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People with IED are more likely to abuse drugs. Istock

People diagnosed with intermittent explosive disorder – a condition characterised by frequent and impulsive aggressive behaviour – may be more at risk of substance abuse, scientists have said.

Intermittent explosive disorder (IED) is listed in the Diagnostic and Statistical Manual of Mental Disorders (DSM–5) - the international reference for the classification of psychiatric disorders. However, much remains to be discovered about its epidemiology.

In the US, it's estimated that 16 million of people suffer from it. That's more than bipolar disorder and schizophrenia combined.

It has previously been shown that a person diagnosed with IED may also be suffering from other mental health problems, such as depression or anxiety disorders.

However, the debate has yet to be settled when it
comes to the relationship between IED and substance use disorders.

While it is well established that drug use can increase the risk of violent outbursts –whether physical or verbal – it is not clear whether people with IED are more prone than others to using drugs and alcohol.

A risk factor

To settle this question, scientists have analysed data from 9,282 people, collected as part of the National Comorbidity Survey Replication – a nationally representative mental health survey. They have looked at the occurrence of substance use disorders with regards to alcohol, tobacco and cannabis, as well as the occurrence of IED in their sample.

Hazards of smoking cannabis
Addressing the problem of IED early enough can delay the onset of substance use disorders. Reuters

Their analysis reveals that people with IED have an elevated risk of also being diagnosed with a substance use disorder. In more than nine cases out of 10, impulsive aggression was observed before the individuals developed a substance disorder. The findings also suggested that as the severity of aggressive behaviour increased, so did levels of daily and weekly substance use.

The researchers concluded that having history of recurrent, problematic, impulsive aggression is
a risk factor for the later development of substance use disorder, rather than the reverse.

The good news is that treating impulsive aggression before the onset of drug abuse may delay or even stop the development of substance use disorders in young people. Strategies to help IED patients could revolve around early psychological intervention, medication and cognitive therapy.

The full study is published in the Journal of Clinical Psychiatry.