Whether you’re young or post-young, there’s no time like the present to get into an exercise routine. Besides helping with weight loss and improving cardiovascular fitness, more and more evidence suggests that aerobic exercise can delay – and even reverse – brain aging.
Many regions of the brain literally shrink in size as adults grow older. The hippocampus, which is associated with memory and spatial tasks, is known to lose about 1-2% of its volume per year. As a resultthough hippocampus shrinkage is not the only cause of memory loss, memory eventually begins to suffer. But hippocampus shrinkage isn’t necessarily inevitable. Adults with higher physical fitness levels have been found to have larger hippocampithe somewhat awkward plural of hippocampus than less fit adults of the same age. Translation: Exercise now can prevent brain loss later in life.
So what if it’s already “later in life”? New research in PNASProceedings of the National Academy of Sciences suggests that older adults (age 55 – 80) can actually reverse the brain aging process by picking up an aerobic exercise plan. In a year-long study, researchers followed 120 previously sedentary adults through either a moderate cardio training routine or a stretching/weight lifting regimen. Though the stretching group – which was the control group for this study – displayed the normal 1-2% loss in hippocampus volume after 1 year, the adults engaged in cardio exercise actually displayed about a 2% increase in hippocampus size after one year.
In a sense, aerobic exercise is the elixir of youth for hippocampi. Here are the details:
Study Participants. Researchers obtained a whole bunch of volunteers from a senior living community to participate in an exercise program. The participants in the study were aged 55 to 80, and were considered to be “sedentary” for at least the last 6 months. The researchers screened the volunteers for previously existing physical or mental health conditions, including diabetes, cardiovascular disease, depression, dementia, stroke, or other neurological disorders. Furthermore, to make sure there were no biased results, only right-handed participants with pretty good eyesight (correctable to 20/40, not color blind) were chosen for the study.
Before the Study. The volunteers’ starting fitness levels were assessed by quantifying their VO2 maxa measurement of the body's maximum ability to transport and use oxygen during exercise via an aerobic walking fitness test. Their brains were also scanned by MRI to see how big their hippocampi were.
The Exercise Protocol. The 120 total participants were randomly placed into an aerobic exercise group or a control group – 60 participants in each. Aerobic exercise consisted of 40 minutes of walking at a pace that targeted 60-75% max heart rate. (Note – the participants built up to this exercise intensity over the first 7 weeks; it’s safest to start slow when beginning an exercise program.) Aerobic walking sessions were held 3 times per week, and participants had an average attendance rate of around 80% – so they were allowed to miss a few sessions here and there.
The control group participated in exercise sessions 3x per week as well, but no cardio training. Instead, their exercise consisted solely of stretching and resistance training. They also had an attendance rate of about 80%.
Measurements. The researchers tested the volunteers after 6 months of exercise, and again after the full one year protocol. Besides hippocampus imaging, they also measured the levels of a certain protein – called BDNFbrain-derived neurotrophic factor – in the volunteers’ blood. BDNF is a protein that helps with neurogenesis – the growth of new brain cells – so higher levels of blood BDNF might be expected for people growing bigger brains. Lastly, the researchers tested the performance of the volunteers on spatial memory tasks (kind of like the game of Concentration).
Results. The aerobic exercise group gained about 2% hippocampus volume after one year. Contrast that to the control group, who lost about 1.4% of their hippocampi volumes. Translation: although stretching and weight lifting are good for you, you need cardio to reverse brain aging.
As expected, greater increases in blood levels of BDNF were associated with greater increases in hippocampus size. Perhaps for average individuals concerned with improving their brain size, a blood test to measure BDNF levels could be performed as a cheaper alternative to getting an MRI.
Lastly, larger hippocampus volume was found to be associated with better performance on spatial memory tasks. However, it is worth noting that both the aerobic group and the control group showed improvements in spatial memory after one year.
Comments. It would be interesting to see this study carried out over a longer term, to see if/when hippocampus growth tapers off. Furthermore, I’m curious if there was a correlation between weight loss and hippocampus growth, though there is no mention of that in this study. It seems reasonable that the aerobic exercisers might have lost more weight than the stretching volunteers.
Conclusion. Young folks: cardio exercise now can preserve your big brain for the future. Post-young folks: cardio exercise now can help you get back that big brain from the past!
Erickson, K., Voss, M., Prakash, R., Basak, C., Szabo, A., Chaddock, L., Kim, J., Heo, S., Alves, H., White, S., Wojcicki, T., Mailey, E., Vieira, V., Martin, S., Pence, B., Woods, J., McAuley, E., & Kramer, A. (2011). Exercise training increases size of hippocampus and improves memory Proceedings of the National Academy of Sciences DOI: 10.1073/pnas.1015950108