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Updated on September 6, 2023
7 min read

Co-Occurring Disorders: Substance Abuse & Mental Illness

Kelly Brown
Dr P. E. Pancoast, MD
Written by 
6 Sources Cited
Kelly Brown
Written by 
6 Sources Cited

Overcoming substance use disorders can be a challenge. It's even trickier when you’re simultaneously battling depressive disorders, anxiety disorders, or another mental illness.

Substance abuse and mental health are among the most common co-occurring disorders. In this article, we'll discuss co-occurring disorders, their symptoms, and treatment options.

What are Co-Occurring Disorders?

A co-occurring disorder is the combination of co-occurring substance use disorder (SUD) and mental illness in a person. Also known as dual diagnosis or comorbidities. This combination of problems is common among people who require medication-assisted treatment (MAT) for successful care.

Co-occurring disorders can either surface at the same time or as overlapping symptoms. As per the National Survey of 2018 on Drug Use and Mental Health, around 38 percent of adults over 18 (approximately 95 million people) are affected by co-occurring disorders.[1] 

Substance abuse can often worsen the effects of mental disorders and vice versa. If you're struggling with co-occurring disorders, the severity of your condition may evolve with time.  

Substance Use Disorders (SUDs) Definition

SUDs are progressive illnesses characterized by genetic predisposition and physical/mental changes. They develop from repeated use of substances that influence brain development and activity.

This condition can make it difficult to control using substances like:

  • Alcohol
  • Tobacco
  • Opioids
  • Stimulants
  • Marijuana
  • Hallucinogens
  • Prescription drugs

Studies show that forty-three percent of adults in SUD treatment for nonmedical use of prescription drugs also have symptoms of mental illness, including anxiety and depression. [2]

Mental Illness Definition

Mental illness, or mental health disorders, relates to various psychological issues. It affects your mood, behavior, and thinking abilities. 

Some common mental illness conditions are: 

  • Generalized anxiety disorder
  • Eating disorders
  • Personality disorders
  • Depressive disorders
  • Post-traumatic stress disorder (PTSD)
  • Psychotic disorders 

Over time, a mental disorder may progress to a severe illness if the ongoing mental health symptoms cause extreme discomfort or affect the brain's function. As a result, at least 1 in 4 adults living with severe mental health conditions may also have a substance abuse disorder.3


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Common Mental Illnesses Linked to Substance Abuse

Mental illness is the leading cause of substance abuse. The latter often results in self-medication.

Co-occurring disorders can pose a severe threat to one’s well-being. The condition may lead to critical morbidity, fatality, and difficulty in the entire health system. 

Common mental illnesses associated with substance abuse disorders include:4

  • Bipolar disorder
  • Attention-deficit / hyperactivity disorder (ADHD)  
  • Depression
  • Anxiety disorders
  • PTSD
  • Addiction disorders
  • Schizophrenia
  • Borderline personality disorder 

Symptoms of Co-Occurring Disorders

People with co-occurring disorder symptoms may often struggle with medical and emotional dysregulation. The results of both include: 

  • Symptomatic relapses 
  • Financial challenges 
  • Social isolation
  • Anxiety attacks 
  • Physical/sexual aggressive behaviors and victimization 
  • Frequent hospitalization 
  • Incarceration 

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Why Are Mental Illnesses Linked to Substance Abuse?

These co-occurring disorders are strongly interconnected and may be related to genealogy. You may be a victim of substance abuse or a mental health disorder because of your genetic history or environment. 

Many people with dysfunctional genetic histories are predisposed to developing co-occurring disorders. Some common risk factors are listed below: 

Genetic Vulnerabilities 

A genetic vulnerability refers to characteristics that are passed on from parents to children that make them more likely to develop an addiction. It’s reported that around forty to sixty percent of people's vulnerability to substance abuse is associated with genetics.5

Epigenetic Influence

Epigenetics discusses how environmental factors can change our genes and regulate their activities. These factors can cause changes in behavior that increase the risk of addiction.

These factors include:

  • Trauma
  • Sexual abuse
  • Chronic stress
  • Drug abuse 

Environmental Factors

External (environmental) influences may also increase the risk of developing a co-occurring disorder. These include factors like:

  • Growing up with a close relative who abuses substances
  • Ease of access to drugs and alcohol
  • Poverty

People who grew up in these conditions are more likely to develop substance issues than those who didn't. 

Brain Chemical Involvement

Common co-occurring disorders also hugely affect crucial brain regions. Frequent drug use often disrupts the feeling-initiated area of our brains that controls:

  • Impulse control
  • Decision-making
  • Emotions

This could potentially lead to the development of distinct psychiatric disorders. 

Which Comes First: Addiction or Mental Illness?

