Brain Talk Session 1: Trauma and the Brain

Introduction:

Post Traumatic Stress Disorder (PTSD) is a highly complex condition, affecting around 12 million adults in the United States alone in the past year. [1] Even more concerning, it is said that 6 out of every 100 people at some point in their lives will experience PTSD [1]. So what is PTSD and how might understanding this disease help treat those that have it, or help in our understanding of how the brain works? PTSD is defined as a mental health condition that can occur after experiencing a traumatic life event, and generally causes flashbacks, intense nightmares, severe anxiety, and changes in mood [2]. This disorder affects specific circuits in the area of the brain known as the limbic system (Figure 1). This includes areas like the hippocampus, the amygdaloid complex, and the orbitofrontal and anterior cingulate[3]. These areas of the brain are heavily involved in memory, emotion, reward learning, and behavioral responses. The limbic portion of the brain, for example, is the part that handles our emotional and behavioral responses to stress. This triggers our “fight or flight” response, which is our body’s response to stress and fear. Meanwhile, the hippocampus is a structure that plays a role in memory and learning. This area of our brain is very sensitive to stress. The amygdaloid complex works with similar areas, such as attention, memory, and emotion. Lastly, the orbitofrontal and anterior cingulate areas communicate, focusing on reward versus punishment and learning. In order for scientists to understand how PTSD is changing these areas in the brain, they first need to know how the brain normally works. In this blog post, you will learn about how PTSD and stress affect the structure and chemistry of our brains

Figure 1: Diagram of the Limbic System This image depicts how the limbic portion of our brains, which controls memory and behavioral responses, is structured. This diagram will be very helpful to come back to throughout this blog post, as it shows many of the structures that we will talk about including the corpus callosum, hippocampus, amygdala, and more. (Macrovector)

The psychological aspects of PTSD:

Some of the first things that people focus on when they think about mental health disorders, such as PTSD, are the terrible symptoms that come with these diseases. However, not many people actually know the reason behind the behavior changes or the ways that we can work to prevent and cure them. Despite the medical advances in understanding other diseases, mental health disorders remain understudied and often negatively stigmatized. The rationale for this can be seen in our daily life, where it is very common to be told that we must conceal our feelings and not talk about them [4]. However, studies have shown that repeatedly talking about past traumatic experiences and gaining support from those around you can actually diminish these symptoms by allowing our brains to come back to what is known as neurological homeostasis. Neurological homeostasis, which is when our brain is in a state of normalcy, has been shown to be restored when we get support from other people and regain emotional control. Some examples of maintaining steady conditions within our brains are having the right body temperature, oxygen levels, and balance of fluids in our brains. Essentially, homeostasis ensures that our bodies are balanced so that we are able to survive in our ever-changing environment. Whereas people who have had traumatic events or who are suffering from PTSD may have chemical and/or structural imbalances in their brains, which leads to many of the symptoms associated with PTSD.

Behavioral changes caused by PTSD can be separated into three different groups: hyperarousal, avoidance, and intrusion (Figure 2).[5] Hyperarousal is caused by a stress-induced malfunction in the autonomic nervous system and amygdala.[5] This causes a reflex in our brains that makes us get startled easily, similar to how we get jumpy when we have had too much caffeine. Hyperarousal makes victims feel tension and their fight or flight responses are constantly turned on. It even causes people to be in a state of paranoia all the time and makes them extremely irritable. Doctors have found that using psychological treatments on patients who experience hyperarousal is the most effective.[6] One of these treatment methods is through prolonged exposure therapy, where PTSD patients can “go back” in time to their past memories and experiences, but in a safe space.[6] The goal of these treatments is to allow patients the opportunity to resolve issues previously out of their control and to physically stimulate blood flow and oxygen back to the brain so that they may return to neurological homeostasis. The brains of patients that have experienced trauma and hyperarousal show a decrease in levels of oxygen and blood flow and increases in inflammation (Figure 3). [7]

The second category of behavioral responses due to PTSD is intrusion. Intrusion is when memories from the past become reality as if they have not already happened.[4] Stimuli in our everyday lives trigger the subcortical systems in our brains and start this response. The subcortical system is located deep within our brains and is involved in memory, pleasure, emotions, and hormone production.[10] After we have been through a traumatic experience in our lives, sometimes our hippocampus is unable to distinguish an event that is currently happening from one that has happened, allowing intrusion to occur. This makes us believe that we are still experiencing this event when in reality we are not. When people go through a traumatic event in their lives, their amygdala “freezes” this memory and then spits it back out at random times.[14] Since people who have not been through traumatic occurrences in their lives don’t have anything for their amygdala to “freeze”, they do not have to worry about intrusion occurring. As such, they do not have to worry about intrusion, as it only draws from past memories.

