Half of Adults with ADHD Have Had a Substance Use Disorder

Nearly one in four reported cannabis use disorder.

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Half of adults aged 20-39 with attention deficit hyperactivity disorder (ADHD) have had a substance use disorder (SUD) in their lifetime according to new research published online ahead of print this month in Alcohol and Alcoholism. This is markedly higher than the 23.6% of young adults without ADHD who have had a substance use disorder in their lifetime.  

Even after considering factors such as age, race, income, education, childhood adversities and other mental illness, young adults with ADHD were still 69% more likely to have had a substance use disorder when compared to their peers without ADHD.

Controlling for lifetime history of mental illness and childhood adversities caused the largest attenuation of the ADHD-SUD relationship.  More than one-quarter (27%) of those with ADHD had a history of depression, which was much higher than the prevalence among those without ADHD (11%).  

โ€œThese results emphasize the importance of addressing depression and anxiety when providing care to those with co-occurring ADHD and SUD,โ€ reported lead author Esme Fuller-Thomson, professor at University of Toronto's Factor-Inwentash Faculty of Social Work and Director of the Institute for Life Course and Aging. โ€œIndividuals with untreated depression and anxiety may self-medicate to manage the symptoms of an untreated psychiatric disorder, which can result in greater substance use.โ€  

Those with ADHD also experienced high levels of adverse childhood experiences, with more than a third of young adults (35%) reporting that they had been physically abused and one in nine reporting that they were a victim of sexual abuse (11%) before the age of 16.

A strong association between childhood adversities and substance use disorder has been found in previous research as well.

โ€œChildhood maltreatment may disrupt emotional regulation and the neuro-development of children, which may predispose them to later developing substance dependenceโ€ says co-author Danielle Lewis, a graduate of the University of Torontoโ€™s Masters of Social Work (MSW) Program.

Alcohol use disorders were the most common substance abuse disorders among young adults with ADHD (36%), followed by cannabis use disorders (23%). Young adults with ADHD were also three times more likely to experience an illicit drug disorder (other than cannabis) when compared to their peers without ADHD (18% vs 5%).

โ€œOne potential explanation for the extremely high rate of illicit drug use among those with ADHD is the accelerated gateway hypothesis,โ€ said co-author Senyo Agbeyaka, a recent University of Toronto MSW graduate who is a social worker at University Health Network. โ€œThis theory posits that people with ADHD tend to initiate substance use at a younger age, resulting in riskier use and greater problem severity in adulthood.โ€

The data were drawn from the Canadian Community Health Survey-Mental Health, a nationally representative sample of 270 respondents aged 20-39 with ADHD and 6,602 without ADHD.

The findings of our study underline the extreme vulnerability of young adults with ADHD.

โ€œThere is a clear need to develop prevention and treatment programs to address substance use issues among those with ADHD, while also promoting mental health and addressing childhood adversities,โ€ said Fuller-Thomson.

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