By Lauren Smith

Last updated: 09 May 2024 & medically reviewed by Hailey Shafir

Substance abuse disorders and mental health conditions frequently co-exist, as people turn to addictive substances to self-medicate, and those substances cause and aggravate existing mental health symptoms. Substance abuse and mental health disorders may also share the same underlying causes, including genetics and early trauma.

Key takeaways:

  • 8% of the 42 million adults with mental health conditions abuse substances.

  • When mental illnesses and substance abuse co-exists, it’s often difficult to determine which came first. The answer is different for everyone.

  • Integrated treatment for co-occurring disorders can be accessed at both inpatient rehab facilities and on an outpatient basis.

Addiction and Mental Health

Substance abuse and co-occurring mental health disorders

In the US, 38% of the 20 million adults with substance abuse disorders have been diagnosed with a mental health condition, a situation known as dual diagnosis. Meanwhile, 18% of the 42 million adults with mental health conditions abuse substances.[1]

However, these figures likely underestimate the prevalence: many mental health conditions are undiagnosed or subclinical (not rising to the level of diagnosis), while patients often underreport their substance use.

Substance abuse and mental health conditions can complicate and impede treatment for either. That’s why it’s essential that these dual diagnoses are treated simultaneously.

What is a co-occurring disorder?

A co-occurring disorder is the co-existence of a substance use disorder and mental illness in the same person at the same time. 

According to the Substance Abuse and Mental Health Services Administration (SAMHSA), 9.5 million people in the US had co-occurring disorders in 2019. Of those, 3.6 million had a serious mental illness and substance use disorder.[2]

Is addiction a mental illness?

In previous generations, addiction to drugs and alcohol was regarded as a moral failing or weakness, and people experiencing it were subjected to imprisonment and scorn. While the media sometimes still deploys these outdated stereotypes and the justice system still criminalizes and jails people addicted to illicit substances, addiction is now widely regarded by doctors and scientists as a medical condition—chronic, sometimes relapsing, but treatable.

The Diagnostic and Statistical Manual of Mental Disorders 5th editions (DSM-5) classifies addiction as a mental health condition called substance use disorder. The National Institute on Drug Abuse (NIDA) and the American Psychiatric Association (APA) both describe addiction as a brain disease, a term that captures the neurological changes caused by repeated exposure to a drug and manifesting as compulsive behavior.

There’s no tension between these two definitions. Researchers have increasingly discovered the neurological underpinnings of many mental health conditions and how our brain informs our thinking and behavior, including the use of drugs. 

Additionally, thinking of addiction as a neuropsychological disorder doesn’t discredit evidence that our social environments also contribute to the development of addiction. Perceptions, availability and use of drugs in our families, friendship groups, and broader society can all predispose someone to addiction and influence how successful their treatment is.

Most scientists, doctors, and mental health professionals endorse a biopsychosocial model of addiction that accounts for all these factors.

What comes first: Substance abuse or the mental health problem?

When mental illnesses and substance abuse co-exists, it’s often difficult to determine which came first. The answer is different for everyone.

Some people with untreated mental illnesses turn to addictive substances to alleviate their symptoms and cope with daily stressors. For instance, people experiencing depression and anxiety may find temporary relief from their symptoms through the use of alcohol, benzodiazepines, or opioids

For others, mental illness predisposes them to experiment with drugs. Some personality disorders and the manic phase of bipolar disorder are characterized by impulsive and risky behavior, including the abuse of substances.

In other cases, addictive substances can cause or aggravate symptoms of mental illness, often by disrupting neurochemical processes. 

For example, alcohol produces an initial rush of pleasurable feelings through a release of dopamine. But as your brain is repeatedly saturated with these neurotransmitters, your body becomes accustomed to high levels and starts to produce less, reduce its number of dopamine receptors, and increase the number of transporters to carry excess dopamine away. That means you have less of the feel-good chemical and without using alcohol, may feel depressed. At least 30-40% of people who abuse alcohol are thought to experience severe depression, although the figure could be as high as 70%.[3] Read here to learn more about alcohol and mental health. 

A similar process happens with opioids and is likely part of the reason that prolonged opioid (30+ days) use increases the risk of developing treatment-resistant depression by more than 25%.[4]

Additionally, in high and prolonged doses, drugs including methamphetamine, cocaine, LSD, and cannabis can induce psychosis and paranoia even in the absence of an underlying mental health condition. The use of drugs, including cannabis, can also accelerate the onset of schizophrenia in young people.[5]

Drug use and dependence can also impact your relationships, career, and health, which can then cause some people to become depressed or anxious.

