What Causes PTSD? Here's What Happens to the Brain After Trauma

There's no threshold for whether something is traumatic enough to cause the disorder, but common triggers include natural disasters and violent assaults.

A violent act, natural disasters, military combat: These are all life events that can prompt post-traumatic stress disorder (PTSD), which affects 8 million Americans, according to the National Alliance on Mental Illness.

The list of triggers for this anxiety disorder is quite long and includes natural disasters such as floods, earthquakes, tsunamis, serious accidents, and witnessing a death, especially a violent one.

"In addition, the PTSD causes we are all familiar with include military combat, terrorist attacks, and violent personal assaults such as sexual assault, mugging, or robbery," says Vonnie Nealon, clinical director of Warriors Heart, an accredited treatment program for military, veterans and first responders, in Bandera, Texas.

Your Brain on PTSD

When people experience traumas like those mentioned above, it's normal to be upset or even experience physical symptoms, like nausea or nightmares. That's known as post-traumatic stress, and it usually resolves on its own within a few days or weeks.

But sometimes it doesn't, disrupting their lives for months or years after the event. Symptoms of PTSD can include rapid heartbeat, nausea, sweating, shortness of breath, and anxious feelings.

To date, most PTSD research has shown that specific parts of the brain—such as the amygdala, hippocampus, and prefrontal cortex—are in some way altered due to trauma, says Kate Cummins, PsyD, a licensed clinical psychologist in San Francisco.

"In addition, cortisol, a stress hormone that increases during long episodes of stress, and norepinephrine, which is responsible for arousal, attention, and vigilance, are seen more in those patients who have been exposed to trauma," Cummins says.

There are some known risk factors for PTSD. Women, for example, are more likely to develop PTSD than men, according to the National Institute of Mental Health, and people with a history of mental health issues are also at increased risk. Lacking emotional support from friends and family after an initial trauma—or experiencing additional stress during the event's aftermath—can also raise a person's risk of developing PTSD.

Your Reaction to Trauma Depends on You

While PTSD often manifests as a reliving of a traumatic event through nightmares and flashbacks, some people are affected more than others. "Some individuals may experience feelings of isolation, irritability, and guilt, and have difficulty sleeping and concentrating," Nealon says.

And, although scientists have been able to define changes in brain structures, more research needs to be done to understand how some individuals end up with a diagnosis of PTSD and others don't, despite being exposed to the same type of trauma, Cummins says.

"For example, some individuals in war combat will endure symptoms of PTSD throughout their life while others won't," Cummins says. "This can happen even if two individuals were on the same deployment and were exposed to the same traumas."

According to the Diagnostic and Statistical Manual of Mental Disorders (DSM-5), a resource manual for mental health professionals, a person must have been exposed to "actual or threatened death, serious injury, or sexual violence" in order to be diagnosed with PTSD.

Besides that, though, there's no threshold for whether something is traumatic enough to cause PTSD; it depends more on the brain's reaction to it, and how seriously (and for how long) a person is affected. PTSD can even be caused by witnessing or learning about a trauma that happened to someone else, or in rare cases, by looking at traumatic videos or photos.

Differentiating Chronic Anxiety and PTSD

PTSD differs from other anxiety disorders because it can be traced to a specific event or events. Symptoms tend to begin within three months of experiencing trauma, but they can also first appear up to a year afterward.

"Another hallmark symptom of PTSD is intrusive flashback memories," says Gail Saltz, MD, an associate professor of psychiatry at the New York Presbyterian Hospital Weill-Cornell School of Medicine. "These can occur during the day, or take the form of nightmares, where it feels almost like you're back there in the situation."

If you have PTSD, you may find yourself avoiding certain situations. "This means you won't do anything that could be a trigger or is reminiscent of the traumatic event," Dr. Saltz says.

How to Know If You Need Help

Though there's no cure for PTSD, you should seek help from a healthcare professional if you can't socialize, function at work, concentrate or sleep at night. A PTSD diagnosis is usually made if you've had symptoms for more than one month.

Current PTSD treatments include medications, mindfulness, service animals (especially dogs), and individual and group therapy, Cummins says. "It could be that your predominant symptoms are anxiety or depression," Dr. Saltz says. "Your treatment should be aimed directly at the symptoms you're experiencing."

Having a solid relationship with your healthcare professional can be pivotal, too.

"Decreased symptoms are typically seen over time when patients establish relationships with their clinicians and feel less alone in handling the challenges that come from PTSD," Cummins says. "Additionally, increased support from friends and family can help reduce the feeling of social isolation that can result from PTSD."

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