PTSD is trauma based, so person is not mentally ill although mentally ill people can also suffer PTSD the two are not related. If you really knew any one who suffers from PTSD you would realize it is not a mental illness. People can also have PTSD from non combat trauma, one of the reasons for many people who suffer with non combat PTSD is being a victim of many years child abuse. PTSD is PTSD no matter the cause the way people with PTSD react is the same they may have different triggers but the internal stress is the same. People with PTSD are more apt to harm themselves than anyone else.