There is no specific order as to which disorder develops first. Any of these can occur depending on the mental condition of the person. 

People with mental illnesses often self-medicate to treat their depression or anxiety, which could result in substance abuse or alcohol use disorder (AUD). A drug addict could also develop a mental health condition due to addiction. Paranoia and depression are often experienced by opiate users who worry about their drug supply or getting in legal jeopardy from ‘drug busts.’

Co-occurring disorders are challenging to identify in a standardized manner. Treatment for dual diagnoses varies greatly, as substance addiction may require a different approach than mental health conditions. In addition, certain pharmacologic treatments must be carefully monitored and controlled when a co-occurring SUD occurs.


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Diagnosing Co-Occurring Disorders

Co-occurring disorders are commonly diagnosed through medical screening and in-depth assessments. These screenings aim to address a person's behavior through different approaches related to their symptoms. 

The diagnosis evaluation typically considers a person's physical and mental history in chronological order, including their history with substance use disorders.

Treatment Options for Co-Occurring Disorders

Different treatment options for co-occurring disorders vary by severity and complexity. The most popular forms of dual diagnosis treatment include inpatient, outpatient, and integrated treatment. 

What is Integrated Treatment?

An integrated treatment program is a medical practice that treats two or more conditions. It uses multiple medications and treatments to control the symptoms of co-occurring disorders.

An integrated treatment approach includes a combination of pharmacotherapy and psychotherapy. The US Department of Health and Human Services of the Substance Abuse and Mental Health Services Administration (SAMHSA) suggests that integrated treatment for co-occurring disorders is the most effective and oriented approach. [6]

Inpatient Treatment

Inpatient treatment is another practical and holistic approach to treating mental illness and substance abuse. These treatment programs require the affected person to stay in a hospital or therapy facility until their symptoms are controlled and stabilized. These programs are particularly important for people without stable home environments.

Partial Hospitalization Programs (PHPs)

A partial hospitalization program (PHP) is a formal treatment program for co-occurring disorders that allows people to return home at night. However, these programs occupy most of the day with structured activities. They aim to encourage people to participate in healthy activities and educate and inform.

Outpatient Treatment

Outpatient treatment is a less intensive program that lasts several hours most weekdays. Treatment is educational and therapeutic.

The process involves relapse prevention planning and isn’t as restrictive as inpatient treatment. Some detox and social support programs are also part of this treatment to help people recover from co-occurring disorders. 

Does Insurance Cover Co-Occurring Disorder Treatment?

Qualified health insurance policies may cover some costs of treatment. The level of financial coverage depends on the treatment location and the specific coverage for each policy.

According to the Affordable Care Act (ACA), mental health services are critical health benefits that insurance companies must cover. Many rehab centers for co-occurring disorders collaborate with insurance companies to help people meet their financial needs.

The limits of coverage vary, as do the deductible amounts and co-pays. Therefore, a majority of health insurance companies offer partial financial coverage for: 

  • Inpatient treatment centers and services 
  • Rehab treatment centers for substance misuse and addiction (provided by addiction specialists)
  • Behavioral therapies (e.g., counseling, mental health communities, and psychotherapy) 


Co-occurring disorders or dual-diagnosis disorders are conditions where someone experiences substance use disorders alongside mental illnesses. The condition can be difficult to treat because addiction can worsen your mental illness and vice versa.

Various mental illnesses are linked to substance abuse, such as bipolar disorder and schizophrenia. Various psychological, genetic, and environmental factors can increase the risk of co-occurring disorders.

Fortunately, there are treatment options that treat addiction and mental illness simultaneously. Treatment is also typically covered by insurance.

Updated on September 6, 2023
6 sources cited
Updated on September 6, 2023
All Alcoholrehabhelp content is medically reviewed or fact checked to ensure as much factual accuracy as possible.

We have strict sourcing guidelines and only link to reputable media sites, academic research institutions and, whenever possible, medically peer reviewed studies.
  1. Substance Abuse and Mental Health Service. “Key Substance Use and Mental Health Indicators in the United States.” Substance Abuse and Mental Health Service, 2019
  2. NIDA. "Part 1: The Connection Between Substance Use Disorders and Mental Illness." National Institute on Drug Abuse, 2021
  3. Mental Health. “Mental Health and Substance Use Co-Occurring Disorders.” Online Publication, 2022
  4. National Institute of Mental Health, NIH. “Substance Use and Co-Occurring Mental Disorders.” NIH online publication, 2021
  5. National Institute of Drug Abuse. “Why is there comorbidity between substance use disorders and mental illnesses?” NIH Online Publication, 2020.
  6. Kelly, T., and Daley, D. “Integrated treatment of substance use and psychiatric disorders.” Social work in public health, 2013.
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