Gross stress reaction is defined as a normal personality using established patterns of reaction to deal with overwhelming fear as a response to conditions of great stress. The diagnosis includes language which relates the condition to combat as well as to "civilian catastrophe".A USAF study carried out in 1979 focused on individuals (civilian and military) who had worked to recover or identify the remains of those who died in Jonestown. The bodies had been dead for several days, and a third of them had been children. The study used the term "dysphoria" to describe PTSD-like symptoms.Early in 1978, the diagnosis term "post-traumatic stress disorder" was first recommended in a working group finding presented to the Committee of Reactive Disorders. The condition was described in the DSM-III (1980) as posttraumatic stress disorder. In the DSM-IV, the spelling "posttraumatic stress disorder" is used, while in the ICD-10, the spelling is "post-traumatic stress disorder".The addition of the term to the DSM-III was greatly influenced by the experiences and conditions of U.S. military veterans of the Vietnam War. Owing to its association with the war in Vietnam, PTSD has become synonymous with many historical war-time diagnoses such as railway spine, stress syndrome, nostalgia, soldiers heart, shell shock, battle fatigue, combat stress reaction, or traumatic war neurosis. Some of these terms date back to the 19th century, which is indicative of the universal nature of the condition.
Diagnosis
PTSD can be difficult to diagnose, because of:

the subjective nature of most of the diagnostic criteria (although this is true for many mental disorders);
the potential for over-reporting, e.g., while seeking disability benefits, or when PTSD could be a mitigating factor at criminal sentencing
the potential for under-reporting, e.g., stigma, pride, fear that a PTSD diagnosis might preclude certain employment opportunities;
symptom overlap with other mental disorders such as obsessive compulsive disorder and generalized anxiety disorder;
association with other mental disorders such as major depressive disorder and generalized anxiety disorder;
substance use disorders, which often produce some of the same signs and symptoms as PTSD; and
substance use disorders can increase vulnerability to PTSD or exacerbate PTSD symptoms or both; and
PTSD increases the risk for developing substance use disorders. the differential expression of symptoms culturally (specifically with respect to avoidance and numbing symptoms, distressing dreams, and somatic symptoms)

Screening
There are a number of PTSD screening instruments for adults, such as the PTSD Checklist for DSM-5 (PCL-5) and the Primary Care PTSD Screen for DSM-5 (PC-PTSD-5).There are also several screening and assessment instruments for use with children and adolescents. These include the Child PTSD Symptom Scale (CPSS), Child Trauma Screening Questionnaire, and UCLA Post-traumatic Stress Disorder Reaction Index for DSM-IV.In addition, there are also screening and assessment instruments for caregivers of very young children (six years of age and younger). These include the Young Child PTSD Screen, the Young Child PTSD Checklist, and the Diagnostic Infant and Preschool Assessment. Assessment
Evidence-based assessment principles, including a multimethod assessment approach, form the foundation of PTSD assessment.