Comorbidity describes two illnesses or disorders occurring in the same individual. These conditions can co-occur or one after the other. Comorbidity also refers to the interactions between the disorders that can worsen both. This guide will discuss substance abuse and mental illnesses and why there is comorbidity between them. For instance, mental health issues, behavioral or emotional problems may prompt drug substance abuse.

Drug addiction and its relation to mental illness

Drug addiction is a mental illness because it interferes with the brain in different ways. It changes the individual’s normal desires and needs and replaces them with other priorities surrounding drug use. As a result, the individual cannot control brain impulses with time and adapts compulsive behaviors.

Many individuals addicted to substance abuse end up developing mental disorders in the same way people with mental illnesses are mostly diagnosed with substance abuse. For instance, the use of opioids in managing chronic pain is controversial because it results in prescription drug addiction. Prescription drug abuse is associated with addiction, anxiety disorders, depression, personality disorder, among other mental illnesses. In the end, prescription drug addiction forces the individual to seek prescription drug rehabilitation

Mental disorders can lead to substance abuse.

Some mental disorders are identified as some of the reasons an individual may develop substance use disorders. According to research, many individuals with mental illnesses use drugs or alcohol as self-medication. Eventually, the mental illness symptoms worsen. The brain changes to accommodate the rewarding effect of substance abuse which exposes the individual to continued and prolonged substance abuse.

Drug addiction and substance abuse may lead to mental illnesses

On the other hand, substance abuse may lead to mental illnesses because the drugs change the brain’s functioning and increase its reliance on the drugs to function well.

Common risk factors that contribute to substance abuse/addiction and mental illnesses

Involvement of the brain

Many components of the brain are affected by substance abuse and mental illnesses. For instance, when an individual is addicted to a particular drug, the brain circuits that facilitate impulse control, decision-making, and emotion control are affected. That may lead to psychiatric disorders such as schizophrenia, depression, and other mental illnesses.


Stress has been associated with substance abuse and mental illnesses. According to research, high-stress levels reduce the prefrontal cortex’s activity and increases the striatum’s responsibility, resulting in increased impulsivity and reduced behavioral control. Early life stress and chronic stress can increase the risks of substance abuse and mental disorders.

Environmental influences

Environmental influences such as adverse childhood experiences, trauma, etc., can increase an individual’s susceptibility to substance abuse and mental illnesses. Therefore, preventive measures are necessary to reduce such risks. Individuals who are physically traumatized are usually at a higher risk of developing drug substance abuse as they use drugs to avoid dealing with the trauma’s consequences.

The treatment of comorbid conditions

A lot of behavioral therapies work effectively in treating comorbid conditions such as drug abuse and mental illnesses. Drug rehabilitation can be tailored according to the patient’s specific needs regarding the particular drug abuse, age, level of addiction, and other factors. Therapeutic communities and support groups focus on resocializing the individual. At the same time, dialectical behavioral therapy reduces the individual’s risk of self-harm behaviors such as suicidal thoughts, urges, attempts ad even more drug use.


Treatment for comorbid conditions should focus on both drug substance abuse and mental disorders to address both. Through rehabilitation, effective medication, and behavioral therapies help treat substance addiction and mental illnesses.