<P> 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). </P> <P> 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 . </P> <P> Persons considered at risk include combat military personnel, victims of natural disasters, concentration camp survivors, and victims of violent crime . Persons employed in occupations that expose them to violence (such as soldiers) or disasters (such as emergency service workers) are also at risk . Other occupations that are at higher risk include police officers, firefighters, ambulance personnel, health care professionals, train drivers, divers, journalists, and sailors, in addition to people who work at banks, post offices or in stores . The size of the hippocampus is inversely related to post-traumatic stress disorder and treatment success; the smaller the hippocampus, the higher risk of PTSD . </P> <P> PTSD has been associated with a wide range of traumatic events . The risk of developing PTSD after a traumatic event varies by trauma type and is highest following exposure to sexual violence (11.4%), particularly rape (19.0%). Men are more likely to experience a traumatic event, but women are more likely to experience the kind of high - impact traumatic event that can lead to PTSD, such as interpersonal violence and sexual assault . </P>

When was post traumatic stress disorder first diagnosed