A previous post, “If You Do Not Like Mnemonic Techniques, Try Walking”, was a little thin given the importance of the topic. So I’ve gone to the original article1. The hippocampus is a component of the brain that is critical to memory function. Unfortunately, the hippocampus shrinks 1-2% annually in older adults without dementia, and this loss of volume increases the risk of developing cognitive impairment. This experiment was undertaken to assess whether exercise and what kind of exercise might mitigate this decline.
Participants between the ages of 55 and 80 years old were recruited, who did not have any pertinent diseases or disabilities. 120 participants were randomly assigned: half to a stretching and resistance training control group, and half to an aerobic walking group. Sessions for each group were held three times a week and lasted roughly one hour. Participants in the aerobic group started walking for ten minutes the first week and increased walking durations by five minute increments until a duration of 40 minutes was reached by week seven. Each session began and ended with approximately 5 minutes of stretching. The control group engaged in four muscle-toning exercises using dumbbells or resistance bands, two exercises designed to improve balance, one yoga sequence and one exercise of their choice. The program lasted for one year. MRIs, fitness, and short term memory were assessed before the program began, 6 months into the program, and at the end of the one-year program. Blood samples were taken at the beginning and end of the program.
Aerobic exercise (walking) increased hippocampal volume by 2%. This increase effectively reverses the expected age-related loss by 1 to 2 years. Moreover, increased hippocampal volume was positively correlated with improvements in short term memory performance. Increased hippocampal volume was also associated with greater levels of serum Brain-derived neurotrophic factor (BDNF), which helps support the survival of existing neurons and encourages the growth and differentiation of new neurons and synapses.
Hippocampal volume did decrease in the control group, but higher preintervention fitness partially attenuated the decline. The control group also exhibited improvement in short term memory performance.
Changes in fitness are associated with increased hippocampal volume. The aerobic exercise group showed a 7.78% improvement in maximal oxygen consumption (VO2) after intervention, whereas the stretching control group showed a 1/11% in VO2 max.
So although both exercise regimes were beneficial, the aerobic regime appeared to be more beneficial, especially with respect to its beneficial effects on hippocampal volume. Given the importance of the hippocampus to brain and memory, this finding is extremely important. Moreover, this aerobic exercise regimen was fairly mild and undemanding.
1Erickson, K.I., Voss, M.W., Prakash, R.S., Basak, C., Szabo, A., Chaddock, L., Kim, J.S., Heo, S., White, S.M., Wojcicki, T.R., Malley, E., Viera, V.J., Martin, S.A., Pence, B.D., Woods, J.A., McAuley, E., & Kramer, A.F. (2011). Exercise Training Increases Size of Hippocampus and Improves Memory. PNAS Early Edition, www.pnas.org/cgi/doi/10.1073/pnas.10159550108.