Extended ADHD age criterion captures more minority, low-income and inattentive children

The fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) includes revisions to the diagnostic criteria for attention-deficit/hyperactivity disorder (ADHD), one of the most common psychiatric disorders of childhood. The revisions aim to better identify ADHD across the life span by providing specific examples of symptom presentation in children, adolescents and adults and by increasing the age-of-onset criterion from 7 to 12 years of age.

The original age of onset, which seems to have been arbitrarily determined, appeared in DSM-III and remained in place for 35 years, although it was not supported by evidence from DSM-IV field trials. The recent change was based on a comprehensive literature review and meta-analysis of evidence regarding age of onset for ADHD and supported by studies showing that most adults report symptoms starting before age 12.

Nevertheless, there is concern that extending the age of onset will increase the already high prevalence of ADHD and lead to the medicalization of normal developmental processes. To examine the clinical validity of increasing the age-of-onset criterion, Jennifer L. Vande Voort, M.D., a psychiatrist at Mayo Clinic's campus in Rochester, Minnesota, and colleagues at the National Institutes of Health studied the prevalence and clinical correlates of DSM-IV versus DSM-5 defined ADHD.

The study focused on 1,894 children and adolescents, ages 12 to 15, drawn from the National Health and Nutrition Examination Survey (NHANES) — a cohort that had aged out of the at-risk period for ADHD as outlined in DSM-5. Parent reports provided information about symptoms, age of onset, impairment, and service and medication use during the 12 months before the study.

12-month prevalence rate increases

The researchers found that expanding the age-of-onset criterion led to an increase in the 12-month prevalence rate of ADHD from 7.38 to 10.84 percent. The greatest increase occurred for the inattentive presentation, confirming findings from earlier studies that children with inattentive symptoms have a later age of onset than do those with primarily hyperactive symptoms.

"Children with the inattentive subtype often go unrecognized until later on, when schoolwork gets more challenging," Dr. Vande Voort says. "Unlike hyperactive kids, they're not disruptive in class, so they tend to be diagnosed later. By then, they're already falling behind academically."

One of the most noteworthy findings is that children whose symptoms began between the ages of 7 and 12 were more likely to come from lower income and ethnic minority families. This may result from a lack of access to health care or failure to understand ADHD symptoms and treatments. By the time some of these children see a doctor, they may be overlooked because they're beyond the age 7 cutoff, Dr. Vande Voort explains.

Although the study has limitations, she says the findings support expanding the age-of-onset criterion. "Nearly 3.5 percent of kids who have ADHD symptoms would not have been recognized simply because of their age," she says. "Our study showed that the severity of symptoms is the same in the early-onset and late-onset groups. These symptoms are impairing academic and social development and need to be addressed and treated.

"My hope is that through our study, we will get the word out to psychiatrists and pediatricians that the diagnostic criterion for ADHD has expanded from 7 to 12 years of age, and that this change can make a difference in children's lives."

The study appeared in the July 2014 issue of the Journal of the American Academy of Child & Adolescent Psychiatry.

For more information

Vande Voort JL, et al. Impact of the DSM-5 attention-deficit/hyperactivity disorder age-of-onset criterion in the US adolescent population. Journal of the American Academy of Child & Adolescent Psychiatry. 2014;53:736.