The American Society of Addiction Medicine (ASAM) defines addiction as a chronic medical illness that involves genetic and environmental factors. Addictions, now also referred to as Substance Use Disorders (SUD) are arguably a form of mental illness involving many of the same brain regions as depression, anxiety, and other mental illnesses.
Additional mental illnesses and addiction are often complexly intertwined, co-occurring in the same person. Mental illness and addiction are highly treatable disorders with similar risk factors, causes, and treatment methods.
Causes of Addiction Disorders
There is no single cause of addiction. There are many contributing factors that all play a role in its development in an individual. Here are some of the causes:
Biological factors include things like metabolism, which can make a person need to take more drugs or drink more alcohol to feel the same effects as another individual. We still know very little about the exact biology of addiction and how to risk-stratify someone based on their biology. However, biology certainly plays a role.
SUD, like other mental illnesses, are likely heritable conditions. Genes and environmental influences on those genes (called epigenetics) potentially account for up to 40% to 60% of the risk for developing a SUD.
While there is no specific gene that has been definitely linked to the onset of addiction, it is widely accepted that genetic factors can contribute. It is also clear that addiction disorders often run in families. Individuals with close family members with substance use disorders are more likely to themselves develop a substance use disorder.
Outside influences can be causes of substance misuse, leading to addiction. This can include the following:
- A lack of family involvement
- Peer pressure
- Parents or caregivers that model risky behaviors, including drug and alcohol use
- Living in a high-stress environment
- Childhood trauma
Environmental aspects can influence a person’s perceptions on drug and alcohol use. They can also be causal factors in drug and alcohol misuse and subsequent addiction.
How Addiction Changes the Brain
Drugs and alcohol make changes to the way your brain processes rewards. Substances interact with chemical messengers in the brain, or neurotransmitters, that are involved in emotional regulation and feelings of pleasure. When you do something that should naturally be pleasurable, such as eating your favorite food, your brain activates your reward system, causing surges of these neurotransmitters and creating sensations of happiness/pleasure. Drugs can increase these “happy” neurotransmitters, such as dopamine, causing false or artificial feelings of euphoria. Drug and alcohol use can create a kind of shortcut to pleasure, flooding the brain with these chemicals. With long-term use, this can actually change the way your brain responds to and processes pleasure. Someone who struggles with SUD will often have difficulties finding pleasure or feeling happy without the drug. The person then needs to continue the use of the drug just to avoid feeling “bad”. The substance becomes necessary just to feel “normal”, creating a viscous cycle of use.
In addition to the changes addiction makes to the reward processing circuitry and its chemical makeup, addiction can also affect other parts of the brain responsible for the following functions:
- Decision-making processes
- Stress regulation
Risk Factors for Addiction & Mental Illness
Just as there are various potential causes for addiction that are likely overlapping, there are also a variety of risk factors that can make addiction and mental illness more likely to occur.
Stress, especially chronic stress, is one of the major risk factors for developing mental illness and addiction.
Stress can interfere with regular brain function, impacting parts of the brain that regulate emotions as well as the reward system. Chronic stress can alter the brain and contribute to addiction.
High levels of stress can cause a person to turn to alcohol or drugs as a method of coping or to escape.
Exposure to trauma, particularly trauma in childhood, drastically increases the risk for addiction and mental health issues. Studies have shown that close to 75% of people in treatment for drug misuse and SUD have a history of childhood trauma and abuse. Trauma can cause high levels of stress as well as the onset of PTSD (post-traumatic stress disorder), which are significant risk factors for addiction. Drugs and alcohol can become a way to escape reality and temporarily “numb” the pain associated with difficult memories and emotions.
If someone in your immediate family struggles with a SUD, this increases the odds that you will also have potential issues with substance misuse. Multiple studies have shown repeatedly that there is a genetic link for SUD, some say as high as 50% risk, although the exact gene(s) responsible have yet to be identified. 
Co-Occurring Mental Health Disorders
Studies show that around half of those with mental illness will also battle a SUD at some point. 
