It got much worse after the Vietnam War, and far worse when women entered the military in larger numbers.
If the VA hospitals would release the stats, you would see that the percentage of women with PTSD is far far higher as a percentage of their population in the military than men.
In previous wars, the soldiers went to war together and came home together and knew each other’s experiences first hand and came hoe to parades. In Vietnam they went separately and came home separately and had to deal with their experiences alone to a hostile country that didn’t appreciate them.