Walking: Could it reverse brain shrinkage?


There is a region of the brain called the hippocampus. This region is important for memory function, but with age the hippocampus starts shrinking. This may explain why elderly individuals start to lose their memory.  However, a 2011 study published in the journal: Proceedings of the National Academy of Sciences (PNAS) suggests that the simple act of vigorous walking could help reverse this shrinkage, and in fact, actually help add volume to the hippocampus.


What did the researchers find?

The scientists discovered the following effects in their subjects after one year of walking: 

  • left hippocampus size increased by 2.12%
  • right hippocampus size increased by 1.97%
  • Greater improvements in fitness was associated with greater increases in size
  • High fitness levels at the start of the study was associated with less of a decline in hippocampus volume
  • Those who had greater increases in the volume of the hippocampus also had higher levels of brain-derived neurotrophic factor (an important protein in memory and learning) 
  • Higher fitness levels was associated with better memory performance
  • improved memory performance was associated with higher hippocampus volume

Note: The control group only stretched and did toning exercises. This group saw a DECREASE in their hippocampal volume after one year. These are significant findings. 


Was the size increase really significant? 

2% does not seem like a lot but it is significant. The hippocampus shrinks at a rate of about 1 to 2% annually in older adults without dementia. The the researchers state:

"a 2% increase in hippocampal volume is equivalent to adding between 1 and 2 years worth of volume to the hippocampus for this age group

Add two years worth of volume by walking for one year? That seems like a worthwhile trade!


How much and how intense must the walking be? 

The exercise protocol was approximately:

  • 40 minutes per session (they got to this level gradually)
  • 60 - 75% of hear rate maximum
  • 3 days per week 




The once-held belief that the brain could not change is outdated and obsolete. Even into the later stages of life, the brain can be changed for good or for ill. This particular study showed that exercises like walking can actually change the size of a portion of the brain. Not only that, but the findings of this study suggest that it may be beneficial to start earlier because higher fitness levels helped slow the decline in loss of hippocampus volume in the non-exercising group. 

The authors of the paper summarize their conclusions in the following way:

"These results clearly indicate that aerobic exercise is neuroprotective and that starting an exercise regiment later in life is not futile for either enhancing cognition or augmenting brain volume." 

So if you want to improve your chances of staying sharp, why not start with some walking?


To read the full paper, click here  

George Cho