You don't have to fight in a war to suffer from post-traumatic stress disorder—commonly called PTSD. When any person goes through a terrifying experience, it can lead to persistent symptoms such as nervousness, sleeplessness and upsetting memories of the event. 

“When you experience a highly arousing event—things that make us sad, angry or afraid—there’s a biological mechanism that encodes and consolidates those memories in a more lasting way than other kinds of memories,” says Steven M. Southwick, MD, professor of Psychiatry at Yale School of Medicine and medical director of the Clinical Neurosciences Division of the Department of Veterans Affairs National Center for PTSD. 

Yale Medicine physicians and scientists have been at the forefront of research and clinical practice concerning PTSD for more than 25 years.

There four categories of symptoms: intrusive memories, avoidance behaviors, negative changes in mood and cognition and increased arousal reactions.

“For your illness to be classified as PTSD, you have to have symptoms from each category and the symptoms need to last for at least a month,” says Dr. Southwick.

• Intrusive memories. They can be recurrent, distressing memories of the traumatic event; nightmares or upsetting dreams; flashbacks in which it can feel as though the person is reliving the event; or a severe physiological response (increased blood pressure or breathing rate, for example), when the person is exposed to a reminder of the event. 
• Avoidance behaviors. People with PTSD may avoid, purposely or subconsciously, things that remind them of the traumatic event, which could mean steering clear of conversations, activities, situations, people or places that somehow bring back the distressing memory. 
• Negative changes in mood and cognition. People experiencing PTSD may develop a persistent, negative belief about the world and about themselves. They may become depressed, lose interest in things they once enjoyed, have trouble remembering the traumatic event and even blame themselves for the event. 
• Increased arousal reactions. A person with PTSD may react more easily to various stimuli and be easily startled, may be more irritable and angry, may feel hyper-vigilant or may have trouble concentrating or sleeping. 

The severity and range of PTSD symptoms can vary, but usually they follow closely after the traumatic event. Some people may exhibit symptoms immediately, at the scene of a disaster, for example, while others will notice symptoms during the days and months that follow. 

Several factors may increase the likelihood that a person develops PTSD.

• Severity of the trauma. The more traumatic or long-lasting the event, the more likely it is that someone will develop PTSD. Some stressors are more likely to cause PTSD than others. One of the most severe is sexual abuse.
• Accompanying physical injury. If the person was injured in the traumatic event, it increases the chance of getting PTSD.  For example, if you lost a limb, that’s a constant reminder of what you’ve gone through.
• A deliberate or manmade event. If the event wasn’t an accident—for example, if someone experiences an assault—it tends to cause a higher rate of PTSD.
• Age. Younger people are more likely to develop PTSD because they may not yet have developed strategies that can help them handle trauma. “Unfortunately, many of our soldiers are pretty young,” Dr. Southwick says.
• Lack of social support. A strong social support network of family and friends tends to help brace against the effects of severe trauma. If you’re with other people, your stress responses tend to be somewhat muted.
• Environment. Jobs that expose people to potentially dangerous situations, such as the military or law enforcement, lead to trauma and higher potential for PTSD, as does living in a dangerous place. 
• Pre-existing history of severe trauma. Someone who has experienced intense trauma or abuse, particularly in childhood, may be more likely to develop PTSD following a traumatic event later in life.
• Pre-existing family history of mental health problems. A family history of depression or PTSD can sometimes make it more likely that an individual will develop PTSD.

If symptoms persist after a traumatic event, a person should seek a consultation from a medical professional. A primary care doctor will probably refer the patient to a psychiatric doctor for a psychological evaluation. The important thing is to seek treatment as soon as possible. If a person experiences symptoms for more than a month, that means it’s time.

“When symptoms persist and they begin to interfere with your life, you need to talk with a health professional," says Dr. Southwick. "Otherwise, if you try to deal with it by yourself, you may end up trying to self-medicate, which could bring additional issues you'll have to deal with.

The most common treatment for PTSD is psychotherapy, though that is often used in combination with medication.

The types of therapies typically used in the treatment of PTSD are:

• Cognitive therapy. Typically, the patient will discuss the traumatic event and the ways he has been processing it. “We’ll look at this event again, what was actually happening, and in a more rational way we’ll try to help the individual understand what really was and wasn’t possible,” says Dr. Southwick.
• Exposure therapy. In this type of therapy, the patient will re-experience the traumatic event in various ways, often through sensory perception, so you come to understand it more deeply. “You try to describe it to the therapist in as great detail as you can,” Dr. Southwick says. “The way things smelled, the way things felt, the sounds and what you saw."
• Medications. The medications that have been approved by the Food and Drug Administration for the treatment of PTSD are sertraline (Zoloft) and paroxetine (Paxil). “They tend not to be curative, but they certainly help many people with PTSD,” Dr. Southwick says. “It can be part of the solution.”

Yale Medicine has been at the forefront of PTSD research for more than 25 years, and its affiliation with the Clinical Neurosciences Division of the Department of Veterans Affairs National Center for PTSD has given researchers the unique perspective of working with veterans while exploring the neurobiological underpinnings of the condition.

“These studies started decades ago, beginning with understanding how the sympathetic nervous system, the fight-or-flight response, can become hyper-responsive in individuals who have PTSD,” says Dr. Southwick. The initial research provided an explanation for why a person with PTSD feels hyper-aroused.

These days, Yale Medicine is continuing to explore the role of neurochemicals and how the brain responds to severe trauma. This research seeks to find more effective treatment options for PTSD. Currently approved medicines are not entirely curative, so researchers at Yale Medicine are working to discover what’s happening on a neurobiological level, and target that more specifically.

“It has taken time to get a better understanding of the fear circuitry in the brain and the various mechanisms that the brain uses to deal with stress and trauma,” Dr. Southwick says. “There’s a tremendous amount still to learn, but we are in a better place to look at interventions that make more sense from what’s known about the underlying biological alterations that characterize PTSD.”