Substance Use Disorder

Find key terminology and best practice supports when someone has an SMI and also abuses marijuana, alcohol, or other substances.

What do I need to know about SMI with SUD?   

Nearly half of people diagnosed with the most severe psychiatric conditions also experience substance use disorder (SUD).  Mental illness with SUD is referred to as a “dual diagnosis.” Providers trained to address these “comorbid” conditions might offer “combined care.” However, that whole person approach is often difficult to find. 

According to a table within the 2024 National Survey on Drug Use and Health, about a third of people who need treatment for mental illness with SUD receive no treatment. Of those who get some care, the majority receive mental health but not SUD treatment. 

Treatment barriers can be substantial when it’s unclear whether mental illness or substance use is the “primary” condition. People with mental illness have a higher risk of developing an SUD, while people who have an SUD are vulnerable to chronic mental illness. If questions about which caused which are getting in the way, focus might shift toward treatment for psychosis, which can result from either condition.  

What are evidence-based treatments for SMI with SUD? 

Schizophrenia spectrum and severe bipolar disorders are the most commonly diagnosed conditions that fit within the broader category of severe mental illness (SMI), which means a condition that significantly disrupts a person’s ability to function and often includes psychosis. An evidence-based treatment protocol for co-occurring SMI with SUD is integrated dual disorder treatment (IDDT). This treatment combines medication with psychological, educational, and social interventions.  

A place to seek combined care is a Certified Community Behavioral Health Clinic (CCBHC). With grant funding from the Substance Abuse and Mental Health Services Administration (SAMHSA), CCBHCs are required to provide combined treatment. Search for CCBHC options in your state.   

Combined care generally includes these components: 

• • • Motivational interviewing, a form of therapy designed to help a person connect a higher quality of life to ongoing treatment adherence. 

• • • Peer support, in which a person in recovery with specialized training supports another person earlier in their healing process. 

• • • Medication assisted therapy, which means prescribed medicine to help a person wean off of substances that cause harm.  

• • • Group meetings, including with organizations such as Alcoholics Anonymous (AA) or Narcotics Anonymous (NA). 

Research in 2025 found that the anti-psychotic medication clozapine reduced substance use while improving psychosis symptoms among people with SMI and SUD conditions, including when symptoms were “treatment resistant,” meaning they didn’t improve when at least two other anti-psychotic medications were tried. Clozapine is the only FDA-approved medication for treatment-resistant schizophrenia.  

How does SUD complicate SMI treatment?  

Psychoactive substances can cause significant problems for a person prescribed medication for SMI. SAMHSA reports that these substances are the most commonly misused: alcohol, tobacco, opioids, stimulants, marijuana, hallucinogens, and prescription drugs. The Mental Disorder Prevalence Study (MDPS), on which TAC was a partner of RTI International, found that alcohol and marijuana were the most frequently abused substance by people who also had SMI.  

Antipsychotics and mood stabilizers don’t work like they should when mixed with alcohol, tobacco, marijuana, amphetamines, opioids, and other synthetic compounds. A person’s treating physicians need to be aware of all substances being used, including supplements and other legal substances, such as tobacco, caffeine, alcohol, and cannabis. Some supplements and substances may have positive benefits, but a provider needs to know the full mix to make informed decisions about medications and dosages.   

Substances can prevent stability in numerous other ways. They can affect sleep, generate financial stress, and make it difficult to stay on a medication schedule. Use of illegal substances carries the risk of arrest and incarceration, further disrupting medication management.   

Some providers may be reluctant to prescribe antipsychotics for someone using substances. Antipsychotics can provide critical protection for someone with SMI. The longer a person stays in untreated psychosis, the higher their risk is for physical changes to the brain that can impact treatment outcomes and social functioning. Reducing harm from untreated psychosis is a priority, and another provider can be sought to prescribe necessary medication.  

What is especially worrisome about marijuana usage and SMI?  

A diagnosis of cannabis-induced psychosis is becoming increasingly common. In Treatment Advocacy Center’s 2019 study Dual Diagnosis: Serious Mental Illness and Co-Occurring Substance Use Disorder, results showed that cannabis (the plant marijuana comes from) is one of the most commonly used drugs by people with SMI, with almost 40 percent of people with SMI reporting usage within the year.  

