Addressing Mental Health, Substance Abuse and Brain Injury
Muhammad Adil 2026-08-31T02:16:44+00:00 August 26th, 2026|Blog|
By Eliza Marie Somers
Knowing the state of your brain before a brain injury can help TBI survivors recognize patterns that may help recovery.
“It's important we acknowledge that we had brains before we were even injured, because that setup is really important to how your brain experiences an injury and recovers from an injury,” said Hollis Brennan, a licensed counselor and certified specialist in psychometry.
Brennan, who holds master’s degrees in biomedical sciences and sport and performance psychology, was the key presenter at the Brain Injury Hope Foundation’s August 14, 2026, Survivor Series: Addressing Mental Health, Substance Abuse and Brain Injury.
- Hollis Brennan, Licensed Professional Counselor, Certified in Psychometry
- Founder, Brain Injury Therapy
- https://www.braininjurytherapy.org/
- hollis@braininjurytherapy.org
- 970-458-5773
- Takes Insurance
- Download Hollis Brennan’s slide presentation.
Brennan noted the brain is not fully developed until about the age of 25. During the first years of a person’s life the brain is reliant on genetics to develop in a specific way. The brain, which is an interactive organ, also develops via the way it experiences the five senses: taste, touch, smell, sight and sound.
“The environment that you grow up in for the first 25 years is actually helping you build the brain that you have,” Brennan said.
Then there is epigenetics, which refers to how your behaviors and environment can cause changes that affect the way your genes work. Unlike genetic changes (mutations), epigenetic changes are reversible and do not change the sequence of DNA bases, but they can change how your body reads a DNA sequence, according to the Centers for Disease Control and Prevention. https://www.cdc.gov/genomics-and-health/epigenetics/index.html
Now add in experiences, such as having supportive parents, birth order, finishing school or dropping out of school.
“Those types of experiences and exposures also change the brain,” Brennan explained. “And then our interpretations. This is a weird one … Our thoughts change our brain. So, I can have thoughts and beliefs that then change the wiring in my brain. … All of that is at play just in having a brain. So, it's important to start there.

Hollis Brennan says how your brain developed plays a key role in how the brain perceives an injury.
“If you had anxiety on board before your injury, it is very likely that after injury, it has gotten louder, maybe harder to manage. And once in a blue moon, I have seen somebody have a mental health diagnosis, and then the brain injury actually changed that for them, and that it's no longer there,” she said.
Brennan gave the example of a person who smoked a pack of cigarettes a day to not smoking after a brain injury, but as she stated it is a rare occurrence.
Along with anxiety, other conditions present before a brain injury that can be intensified after an injury include but not limited to depression, mania, apathy, irritability, obsessive compulsive disorder and substance use disorder.
Brennan added that humans have been using substances, such as cacao, teas and tobacco for eons.
“We've always tried to supplement our experiences, and we really like ones that change our brain and change our experience. But the way that you can tell for yourself if that substance relationship has started to get unhealthy is that the substance has a lot more power in the relationship than you do. If you can't stop, moderate, or refuse that relationship, or set boundaries that's probably telling us that OK, we need some help and support,” Brennan said.

A brain injury affects the chemicals in the brain along with how the chemicals are received throughout the body. This slide shows the chemicals reactions immediately after a BI.
Brennan then pointed to a slide depicting the chemicals in the brain and what happens to the production and/or the ability of the brain to receive those chemicals after a brain injury.
The chemicals in order, left to right on the slide, are glutamate (Glu), GABA, Acetylcholine (ACh), Norepinephrine (NE), dopamine (da), and serotonin (5HT).
Glutamate is the most abundant chemical and plays a key role in cognitive functions like thinking, learning and memory. After a brain injury, glutamate is suppressed. https://my.clevelandclinic.org/health/articles/22513-neurotransmitters
“Glutamate's big role in our brain is to tell other neurons to turn on and then they pass that message wherever we're asking to turn on, whether that's my hand movement. … So, you can imagine that if all of this glutamate is released, but it's not messaging, things are sort of turning on sometimes when they're not supposed. … So, you can feel really slow and confused and just sort of gloopy,” Brennan explained.
https://share.upmc.com/2016/09/about-brain-chemicals/
GABA or gamma-aminobutryic acid, regulates anxiety, irritability, concentration, sleep, seizures and depression. This chemical is depressed after a head injury.
“Gaba is the turn off or slow down signal. … So, if we have an impulse of some sort, we're not getting the message to reduce that impulse. GABA has a lot to do with our sense of slowing down, feeling restful, being able to sort of chill out. Without that, it is hard to sleep,” Brennan said.
Acetylcholine (ACh) supports sleep, attention, concentration, memory, and muscle contractions. Brennan said this chemical also plays a role the ability to “chill out,” and is depressed after a head injury.
Norepinephrine affects alertness, arousal, decision-making, attention and focus and can increase after a brain injury, causing heighten fight-or-flight responses.
“Norepinephrine is basically adrenaline, and it is welling. It's just so much in your system (after a BI). So, you are in this elevated state feeling like you need to fight or flight. I mean, if we look backward, your chill-outs are not happening, your slowdowns are not happening. So, sometimes you feel on edge, and you just can't bring that down,” Brennan explained.
Dopamine plays a role in your body’s reward system, which includes feeling pleasure, achieving heightened arousal and learning. Dopamine also helps with focus, concentration, memory, sleep, mood and motivation.
“Dopamine is sort of your motivator. That one is also getting upregulated, part of that is it also actually helps other neurotransmitters do what they need to do during the repair process. But you can also see where now I've got fight or flight, I've got a lot of motivation, a lot of intensity. But I'm not able to do things right,” she said.
Serotonin (5HT) helps regulate mood, sleep patterns, sexuality, anxiety, appetite and pain. Brennan said there’s a lot less serotonin in the brain after a brain injury, and that 90 precent of serotonin is made in the gut. To help serotonin production, a survivor can eat salmon, eggs, cheese, turkey, tofu, nuts and seeds, along with getting sunlight, especially in the morning. https://my.clevelandclinic.org/health/articles/22572-serotonin
“So, all of that to say that there are some immediate big chemical changes in your brain right after an injury that directly mimic depression,” Brennan said.

