The Complex Relationship Between Mental Health and Substance Use Disorders

When a person has both a mental illness and a substance use disorder, it is called co-occurring disorders. These health problems often affect each other, making it complicated to diagnose, treat, and support people — understanding how they are connected can help reduce stigma and lead to better care.

According to the 2023 National Survey on Drug Use and Health, one third of adults with mental illness had a substance use disorder, with adults from the ages of 18 to 25 and those with serious mental illness being the most impacted. When considering adults with substance use disorder, closer to half have any mental illness.

Mental illness and substance use disorders often make each other worse. Using substances to treat distressing symptoms can make accessing treatment more complex. Shame and stigma make it difficult to ask for help. Injuries and overdoses can worsen these feelings and can cause lasting injuries or death, and feelings of hopelessness or thoughts of suicide are common. Substance use can also cause or worsen mental and physical illness, sometimes with lasting impacts. Family and relationship dysfunction is common and can deepen feelings of isolation.

Many factors can lead to co-occurring disorders, including:

• Family history (genetics)

• Adverse childhood experiences (ACEs)

• Stress, trauma, or bad experiences

Identifying co-occurring disorders can be challenging because symptoms of substance use and mental health disorders often overlap. Some common signs include:

• Withdrawal from friends, work, or activities.
• Mood swings, depression, or anxiety that persist even during periods of abstinence.
• Increased tolerance or dependence on substances as a coping mechanism.
• Difficulty maintaining employment, relationships, or self-care.

Accurate diagnosis requires a thorough assessment by a healthcare professional, ideally one trained in substance use and/or mental health, to distinguish between substance-induced symptoms and independent mental health conditions.

Treatment for co-occurring disorders must be integrated, addressing both conditions simultaneously. Behavioral therapies paired with medications for addiction treatment (MAT) have proven to be effective. This integrated model of care involves stabilizing mental health conditions while treating substance use and prioritizing safety through a harm reduction approach.

Co-occurring mental illness and substance use disorders are complex but treatable conditions. Raising awareness, reducing stigma, and providing integrated care are critical steps toward helping individuals heal. With the right support, recovery is possible.

Dr. Elizabeth McNamara is a board-certified emergency medicine and board-eligible addiction medicine physician at Barton Health. For more information about the Barton MAT program, visit BartonHealth.org/MAT.