The last category is avoidance. The term avoidance is exactly as it sounds. Avoidance is completely steering clear from other people and situations, like denial. For instance, people who have experienced PTSD might avoid new job opportunities, family get-togethers, or relationships in general. It has been shown that avoidance is involved with our amygdala and our anterior prefrontal cortex, which has control over our amygdala.[15] Scientists have observed increases in brain activity within these regions, which is not typical.[4] Research has shown that gaining exposure to people and situations overall can help those with PTSD overcome avoidance and become more comfortable with day-to-day life. Overall, understanding the psychological aspects of PTSD is just as important as understanding the biological aspects. Not only is rewiring our brains the only way to protect ourselves from PTSD, but also gaining a support system that allows us to obtain control within our lives.

Figure 2. The Prevalence of the Three Post-Traumatic Symptom Substets This graph above comes from a study showing the symptoms of many different people who had all undergone the same traumatic sports injury. The results were averaged out and showed that 87.5% of patients experienced avoidance, 83.3% of patients experienced intrusion, and 75% of patients experienced hyperarousal. (Orthopaedic journal of sports medicine)

How Your Brain is Structured:

Although PTSD is typically associated with nonphysical symptoms, such as behavioral and personality disorders, studies have shown that it can also cause changes to the structure of our brains (Table 1). Many people do not realize that physical trauma is not the only factor that can change the structure of the brain. Verbal and other types of trauma work to change the structure in our brains as well, even if they are not necessarily touching or damaging the brain physically. In order for scientists and doctors to see and understand the brain’s complex physical processes better, they use tools such as functional magnetic resonance imaging(fMRI), positron emission tomography (PET), and diffusion tensor imaging(DTI) to gather different types of images of the brain.[11] MRIs show images of organs and body structures using magnets and radio waves, while PET scans are used to find out how an organ is functioning by using radioactive tracers.[12] PET scans can even detect changes in organs and tissues at the cellular level [9]. Unlike MRIs and PET scans, DTIs show microstructural changes by seeing the mobility of water molecules in the brain tissue.[11] These devices can be used to measure changes in brain activity while patients with PTSD are performing tasks or experiencing traumatic episodes, and then be compared to patients without PTSD.

One study compared the brains of veterans with PTSD to normal control subjects [3]. The results demonstrated that there was tissue loss in the hippocampus of patients’ brains with PTSD compared to the brain tissue of patients without PTSD. Moreover, this loss of tissue in their brains increased their probability of getting dementia. Another study pooled data from a variety of different studies, which involved research on brains with PTSD, and found that there was smaller hippocampal volume for both the right and left sides of men’s and women’s brains.[2] This demonstrates the effect that malfunctions or abnormalities in brain structures can affect our overall well-being, as well as showing how the brains of people put under different levels of stress are very different.

Table 1. Grey matter in the brain in accordance with PTSD. The table above demonstrates structural brain changes, comparing the normal healthy brain to the brain of a veteran with PTSD. In the far right column, we can see that the percentage of grey matter is increased or decreased for different structures in our brains for PTSD patients. For instance, there shows to be brain tissue loss in the frontal and temporal lobes and the cerebellum. (NIH)

How Your Brain is Chemically Wired

It is known that our brains grow the most when we are children, however, many people do not realize that our brains continue to grow even when we are well into adulthood. This means that our brains are constantly changing, causing people to experience trauma differently depending on their age. For instance, people who have experienced continuous trauma from a young age are more likely to be diagnosed with PTSD later on in life after experiencing a major traumatic event. [3] Brain imagining from PET scans shows alterations in circuits in the amygdala, prefrontal cortex, and hippocampus of people with PTSD. Additionally, they found that patients with PTSD had decreased blood flow in many areas of the brain.[2]

