Can Drug Addiction Cause Brain Damage?
Introduction:
Drug addiction is a chronic disorder that affects millions worldwide, with substances like alcohol, cocaine, heroin, cannabis, nicotine, and methamphetamine being among the most commonly misused. Taking and misusing drugs cause a tremendous toll on individuals, families, and society as a whole.
In this article, we'll examine the complex world of addiction neuroscience and how the brain changes with drug use. We'll explore research, including MRI studies, that reveal how addiction impacts areas of the brain and the nervous system. We'll also look into the brain's remarkable capacity to repair. The most important question we need to answer is, "does the brain recover from drug addiction?"
How Addiction Affects the Brain Through Dopamine
At its core, addiction is a brain disease that changes the way the nervous system functions. When someone uses an addictive substance, it triggers a rush of the neurotransmitter dopamine in the brain's reward center. This part of the brain includes areas like the ventral tegmental area, nucleus accumbens, and prefrontal cortex. Dopamine is often called the "feel-good" neurotransmitter, is associated with pleasure, motivation, and reinforcement of behaviors. Why do we love sex, sugar, shelter, and our partners? It's because of dopamine!! Drugs of abuse essentially hijack this system releasing more dopamine than what naturally occurs. Repeated exposure to these drugs flood these areas of the brain with dopamine and creating an intense euphoria that strongly reinforces the act of drug-taking (compulsive drug use). There is a whole list of addictive drugs that do this to the brain.
Over time, repeated exposure leads to lasting changes in the brain. The brain adapts to the drug's presence and may produce less dopamine on its own. So, now you need the drugs to feel normal. This is often referred to as drug dependence. The brain may also become less sensitive to the dopamine neurotransmitter. As a result, people need to take larger amounts of the drug to achieve the same desired effect—an effect known as tolerance. The pursuit of that rewarding high can lead to compulsive use and addiction, even when the drug use causes negative consequences.
Long Term Consequences of Drug Addiction on the Brain
One of the most concerning findings from long-term studies of addiction is the potential for cognitive impairment. A study by Gould (2010) found that chronic alcohol use can lead to deficits in memory, attention, and problem-solving that may persist even after years of sobriety. Similarly, a study by Ersche et al. (2006) found that cocaine users who had been abstinent for an average of four years still showed impairments in decision-making and response inhibition compared to healthy controls.
Furthermore, long-term drug use can also increase the risk of developing other neurological and psychiatric disorders. For example, chronic alcohol use is a significant risk factor for dementia (Sachdeva et al., 2016), while chronic stimulant use has been linked to an increased risk of Parkinson's disease (Curtin et al., 2015).
What MRI Reveals Addiction and Parts of the Brain
Thanks to advanced brain imaging techniques like MRI, we now have a window into how addiction affects the brain on a structural and functional level. MRI studies have consistently shown that chronic drug use is associated with changes in brain anatomy. For example, alcohol use disorder has been linked to reductions in gray matter volume in the frontal lobes, which are crucial for functions like decision-making and impulse control. Stimulant drugs like cocaine and methamphetamine have been associated with volume reductions in the hippocampus, a key area for learning and memory.
MRI studies have shown that chronic opioid use can lead to decreased gray matter volume in regions such as the prefrontal cortex, anterior cingulate cortex, and insula, which are involved in decision-making, emotional regulation, and self-awareness.
Functional MRI (fMRI) studies have also yielded valuable insights. When individuals with substance use disorders are shown drug-related cues, like images of drug paraphernalia like needles and syringes, fMRI reveals heightened activity in brain's cerebral regions involved in craving and reward, such as the prefrontal cortex and striatum. At the same time, brain circuits involved in executive control often show reduced activation, which may contribute to poor decision-making and difficulty resisting urges.
