A new nationally representative study published online in the Journal of Affective Disorders found that one in four adults aged 20-39 with attention deficit hyperactivity disorder (ADHD) had generalized anxiety disorder (GAD).

Those with ADHD were four times more likely to have GAD at some point in their life, when compared to those without ADHD. Even after controlling for other relevant factors, including sociodemographics, adverse childhood experiences, and a lifetime history of substance use disorders and major depressive disorders, those with ADHD still had more than double the odds of GAD.

"These findings underline how vulnerable adults with ADHD are to generalized anxiety disorders," says lead author Esme Fuller-Thomson, professor at the University of Toronto's Factor-Inwentash Faculty of Social Work and Director of the Institute for Life Course & Aging. "There are many studies linking adult ADHD to depression and suicidality, but less attention has been paid to generalized activity disorders and other adverse outcomes across the life course."

The study identified several factors that were associated with GAD among those with ADHD. Female respondents with ADHD had nearly five times higher odds of GAD, even after controlling for other covariates.

"ADHD has been severely underdiagnosed and undertreated in girls and women," says co-author Andie MacNeil, a recent Master of Social Work (MSW) graduate from the University of Toronto. "These findings suggest that women with ADHD may also be more susceptible to experiencing anxiety, emphasizing the need for greater support for women with ADHD."

Adults who had experienced adverse childhood experiences such as childhood sexual or physical abuse or chronic parental domestic violence were three times more likely to have a generalized anxiety disorder. Sixty percent of those with ADHD who had anxiety disorders had experienced at least one of these adverse childhood experiences.

Other factors associated with GAD among adults with ADHD include having an income below $40,000, having fewer close relationships, and having a lifetime history of major depressive disorder. The odds of GAD among those with ADHD were six-fold for those with a lifetime history of major depressive disorder.

"These results highlight the importance of screening for mental illness and addressing depressive symptoms when providing support to those with ADHD," said Lauren Carrique, a recent graduate of University of Toronto's MSW program who is a social worker at Toronto General Hospital. "Individuals experiencing ADHD, GAD, and depression are a particularly vulnerable subgroup that may need targeted outreach by health professionals."

Investigators examined a nationally representative sample of 6,898 respondents from the Canadian Community Health Survey-Mental Health aged 20-39, of whom 272 had ADHD and 682 had GAD.

Unfortunately, the researchers did not have access to information on what treatments, if any, respondents with ADHD were receiving to address their anxiety. One particularly promising talk-based therapy, cognitive behavioral therapy, also called CBT, has been shown to be very effective for improving anxiety, depression, and ADHD symptoms.

"It is crucial that those with ADHD who are struggling with mental health issues reach out for help from their family doctor or other mental health professional including social workers, psychologists and psychiatrists. Effective treatments, such as CBT, are available and these can dramatically improve one's quality of life", said Fuller-Thomson.