One way in which our brains form new connections is through reward learning (Figure 4). Reward learning is when our brains acquire information about stimuli or other triggers within our environments, which changes the way that we act.[13] For instance, many young people today go on social media during their free time because it releases serotonin in our brains, which makes us want to continue using the app. Our brains make connections between our actions on social media and how they make us feel. Conversely, there is also negative learning, where our brains make associations of actions, spaces, or things with negative feelings or memories.[cite] For example, let’s say that you have a final exam in one specific room in your school throughout the year. Without even beginning the exam, our brains have already collected information on this room, and remind us of how nervous we were the last time we were there. This results in involuntary responses, such as sweaty palms, anxious feelings, or a faster heart rate, when we see it again. Generally, reward and negative learning create associations and connections over repeated exposure to the reward or negative stimuli. However, single events that are extremely rewarding or negative can be enough to create a new connection as well. Understanding these mechanisms can help us to better understand PTSD. For patients with PTSD, there are certain triggers that remind their brains of traumatic experience(s) or event(s) that caused them to be severely stressed or fearful and caused intrusion within their lives. For instance, sexual assault victims may be triggered by someone touching them because their brains have collected information on the way that being touched has made them feel in the past. Another example would be having an intrusion after seeing a car that is the same color as the one you were driving in a car accident. Having an understanding of how this association works can be helpful in creating therapies that train people’s brains to have positive memories of certain aspects of their lives that may have once been tied to something traumatic.

Figure 3. A CT scan of Healthy vs PTSD Brain. This image above is from a CT scan, comparing the healthy brain to the brain of someone with PTSD. This scan shows the inflammatory responses due to cortisol (the red parts in the image). As you can see, the PTSD brain has more inflammation throughout the brain, which is dangerous as it can impair mental performance. (PTSD Vietnam 1)

How Our Brains Are Structured:

As mentioned earlier, our brains are constantly growing and expanding based on our environment and surroundings. While being in a safe and healthy environment enables our brains to grow and advance in a neurotypical way, being in an unsafe or stressful environment can cause changes in the way we act and in the way our brains are structured. Scientists have found that stressful situations trigger circuits in the limbic portion of our brains, such as the hippocampus, amygdala, and medial frontal cortex.[7] When people are faced with stressful or fear-inducing experiences, it has been shown that neurogenesis, the growth of nervous tissue, in our hippocampus is altered.[cite] A lack of neurogenesis causes our hippocampal volume to essentially decrease, and our frontal lobes become impaired.[cite] Studies have also demonstrated that children with PTSD have smaller volumes of the corpus callosum, which are nerve fibers that help the left and right sides of our brains communicate.[cite] Interestingly, there is no change in this structure if you are an adult when you experience PTSD. This demonstrates that environmental factors in our lives can affect the structure of our brains differently depending on when we experience these factors. This is because our brains are developing at a faster rate when we are younger and slower as we age.

Figure 4. Reward learning and the brain. The diagram above is used to demonstrate the concept of reward learning. The computer system is used to represent our brains collecting information on our surroundings and environment. The information that the computer system gathers goes up to our brain, indicating whether it is a “reward”, or whether it is negative. Afterward, our brain responds to this through our behavior and actions. (Bonsai)

The effects of stress on the chemistry of our brains:

