Physical exercise triggers the growth of both brain cells and new connections between them. Until now, aerobic exercise was the kind of exercise mostly studied. It is has been shown to boost cognitive functions and is associated with lower risks of developing Alzheimer’s Disease. A new study shows that weight training may also be protective.
The study involved 86 women between the ages of 70 and 80 who had probable Mild Cognitive Impairment (MCI). MCI is a condition where people have mostly memory problems which are not severe enough to interfere with daily life. It is often considered to be the very early stage of Alzheimer’s Disease.
The women were divided into 3 groups: 1) a resistance training group, 2) an aerobic exercise group and , 3) a balance and tone training group. Each group exercised twice a week for six months.
Participants’ cognitive skills were measured with tests assessing executive functions (such as attention, problem solving, and decision making) and memory. The brains of 22 of the participants were also imaged using functional MRI.
The results showed that resistance training improved both executive functions and memory performance. Brain scans demonstrated increased blood flow to areas of the brain associated with the improved performance (such as the occipital and frontal regions of the brain).
In contrast to prior studies, there was no benefit of the aerobic training on cognitive performance (even though the cardiovascular performance of the participants in this group did improve).
This study is one of the first randomized controlled trials comparing the efficacy of both resistance and aerobic training to improve cognitive functions.
It confirms the results obtained a few years ago by the same team of researchers showing that 12 months of once- or twice-weekly strength training improved executive functions in healthy women ages 65- to 75 years old for up to 1 year after the training (Davis et al., 2010).
The novelty of the study is to show that even after a short period of time (6 months) the effects of strength training can benefit people who are already suffering from cognitive impairment. In addition, the functions that were boosted by the training are functions that are highly sensitive to the effect of age and disease.
So far the evidence that strength exercise is beneficial for the brain is scarce, so it is encouraging to see evidence accumulate. Such study puts strength training on the list of potential things to do to keep the brain healthy and protect it against decline.
The evidence that aerobic exercise triggers neurogenesis and thus increases gray matter volume is numerous. Prior evidence has also shown that aerobic exercise can boost cognitive skills in healthy older adults as well in people with MCI. The absence of cognitive boost or brain change in the aerobic training group in this study is thus unclear at this time.
Of note, the large and rigorous 2010 meta-analysis conducted by the NIH concluded that aerobic exercise was a factor associated with decreased risks for both Alzheimer’s Disease and cognitive decline (Williams et al., 2010). So there does not seem to have any questions that aerobic exercise can impact brain health. Its effect may be smaller or larger depending on the intensity of the exercise, the age and the health and cognitive status of the participants though. More research is needed to answer these questions.
- Davis, JC et al. (2010). Sustained Cognitive and Economic Benefits of Resistance Training Among Community- Dwelling Senior Women: A 1-Year Follow-up Study of the Brain Power Study. Arch Intern Med., 170(22), 2036-2038.
- Nagamatsu LS, et al “Resistance training promotes cognitive and functional brain plasticity in seniors with probable mild cognitive impairment” Arch Intern Med 2012; 172(8): 666-668.
- Williams, J. W., Plassman, B. L., Burke, J., Holsinger, T., & Benjamin, S. (2010). Preventing Alzheimer’s Disease and Cognitive Decline. NIH Evidence Report: AHRQ Publication.
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