The part of the cannabis plant that causes a “high” is THC, which is short for the chemical tetrahydrocannabinol, which occurs in the plant and can be synthesized in a laboratory. Modern products containing THC are much more potent than those used three decades ago, according to the National Institute on Drug Abuse. 

High-potency THC products may be marketed as snacks and treats that are disguised in packages very similar to those that don’t contain psychoactive substances. THC can be extremely concentrated for use in a portable vaporizer, called a “vape” or “dab pen.”

Research showing a link between cannabis usage and the onset of schizophrenia offers the following information:     

• • • THC, the active ingredient in marijuana, can cause temporary psychotic symptoms, which may increase the risk of developing a mental health disorder.   

• • • Cannabis use increases the likelihood that adolescents will develop schizophrenia or bipolar disorder, particularly if they have other risk factors.   

• • • Individuals with schizophrenia tend to use marijuana at higher rates.   

• • • Education about linkages between cannabis use and psychosis is needed.   

Professional care is necessary to determine whether psychosis related to cannabis use is temporary or if there is onset of a chronic mental illness. A parent-run website, Johnny’s Ambassadors, offers information and resources about early onset psychosis and cannabis use. Included is a state-by-state list of treatment options for youth and young adults.  

What is the linkage between alcohol abuse and SMI? 

Among those with SMI, people diagnosed with bipolar disorder are the most likely to also have alcohol use disorder (AUD), with a lifetime prevalence rate of more than 40 percent. The numbers are nearly as high for those with major depressive disorder. Among people in treatment for schizophrenia, the lifetime prevalence of AUD is about 21 percent. According to national research, several mechanisms may explain the common co-occurrence of AUD and psychiatric disorders: 

• • • Pre-existing psychiatric disorders may increase the risk of developing AUD, in part because alcohol is often used to cope with symptoms of psychiatric disorders, even if alcohol ultimately makes the problems worse. 

• • • Alcohol use—especially adolescent drinking and long-term exposure to alcohol—may predispose individuals to develop psychiatric disorders. 

• • • AUD and other psychiatric disorders often share genetic risks and environmental vulnerabilities such as trauma and adverse childhood experiences. 

How can care partners support someone with co-occurring SUD and SMI?   

A care partner is a family member, friend, or someone else walking alongside a person who is unwell. 

Helping someone with co-occurring SMI and SUD is challenging. Appropriate programs are extremely limited and may have significant waitlists. Cost can be a major hurdle if insurance doesn’t cover treatment. The most difficult challenge may be that a loved one won’t pursue treatment for one or both of their co-occurring disorders. Appropriate boundaries and self-care are critically important for anyone attempting to support a person with a persistent, disabling, and often treatment resistant disease.   

SAMHSA’s support portal includes information to help you find health care, cope with your own illness or the illness of a loved one, understand different types of treatment, and figure out a way to pay for needed care. 

Note that some treatment programs (including some prominent ones, such as specific AA chapters) encourage the discontinuation of all medications in order to be “sober.” For obvious reasons this could prove catastrophic for people with SMI, so it is important to investigate the treatment philosophy of potential programs to ensure that they are compatible with the needs of the person with SMI.  

Learning to speak the “language” is a place for care partners to begin. For example, medication assisted treatment (MAT) may be an important component of SUD treatment, especially for opioid use disorder. MAT includes medications such as methadone, naltrexone, and buprenorphine to reduce symptoms of withdrawal and craving. Helping someone advocate for MAT could be part of a care partner’s role. 

Places to seek help  

• • • Certified Community Behavioral Health Centers (CCBHC) (thenationalcouncil.org): Options are listed by state.    

• • • SAMHSA provides tools and resources for seeking substance use treatment, including medication assistant treatment and various ways to utilize a national helpline: 1-800-662-HELP (4357). 

• • • Free Rehab Centers (freerehabcenters.org): Addiction support and recovery options are listed by state.   

• • • Discover the Types of Rehab Used to Treat Co-occurring Disorders (startyourrecovery.org): Browse for resources by state at the end of the article about co-occurring disorders.  

• • • Johnny’s Ambassadors: places to seek early intervention for youth and young adults with psychosis and a history of cannabis use.  
    • The National Substance Abuse Hotline (nationalrehabhotline.org) provides a 24/7 place to seek state-by-state resources online or by phone: 866-210-1303. 
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