I'd be interested in the cumulative effects studies when they start to be published. The pilot I could find on the subject covered brain perturbation linked to the repeated low level blast exposure of those in breaching operations.There is also a lot of research, especially in the SOF community, being done on the cumulative affect of low intensity blast exposure -like from CQB and even firing heavy weapons.
There is a lot of interest on the affect blasts have on the pituitary gland. I'm not a medical professional and can't speak intelligently on the matter, but from what I gather, it is incredibly delicate and particular sensitive to blasts due to its location. Low testosterone levels in surprisingly young members of SOF have been attributed to this, and of course all of the negative physical, mental, and emotional things that come with such changes.