Mental illnesses, such as depression, schizophrenia, bipolar disorder, antisocial personality disorder, and anxiety, often co-occur with addiction. This might be related to the fact that many overlapping brain regions are likely involved in the onset of both disorders.
Early Substance Use
Initiating substance use as a child or teenager (while the brain is in its critical development period) greatly increases the risk for developing SUD as an adult. Children who start drinking alcohol before the age of 15 have a much higher risk for an alcohol use disorder later in life than their peers. Drug and alcohol use at a young age rewires the brain while it is still potentially developing and can be a significant risk factor for addiction.
Type of Drug & Method of Abuse
Some drugs are more addictive than others. Using these substances can greatly increase the risk of addiction. For instance, cocaine, methamphetamine, and opioid drugs are highly addictive. They can lead to compulsive use and drug dependence faster and in fewer uses than hallucinogens or marijuana.
Home environments can greatly impact the likelihood of drug and alcohol misuse. People who live in a chaotic and unstable home environment or who observe substance misuse in their family members at a young age have been shown to have a higher risk of using later in life.
Drug and alcohol use can be a result of peer pressure or a desire to fit in, particularly in young adults. It is also clear that individuals who surround themselves with others using substances are more likely to continue to use themselves. Part of many SUD treatment programs encourage thinking deliberately about one’s peer group and whether or not they are positive influences or whether they actually encourage us to continue to use.
The Stigma of Addiction
Even though addiction is classified as a medical/mental health condition, there is still much historical stigma surrounding it.
People often wrongfully assume that addiction is a moral failure, a defect of character, or a lack of willpower. This is simply not true.
Addiction impacts the brain just as a mental illness does. Compulsive drug or alcohol use and the inability to stop using substances are often related to physical drug dependence and withdrawal symptoms. This makes it arguably a physical disease as much so as diabetes, high blood pressure, or cancer.
The stigma of having a SUD can be a barrier to desperately needed and highly efficacious treatment.
By combating the stigma of addiction and reframing it as a mental health/medical condition, individuals can hopefully more easily access needed treatment.
Treatment for a Mental Illness
Mental illness and addiction require comprehensive treatments to address the complex nature of these conditions.
There are a variety of different forms of treatment methods and levels of care available, depending on individual need. An inpatient, or residential, treatment program offers a highly structured environment with around-the-clock care for those who need to focus completely on healing. These are often appropriate for those struggling with severe SUD or mental health issues.
Outpatient programs are generally more flexible. In many cases, Medication for Addiction Treatment and comprehensive addiction treatment programs can be offered on an outpatient basis, even via telehealth appointments. This option might be appropriate for someone with less severe disease, and with good social support.
When two disorders are present in the same person at the same time, such as addiction and depression, dual diagnosis treatment can help manage them both simultaneously. This ensures the best chances of recovery on all fronts.
Treatment services and methods within these programs can include the following:
- Detox: This is a program that is short term (days) that offers medications and supportive care while the drugs or alcohol process safely out of the body.
- Behavioral therapies: These sessions can help to increase mindfulness and emotional regulation, teaching coping mechanisms and tools for managing triggers to use substances.
- Group and individual counseling: This involves working both in a group setting with similar individuals and alone to discover the root causes of mental illness and addiction as well as how to decrease future risk factors.
- Support group meetings: This involves meeting with individuals in similar circumstances to get support, encouragement, and help with relapse prevention.
- Medication management: Medications are often a vital part of a treatment plan that can help to manage mental health symptoms as well as dispel drug and alcohol cravings and support recovery. Medications like Suboxone can be used on a long-term basis to manage opioid use disorder, and other supportive medications may also be used for SUD.
Addiction is a highly treatable mental illness. With a comprehensive treatment model that aims to work through all the potential contributing factors, you can support a long and healthy life in recovery.
Medically Reviewed By Elena Hill, MD, MPH
Elena Hill, MD; MPH received her MD and Masters of Public Health degrees at Tufts Medical School and completed her family medicine residency at Boston Medical Center. She is currently an attending physician at Bronxcare Health Systems in the Bronx, NY where ... Read More
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