What PET Scans Reveal About The Long Term Effects of Drug Abuse
There are several PET (Positron Emission Tomography) scan studies that demonstrate similar long-term effects of drug use on the brain, even after the user has stopped using drugs. Here are a few examples:
Methamphetamine: A study by Volkow et al. (2001) found that former methamphetamine users had a greater than 20% decreases in dopamine transporter (DAT) density in the striatum, even after 11 months of abstinence. This suggests long-lasting changes in the brain's dopamine system.
Cocaine: A study by Volkow et al. (1993) showed that chronic cocaine users had decreased glucose metabolism in several brain regions, including the frontal cortex, even after 3-4 months of abstinence. This indicates persistent changes in brain function.
These studies, among others, show a consistent anatomical and functional change in the brain with drug abuse.
The Road to Recovery: What MRI Shows About the Brain in Recovery
Just as MRI has revealed the damaging effects of addiction on the brain, it has also provided hope by demonstrating the brain's remarkable capacity for recovery. Numerous studies have used MRI to track the changes that occur in the brain as individuals progress through addiction treatment and maintain abstinence.
fMRI studies have also provided evidence of functional recovery in the addicted brain. A study by Volkow et al. (2001) found that methamphetamine users who remained abstinent for 9 months showed significant increases in dopamine transporter levels, suggesting a restoration of dopamine function. Another study by Nestor et al. (2011) found that cocaine users who remained abstinent for several weeks showed increased activation in the prefrontal cortex during a working memory task, indicating improved cognitive control.
MRI scans of former substance abusers abstinent for approximately 5-8 years suggest that certain brain regions may recover volume with extended abstinence. The subcortical regions, involved in reward and habit formation, positively correlated with abstinence duration, especially in former cocaine addicts. However, the prefrontal cortex, responsible for executive functions like decision-making, showed lower volume in former alcohol and cannabis users compared to controls, but not in former cocaine users. This implies that while long-term recovery is possible, prefrontal cortical deficits may persist for alcohol and cannabis users, whereas cocaine users displayed more widespread signs of recovery.
Conclusion:
The long-term consequences of addiction, including cognitive impairment and damage to the brain's reward system, can persist even after years of sobriety. Could these findings contribute to Post Acute Withdrawal Syndrome (PAWS)? I believe so.
These findings highlights the importance of achieving sobriety and also focussing on the brain. We don't know if the structural and functional changes to the brain can be repaired back to normal. Regardless of what the current science shows, I believe that optimizing sleep, exercise, and correcting nutritional deficiencies give the brain the most optimal chance of recovering normal function or developing new regions to take over executive functioning. Optimizing magnesium, omega 3, and other building blocks of a healthy brain may be the missing key.
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Volkow, N. D., Fowler, J. S., Wang, G. J., Hitzemann, R., Logan, J., Schlyer, D. J., Dewey, S. L., & Wolf, A. P. (1993). Decreased dopamine D2 receptor availability is associated with reduced frontal metabolism in cocaine abusers. Synapse, 14(2), 169-177. https://doi.org/10.1002/syn.890140210
Volkow, N. D., Fowler, J. S., & Wang, G.-J. (2003). The addicted human brain: Insights from imaging studies. Journal of Clinical Investigation, 111(10), 1444–1451. https://doi.org/10.1172/JCI200318533
Fowler, J. S., Volkow, N. D., Kassed, C. A., & Chang, L. (2007). Imaging the addicted human brain. Science & Practice Perspectives, 4(1), 4–10.
Zahr, N. M., & Pfefferbaum, A. (2017). Alcohol’s effects on the brain: Neuroimaging results in humans and animal models. Alcohol Research: Current Reviews, 38(2), 184–206.
About the author:
Dr. Harold Pierre is a board-certified anesthesiologist and addiction medicine specialist with over 25 years of experience. He is board-certified by the American Board of Anesthesiology and the American Board of Preventive Medicine.
*Disclaimer: This blog post is for informational purposes only and is not intended as a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of your doctor or other qualified health provider with any questions you may have regarding your health or a medical condition.
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