Posttraumatic stress disorder (PTSD) is a mental disorder that can develop after a person is exposed to a traumatic event, such as sexual assault, warfare, traffic collisions, or other threats on a person's life. Symptoms may include disturbing thoughts, feelings, or dreams related to the events, mental or physical distress to trauma-related cues, attempts to avoid trauma-related cues, alterations in how a person thinks and feels, and an increase in the fight-or-flight response. These symptoms last for more than a month after the event. Young children are less likely to show distress, but instead may express their memories through play. A person with PTSD is at a higher risk for suicide and intentional self-harm. Most people who experience a traumatic event do not develop PTSD. People who experience interpersonal trauma such as rape or child abuse are more likely to develop PTSD, as compared to people who experience non-assault based trauma, such as accidents and natural disasters. About half of people develop PTSD following rape. Children are less likely than adults to develop PTSD after trauma, especially if they are under 10 years of age. Diagnosis is based on the presence of specific symptoms following a traumatic event. Prevention may be possible when counselling is targeted at those with early symptoms but is not effective when provided to all trauma-exposed individuals whether or not symptoms are present. The main treatments for people with PTSD are counselling (psychotherapy) and medication. Antidepressants of the selective serotonin reuptake inhibitor type are the first-line medications for PTSD and result in benefit in about half of people. Benefits from medication are less than those seen with counselling. It is not known whether using medications and counselling together has greater benefit than either method separately. Other medications do not have enough evidence to support their use and, in the case of benzodiazepines, may worsen outcomes. In the United States, about 3.5% of adults have PTSD in a given year, and 9% of people develop it at some point in their life. In much of the rest of the world, rates during a given year are between 0.5% and 1%. Higher rates may occur in regions of armed conflict. It is more common in women than men. Symptoms of trauma-related mental disorders have been documented since at least the time of the ancient Greeks. During the World Wars, the condition was known under various terms including 'shell shock' and 'combat neurosis'. The term 'posttraumatic stress disorder' came into use in the 1970s in large part due to the diagnoses of U.S. military veterans of the Vietnam War. It was officially recognized by the American Psychiatric Association in 1980 in the third edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-III). Symptoms of PTSD generally begin within the first 3 months after the inciting traumatic event, but may not begin until years later. In the typical case, the individual with PTSD persistently avoids trauma-related thoughts and emotions, and discussion of the traumatic event, and may even have amnesia of the event. However, the event is commonly relived by the individual through intrusive, recurrent recollections, dissociative episodes of reliving the trauma ('flashbacks'), and nightmares. While it is common to have symptoms after any traumatic event, these must persist to a sufficient degree (i.e., causing dysfunction in life or clinical levels of distress) for longer than one month after the trauma to be classified as PTSD (clinically significant dysfunction or distress for less than one month after the trauma may be acute stress disorder). Some following a traumatic event experience posttraumatic growth. Trauma survivors often develop depression, anxiety disorders, and mood disorders in addition to PTSD. Drug abuse and alcohol abuse commonly co-occur with PTSD. Recovery from posttraumatic stress disorder or other anxiety disorders may be hindered, or the condition worsened, when substance use disorders are comorbid with PTSD. Resolving these problems can bring about improvement in an individual's mental health status and anxiety levels.