ADHD News & Research

Study: Adult ADHD and Depression, Anxiety Strongly Linked

ADHD traits are linked to more severe anxiety and depression symptoms in adults than are traits of autism spectrum disorder, according to a new U.K. study that underscores the importance of screening of ADHD comorbidities.

February 4, 2023

ADHD is a stronger predictor of depression and anxiety in adults than is autism spectrum disorder, according to a new study that suggests patients with attention deficit hyperactive disorder are more likely that autistic patients to experience “internalizing problems” like mood disorder. The study, led by researchers at the University of Bath and published in Scientific Reports, underscores the importance of screening for comorbid conditions in adults with ADHD. 1

As many as 80% of adults with ADHD have at least one co-existing psychiatric disorder.2 According to a recent ADDitude survey of 1,500 readers, anxiety and depression are the two most common comorbid conditions diagnosed alongside ADHD in adults, with co-diagnosis rates of 72% and 70%, respectively.

Despite this high rate of comorbidity, researchers said, “ASD has often been prioritized over ADHD in both research on internalizing problems and clinical practice, particularly for anxiety.”3

Notably, approximately 28% of autistic individuals have ADHD, making it difficult to determine which disorder — ASD or ADHD — more significantly impacts mental health outcomes.2 (The ADDitude reader survey found that 9% of adults with ADHD have ASD.)

Researchers aimed to clarify the associations between self-reported ASD traits and ADHD traits with mental health conditions like anxiety and depression using a general population sample, which included 504 adults from the U.K. (49% male, 51% female) aged 18–79 years.

While the results linked both ASD and ADHD with anxiety and depression, ADHD was a stronger statistical predictor of both mental-health conditions than was ASD. Further analysis confirmed that ADHD traits were associated with more severe anxiety and depression symptoms in adults than were ASD traits.

Researchers “speculate that response inhibition difficulties, which appear to be a cognitive feature of ADHD, may also potentially underpin the stronger association between ADHD traits and internalizing problems.”

To the researchers’ knowledge, this is the first study showing ADHD more strongly predicts mental health outcomes in adults than do other neurodevelopmental conditions, like ASD.

“Our finding that ADHD traits dominated ASD traits in predicting internalizing disorder symptoms could inform strategies to identify individuals who are at an increased risk of internalizing problems,” researchers said. “This might allow preventative measures and interventions to be implemented at an earlier age, which, for example, could focus on managing ADHD symptoms for a greater impact on ameliorating internalizing problems and improving mental wellbeing in adults.”

Recognizing complex ADHD (attention deficit plus one or more co-occurring conditions) is of “high clinical importance,” said Theresa Cerulli, M.D., of Beth Israel Deaconess Medical Center and the Neuroscience Education Institute, in the ADDitude webinar titled, “Complex ADHD: The New Approach to Understanding, Diagnosing, and Treating Comorbidities in Concert.”

“The presence of co-occurring conditions almost always muddles the diagnosis, treatment, and prognosis of ADHD,” she said. “ADHD and comorbidities may also influence the presentation and severity of one another, which can complicate the detection and treatment of symptoms, and impair overall quality of life.”

Researchers hope the study’s findings will encourage more research probing whether genetics help explain why ADHD traits are more strongly associated with internalizing problems than are autistic traits.

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1Hargitai, L.D., Livingston, L.A., Waldren, L.H. et al. (2023). Attention-Deficit Hyperactivity Disorder Traits Are a More Important Predictor of Internalising Problems Than Autistic Traits. Sci Rep. 13, 31.

2Katzman, M. A., Bilkey, T. S., Chokka, P. R., Fallu, A., & Klassen, L. J. (2017). Adult ADHD and Comorbid Disorders: Clinical Implications of a Dimensional Approach. BMC psychiatry. 17(1), 302.

3Bishop, D. V. M. (2010). Which Neurodevelopmental Disorders Get Researched and Why? PLoS ONE 5, e15112/

4Young, S. et al. (2021). Failure of Healthcare Provision for Attention-Deficit/Hyperactivity Disorder in the United Kingdom: A Consensus Statement. Front. Psychiatry 12, 324.