The Impact of Addiction on the Brain
A substance use disorder is a difficult thing to overcome. Beyond the psychological dependence on a substance is the physical dependence, which is rooted in how the brain uses certain chemicals. While some symptoms are short-lived, others can be long-lasting, significantly changing how a person reacts to a substance.
According to the Substance Abuse and Mental Health Services Administration, 24 million Americans have been diagnosed with a substance use disorder, and 29.5 million people have been diagnosed with an alcohol use disorder, bringing total numbers to 53.5 million. Over 26 million Americans fit the criteria for a substance use disorder, including those who have already been diagnosed.
However, there is always hope. If you or someone you care about is struggling with substance dependence or a substance use disorder, help can be found with a single phone call or mouse click. The National Rehab Hotline, for example, is an excellent resource for starting your healing journey. The key to reclaiming your life is taking the first step, which is often the hardest. But from there, you can receive the help you need anywhere in the country.
Substance Use and Biochemistry: How the Brain Gets Hijacked
The brain is essentially a living computer that controls everything you do, feel, and think. It is an incredible mechanism that allows you to pay attention, imagine things, and plan for the future. It is also responsible for rewarding certain behaviors. This is where substances come into the equation.
Yale’s Department of Medicine explains the interaction between substances and the brain. When behaviors are rewarding, a substance called dopamine flows through the brain. This neurotransmitter is key to feeling pleasure of any kind. The problem with substance use is that the dopamine response is multiplied by at least 10 times compared with normal rewarded behaviors. This is what creates the “high” of substance use.
The brain is also responsible for remembering, and it specifically remembers the excessive rush of dopamine associated with substance use. The brain is hardwired to seek out rewarding behaviors — hence the reason for activities like sex drive, eating certain types of foods, and exercising. The brain remembers how these behaviors affect it, and it encourages us to do more of them.
The problem with dopamine is that the brain becomes desensitized to high levels over time. This natural reaction is meant to keep you from doing things in excess.
In addition to the reward system being hijacked, the brain in general responds to higher levels of stimulation. In order to manage the flood of dopamine, the brain will actually decrease the connections that transport dopamine (called synapses). This, in turn, decreases the pleasure response with regard to all things, including normal rewarded behaviors.
How Substance Use Disorder Develops
These two reactions — the flood of dopamine and the decrease of dopamine receptors — are key in the development of a substance use disorder. At first, the need for a normal or heightened pleasure response feels necessary, which is the basis for psychological dependence. Taking increasing levels of the substance will bring the pleasure response levels back up, while making the person feel better overall.
If this goes on long enough, the dopamine levels will drop very low, making increasingly higher doses of the substance necessary for the individual to function. This is what is called physical dependence.
The further one gets into physical dependence, the harder it can be to stop using the addictive substance. From this point, the chronic need to use the substance constitutes what mental health and healthcare professionals call a substance use disorder. The same general principles apply to alcohol use disorders as well. You may hear someone talk about a “drug habit” or “alcohol habit.” What is described above is the basis for that habit.
Unfortunately, many people think that addiction only has to do with “making poor choices” and that people can simply “stop if they want to” or stop if they have enough willpower. This is patently false. The science of substance use proves the opposite is, in fact, true. A substance use disorder is a result of a complex biological process in which the brain is hijacked and then responds in ways that ultimately strengthens the urge to use. It is not anyone’s fault. From a medical standpoint, it is quite literally a disease.
Genetic and Environmental Factors
There is an ongoing discussion in healthcare over whether environment or genetics determines the likelihood that a person will develop a substance use disorder. In layman’s terms, this is the “nature versus nurture” debate. Recent advancements in genetic testing and the discipline of genetics, as a whole, have come close to ending this debate, indicating that it is both nature and nurture that contribute to substance use.
Studies from the American Psychological Association have shown that 60% of the tendency to develop a substance use disorder comes from genetics. At the same time, genetics accounts for 54% of one’s ability to quit a substance or alcohol. This means that a person’s genes account for over half the risk of developing a substance use disorder.
A child of someone with a substance use disorder is eight times more likely to develop a substance use disorder themselves. While this may be due to genetic factors, it is also possible that exposure to substances and substance use behaviors may increase the predilection to misuse a substance.
Other environmental factors influence the likelihood of developing a substance use disorder, though it is not clear how great an influence each factor can have. The risk factors include:
- Access and proximity to substances that are commonly misused
- Barriers to treatment within one’s environment
- Belonging to a race or culture with a higher instance of substance misuse
- Belonging to a lower economic class
- One’s location, especially in childhood
The evidence is pretty clear that both nature (genetics) and nurture (environment) contribute to the development of substance use disorders. However, what does this have to do with the brain and the role it plays in substance use?
The answer may not be obvious, but many studies have illustrated the risk factors. Those with a genetic predisposition do not necessarily develop a substance use disorder, but the risk is still present.
One recent study of biological siblings showed that, when one sibling struggled with a substance use disorder, both siblings showed differences from a control group when it came to the wiring of habit-forming and reward system sections of the brain. The control group, none of whom had a substance use disorder, showed no such abnormalities. This indicates a strong genetic factor in the structure of the brain when it comes to substance use.
Other studies have shown that conditions such as poverty and high levels of stress have an impact on the brain. When both genetic and environmental factors are taken into account, it is called epigenetics. What epigenetics shows is that nature and nurture have profound impacts on both the structure of the brain and the likelihood that someone will develop a substance use disorder. This should put to rest the assumptions that substance use is simply a result of bad choices or a lack of willpower.
Substance Use and Withdrawal
The same parts of the brain that play a role in substance use disorders are also active during withdrawal from a substance. These areas include the basal ganglia, which is in charge of the brain’s reward system. There is also the extended amygdala, which is in charge of stress reactions. Finally, there is the prefrontal cortex, which controls executive function and helps the brain reason through. It also prevents substance-taking decisions.
The activity of the basal ganglia slows down due to substance use. As a result, naturally rewarding behaviors no longer receive the level of dopamine that they did before the substance-taking behaviors began. As stated earlier, the reward system of the brain, located in the basal ganglia, has reduced active dopamine receptors in an attempt to adjust to the strong response that a substance may generate.
The extended amygdala is sent into hyperdrive by long-term substance use. This increases the intensity of stress reactions and magnifies the need to take a substance to cope.
Finally, the prefrontal cortex is affected. During substance use, this part of the brain is either slowed or bypassed, temporarily hijacking the brain’s decision-making mechanisms. During withdrawal, this part of the brain slowly begins to reassert itself, allowing the users to regain some level of control over whether or not to use. While this process is slow, it can be vital to becoming clean and maintaining long-term sobriety.
Long-Term Concerns
While no study has shown conclusively that the brain is permanently altered by moderate long-term substance use, it is understood that parts of the brain undergo lasting changes that continue even after a person has attained sobriety.
Some substances are more harmful than others when it comes to long-term use. For example, heroin degrades the white matter of the brain, causing a long-lasting reduction in cognitive ability and stress management. It is not known if this effect can be reversed. It also alters the hormonal and neurochemical balances within the brain, a state which is reversible but not always easily achieved.
Even though these effects seem severe, it is important to realize sobriety is an achievable goal for those willing to seek it out.
Hope and Help Are Available
Remember that the brain, like the body, has incredible restorative properties. If you or someone you care about is currently struggling with a substance use disorder, there are always options. The National Rehab Hotline has resources for immediate help. We can be reached through our website or by calling 866-210-1303. You can contact the hotline for yourself or a friend. Your body, brain, and life can be restored to health. The vital part is taking that first step of seeking help. From that point on, you will not be alone in your sobriety journey.