Impulsivity, Not Inattention, Predicts Externalizing Disorders

Impulsivity, Not Inattention, Predicts Externalizing Disorders 1024 683 Natalie Wilson
Black and white image of five smiling kids/adolescents

Without early intervention, children with hyperactive-impulsive symptoms of attention-deficit/hyperactivity disorder may be vulnerable to developing other externalizing behavior disorders.

Contributing to a small but growing body of litera­ture evaluating trait impulsivity theory, a team of researchers led by Mary A. Fristad, PhD, ABPP, director of Academic Affairs and Research Development in the Division of Child & Family Psychiatry at The Ohio State University College of Medicine and Big Lots Behavioral Health Services at Nationwide Children’s Hospital, recently identified independent relationships between hyperactive-impulsive (HI) symptoms of attention-deficit/hyperactivity disorder (ADHD) and the later development of additional externalizing behavior disorders. Their analyses were published in the Journal of the American Academy of Child and Adolescent Psychiatry.

While externalizing disorders — which include ADHD, oppositional defiant disorder (ODD), conduct disorder (CD) and substance use disorders (SUDs) — have traditionally been treated as distinct by the Diagnostic and Statistical Manual of Mental Disorders (DSM), they are frequently comorbid. Many children who are diag­nosed with one will be diagnosed with another sometime in their life, either simultaneously or sequentially.

A single, highly heritable trait, linked to the brain’s dopamine response and expressed as impulsivity, is associated with these disorders. Trait impulsivity theory suggests that this trait, particularly when accompanied by environmental risks, predisposes some individuals to a specific pathway of externalizing disorder development, whereby HI symptoms of ADHD may precede ODD, ODD may precede CD and CD may precede SUDs.

To test this theory, Dr. Fristad and her colleagues analyzed data from the Longitudinal Assessment of Manic Symptoms (LAMS) Study, which recruited 458 boys and 227 girls, ages 6-12, from nine child outpatient mental health clinics in the Midwestern United States and followed them for up to eight years. Participants and their parents completed interviews and questionnaires every six months.

The team found participants’ baseline levels of HI symptoms of ADHD when they joined the LAMS study predicted their levels of ODD and CD symptoms eight years later. Diagnoses of ADHD-HI/C (ADHD with primarily HI symptoms or with a combination of both HI and inattentive symptoms) at 48 months predicted diagnosis of ODD at 96 months, diagnoses of ODD at 48 months predicted CD at 96 months and diagnoses of CD at 48 months predicted SUD at 96 months. ODD and SUDs did not predict later ADHD.

“In this large data set, we found strong evidence of symptom progression predicted by hyperactive-impulsive symptoms of ADHD,” says Dr. Fristad. “Inattentive ADHD symptoms did not predict this progression.”

Additionally, researchers also found participants in families who reported greater parental stress, more neighborhood violence and less parental monitoring of their child experienced accelerated progression through increasingly severe externalizing disorders.

“Our findings extend existing literature and point toward the importance of early diagnosis, treatment and family interventions for young children with ADHD-HI/C,” says Dr. Fristad. “Reversing established conduct problems is more difficult than preventing them among vulnerable children.”

This article appears in the 2021 Fall/Winter print issue. Download the full issue.


Bell ZE, Fristad MA, Youngstrom EA, Arnold LE, Beauchaine TP; LAMS Consortium. Atten­tion-deficit/hyperactivity disorder symptoms and externalizing progression in the LAMS Study: A test of trait impulsivity theory. Journal of the American Academy of Child and Adolescent Psychiatry. 2021 Jun 4:S0890-8567(21)00362-2. [Epub ahead of print.]

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About the author

Marketing Strategist, Research Communications

Natalie is a passionate and enthusiastic writer working to highlight the groundbreaking research of the incredible faculty and staff across Nationwide Children's Hospital and the Abigail Wexner Research Institute. Her work at Nationwide Children's marries her past interests and experiences with her passion for helping children thrive and a long-held scientific curiosity that dates back to competing in the Jefferson Lab Science Bowl in middle school. Natalie holds a bachelor’s degree in sociology from Wake Forest University, as well as minors in women's, gender & sexuality studies and interdisciplinary writing. As an undergraduate student, Natalie studied writing and journalism, engaged with anthropological and sociological research with a focus on race and ethnic relations, served as executive editor for the student newspaper, the Old Gold & Black, and gained marketing experience as an intern for a nonprofit entrepreneurial incubator, Winston Starts, as well as by working for Wake Forest University School of Law Office of Communication and Public Relations and its Innocence and Justice Clinic.