Here’s a BYU study on the effects of PTSD on soldiers prior to the battle and after the battle. It’s light to medium reading (29 pages).
Apparently the belief is that Custer may have had brain damage from a fall in 1864 that severely impacted his temperment and demeanor. PTSD is suspected and it goes hand-in-hand with a post upthread here where a poster (I forget who - sorry!) states he was a different man after the CW and hated by his troops.
It’s a good read.
https://scholarsarchive.byu.edu/cgi/viewcontent.cgi?article=1004&context=sahs_review
“...where a poster (I forget who - sorry!) states he was a different man after the CW and hated by his troops.”
Probably because he quit drinking.