Exercise Benefits, Research

Research: Exercise increases brain size & memory.

TitleExercise training increases size of hippocampus and improves memory (full article)

Authors: Kirk I. EricksonMichelle W. VossRuchika Shaurya PrakashChandramallika BasakAmanda Szabo, Laura ChaddockJennifer S. KimSusie HeoHeloisa AlvesSiobhan M. WhiteThomas R. WojcickiEmily MaileyVictoria J. VieiraStephen A. MartinBrandt D. PenceJeffrey A. WoodsEdward McAuley, and Arthur F. Kramer

Published: Proceedings of the National Academy of Sciences of the United States of America (PNAS)

Date: 2010

Type: Randomised control trial – 120 participants

Major Findings: Hippocampus volume increase by 2% during the trial time equivalent to 1-2 years of age related hippocampal loss.


In a fascinating research article that adds volume to those already screaming about the benefits of physical activity. This randomised control trial involving 120 participants, provided insight into the connection between brain function, memory retention and an individual’s physical state.

In the trial, the authors and researchers aimed to identify whether a link exists between increased physical activity and brain size, cognitive function and memory retention.

Of the 120 participants, they were divided into two groups for the 1 year duration of the trial:

  • 60 participants were randomly assigned to a 3 day/week moderate intensity aerobic exercise group.
  • 60 participants in the control group was assigned simple stretching exercises.
Characteristics for the aerobic exercise and stretching control groups

Table 1 – Characteristics for the aerobic exercise and stretching control groups


There were several areas of note for the researchers. Their results are outlined using original figures from the article below.

Figure 1 outlines the changes in brain structure (using MRI imaging). The change in the hippocampus was statistically significant while the caudate nucleaus and thalmus were not expected to result in any differences between the two groups.

(A) Example of hippocampus segmentation and graphs demonstrating an increase in hippocampus volume for the aerobic exercise group and a decrease in volume for the stretching control group. The Time × Group interaction was significant (P  0.10). (C) Example of thalamus segmentation and graph demonstrating the change in volume for both groups. None of the changes were significant for the thalamus. Error bars represent SEM.

Figure 1 – (A) Example of hippocampus segmentation and graphs demonstrating an increase in hippocampus volume for the aerobic exercise group and a decrease in volume for the stretching control group. The Time × Group interaction was significant (P < 0.001) for both left and right regions. (B) Example of caudate nucleus segmentation and graphs demonstrating the changes in volume for both groups. Although the exercise group showed an attenuation of decline, this did not reach significance (both P > 0.10). (C) Example of thalamus segmentation and graph demonstrating the change in volume for both groups. None of the changes were significant for the thalamus. Error bars represent SEM.


Figure 2 zooms in on significant changes in the hippocampus specifically. The anterior hippocampus seems to experience the greatest effect following exercise, especially given the decline in the control group during the same time period.

Figure 2 - The exercise group showed a selective increase in the anterior hippocampus and no change in the posterior hippocampus.

Figure 2 – The exercise group showed a selective increase in the anterior hippocampus and no change in the posterior hippocampus.


The authors state that:

Our results demonstrate that the size of the hippocampus is modifiable in late adulthood and that moderate-intensity aerobic exercise is effective at reversing volume loss.


Other notable results include:

  • Increased fitness improvement correlates with increased hippocampal volume increase. (The fitter a individual gets, the greater the benefits on brain size).
  • Greater initial fitness also results in a reduced decline in hippocampal volume in the absence of regular exercise.
  • Researchers also “found that higher aerobic fitness levels at baseline and after intervention were associated with better memory performance on the spatial memory task.”



Research to practice

It can often be difficult to translate findings from a research setting and apply them to yourself, family members or clients. The findings of this study are favourable to encouraging the initiation and maintenance of physical activity as we age.

Without regular exercise, the hippocampus decays at a rate of 1-2% per year as we age. This loss of hippocampal volume is known to increase the risk of cognitive impairment.

The stress on the healthcare system associated with the ageing population and cognitive decline is well established. Exercise proves to be a fairly simple and low cost intervention that can assist on an individual level as well as on a societal level.

Its important to acknowledge the vast benefits of exercise beyond that of “looking healthy.” Participation in regular, structured physical activity is multifaceted. This research helps highlight one of the more discrete benefits of exercise – improved cognition.


Citation

Erickson, K., Voss, M., Prakash, R., Basak, C., Szabo, A., Chaddock, L., … Kramer, A. (2010). Exercise training increases size of hippocampus and improves memory. Proceedings of the National Academy of Sciences, 108(7), 3017-3022. Retrieved November 6, 2014, from http://www.pnas.org/content/108/7/3017.full

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