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Neurobiology of Addiction: Implications for Occupational Therapy Intervention

Neurobiology of Addiction: Implications for Occupational Therapy Intervention
Catherine McDowell, OTR/L, LMBT, E-RYT200/RYT500
February 15, 2019

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Catherine: Good afternoon, I am glad to be here. This is my one of favorite topics lately, and I am really excited to try to bring some more knowledge and understanding of the disease of addiction to everyone.

Why Is This Important?

Understanding the foundation of this disease is important because of the scientific explanation for irrational behavior, in an otherwise a typical person. It also helps in developing new strategies for behavioral and pharmacological treatments, and answers the big question, what is an addiction? It helps to reduce the stigma, shame, guilt, and anger experienced not only by clients but family members, employers, etc. Everyone that surrounds the addicted person is somehow affected by this. When I present this talk in person, I ask everyone to raise their hand if they are personally affected or know someone affected by addiction. Inevitably, there are always a few audience members that do not raise their hand as they do not feel that addiction has affected their lives. And then I ask them if they pay taxes. That pretty much ends the discussion. This disease has so influenced our society and what is going on in our country right down to the cost of it. It affects all of us.

Reluctance to Accept Disease-Model of Addiction

Every once in a while on Facebook, a little picture pops up with the question, "Is addiction a choice or a disease?" Which came first, the chicken or the egg? This is a really hard concept for many people to grasp including many professionals. People in recovery even have difficulties accepting the disease model at times. Some feel that it is a cop-out. Why do people engage in these irrational behaviors?

Alcoholism was first described as a disease in the "Big Book" by Alcoholics Anonymous over 80 years ago. At that time, it was described as an allergy and was very close to hitting the mark of what really does occur in this addiction process. Even though that was over 80 years ago and with all of the scientific research that has gone on, you would think that the mindset would have changed. Yet here we are, a group of educated professionals, still having an internal argument regarding this disease concept. We are looking at the behaviors, and they appear to be behaviors of choice. You have a choice whether to engage in this action or not. There are other disorders with irrational compulsive behaviors as well, and we do not question those like OCD, Tourette's, and eating disorders. Similarly, the same areas of the brain are disrupted in addiction.

Substance Use Disorder Definition

The definition of substance use disorder from the American Society of Addiction Medicine is primary chronic brain disorder with genetic, psychosocial, and environmental factors which influence its course. And, it is also a chronic relapsing disease characterized by impaired control and preoccupation with use despite adverse consequences and distorted thinking, most notably denial. I do not think anyone can argue with that description if they have had any contact with this population. Everyone is putting out pretty a much similar definition, but I like this definition from the American Society of Addiction Medicine.

"Addiction is a primary, chronic disease of brain reward, motivation, memory, and related circuitry. Dysfunction in these circuits leads to characteristic biological, psychological, social and spiritual manifestations. This is reflected in an individual pathologically pursuing reward and/or relief by substance use and other behaviors.

Addiction is characterized by an inability to consistently abstain, impairment in behavioral control, craving, diminished recognition of significant problems with one's behaviors and interpersonal relationships, and a dysfunctional emotional response. Like other chronic diseases, addiction often involves cycles of relapse and remission. Without treatment or engagement in recovery activities, addiction is progressive and can result in disability or premature death.”

American Society of Addiction Medicine

It is characterized by the inability to consistently abstain, impairment and behavioral control, craving, and diminished recognition of significant problems. It goes in a little bit deeper to give a more refined description of what is going on here. Without treatment or engagement in recovery activities, addiction is progressive and can result in disability or premature death.

Primary Neurologic Disorder

Why is it a primary neurologic disorder? Both addiction and Parkinson's disease are diseases of dopamine dysfunction. The difference here is perception. Why does Michael J. Fox get support and recognition, while Ben Affleck has his face splashed across the tabloids when a relapse occurs? When was addiction demonized? There is a great book written by Johann Hari called, "Chasing the Scream." He did in-depth research over the history of addiction. It delves into what our society has done in regards to addiction and why we are where we are at today. It is very interesting to go through and look at the entire history of this issue.

Addiction is a primary as it is not due to something else. This is a bit of where it starts to get foggy. Anxiety, depression, and trauma did not cause it. However, anxiety, depression, and trauma are a really good reason to drink or use drugs. Many times, there is difficulty in differentiating between the primary versus a secondary psychiatric disorder. Again, we are back to which came first, the chicken or the egg?

