Understanding Co-Occurring Disorders

Table of Contents

Multiple disorders can co-occur in treating mental health and substance abuse disorders. A dual diagnosis means a person meets the criteria for various disorders simultaneously. Meaning that both a substance use disorder and one or more mental health disorders are present. 

In such cases, the two conditions—i.e., substance use disorder and mental health disorder—are known as “co-occurring” or “comorbid.” 

Dual diagnosis disorders are relatively common when treating mental and behavioral health. More than 50% of people with a severe mental illness also have a substance use disorder.

People who may have co-occurring disorders should seek specialized treatment options. Treating substance use disorder and other conditions the person may have is essential.

What are Co-Occurring Disorders?

Substance use disorder (SUD) is a condition defined by the uncontrolled use of alcohol or drugs. People with SUD will not stay sober despite the negative consequences of their substance use. These consequences may include health problems and failure to meet work, school, or home responsibilities.

A person with a dual diagnosis may display mental health symptoms long before they develop substance use issues. On the other hand, signs of long-term substance abuse may appear before a mental health disorder develops.

People with a dual diagnosis often initially seek treatment for either a mental health disorder or the substance use disorder. It is only later that they are also diagnosed with the second disorder.

In any case, those struggling with addiction and mental illness must be treated at the same time for both conditions. If they receive comprehensive treatment for both conditions, they have the most excellent chance of full recovery.

Mental Health Disorders that Co-Occur with Substance Abuse

There are a few mental health conditions that commonly occur with substance abuse. People who believe they may be struggling with symptoms of a mental health condition should contact a professional. Medical and mental health professionals can help identify and diagnose specific mental health disorders. 

Mental health disorders that often co-occur with a substance abuse disorder include:

A person struggling with one of these mental illnesses may use drugs or alcohol as a coping mechanism. They may use drugs and alcohol as a way to alleviate the symptoms temporarily.

Types of Substance Abuse that Co-Occur with Mental Disorders

Mental health disorders that often co-occur with a substance abuse disorder include:

Among people diagnosed with co-occurring disorders, the drug most frequently misused is alcohol, followed by marijuana and cocaine.

Whichever of these substances is being misused, the presence of a co-occurring mental disorder can complicate the recovery process. Abusing a substance will never offer more than temporary relief from the symptoms of a mental illness. In most cases, substance abuse will likely obscure the root cause of the problem.

Is Drug Addiction a Mental Illness?

A person with a co-occurring disorder suffers from a substance use disorder (SUD) and another mental health disorder.

But it’s important to acknowledge that addiction is a mental illness. Like other mental illnesses, addiction has both behavioral and physiological components.

Addiction negatively affects the structure and function of the brain. It disturbs a person’s typical hierarchy of needs and desires. The addict’s compulsive behaviors and weakened impulse control are very similar to symptoms of other mental illnesses.

Are Co-Occurring Disorders and Dual Diagnosis Similar?

Dual diagnosis is sometimes referred to as comorbidity or co-occurring disorders. These three words/phrases are, for the most part, used interchangeably. They refer to the same thing: the co-occurrence of addiction and mental illness within the same person.

“comorbidity” describes two or more disorders in the same person. The two disorders may co-occur—or one after the other. Comorbidity also implies an interaction between the two illnesses that can complicate, aggravate, or intensify them.  

The National Alliance on Mental Illness (NAMI) recommends simultaneously treating dual diagnosis patients for both conditions. This can be more effective than treating the disorders separately. This is because the two diagnoses tend to influence one another. Therefore, addressing one without the other can increase the risk of a relapse.

Statistics About Co-Occurring Disorders

In 2018, an estimated 7.7 million American adults had co-occurring mental and substance use disorders. Based on the statistics, it is clear that many people can struggle with a dual diagnosis. Understanding some of the basics about co-occurring conditions is essential to determine if someone is at risk for dual diagnosis.

Some vital statistics about co-occurring disorders include:

Understanding Co-Occurring Disorders

According to an April 2020 report by the National Institute on Drug Abuse:

Understanding Co-Occurring Disorders

Why Do Substance Abuse & Mental Health Disorders Overlap?

In a dual diagnosis, two conditions—substance abuse and mental illness—co-occur. There are a variety of reasons as to why this occurs. However, it is not always the case that one condition causes the other.

Correlation & Causation

An essential principle of logical reasoning is that correlation does not imply causation. Just because two things appear together simultaneously does not necessarily mean that one of those things caused the other one. 

For instance:

  • A cat-heads and cat-tails often appear together (i.e., are correlated). But this doesn’t mean that the cat’s head causes the cat’s tail or vice versa. Cat-heads and cat-tails appear together because they are two parts of the same organism: a cat.
  • Melting ice-cream cones and wilting flowers may appear together (i.e., be correlated). The two are correlated because they share a common cause: a hot sun.

Substance Abuse Disorders & Mental Health Disorders

(1) Substance abuse and mental health disorders have their etiology—their causes and conditions. Though the two appear within the same person, there is no causal connection between them. 

(2) Common risk factors can contribute to mental illness, substance use, and addiction. This scenario is akin to the example above: hot sunshine leading to wilting flowers and melting ice cream. Several factors predispose a person to addiction, and mental illness includes several elements. 