As we already have talked about, trauma and stress can change the structure of our brains, and cause negative associations that bring unwanted feelings or intrusions into our everyday lives. But, how does trauma change the chemicals in our brains? One chemical that plays a significant role in the brain during traumatic events is cortisol (Figure 5). Cortisol is known as the stress hormone and increases the glucose levels in our bloodstream.[9] It increases when exposed to high-stress situations and contributes to our fight-or-flight responses by helping our bodies focus on only the essential functions that we would need in such a situation.[9] You can think of it as an “alarm system” for your brain. One study compared the cortisol levels of children from a Romanian orphanage compared to control subjects and found that the orphaned children had increased levels of cortisol [2]. The conditions that the orphaned children were under were a lack of basic human needs and hygiene within the orphanage, along with constant exposure to infection. This constant stress in the children’s lives is what caused them stress, and resulted in cortisol elevation. The study found that this elevation in cortisol was mostly in the limbic portion of the brain, which is dangerous as the limbic brain controls memory and behavior. Elevated cortisol levels in our brains can be very dangerous because they can cause long-term changes in the stress systems within our brains.[16] In addition, high cortisol levels over long periods of time have been shown to be a trigger for the development of dementia, which is a condition that typically occurs in older people, limits at least two brain functions, and disables the ability to think and make decisions.[8] Elevated levels of this “stress hormone” also cause higher blood sugar and suppress your immune system, making you more vulnerable to colds and other illnesses.[9] Additionally, your risk of getting cancer and other diseases is also increased, and even your susceptibility to developing food allergies is elevated.[9] We now know that high cortisol levels are a result of excessive amounts of stress, but what are some ways that we can manage this? Managing our stress in ways such as meditation and other calming exercises is beneficial for keeping a healthy cortisol level.

Another important chemical in our brains is the corticotropin-releasing factor (CRF), which is released into our amygdala when we are exposed to high levels of stress.[2] Moreover, when we are constantly releasing CRF because of traumatic situations, brain abnormalities and malfunctions can occur in the amygdala.[2] Scientists believe that by “rewiring” our brains and using therapies by a doctor, we can reduce hypersensitivity and protect our amygdala.

Figure 5. Stress and How We Respond. Here is an overview of the way that cortisol is released in our brains and the long-term effects that it has on our brains. As shown in the diagram, cortisol comes from the pituitary gland in our brains as a hormone. This hormone moves through the adrenal glands (where adrenaline comes from) and produces cortisol. Cortisol then gets released into our bloodstream which activates a series of different long-term responses. This includes a slow down in digestion, accelerated heart rate, fast breathing, increased sweating, etc. (Endocrine Web).

Conclusion:

Overall, trauma is a factor in some people’s lives that changes not only the way that they behave but also the way that their entire brain is wired and structured. In this blog post, we talked about the effects of trauma on our brains, physically and chemically, and how these factors cause behavioral changes in PTSD victims such as hyperarousal, intrusion, and avoidance. We saw that a control brain compared to a brain that has undergone PTSD had significant structural differences (including a decrease in hippocampal volume and frontal lobe impairments), and even produced chemical differences (the increase of cortisol and CRF). Learning about the chemistry and structure of our brains and how this is changed by PTSD can be beneficial to doctors and scientists because it helps them create new solutions for problems with this conflict of PTSD and the brain. In addition, knowing about these complex structures in the brain can help scientists and doctors protect their patients from future problems.

References:

[1] USA Department of Veteran Affairs. (https://www.ptsd.va.gov/understand/common/common_adults.asp#:~:text=About%206%20out%20of%20every,have%20gone%20through%20a%20trauma)

[2] Dialogues in Clinical Neuroscience (https://www.tandfonline.com/doi/full/10.31887/DCNS.2006.8.4/jbremner)

[3] National Library of Medicine

(https://www.ncbi.nlm.nih.gov/books/NBK538491/)

[4] The Neuroscience of Psychotherapy (https://books.google.com/books?hl=en&lr=&id=0R0ePBdoLl0C&oi=fnd&pg=PR1&dq=how+ptsd+affects+the+chemistry+of+our+brains&ots=eUIOSVwJGx&sig=YZ9ufINT2uEq9EE9CzGa9PmzJFw#v=onepage&q&f=false) Page 262

[5] American Psychiatric Association

(https://psychiatry.org/patients-families/ptsd/what-is-ptsd)

[6] Web MD

(https://www.webmd.com/mental-health/what-is-hyperarousal-in-ptsd)

[7] National Library of Medicine (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3025168/#:~:text=Antidepressant%20drugs%20inhibit%20the%20reuptake,hence%20in%20increased%20postsynaptic%20neurotransmission.)

[8] Bright Focus Foundation (https://www.brightfocus.org/alzheimers/article/what-dementia?gclid=CjwKCAjw-rOaBhA9EiwAUkLV4k1xPrFUB5b7BvgYNWyMHx92_TprIdbzqISvFq5fI0vIeknViKWowBoCW7cQAvD_BwE)