According to John J. Ratey MD, associate clinical professor of psychiatry at Harvard Medical School and author of the book Spark: The Revolutionary New Science of Exercise and the Brain, “While dopamine in the reward center causes the initial interest in the drug, and the motivation to get it, what makes addiction such a stubborn problem is the structural changes it causes in the brain (Ratey, 2008).” These structural and functional changes affect several aspects of the brain, including multiple circuits, neurons, and receptors. These areas control everything from reward-processing and executive functions to impulse control and several systems throughout the body.
However, one key area of the brain affected by substance use disorders (SUDs) is the prefrontal cortex (PFC). The PFC is responsible for self-regulation, goal-setting, and predicting consequences of behavior (Miller, J., 2019). During chronic substance use, the prefrontal cortex wires in the memory of the dopamine reward. Whenever this reward circuit activates, the brain makes notes of it and teaches individuals to do it again and again. Once the memory forms, it becomes reflexive – creating a SUD. Luckily, during addiction recovery, exercise can promote the same mechanism of action in the PFC. New frontiers in research and addiction treatment are using exercise as targeted therapy to help regulate impulsivity and drug cravings, wiring in a healthier, substance-free lifestyle.
In part three of our Addiction: Head to Toe series, we examine the role of the prefrontal cortex in substance use disorders and share new studies and insight on this vital region. We also highlight the latest research and interviews from leading addiction recovery professionals on how exercise may be our best defense, and clinical tool, in rebuilding and strengthening the prefrontal cortex during addiction recovery.
A Quick Roadmap on Addiction and the Brain
Impairment from SUDs typically begins in more primitive areas of the brain that process reward and moves on to other areas responsible for more complex cognitive functions. These changes cause severe disruptions in learning, executive function, cognitive awareness, and even emotional functions (Volkow, N. et al., 2010). Some of the critical brain areas affected by substance use include the basal ganglia, extended amygdala, and the prefrontal cortex. According to the National Institute on Drug Abuse (NIDA), the prefrontal cortex powers the ability to think, make decisions and use self-control over impulses. Shifting balance between this circuit and the areas of the basal ganglia and extended amygdala make a person with a substance use disorder seek the drug compulsively with reduced impulse control (NIDA). This imbalance results in a decreased sensitivity of reward circuits, enhanced sensitivity of memory circuits to conditioned expectations of drugs and drug cues, and a negative mood – turning drug use into an automatic behavior (Volkow, N. et al., 2010).
A Deep Dive into the Prefrontal Cortex
The PFC is a complex structure and houses several sub-regions depending on the function. For easier reference, this region of the brain can be separated into dorsal, medial, and ventral prefrontal cortices. The dorsolateral prefrontal cortex is involved in higher-order processing, whereas the ventral and medial prefrontal cortices play a part in the regulation of emotions. The PFC also connects to limbic areas, the ventral striatum, and the hypothalamus (Hika, B. & Khalili, Y.A., 2019). Because of its engagement in higher-order executive functions and regulation of limbic reward regions, imaging studies have identified the prefrontal cortex’s key involvement in addictive behaviors (Goldstein, R. Z. & Volkow, N. D., 2011). During chronic drug use, the PFC wires in the memory of the dopamine reward. Once the reward has the brain’s attention, the brain remembers the sensation in vivid detail. Once this memory is wired in, it becomes automatic. “With those suffering from a SUD, it’s not so much that they make bad choices; they fail to inhibit behavior that has become reflexive,” states Ratey.
Researchers in neuroscience are also finding structural differences in the PFC may play a role in addictive responses to various drugs. The latest research on addiction vulnerability from The University of Cambridge identified abnormalities in the PFC region. Participants included those exposed to stimulant drugs (with and without clinically diagnosed SUD), siblings of addicted individuals, and control volunteers. The study found that participants (without familial risk) who did not develop an addiction to stimulants despite regular use had a strong connection between the frontal cortex and the striatum networks. The first network consisted of the medial caudate nucleus and the lateral prefrontal cortex; the second included the superior medial prefrontal cortex and the outer part of the lentiform nucleus. These networks play a role in forming goals, controlling behavior, and habit regulation.
By contrast, researchers found the likelihood of developing an addiction was associated with significant hypoconnectivity in the orbitofrontal and ventromedial prefrontal cortical-striatal circuits. These pathways are associated with decision-making. These findings hint at the possibility of differences in brain connections playing a role in compulsion and addictive responses to different drugs (Ersche, K.D. et al., 2020). For more than three decades of research on drug use, little attention was paid to the importance of the prefrontal cortex. Today, researchers and professionals in addiction recovery are looking at this part of the brain for answers – especially when it comes to using exercise to heal and rewire the brain during treatment.
How Exercise Strengthens the PFC
During SUD treatment, addiction professionals agree that strengthening the prefrontal cortex is essential for rebuilding critical thinking skills and informed decision making. However, overcoming the reflexive nature of addiction and rewiring this area of the brain takes specific therapeutic methods. Cognitive-behavioral therapy (CBT) targets the PFC and modifies dysfunctional emotions and behaviors by eradicating negative beliefs and replacing them with healthier thoughts and problem-solving skills (Psychology Today). Treatment modalities like CBT help the mind – but what about the body? Remember, the prefrontal cortex wires in the memory of the substance reward and what fires together wires together. During active addiction, individuals use substances to respond to stress or triggers. When stressful triggers or other cues happen again during sobriety, the brain and body are still hardwired to turn to drugs or alcohol.
