How Exercise Helps the Brain

The hippocampus is deep in the temporal lobe. It helps us remember and learn.

We've known for a while that exercise is good for the brain. For example, I remember reading a while back how exercise led to the increase in BDNF (brain derived neurotropic factor) which helps students perform better in school. BDNF is like miracle grow for the brain. 

But exercise can also help with slowing the ageing process and cognitive decline. This shouldn't come as a surprise to many but the mechanism might be. 

The benefits mentioned above are related to the increased plasticity  and reduced inflammation within the hippocampus. The hippocampus is found deep in the temporal lobe and plays a big role in memory and learning.

So why does exercise help?

A recent study helps to answer this question.

Well, when the plasma of running mice is injected into sedentary mice there was decreased neuro-inflammatory gene expression. When the plasma (i.e. the liquid portion of the blood) was further analyzed for proteins it was found to contain higher levels of complement cascade inhibitors, including clusterin. 

Clusterin is important is it helps clears cellular debris and plays a role in apoptosis (i.e. programmed cell death).

So, now it should be a little more clear why clusterin is important for memory and frequently comes up when you read up on Alzheimer's and other cognitive function problems. 

When clusterin is injected into mice, it binds to the neural endothelial cells and reduces the expression of genes related to brain inflammation. 

When humans exercise for 6 months, higher levels of clusterin are detected in the brain. 

Another good reason to stay active and exercise as long through as possible.

Reference

De Miguel, Z., Khoury, N., Betley, M.J. et al. Exercise plasma boosts memory and dampens brain inflammation via clusterin. Nature (2021). https://doi.org/10.1038/s41586-021-04183-