Post-traumatic stress disorder is an anxiety disorder that can occur after living through a traumatic event, such as military combat.

Not every combat veteran will get PTSD. But those who do can become easily startled and irritable, and they often feel that they are on guard. They might constantly relive a life-threatening event through flashbacks or nightmares, which often trigger intense feelings of fear, helplessness and horror. Others may isolate themselves or try to numb their memories with drugs or alcohol.

People with PTSD suffer more unemployment, divorce or separation and spousal abuse than people without PTSD.

Source: Department of Veterans Affairs National Center for PTSD