Traumatic experiences don’t just change our perspective on life. Science tells us that emotional trauma also affects the physical wiring of the brain.

Evolution has taught certain parts of the brain to respond and adapt to trauma, resulting in consistent changes in regions of the brain associated with memory and the regulation of fear, according to research. Chronic stress, aging, prior experience, and even our genes can affect parts of the brain, which could explain why some people are more susceptible to depression and post-traumatic stress disorder (PTSD), and why children who are exposed to trauma may exhibit different symptoms than adults, the study notes.

That’s why it’s so important to learn to manage stress, work to heal from trauma, and take care of our brains, says Rene Hen, PhD, a professor of neuroscience at Columbia University in New York City.

Here’s what we know about emotional trauma and what it does to the brain.

Changes in the Brain: What Happens After Trauma?

Research is emerging and more needs to be done, because trauma responses are unique to each person and the nature of the trauma itself. Yet, while changes in the brain aren’t always clear-cut, well understood, or universally applicable to all groups, here’s what we do know.

When faced with a threat — real or perceived — our brains tend to shut down all nonessential systems and activate the fear response, also known as the primitive brain, notes the UK-based foster care organization ISP. In normal circumstances for both healthy children and adults, the parasympathetic nervous system (“rest and digest” mode) will kick in after the threat has passed and that person is able to relax. But when a stress response is triggered repeatedly over a long period of time, or in other words, traumas keep happening and the brain is forced to operate in survival mode as a result, it can physically alter the brain, per ISP.

Areas of the Brain Affected by Trauma

In general, three parts of the brain appear to be the most affected by traumatic experiences: the hippocampus, the amygdala, and the prefrontal cortex, according to the aforementioned research. Perhaps unsurprisingly, they also correlate with symptoms associated with PTSD, says James Bremner, MD, a professor of psychiatry and behavioral sciences and radiology at Emory University School of Medicine in Atlanta.

When people develop PTSD, Dr. Bremner explains, brain scans show patterns of increased activity in the amygdala, the part of the brain involved in registering fear. The hippocampus, which helps with memory, appears to shrink, and there’s dysfunction in the prefrontal cortex, which is associated with the regulation of emotion.

Symptomatically, individuals with PTSD may be easily startled and feel constantly on edge, may experience intrusive memories of the traumatic event while struggling with new short-term memory impairment, and may feel irritable or depressed, among other things, according to the International Society for Traumatic Stress Studies (ISTSS). All this seems to be expressed by a brain that’s living in fight-or-flight mode from trauma.

“[In a healthy person], when you have a trigger, the amygdala is the fear reaction, so that might activate,” Bremner says. “Then the hippocampus is involved in putting the breaks on the amygdala, as well as the prefrontal cortex.” This is known as fear circuitry, your brain-orchestrated defense mechanism in response to environmental threats, and it is evolutionarily critical to survival; but if it becomes dysfunctional (meaning it can’t flip back into parasympathetic mode) it may contribute to psychiatric conditions, notes one review.

In patients with PTSD, Bremner continues, the hippocampus and the prefrontal cortex fail to soothe the amygdala-based fear response. But it’s the hippocampus that appears to be most heavily affected by stress and trauma, Dr. Hen says. In animal models, which are likely applicable to humans, trauma appears to slow the creation of new cells in the hippocampus, according to research. Dendrites — the parts of brain cells that connect and communicate with other cells — also appear to shrink following traumatic events, according to another recent study.

These animal models seem to help explain why repeated exposure to trauma is associated with more severe mental health symptoms, Hen says. Chronic stress, like that felt after a trauma, appears to be the main driver of what Hen describes as the atrophy of the hippocampus. Aging and genetic factors may also play a role, he says, perhaps making people more vulnerable to developing conditions like PTSD as they get older. Yet, recent research suggests that non-ideal environmental conditions, such as living conditions with constant stress, may have a greater impact than genetics on the hippocampus.

Trauma May Impact Your Memory

The impact of stress and trauma on the hippocampus, which is primarily involved in memory and learning functions, helps to explain many of the symptoms associated with PTSD, Hen says. Trauma tends to make our memories of events associated with stressful feelings stronger, and less accurate, he explains.

The hippocampus is largely responsible for episodic memory, aka declarative memory — that is, the kind of memory that allows you to recall and talk about what you did and how you felt, per the American Psychological Association (APA). We all have another form of memory, implicit memory, that stores what we've learned, such as how to ride a bike or drive a car, but its function lives in other regions of the brain — the basal ganglia and cerebellum, per the University of Queensland — so it isn’t affected by psychological trauma, Hen says.

But the impacts of psychological trauma on episodic memory are readily apparent, if somewhat contradictory. Victims of trauma may find they have difficulty remembering the specifics of what happened, yet the emotions brought up by what they do remember may feel stronger than emotions for other memories, Hen explains.

