People with intermittent explosive disorder (IED) -- a condition marked by frequent physical or verbal outbursts -- are at five times greater risk for abusing substances such as alcohol, tobacco and marijuana than those who don't display frequent aggressive behavior, according to a new study by researchers from the University of Chicago.

In the study, published Feb. 28, 2017 in the Journal of Clinical Psychiatry, Emil Coccaro, MD, and colleagues analyzed data from more than 9,200 subjects in the National Comorbidity Survey, a national survey of mental health in the United States. They found that as the severity of aggressive behavior increased, so did levels of daily and weekly substance use. The findings suggest that a history of frequent, aggressive behavior is a risk factor for later substance abuse, and effective treatment of aggression could delay or even prevent substance abuse in young people.

IED affects as many as 16 million Americans, more than bipolar disorder and schizophrenia combined. It is often first diagnosed in adolescents, some of whom are as young as 11, years before substance abuse problems usually develop. IED runs in families and is thought to have a significant genetic component, although Coccaro said people tend to treat it as a social-behavioral issue instead of as a true neurobiological disorder.

"People don't see this as a medical problem. They think of it as simply bad behavior they have developed over the course of their lives, but it isn't. It has significant biology and neuroscience behind it," said Coccaro, who is the Ellen C. Manning Professor of Psychiatry and Behavioral Neuroscience at UChicago.

Previous research has implied that aggressive behavior in IED is due to the presence of other psychiatric disorders, such as anxiety or depression. But the new UChicago study found no such relationship. While substance abuse, like excessive drinking, can clearly make aggressive behavior worse, the onset of IED almost always precedes the development of chronic substance abuse. Coccaro and his team found that IED preceded substance abuse in 92.5 percent of the cases where subjects developed both disorders.

Coccaro emphasized that early psychological intervention, medication and cognitive therapy are the most effective treatments to prevent, or at least delay, substance abuse problems in adolescents diagnosed with IED.

"What you're really treating is the emotional dysregulation that leads to aggression," Coccaro said. "The earlier you treat this dysregulation, the more likely you are to offset other disorders that come later down the road."

Materials provided by University of Chicago Medical Center. Note: Content may be edited for style and length.

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Primary Resource:

Coccaro, E. F., Fanning, J. R., & Lee, R. (2017). Intermittent Explosive Disorder and Substance Use Disorder: Analysis of the National Comorbidity Survey Replication Sample. The Journal of clinical psychiatry. DOI: 10.4088/JCP.15m10306