How much does our brain shrink by 70?

In general, brain volume will decline by 5% every 10 years after you 40 years old so it would be 15% shrink by 70 yo but there are difference rate in other areas. The rate of decline will increase after 70 years old.
.White matter of the brain declines faster than gray matter.

The answer would be WAR. That would be the only time a draft would be put into place.