(From the National Center for PTSD)

What is PTSD?
Post Traumatic Stress Disorder, or PTSD, is a psychiatric disorder that can occur following the experience or witnessing of life-threatening events such as military combat, natural disasters, terrorist incidents, serious accidents, or violent personal assaults like rape. People who suffer from PTSD often relive the experience through nightmares and flashbacks, have difficulty sleeping, and feel detached or estranged, and these symptoms can be severe enough and last long enough to significantly impair the person’s daily life.

PTSD is marked by clear biological changes as well as psychological symptoms. PTSD is complicated by the fact that it frequently occurs in conjunction with related disorders such as depression, substance abuse, problems of memory and cognition, and other problems of physical and mental health. The disorder is also associated with impairment of the person’s ability to function in social or family life, including occupational instability, marital problems and divorces, family discord, and difficulties in parenting.

Understanding PTSD
PTSD is not a new disorder. There are written accounts of similar symptoms that go back to ancient times, and there is clear documentation in the historical medical literature starting with the Civil War, when a PTSD-like disorder was known as "Da Costa’s Syndrome." There are particularly good descriptions of posttraumatic stress symptoms in the medical literature on combat veterans of World War II and on Holocaust survivors.

Careful research and documentation of PTSD began in earnest after the Vietnam War. The National Vietnam Veterans Readjustment Study estimated in 1988 that the prevalence of PTSD in that group was 15.2% at that time and that 30% had experienced the disorder at some point since returning from Vietnam.

PTSD has subsequently been observed in all veteran populations that have been studied, including World War II, Korean conflict, and Persian Gulf populations, and in United Nations peacekeeping forces deployed to other war zones around the world. There are remarkably similar findings of PTSD in military veterans in other countries. For example, Australian Vietnam veterans experience many of the same symptoms that American Vietnam veterans experience.

PTSD is not only a problem for veterans, however. Although there are unique cultural- and gender-based aspects of the disorder, it occurs in men and women, adults and children, Western and non-Western cultural groups, and all socioeconomic strata. A national study of American civilians conducted in 1995 estimated that the lifetime prevalence of PTSD was 5% in men and 10% in women.

How does PTSD develop?
Most people who are exposed to a traumatic, stressful event experience some of the symptoms of PTSD in the days and weeks following exposure. Available data suggest that about 8% of men and 20% of women go on to develop PTSD, and roughly 30% of these individuals develop a chronic form that persists throughout their lifetimes.

What are the consequences associated with PTSD?
PTSD is associated with a number of distinctive neurobiological and physiological changes. PTSD may be associated with stable neurobiological alterations in both the central and autonomic nervous systems, such as altered brainwave activity, decreased volume of the hippocampus, and abnormal activation of the amygdala. Both the hippocampus and the amygdala are involved in the processing and integration of memory. The amygdala has also been found to be involved in coordinating the body's fear response.

Psychophysiological alterations associated with PTSD include hyper-arousal of the sympathetic nervous system, increased sensitivity of the startle reflex, and sleep abnormalities.

People with PTSD tend to have abnormal levels of key hormones involved in the body’s response to stress. Thyroid function also seems to be enhanced in people with PTSD. Some studies have shown that cortisol levels in those with PTSD are lower than normal and epinephrine and norepinephrine levels are higher than normal. People with PTSD also continue to produce higher than normal levels of natural opiates after the trauma has passed. An important finding is that the neurohormonal changes seen in PTSD are distinct from, and actually opposite to, those seen in major depression. The distinctive profile associated with PTSD is also seen in individuals who have both PTSD and depression.

PTSD is associated with the increased likelihood of co-occurring psychiatric disorders. In a large-scale study, 88 percent of men and 79 percent of women with PTSD met criteria for another psychiatric disorder. The co-occurring disorders most prevalent for men with PTSD were alcohol abuse or dependence (51.9 percent), major depressive episodes (47.9 percent), conduct disorders (43.3 percent), and drug abuse and dependence (34.5 percent). The disorders most frequently comorbid with PTSD among women were major depressive disorders (48.5 percent), simple phobias (29 percent), social phobias (28.4 percent), and alcohol abuse/dependence (27.9 percent).

PTSD also significantly impacts psychosocial functioning, independent of comorbid conditions. For instance, Vietnam veterans with PTSD were found to have profound and pervasive problems in their daily lives. These included problems in family and other interpersonal relationships, problems with employment, and involvement with the criminal justice system.

Headaches, gastrointestinal complaints, immune system problems, dizziness, chest pain, and discomfort in other parts of the body are common in people with PTSD. Often, medical doctors treat the symptoms without being aware that they stem from PTSD.