Guest Blog: Co-Occurring Disorders: The Link Between Mental Illness and Substance Abuse

Co-occurring disorders, the presence of a mental illness and a substance use disorder simultaneously, is common among those with substance addictions. Over 8 million Americans with a mental illness also struggle with substance abuse. Often, the severity of a mental illness is exacerbated by substance abuse, and substance addiction is intensified if an individual suffers from a co-occurring mental illness.

Personality disorders are the most common type of mental illness associated with substance abuse and can manifest themselves in almost any disorder or substance. Attention Deficit Hyperactivity Disorder, Post-traumatic Stress Disorder, Depression and Anxiety are other disorders commonly associated with substance use disorders.

What Causes Co-Occurring Disorders?

Generally, there are four factors to consider when determining the cause of co-occurring disorders.

1. Genetic Predisposition- as with other medical conditions, genes that make people more susceptible to developing mental illnesses and substance use disorders are frequently passed down from parents, grandparents or other family members. For example, genes passed down from a mother who had anxiety and drank to feel better may make an individual more prone to similar behavior.

2. Environmental Triggers- stress, trauma and other events can play a huge role in the development of a mental illness or substance addiction. For example, 48 percent of female rape victims develop PTSD, and about 45 percent of individuals with PTSD also have a substance use disorder.

3. Affect on Similar Brain Regions- depending on the mental illness and the type of substance used, possible simultaneous effects in the same brain region may intensify the development of substance addiction and or mental illness.

4. Early Development of Substance Use or Mental Illness- suffering from a substance use disorder or mental illness during the cognitive development in adolescence can cause the development of co-occurring disorders in the future. For example, early use of marijuana and other hallucinogens may increase the rate of development of mental disorders like schizophrenia.

Seek Help: If you suspect you or someone you know is suffering from co-occurring disorders, seek help. Specialty treatment programs called dual recovery programs aim to treat both disorders simultaneously, giving individuals the best chance to reach recovery.

About the Author: Trey Dyer is content creator for and an advocate for mental health and substance abuse treatment. When Trey is not writing, he can be found fly fishing the lagoons of Florida and cheering on the Florida Gators football team.


American Psychological Association. (2007, June 1). Comorbid Drug Abuse and Mental Illness Retrieved from

American Academy of Experts in Traumatic Stress. (2014). PTSD and Problems with Alcohol Use. Retrieved from

National Institute of Mental Health. (n.d.). What is Post-traumatic Stress Disorder (PTSD)?. Retrieved from:

Lange, J. Lange, C. (2000, September). Primary Care Treatment of Post-traumatic Stress Disorder. Retrieved from

Substance Abuse and Mental Health Services Administration. (2015, December 4). Mental and Substance Use Disorders. Retrieved from

U.S. Department of Veterans Affairs. (2015, August 13). PTSD: National Center for PTSD. Retrieved from


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