"Trauma is an emotional response to a terrible event like an accident, rape, or natural disaster. Immediately after the event, shock and denial are typical. Longer term reactions include unpredictable emotions, flashbacks, strained relationships, and even physical symptoms like headaches or nausea."

Source: American Psychological Association

"Posttraumatic stress disorder (PTSD) may develop in some people after extremely traumatic events, such as combat, a terrorist attack, crime, an accident, or a natural disaster. People with PTSD may relive the trauma in painful recollections, flashbacks, or recurrent dreams or nightmares; avoid activities or places that recall the traumatic event; or experience physiological arousal, leading to symptoms such as an exaggerated startle response, disturbed sleep, difficulty in concentrating or remembering, and guilt about surviving the trauma when others did not."

Source: American Psychological Association

"Substance use disorder (SUD) is complex a condition in which there is uncontrolled use of a substance despite harmful consequence. People with SUD have an intense focus on using a certain substance(s) such as alcohol, tobacco, or illicit drugs, to the point where the person's ability to function in day to day life becomes impaired. People keep using the substance even when they know it is causing or will cause problems. The most severe SUDs are sometimes called addictions."

Source: American Psychological Association