These essential factors come down to two categories, genetics, and environmental factors. Genetic factors are related to a person’s family history or genetic predisposition. Environmental factors include poverty, trauma exposure, or early exposure to drugs and alcohol. 

(3) Mental illness may cause or at least contribute to substance abuse and addiction. A person with a mental illness may use alcohol or drugs to “self-medicate.” They may use drugs or alcohol to avoid the symptoms of their mental illness. 

While alcohol consumption or drug use may temporarily mask symptoms, it does nothing to address the underlying illness. And substance abuse may exacerbate the symptoms.

(4) A substance use disorder may cause or contribute to developing a mental illness. For instance, alcohol- or drug-induced changes in brain chemistry can increase the likelihood of developing a mental disorder. Areas of the brain most likely to be damaged by drug or alcohol abuse are associated with anxiety, mood, and impulse-control disorders. Or, traumatic events that happen during and are linked to addiction may result in post-traumatic stress disorder (PTSD).

The mechanisms described above in numbers 2, 3, and 4 correspond to what researchers have identified as three main pathways that can contribute to comorbidity. Addiction and mental disorders may also have a bidirectional relationship. This means that they each negatively influence the other.

Some individuals with a dual diagnosis may know they have substance abuse problems. However, they may not be aware of their mental health disorder. Others may be aware of their mental health disorder but don’t consider their drinking or drug use a problem. It can be challenging for clinicians to determine which condition came first. 

Professionals may not fully understand if the addiction or the mental illness was present first. In some cases, they may not be able to identify why the two disorders occurred in the first place.

Treatment of Co-Occurring Disorders

Finding effective treatment for someone with a mental illness and a substance use disorder can be challenging. As a general rule, it’s best to treat the addiction and the co-occurring mental disorders together rather than separately. A health care provider should evaluate individuals seeking help for a dual diagnosis for both diseases.

But many programs that offer psychological treatment for people with mental disorders are not equipped to treat addictions. And programs specializing in addiction recovery are often not geared to address other serious mental illnesses.

Clinicians treating addictions are often not qualified to treat other mental illnesses. And clinicians with advanced counseling or psychiatric skills may not be trained in addiction recovery protocols.

As a result, people with dual diagnoses often get bounced from one program to another. And they may be refused treatment by single-diagnosis facilities.

Because of overlapping symptoms (between addiction and mental illness), it can be difficult for a mental health practitioner to make an accurate diagnosis. Therefore, the use of comprehensive assessment tools is necessary. These tools help reduce the chance of a missed diagnosis and support creating an effective treatment plan.

Because of the complex nature of co-occurring disorders, treatment must be tailored to each client’s unique circumstances. This includes the person’s specific symptoms, the particular substance they are abusing, and the specific mental disorder they’re experiencing.

Behavioral Therapies & Dual Diagnosis

Behavioral therapies are one form of treatment that has proven particularly promising in supporting recovery from co-occurring disorders.

Some examples of effective behavioral therapies for individuals with addictions and co-occurring mental disorders include:

helps people learn how to cope with difficult situations by challenging irrational thought patterns and changing behaviors.

employs mindfulness and nonjudgmental awareness of the current circumstances, including physical sensations, thoughts, and emotions.

Assertive Community Treatment (ACT)

community-based mental health care that emphasizes individual treatment and outreach to the community.

Therapeutic Communities (TC)

long-term residential treatment focuses on helping people develop new and healthier values, attitudes, and behaviors.

Contingency Management (CM)

encourages healthy behaviors by offering vouchers or rewards for desired behaviors.

Begin Your Healing Journey Today

While the therapeutic process for someone with a dual diagnosis may be more complex, full recovery and healing are possible! The first step in such healing is finding a treatment centered on handling co-occurring disorders.

Everlast Recovery offers effective dual diagnosis treatment programs. Our programs are aimed at supporting clients who are suffering from both addiction and a mental disorder.

Therapeutic modalities used at Everlast Recovery to support the successful treatment of co-occurring disorders include:


Co-occurring disorders and other health conditions. SAMHSA. (n.d.). Retrieved August 1, 2022, from https://www.samhsa.gov/medication-assisted-treatment/medications-counseling-related-conditions/co-occurring-disorders

Dual diagnosis – nami. National Alliance on Mental Illness. (n.d.). Retrieved August 1, 2022, from https://www.nami.org/NAMI/media/NAMI-Media/Images/FactSheets/Dual-Diagnosis-FS.pdf

National Institute on Drug Abuse. (2020, April). Common comorbidities substance use disorders research report – nida.nih.gov. Common Comorbidities with Substance Use Disorders Research Report. Retrieved August 1, 2022, from https://nida.nih.gov/download/1155/common-comorbidities-substance-use-disorders-research-report.pdf

NIDA’s (National Institute of Drug Addiction). (n.d.). Dual diagnosis: Mental illness and substance abuse – dartmouth. Dartmouth. Retrieved August 1, 2022, from https://www.dartmouth.edu/eap/library/dualdiagnosis1.pdf

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U.S. Department of Health and Human Services. (2022, June 3). Comorbidity: Substance use and other mental disorders. National Institutes of Health. Retrieved August 1, 2022, from https://nida.nih.gov/research-topics/trends-statistics/infographics/comorbidity-substance-use-other-mental-disorders