ADHD is Persistent and Undertreated
Ruth Gerson, MD
Clinical assistant professor
Department of Child and Adolescent Psychiatry
NYU School of Medicine
Dr. Gerson has disclosed that she has no relevant financial or other interests in any commercial companies pertaining to this educational activity.
The seminal study of preschool ADHD, the Preschool ADHD Treatment Study (PATS), examined the efficacy of stimulant medication (methylphenidate) when added to parent training in preschoolers age three to five years old (Greenhill L et al, JAACAP 2006;45(11):1284-1293). This multicenter, randomized trial has now published its six-year follow-up data, with important findings for anyone treating patients with ADHD.
The initial PATS study took a sample of children aged three to five years old who met criteria for ADHD through interviews and a rigorous battery of scales (including both parent and teacher Connors rating scales). The study enrolled their families in a 10-week parent-training course, and then randomized the children to a double-blind, placebo-controlled trial of methylphenidate. Treatment lasted up to 10 months, and after the completion of the study, children engaged in community treatment at their parents’ discretion.
In this follow-up study, children were assessed again at three years, four years, and six years after the completion of the original study. Sixty-eight percent of children in the original study participated in all three follow-up assessments. Demographic factors did not differ in those who were lost to follow-up compared to those who participated, although baseline symptom severity was not examined as a predictor of attrition.
At six-year follow-up, almost 90% of children (now an average age of 10.4 years old) still met criteria for moderate-to-severe ADHD. While the authors (and clinical wisdom) expected hyperactivity and impulsivity to decline with age, there was no significant decline in any of the symptom categories with age. While the majority of the participants (almost 75%) were boys, girls were rated higher on symptoms of both inattention and hyperactivity/impulsivity. Comorbid ODD or conduct disorder predicted greater ADHD symptoms, and lower IQ was associated with greater inattention.
What is most striking about this study is that so many children continued to experience moderate-to-severe ADHD symptoms at follow-up despite the fact that a majority of them were on medication (mostly stimulants). The authors struggle to explain this, lacking more detailed data about dosing and compliance with medication. The finding suggests, however, that community providers may be under-treating these children, and if they are not using rating scales like the Connors to assess for efficacy, may not realize that these patients are still quite impaired and in need of additional medication, further parent training and support, or evaluation for comorbid learning disorders or other conditions (Riddle MA et al, JAACAP 2013;52(3):264-278e2).
CCPR’s Take: ADHD in preschoolers is real and persists through school age. We should titrate medication carefully in these cases, and consider monitoring response with rating scales or other objective measures of residual symptoms. Is it possible that stimulants stop working as well over time? There’s no evidence of this, but it certainly hasn’t been well studied, either. More studies— and our own clinical experience keeping track of concrete measures—will tell us if this is a dosing problem, an efficacy problem, or something else.