aging. More recently, investigators looked at the effects of resistance training as a protective measure against cognitive dysfunction. One study included 100 participants between the ages of 55 and 86 who suffered from mild cognitive impairment. They found that six months of resistance exercise improved memory, attention, and executive function. Importantly, these benefits persisted for more than a year after the intervention was terminated.

In 2020, the University of Sydney published research that studied the effect of weightlifting as a preventative measure against the development of Alzheimer’s disease. Study participants were randomly assigned to groups that used either computerized brain training, strength training, or combined computer and strength training for six months. The results showed that strength training led to overall benefits in cognitive performance. This was most evident as a protective factor of the hippocampus, the area of your brain that plays a significant role in learning and memory. The group that did not have strength training showed shrinkage of their hippocampus on brain imaging. In contrast, those who participated in strength training showed minimal or no changes. Professor and lead investigator Michael Valenzuela stated, “Resistance exercise should become a standard part of dementia risk-reduction strategies.”

Last year, The British Medical Journal published a study examining the effect of genetically determined lean muscle mass on the risk of Alzheimer’s. In this study, researchers collected information on the genetics, lean muscle mass, cognition, and health data of 450,243 participants from the U.K. Biobank. They found that higher amounts of lean muscle mass appeared to be a protective factor against the development of the disease. However, they did not explain how this protective factor produced its positive effect.

There are some theories about why this association exists. Mitochondria are the cellular components that generate most of the chemical energy needed to power the cell’s biochemical reactions. Mitochondrial dysfunction is found in many disease states and in the natural loss of skeletal muscle as we age. We thrive when our muscles and brain cells have healthy mitochondria. The opposite is true when they are dysfunctional. Reduced muscle mass can put us at risk for falls and fractures, as well as cognitive decline. Myokines are proteins released by our muscles that affect other body tissues. In experimental studies, they are increased by exercise and positively influence brain function. Irisin is a membrane protein found in skeletal muscle and fat. During exercise, it is released into our bloodstream and can be found in our nerve tissue. Some researchers hypothesize that it may act as a potential regulator of neuroinflammation, which is found in patients with Alzheimer’s disease.

How to Increase Lean Muscle Mass

Although the mechanism by which lean muscle mass may be protective against Alzheimer’s disease and other dementias is not entirely clear, it is undeniable that exercise has a positive effect on brain health. Here are some ways to effectively increase your overall lean body mass:

• Aerobic activity: Aim for 150 minutes of moderate or 75 minutes of vigorous aerobic activity per week. Although more significant amounts will provide more benefits, even small amounts of physical activity are helpful.
• Strength training: Train all major muscle groups at least twice weekly. Use resistance bands or weights heavy enough to fatigue your muscles after 12 to 15 reps.
• Incorporate protein into your diet. Protein is essential for building muscle. Research suggests a good guideline is 1.4 to 2 grams of proteins per kilogram of body weight.