When we are stressed, our brain ignores the broader environment around us and other details it deems unnecessary in order to focus on the immediate threat, Hen says. In PTSD, the brain becomes stuck in this stress response and may begin to overgeneralize, or become unable to separate the present moment with no threat from the past trauma. For example, to someone who witnessed the 9/11 attacks, entering any high-rise building may be terrifying because the details of what is currently happening become less important to the brain than the memories of the trauma, Hen explains.

“Normally you can discriminate [the present] from a past event,” Hen says, “but someone with PTSD cannot do that discrimination effectively. So even though the memory is stronger, it is less precise [in reality].”

Trauma May Impact Your Brain’s Ability to Concentrate and Rest

The neurological impacts of trauma may be centered in the hippocampus, but memory is far from the only aspect of day-to-day life that's compromised by these physiological changes.

People with trauma-induced PTSD often experience symptoms such as trouble with concentration, poor sleep, and recurrent nightmares and flashbacks related to the traumatic incident, per the ISTSS. These symptoms, Bremner says, are likely also related to dysfunction in the hippocampus.

PTSD causes the brain to overgeneralize, or assume that specific details of a traumatic experience apply to all other scenarios, which means that people with PTSD are constantly on guard, scanning their surroundings for signs that the trauma is happening again. This, Bremner says, could explain why people with PTSD have difficulty focusing and can suffer from insomnia — the brain essentially perceives that it’s besieged by threats and is unable to relax.

Trauma Responses in Children Vary, Too

Children have a notably different physiological and even cellular-level response to trauma, says Martin Teicher, MD, PhD, the director of the developmental biopsychiatry research program at McLean Hospital in Belmont, Massachusetts.

When adults are exposed to trauma, the impact in the brain is primarily constrained to hyperactivity in key areas like the hippocampus and the amygdala, Dr. Teicher explains. But when young children are exposed to trauma, the brain, which is still developing, may become underreactive, rather than overreactive, to perceived threats in the environment. Therefore, children may oscillate between heightened or numbed states, or both, and feel a different experience of the aftermath of trauma, per ISP.

This makes sense from a certain evolutionary perspective, Teicher says. A child may not be able to effectively run away from or fight off an abuser, so decreasing the child’s sense of fear or pain might reduce their distress and ensure that the child remains bonded to caregivers on whom they depend for survival — even if those caregivers are the source of the trauma, he says. This may create problems later in life.

“The blunted response makes it hard to detect threats,” Teicher says. “Individuals with that kind of exposure often wind up taking risks [later on], because they don’t realize certain things are threats. They wind up in bad relationships because they don’t read the situation correctly, and they are more in danger of developing substance abuse and conduct disorders.”

Childhood trauma also appears to impact the brain’s sensory systems, like those associated with vision, touch, hearing, taste, smell, and balance, according to a systematic review, as well as its reward centers, per other research. And childhood abuse is also associated with decreased coordination between the two hemispheres of the brain, which may lead to emotional instability, notes the authors of the systematic review.

Recovery in the Brain After Trauma

If exposure to trauma can cause physical changes in the brain, then the natural assumption, Teicher says, is that these changes could be reversed with treatment — and perhaps never occur in the majority of people who don’t develop mental health conditions following trauma.

But surprising results from more recent research suggests this may not be the case, Teicher says. This study, which looked at natural-disaster survivors with PTSD, found that while certain therapies can help treat and mitigate psychological symptoms from trauma, they do so by causing additional — potentially compensatory — changes in the brain, rather than by reversing the initial alterations caused by the trauma itself.

Behavioral therapies such as cognitive processing therapy (CPT), prolonged exposure therapy (PE), and eye movement desensitization and reprocessing (EMDR), as well as certain medications, have been shown to reduce the symptoms associated with PTSD, Hen says. In some of these patients, these recovery techniques have improved signs of physical impact to the brain’s structure, he explains.

In other cases, Hen notes, recovery appeared to trigger still more changes in the brain. Some people who have healed from trauma exhibit more positive alterations in other regions in the brain — the blueprint, perhaps, of a brain that has learned to become more resilient, Teicher says.

But because the effects of trauma on the brain may not be reversible, Hen says it is important to maintain a healthy lifestyle, manage stress, and seek professional treatment as soon as possible should mental health symptoms emerge following a traumatic experience. Trauma and trauma responses are different for everyone, so getting care early and often from medical professionals who know your history and circumstances is key. “The earlier you intervene,” Hen says, the better your odds of “mitigating the possibility that it becomes a chronic condition.”

Summary

Exposure to traumatic experiences primarily impacts three regions of the brain, and expresses differently and variably in both children and adults. In adults, the hippocampus, which is responsible for episodic memory, is most impacted by trauma. Animal studies suggest the physical effects of trauma on the brain are more a result of chronic stress than of a single, particularly intense event.

Treatment may not always reverse the effects of stress on the brain, so prevention may be the best strategy to avoid cumulative damage to the hippocampus and the symptoms associated with it. If you are recovering from trauma, be sure to speak with your doctor about the best care approach for you so you can heal effectively and promptly.

If you or someone you know is struggling or in crisis, help is available. Call or text 988 or chat at 988lifeline.org.