Understanding how drugs and alcohol affect the brain can be a helpful motivator for someone looking to quit using substances. In the past few decades, there have been scientific breakthroughs transforming the understanding of substance use and its effects on the brain.
These have helped dispel the previously common belief that addiction is a moral failing. Read on to learn more about the impact on various regions of the brain substance abuse has on your physical and mental health.
How Do Drugs and Alcohol Affect the Brain?
Evidence now suggests that the addiction process involves a three-stage cycle [1]:
- Binge
- Withdrawal/negative affect
- Preoccupation/anticipation
As a person continues substance use and as it produces dramatic changes in brain function that reduce a person’s ability to control their substance use, this cycle becomes more severe.
These changes in the brain persist long after substance use stops. Research is still ongoing to explore how these changes can be reversed. Studies are particularly looking at adolscence, where many are at a higher “risk” for long-term effects as their brain develops.
With continued substance misuse, progressive changes called neuroadaptations occur throughout structures in the brain. They compromise brain function and drive the transition from controlled, occasional substance use to chronic misuse, which can be difficult to control.
These changes can persist long after a person stops using substances. They may also produce continued, periodic cravings for the substances that can lead to relapse—more than 60% of people treated for substance use disorder relapse within the first year following treatment. And a person can remain at increased risk of relapse for many years. However, there are successful treatments.
What Parts of the Brain Are Affected by Drug Use?
In the past, most research on addiction was done on animals. Now, we have brain tech that allows us to “see inside” the human brain. This has revealed 3 main regions of the brain affected by drug use.
Basal Ganglia
This drives feelings of reward and pleasure in addiction. It is located deep in the brain and plays a large role in routine & habit formation.
Two sub-regions are especially important in substance use disorders:
- The nucleus accumbens, involved in motivation and the experience of reward
- The dorsal atrium, involved in forming habits and other routine behaviors
The basal ganglia is mainly involved with the binge intoxication stage. The “reward circuitry” in the nucleus accumbens, along with the neurotransmitter dopamine, which is related to feeling pleasure, together with naturally occurring opioids, play a key role in the rewarding effects of alcohol and other substances and the ability of cues associated with those substances to trigger craving, substance seeking and use. Repeated activation of the “habit circuitry” in the dorsal striatum contributes to the compulsive substance seeking and taking involved with addiction.
Extended Amygdala
This is involved in stress and feelings of unease, anxiety, and irritability that typically accompany substance withdrawal. Located beneath the basal ganglia, the extended amygdala regulates the brain’s reactions to stress, including behavioral responses like “fight or flight” and negative emotions like unease, anxiety, and irritability.
It also interacts with hormone-producing glands which control reactions to stress and regulate many other bodily processes. This part of the brain is particularly involved with the withdrawal/negative affect stage of substance use.
This stage involves a decrease in the function of the brain reward systems and activation of stress neurotransmitters in the extended amygdala. This creates a powerful neurochemical basis for the negative emotional state associated with withdrawal. The drive to alleviate these negative feelings negatively reinforces alcohol or drug use and drives compulsive substance taking.
Prefrontal Cortex
This is involved in executive functions (such as the ability to organize thoughts and activities, prioritize tasks, manage time, and make decisions), including exerting control over substance taking. Located at the front of the brain, over the eyes, it is responsible for complex cognitive processes called “executive function.”
This is the ability to organize thoughts and activities, prioritize tasks, manage time, make decisions, and regulate one’s actions, emotions, and impulses. It is particularly involved with the preoccupation/anticipation stage of substance abuse.
This stage involves a disruption of executive function caused by a compromised prefrontal cortex. The activity of the neurotransmitter glutamate is increased which drives habits of craving and disrupts how dopamine influences the prefrontal cortex. Habit-like substance seeking is promoted, as well as impulsive and compulsive substance seeking, as the executive function to stop this is compromised.
Impacts of Substance Use On Brain Functioning
Disruptions in the functioning of these areas of the brain have a variety of impacts, including:
- Enabling substance-associated cues such as people, places or things to trigger substance seeking. This is called increased incentive salience, a term that refers to the psychological process of directing behavior toward naturally sought-after rewards for survival, such as food, water, and sex.
- Reducing the sensitivity of brain systems involved in the experience of pleasure or reward and heightening activation of brain stress systems
- Reducing the functioning of brain executive control systems, which are involved in the ability to make decisions and regulate one’s actions, emotions, and impulses
Long-Term Effects of Drugs On the Brain
Continued research is required to more thoroughly explain how substance use affects the brain at various levels. Various drugs have different impacts on brain functions. Here are three main groups:
Alcohol
Alcohol produces chemical imbalances in specific neurocircuits and can be neurotoxic. Chronic heavy drinking can, for example, damage brain regions involved in memory, decision-making, impulse control, attention, sleep regulation, and other cognitive functions. Once alcohol use disorder progresses, these and other brain changes can make it very difficult to stop drinking without assistance.
Methamphetamines
Chronic methamphetamine abuse has devastating effects on the central nervous system.
With repeated use in humans, meth depletes the brain’s store of dopamine and damages both dopamine and serotonin neurotransmitters. This leads to 40% of meth users with abnormalities on neuropsychiatric tests [4].
Meth users have deficits in episodic memory (the ability to re-experience past events), executive function, and motor function. As a result, meth exerts a powerful negative influence on behavior and decision-making. Other effects of meth use include:
- Increased death of neurons in the central nervous system and the brain
- Increased death of glial cells in the prefrontal cortex. These cells have signaling capacities, fight infection, and develop myelin (the fatty sheath of white matter that neurons use to communicate)
- Decreased white matter
- Increases in the neurotransmitter glutamate. It has an excitatory function and overproduction can be neurotoxic, damaging the central nervous system
- Damage to the brain’s circulatory system with the risk of stroke
Opioids
This is one of the most dangerous drugs, with a high risk of overdose & death. Opioids can cut off oxygen to the brain, slow breathing, and result in coma or severe brain damage. Researchers are also investigating the long-term effects of opioid addiction on the brain, including whether damage can be reversed.
Substance Abuse Treatment in Michigan
Rushton Recovery understands the complex nature of drug & alcohol recovery. We prioritize your well-being, safety, and comfort during treatment. Our detox and residential treatment center in Michigan offers a healing space to embark on your journey toward sobriety.
We offer evidence-based therapies designed to evolve with your individual needs and address the root of your substance abuse. Let our team help you get clean, repair relationships, and equip you with the skills to achieve long-term recovery. Reach out to our Admissions team now.
Sources
[1] National Institute on Alcohol Abuse and Alcoholism. 2023. Neuroscience: The Brain in Addiction and Recovery
[2] Koob, G., Volkow, N. 2010. Neurocircuitry of Addiction. Neuropsychopharmacol 35, 217–238 (2010).
[3] Substance Abuse and Mental Health Services Administration (US); 2016. Facing Addiction in America: The Surgeon General’s Report on Alcohol, Drugs, and Health [Internet]. 2016 Nov. CHAPTER 2, THE NEUROBIOLOGY OF SUBSTANCE USE, MISUSE, AND ADDICTION.
[4] Rusyniak DE. 2011. Neurologic manifestations of chronic methamphetamine abuse. Neurol Clin. 2011 Aug;29(3):641-55.