Mounting scientific evidence suggests that exercise is key to rewiring this area – healing both the mind and body during recovery. How is this possible? The short answer is that the brain rewards healthy behaviors like exercising. It does this by switching on the same circuits in the frontal regions of the brain that make a person feel good, which then motivates them to repeat those behaviors – similar to the process of addiction (NIH News in Health, 2015). Exercise also helps regulate impulsivity and drug cravings by re-strengthening the PFC. One study found that physical fitness in SUD patients increased prefrontal cortex oxygenation. This process led to greater inhibitory control and improved memory, attention, and speed processing in polysubstance users (Costa, K.G. et al., 2019). However, new targeted exercise techniques being implemented by addiction professionals is where the real revolution in treatment is happening.
New Frontiers in Exercise and Addiction Recovery
According to Daniel J. Siegel, MD, clinical professor of psychiatry at UCLA and author of The Mindful Brain: Reflection and Attunement in the Cultivation of Well-Being, “How you focus your attention shapes the structure of the brain, balancing mental, physical and relational health (Siegel, 2007).” One center, Tree House Recovery (THR), incorporates Siegel’s methodology into their program. As their website states, “Dr. Dan Siegel hypothesized that there are nine critical functions of the prefrontal cortex including empathy, morality, and communication that, when dysregulated, creates a poor social animal. For people with addiction, a lack of meaningful social connections increases the chances of using, abusing, and relapsing. Tree House Recovery seeks to strengthen the prefrontal cortex as a means to sobriety.” In a recent interview with THR addiction professional Ryan Bain, developer of the ESM fitness program, he discusses how exercise can help heal the brain and body during recovery. ESM is the Latin abbreviation for Exercitium Semita Medela or roughly translated, “Exercise as a Pathway to Healing.” Bain’s exercise program teaches those in recovery how to combat addiction and rewire their brain for better health. He explains, “Moderate to vigorous exercise has repeatedly been linked to PFC activation, increasing memory and processing speeds, enhancing overall cognitive function, and goal-directed behavior. These processes are heightened in the minutes, and potentially hours, after physical exertion.” The ESM approach not only targets the prefrontal cortex, but it also helps grow new brain cells. Bain points to four essential proteins, or neurotrophins, released during ESM styled exercise, including:
- Brain-Derived Neurotrophic Factor – stimulates the growth neurons or Miracle-Gro for the brain.
- Insulin-like Growth Factor – works with insulin to deliver glucose to muscles and the brain.
- Vascular Endothelial Growth Factor – helps build new blood vessels that carry fuel to the brain.
- Fibroblast Growth Factor – helps build brain cells in the hippocampus.
Once released during exercise, these proteins promote stem-cell division, helping to repair damaged cells, and grow new ones.
Time for Revolutionary Action
Addiction recovery professionals and scientists agree that physical exercise may be our best defense in rebuilding the prefrontal cortex and wiring in a healthier, substance-free lifestyle during addiction recovery. According to Bain, “We’ve had clients come through completely emaciated from active addiction and leave looking and feeling like some of the healthiest human beings you’d come across. We’ve also had veterans with extreme war-related injuries doubting their ability to engage with such a rigorous program only to realize they “still got it.” It’s clear that exercise during recovery is not only vital for the body and brain, it is crucial in making people whole again. Now that we know physical activity can treat those with a SUD on a targeted neurological level, we need to expand the current addiction treatment protocols to include exercise as a clinical standard of care.
Follow us as we continue our Addiction: Head to Toe series examining the latest research and insight from leading healthcare professionals on how exercise may be our best defense in sustaining abstinence and preventing relapse for those in addiction recovery.
Disclaimer: The exercise and medical information in this paper should not be followed without first consulting a medical health professional. This article is for informational purposes only and is not intended to prevent, cure, or treat any diseases.
References:
Costa, K.G. et al. (2019). Rewiring the addicted brain through a psychobiological model of physical exercise. Frontiers in Psychiatry. 10: 600. Doi.org/10.3389/fpsyt.2019.00600.
Ersche, K.D. et al. (2020). Brain networks underlying vulnerability and resilience to drug addiction. Proceedings of the National Academy of Sciences. 117(26), 15253-15261. Doi:10.1073/pnas.2002509117
Goldstein, R. Z. & Volkow, N. D. (2011). Dysfunction of the prefrontal cortex in addiction: neuroimaging findings and clinical implications. Nature Reviews. Neuroscience. 12(11), 652–669. Doi.org/10.1038/nrn3119
Hika, B. & Khalili, Y.A. (2019). Neuroanatomy, prefrontal association cortex. StatPearls. Stat Pearls Publishing.
Miller, J. (2019, October 8). Researchers Investigate Why Certain Brains Are More Vulnerable to Addiction. USC News. Retrieved August, 2020 from https://news.usc.edu/161464/opioid-addiction-brain-science-usc-study/
National Institute on Drug Abuse (NIDA). Drugs, Brains, and Behavior: The Science of Addiction, Drugs, and the Brain. (July, 2020). Retrieved August, 2020 from https://www.drugabuse.gov/publications/drugs-brains-behavior-science-addiction/drugs-brain
NIH News in Health (2015, October). Biology of Addiction: Drugs and Alcohol Can Hijack Your Brain. Retrieved August, 2020 from https://newsinhealth.nih.gov/2015/10/biology-addiction
Psychology Today. Cognitive Behavioral Therapy. Retrieved August, 2020 from https://www.psychologytoday.com/us/basics/cognitive-behavioral-therapy
Ratey, J. J. (2008). Spark: The Revolutionary New Science of Exercise and the Brain. Little, Brown, and Company.
Siegel, D.J. (2007). The Mindful Brain: Reflection and Attunement in the Cultivation of Well-Being. W. W. Norton and Company.
Volkow, N. D. et al. (2010). Addiction: decreased reward sensitivity and increased expectation sensitivity conspire to overwhelm the brain’s control circuit. BioEssays: News and reviews in molecular, cellular, and developmental biology. 32(9), 748–755. Doi.org/10.1002/bies.201000042