Dependence is when you need one or more substance to function. Abuse is taking more medication than is prescribed, taking illegal drugs, using any substance despite the adverse consequences. Addiction is defined as a chronic, relapsing disorder characterized by compulsive drug seeking, continued use despite harmful consequences, & long-lasting changes in the brain. It is considered both a complex brain disorder and a mental illness. Addiction is the most severe
Post-traumatic stress disorder (PTSD) is a mental health condition that's triggered by a terrifying event — either experiencing it or witnessing it. Symptoms may include flashbacks, nightmares and severe anxiety, as well as uncontrollable thoughts about the event.