I was working with a young woman recently who was focused on her anxiety disorder. I had her take some time to describe her symptoms. She is a college student and she explained that she gets up in the morning and has panic attacks. She shakes, sweats, and is nauseous. She feels like she cannot face the day. By the time she was done with her description, I realized what she was experiencing was not anxiety but withdrawal. It was the same shaking and dizziness that occurs with withdrawal from alcohol. It can be difficult to tease out the cause of what is going on? Typically, the person with substance use disorder is not saying, "I drink three bottles of wine a night and wake up shaky." Instead, they may say, "I wake up shaky. It has to be anxiety." 

How Common Is SUD?

How common is substance use disorder? Eighty-five to ninety percent of the adult U.S. population uses alcohol or other mood-altering substances at one time or another. At some point, drugs and alcohol have crossed pretty much all of our paths. Yet only 10 to 12 have a substance use disorder. What makes them different than the typical brain? Even some of the research we're looking at now is showing, it says that there's an eightfold increase, that there's so many more affected by what's going on than what we're very aware of. So what makes them different? What makes the person with substance use disorder fall into addiction so rapidly?


One of the reasons is genetics. One of the great twin studies came out of the Netherlands and Finland where they had open adoptions. They were able to follow twins as they were put up for adoption and follow their lives. These family studies showed that children of alcoholics were three to four times more likely to be alcoholic than the general population. These studies also showed that biological children of alcoholics have a much higher risk of alcoholism, regardless of who parents them. Thus, if a set of twins from biologically addicted substance use disorder parents are separated, one to a home that had no alcohol and the other child to a family of drinkers, they would both, by the age of 30, end up addicted to alcohol or some substance. The difference is that the child that went to a home where alcohol was present picked it up earlier. They would start using at a younger age or maybe their use would be more intense. But in the end, by age 30, both of those children were addicted. This is the same in reverse. Children, who are not genetically predisposed to have an addiction and are separated, did not become alcoholic even if raised in a home with alcoholics. With these studies, there is definitive proof that there is a genetic component to this. One of the biggest outcomes of these studies is that you cannot parent alcoholism out of a genetic alcoholic. And, bad parenting does not cause alcoholism or addiction. Great parenting also cannot fix it. If there is a genetic predisposition, it is there. You have blue eyes, red hair, and addiction. Genetic predisposition accounts for 50 to 60% of the vulnerability in addiction. Now, even if there is a genetic predisposition, you might not necessarily become an addict, but you have a 50 to 60% increased risk. Higher vulnerability, from other family-related illnesses, is the same for other issues like diabetes, hypertension, and breast cancer. Additionally, if you also have a co-occurring diagnosis of attention deficit or anxiety, this can also increase your risk. Genetics, therefore, can increase your risk or mitigate the risk. This also explains why in some sibling pairs, one has it and the other does not.

Biopsychosocial Model

Biological, neurologic, and genetics all influence outcomes. If there is alcoholism in the house, then it is easier to experiment. However, that will not make you an addict. Many times, we see families that go to church, provide good support, are socioeconomically secure. Everything is set up for the child to have a fabulous life, and yet they end up addicted. It is not based on your environment. However, if you are predisposed genetically and are in an unstable environment, then your chances increase rapidly.


Alcoholics having pre-existing abnormalities as per EEG studies. They show that P300 is decreased in alcohol-naive sons of alcoholics, and decreased theta waves prior to the first drink. What these EEG studies are showing is that in the male children of alcoholics, there is a decrease in their theta brain waves prior to taking the first drink. Again, the alcoholic's brain is different before that individual ever takes their first drink. Drinking does not cause addiction. The addiction is there.

Pre-morbid Differences

  • Euphoria – first-time drinkers report of the intensity of euphoria
  • FHP (family history positive) report MUCH greater euphoria with alcohol exposure than FHN (family history negative)
  • First-time drinkers report of negative side effects of acute alcohol exposure

Premorbid differences in the alcoholic or the addicted brain versus the typical brain include euphoria. They have a much greater euphoria with the first alcohol exposure than someone who comes from a family that does not have that history. First-time drinkers also report negative side effects of acute alcohol exposure. We hear frequently from people in the recovery rooms that they were horribly sick when they took their first drink. You hear that type of description, and you would swear this person would never ever consider using again. Then they say, "I woke up, shook it off, and couldn't wait to drink again." Already from the first drink, there is a difference in the person who has the potential to be an alcoholic. Also, in a typical brain in an average drinker, they will have one or two drinks, start to feel tipsy, and then stop. But in the body of an individual with a substance use disorder, their feeling, after one or two drinks is, "I'm just getting started." That has not even scratched the itch yet. As soon as the substance is put into the bloodstream, the brain starts to request more and starts to need more.

