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/intoxication
- 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. It’s not yet known how much these changes may be reversed or how long that process may take. And adolescence is a critical “at risk period” for substance use and addiction because adolescent brains are still undergoing significant development.
All addictive substances have powerful effects on the brain. They account for the euphoric or intensely pleasurable feelings people experience during their initial use of alcohol or other substances. These feelings motivate people to use these substances again and again, despite the risks for significant harms.
With continued substance misuse, progressive changes called neuroadaptations occur in the structure and function of 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 craving 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?
Originally most research on addiction and the brain was done on animals in controlled environments and for ethical reasons. Now studies on humans are possible using brain imaging techniques such as MRI and PET scans. This allows researchers to “see” inside the living human brain.
Evidence shows that three areas of the brain are particularly important in the onset, development and maintenance of substance use disorders. As you’ll see, substance abuse is very complex as it relates to the brain. I’ll keep it as simple as possible. [2] [3]:
Basal Ganglia
The basal ganglia control the rewarding, or pleasurable, effects of substance use and are also responsible for the formation of habitual substance taking. The basal ganglia are located deep within the brain. Among other things, they are involved in learning routine behaviors and forming habits.
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 particularly 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 an 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 organise thoughts and activities, prioritize tasks, manage time, and make decisions) including exerting control over substance taking. Located at the very front of the brain, over the eyes, it is responsible for complex cognitive processes called “executive function”.
This is the ability to organise 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 towards 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 heighten activation of brain stress systems
- Reducing 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 (Oxycontin/Heroin/Fentanyl)
Opioid misuse can cause slowed breathing which can cause hypoxia resulting from too little oxygen reaching the brain. This can have short- and long-term psychological and neurological effects, including coma, permanent brain damage and death. 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.