Other theories suggest that mental illness and addiction are intertwined even more closely, with overlapping risk factors in the form of genetic vulnerabilities, brain structures, and environmental influences such as early childhood trauma.

Ultimately, there's no definitive answer to this chicken-egg problem for many people. It may be unimportant which condition came first, as long as they are treated together.

How to recognize a co-occurring disorder

Diagnosing co-occurring disorders can be difficult due to addiction’s significant impact on behavior and the overlapping symptoms of drug dependence/withdrawal and mental health problems. 

However, some signs indicate to medical professionals that a mental health condition co-exists with addiction:

  • You felt depressed or anxious before you started using the addictive substance.

  • You began using the substance to adjust your moods, reduce worries or social anxiety, cope with painful memories, or stay focused.

  • You've experienced trauma and abuse, especially at a young age.

  • You have a family history of mental illness.

  • Mental health symptoms worsen as you receive treatment for addiction and are no longer using drugs to mask or manage them.

  • Suicidal thoughts

How to spot a substance use disorder

The external physical and behavioral warning signs of a substance use disorder vary depending on the person, the substance(s) they’re using, and their patterns of use. 

These signs may include:

  • personality and mood changes: such as increased irritability, paranoia, confidence, energy; mood swings; impaired judgment; lack of motivation; lapses in memory

  • physical changes: such as weight loss or gain, tremors, slurring, dilated pupils, bloodshot eyes, frequent bloody noses, neglected personal hygiene, and appearance

  • behavioral changes: such as a drop in performance at work or school; frequent absences; disinterest in work, school, and hobbies; secretiveness

  • social changes: such as increased isolation from family and friends and conflict with them over substance use

  • financial problems: such as the inability to pay bills and meet financial obligations and frequent requests for money from family or friends

What are the most common co-occurring mental health disorders with addiction?

Substance abuse disorders commonly co-occur with:

While mental health conditions and drug addictions can and do occur in any permutation, professionals do see patterns in abuse. Individuals with mental health conditions that cause stress and stimulating symptoms often turn to depressants like alcohol, benzos, and opioids to dull those feelings. Conversely, people with depressive symptoms may rely on stimulants for motivation and happiness. 

Treatment options for co-occurring disorders

If you are diagnosed as having both an addiction and a mental health disorder, it’s crucial that treatment addresses both simultaneously for the best chance of recovery

Failing to treat a co-existing mental health disorder alongside addiction can make it more difficult for you to abstain from drugs, often leading to relapse. You may also find that your mood and mental health symptoms worsen as treatment for addiction progresses and you’re no longer self-medicating.

Conversely, you can’t treat mental health conditions without addressing addiction, given substance abuse’s harmful impact on mental and physical health, relationships, daily functioning, and other aspects of our lives. Drug and alcohol use can also make some medications for mental health conditions less effective.

It’s recommended by the SAMHSA and the APA, that treatment of co-occurring disorders takes an integrated approach. That means treating mental health/addiction at the same time, usually with the same team of professionals, and using multiple and personalized therapeutic and pharmacological interventions. Integrated therapy has been found to significantly reduce the rates of relapse of both substance use and mental illness.

Integrated treatment for co-occurring disorders can be accessed at both inpatient rehab facilities and on an outpatient basis. However, when a patient’s case is complex, as it is with a dual diagnosis, a period of inpatient treatment is often recommended.

Treatment for co-occurring disorders may include:

  • cognitive behavioral therapy (CBT): talking therapy that helps you change the way you think and behave, erasing old coping mechanisms such as substance abuse and learning new strategies that can be applied to triggers for both conditions.

  • dialectical behavioral therapy (DBT): talking therapy that helps you modify ways of thinking so you can accept yourself, feel safe, and manage emotions and turn away from harmful behaviors, such as substance use.

  • pharmacological: non-addictive prescription medicine for mental illness such as antidepressants, mood stabilizers, and antipsychotics.

If you or someone you care about is suffering from a substance use disorder, mental health condition, or co-occurring disorder, then seeking one or a combination of the above treatments can help. Both inpatient and outpatient rehab settings provide these services as part of addiction treatment programs that are proven to greatly increase the chances of long-term sobriety. 

Visit our rehab directory today to find an addiction treatment option near you.