Other Premorbid Differences

  • FHP report less negative effects than FHN
    • Less body sway
    • Less nausea
    • Less disorientation
    • Better cognitive abilities and physical performance on driving tests

From the first drink, they have less body sway, less nausea, and less disorientation. In a typical brain, one or two glasses of wine may have that person's head spinning, but in the person, who has a predisposition, are walking as straight as an arrow after many drinks. They are the individuals who think they drive better when drinking, and that they have better cognitive abilities and physical performance while using substances. They also have a weaker warning system. Their bodies do not tell them to stop.

  • PET Scans demonstrate compromised dopamine D2 receptor activity
  • Lack of dopamine activity increases the risk
  • PET Scan reveal D2 receptors in obese patients – inverse relation to BMI (the lower the dopamine-the higher the BMI)

PET Scans have demonstrated compromised dopamine (D2) receptor activity, and this is where we are going to start to get into brain function. The lack of dopamine activity increases the risk of addiction. PET Scans also reveal D2 receptors in obese patients that have an inverse relation to BMI. What this is pointing out is that the individual with addiction has the same activity occurring in the brain as the individual with obesity. This is relevant because these two separate issues start in the same area of the brain due to dopamine levels. PET scans and functional MRIs that show low baseline levels of dopamine indicate an increased risk for addiction. On a side note, I have seen a disproportionate amount of individuals, who have had bariatric surgery, rapidly become full-blown alcoholics.

The Brain

Let's do a quick basic review of how neurons work. Neurons send out signals to connect with other neurons to communicate with the rest of the brain and body. When the nerve is stimulated, it sends an electrical impulse down the nerve and stimulates the end bulb to release a peptide. Now, dopamine will release into the gap and connect with a specific receptor. When it finds the right receptor, it acts like a lock and key. When you release a lot of dopamine, you have that much of a greater sensation. If there is a little release, there is a little reaction, while a greater release causes a greater reaction. This is how medications and drugs work, as well as alcohol. Some will cause the cells to release a lot of dopamine, and some will prevent the dopamine from being reabsorbed by the cell and recycled. For example, you are driving down the road and a deer jumps out in front of the car. All of the sudden, the floodgates open and the dopamine is released. Once the perceived threat has passed and you are safe, that dopamine is quickly reabsorbed. Because you close the door with the drug, you get a lot of dopamine stuck in the gap. This is what drugs and alcohol begin to do. They not only affect the secretion of the dopamine but also the reabsorption. With repeated drug or alcohol use, there will be a decrease in the number of receptors.

Addiction=Reward Deficiency Syndrome

A decrease in neurotransmitters leads to a sensation of incompleteness, decreased pain tolerance, and anxiety. The level is going to be different based on each individual. For this example, however, let's say everyone's brain functions the same. If there is not enough dopamine produced or enough of it is able to be secreted and reabsorbed properly, that individual never feels truly awake, aware, or connected. They are floating around on a slower, lower plane than everyone else. Since 80 to 95% of the U.S. population is exposed to drugs or alcohol during their lifetime, the person genetically predisposed to addiction is very likely to find what replaces or fixes their reward deficiency. The first time this individual takes a drink, all of the sudden, they feel like they can breathe. They are now able to dance, talk to people, and feel awake and alive. This is what the reward deficiency syndrome is in the individual with a genetic predisposition. They are often unaware of it until the moment they come in contact with the substance that fixes it. It becomes their solution.

New Brain Vs. Old Brain

Let's talk new versus old brain. Dopamine secretion takes place in the primitive, limbic area of the brain. Different neurotransmitters, like norepinephrine, GABA, or serotonin, may be released in a lot of different areas of the brain. Indirectly or directly, this causes the release of dopamine in this primitive area the brain. This is the fight-or-flight or survival area of the brain. Imagine hundreds of years ago, a primitive man hunting in the woods. He is out to get food to survive and sees a deer. This instinct to hunt completely floods his brain and drives all of his movement. 

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catherine mcdowell

Catherine McDowell, OTR/L, LMBT, E-RYT200/RYT500

Catherine McDowell has been an Occupational Therapist for over 20 years. After many years in the field of Occupational Therapy, first as a COTA, then OTR, becoming Director of Occupational Therapy at a nationally recognized United Cerebral Palsy program. Catherine took some time to explore a number of other health-related fields, becoming a Licensed Massage & Bodywork Therapist, Yoga Therapist, RYT500/ E-RYT200 Yoga Alliance teacher, and Certified Holistic Health Practitioner. Catherine is currently the Executive Director of June10 inc; a new concept in long-term residential substance abuse treatment program, which serves women, pregnant women and women with infants, she is also the Health & Wellness Coordinator at Pavillon By the Sea an IOP for substance use disorder. She has been appointed to the Governor’s Counsel for Women.

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