This slide shows how the long-term effects on brain chemicals after a brain injury. Note they are all suppressed.
The bottom half of the slide depicts all the chemicals depressed in the long-term. “There's a massive suppression of communication happening in the brain,” Brennan explained. “Part of that is there is some massive inflammation that happens in the brain, which is actually necessary. Inflammation brings in more blood flow, brings in more nutrients, and that is actually necessary to be able to start the repair process. The complicated thing here is that where your injury is in your brain has a lot to do with how those outcomes go, a lot to do with all of these neurotransmitter changes, because there's certain parts of your brain that actually produce these neurotransmitters. … This is an average of what we see, especially for people who report depression. After their brain injury, we see a massive suppression of those neurotransmitters.”
Brennan discussed the overlap of suppression of brain chemicals and substance abuse, such as using caffeine to just get through your day and then escalating to abuse of Adderall or cocaine. Then there is the attribution trap.
“An attribution trap is when everything you are experiencing gets attributed back to your brain injury,” Brennan explained. “Let's say that you are worried. You're worried you're going to fall again. So, you don't want to get back out on the ski hill. That worry starts building, and now it's not just about the injury. Now it's also about your kids. Are they going to be OK? Are they doing well in school? Did I remember to do that thing for them? Your worries start to get bigger, and you start to have less control, and they start to affect your physical well-being. That’s anxiety. But when we tell a doctor they tell you that's normal; that's part of a brain injury. That's an attribution trap that dismisses what you're going through and usually leads them away from trying to get you treatment for anxiety.
“Anxiety, depression, OCD, all the things we talked about are very treatable, even with a brain injury. So that's sort of the attribution trap.”
Brain injury survivors then don’t get the treatment they need to address these mental health issues. “You end up going back home and like, OK, it's just the brain injury. But then what? What are you supposed to do with it?” she said.
That’s when brain injury survivors tend to turn to substance use.
“It's very important to understand the reason that the relationship with substances in our life starts to have a power dynamic that leads to it actually becoming a diagnosable issue,” Brennan said. “Specifically, we have a lot of very good reasons to turn toward substances, even though, remember all those chemicals that are already messed up in the brain. Having more chemicals in the brain is not a really great way to let your brain heal, but it's understandable.
“Substance use most of the time starts to build this imbalance because it's a coping mechanism,” she continued. “You have a beer after a stressful day, and it helps us chill out. We smoke cannabis because we are anxious, and that helps us regulate. It's a coping skill that ends up doing damage to us long-term, especially when that substance has more power than you do. But it's a coping thing, which means that if you want to change anything with your substance use you've got to have other coping skills available. Decreasing substance use and having no other coping thing to go to is a surefire way to have a terrible time.”
Some coping skills to use are self-care, stress management and positive reinforcement. Other healthy detractions can be taking a walk, working out, coloring, painting, taking a class or enlisting social support by calling a friend or family member.
More on coping skills along with a worksheet
- https://www.bhgrecovery.com/coping-skills-to-manage-cravings-in-recovery/
- https://www.therapistaid.com/therapy-worksheet/coping-skills-addictions
Some other therapies Brennan suggested are cognitive behavioral therapy, narrative therapy, pain reprocessing therapy and EDMR (eye movement desensitization and reprocessing). https://my.clevelandclinic.org/health/treatments/22641-emdr-therapy
And physical activity can be an effective therapy that doesn’t take a lot of money.
Brain Injury Survivor Series from February 2024 on Mental Health and Substance Use
“One of the things that we know just across the board that is very good for brain injury recovery is movement,” Brennan said. “Movement of almost any kind. And this does not need to be top-tier level athletics and running 10 miles.
“We're not exercising. We're moving. And if you are in a space where you have hemiplegia or some parts of your body don't move the way that they used to this is going to look very different. But any sort of rhythmic movement that you can do is going to produce a different kind of brain chemical called BDNF (brain-derived neurotropic factor) that actually helps with the process of healing by growing new neurons.”
Brennan ended the Survivor Series by circling back around to early brain development.
“Your brain existed before your injury. Injuries change how your brain works, mental health challenges exist because of/or alongside injury, and they are treatable. Substance use is a coping skill that also tends to harden your brain. We can control a couple aspects of our healing. And you can advocate for brain injury informed care. You deserve that,” she concluded.





















