by Sal Mannuzza, Ph.D.
Attention-Deficit/Hyperactivity Disorder (ADHD) probably accounts for more child psychiatric outpatients than any other single disorder. It is estimated that 3-7% of school-age children have the disorder, with much higher rates reported in some studies. The childhood syndrome primarily consists of three core symptoms, inattention (concentration difficulties, short attention span, distractibility), impulsivity (impatience, acting without thinking), and hyperactivity (restlessness, always on the go). The long-term progress or outcome of children with ADHD has drawn considerable attention, partly because of the disorder’s high prevalence, and partly because a significant minority of children with ADHD become known to the criminal justice system in adolescence or young adulthood, thus constituting a major public health concern.
This article reports on the long-term outcome of children with ADHD, as shown by controlled, prospective follow-up studies into young adulthood and adulthood (i.e., late teens to mid-twenties). Since both epidemiological and clinical studies consistently have found that ADHD is more common in boys, follow-up studies have either restricted their samples to boys or have included relatively few girls. In addition, nearly all follow-up studies have been limited to white children. Therefore, the results presented in this article are based on studies of predominantly white boys with ADHD.
Early-Middle Adolescent Outcome (ages 13-15 )
Several prospective studies have followed children with ADHD into their early-mid teens. These studies fairly consistently have shown that, compared to normal controls, children with ADHD exhibit impaired academic functioning (obtain lower test scores, more often repeat grades, etc.) and perform more poorly on cognitive tasks.
In addition, at follow-up, children with ADHD are more often characterized by low self-esteem and poor social functioning (e.g., described by their mothers as having no steady friends). Two-thirds to three-quarters of cases continue to meet full criteria for ADHD, and a substantial proportion (30-50% in some studies) exhibit pervasive conduct problems.
Young Adult Outcome (ages 16-19)
Follow-up studies into young adulthood have addressed outcome in four major domains, academic performance, self-esteem and social functioning, arrest history (criminality), and mental status.
As noted, several short-term follow-up studies have reported academic difficulties among children with ADHD in early-middle adolescence. These difficulties persist into young adulthood. Compared to their peers, ADHD subjects complete less formal schooling, achieve lower grades, fail more courses, perform worse on standardized achievement tests, and are more likely to attend special schools.
Self-Esteem and Social Functioning
As with impaired academic functioning, low self-esteem and poor social functioning continue to characterize the child with ADHD in young adulthood. Compared to controls, children with ADHD in their late teens have fewer friends, score more poorly on tests of social skills and self-esteem, and are rated by clinicians as having poorer psychosocial adjustment.
Two controlled, prospective studies, one in New York (Klein & Mannuzza) and the other in Los Angeles (Satterfield), obtained the official arrest records of all subjects who resided in their state of origin during the follow-up interval.
These data provide an objective index of the severity and pervasiveness of antisocial behavior that are not susceptible to the usual sources of unreliability which sometimes characterize interview data (forgetting, minimizing, denying, selective recall, etc.).
Both studies found that ADHD subjects fared poorly with regard to indices of criminality. Compared to controls, these individuals showed significantly higher rates of arrests (36-58% vs. 2-20%, depending on study and social class), convictions, incarcerations (9-25% vs. 1%), multiple arrests, multiple convictions, aggressive offenses, felonies, and multiple felonies. In the New York study, the presence of an antisocial disorder (i.e., conduct disorder or antisocial personality disorder) in young adulthood almost completely accounted for the increased risk of criminality in ADHD subjects.
When subjects without an antisocial disorder were compared, ADHD proband and control groups did not differ significantly, in arrest rates (28% vs. 16%). Therefore, antisocial disorder was a powerful mediating factor regarding arrest history.
This finding suggests that children with ADHD are not uniformly at risk for later criminality, and only those who develop the more pervasive, antisocial syndrome are more likely to become known to the criminal justice system.
To date, only the New York study by Rachel Klein and Sal Mannuzza (2000) has reported the prevalence of clinical diagnoses in young adulthood. The methodology of this study will be reviewed briefly. Follow-up studies of 115 non-psychotic, cross-situationally hyperactive white children of average intelligence, who were between 6 and 12 years of age, were done after 9 years (young adult) and after 16 years (adult). All were referred by teachers because of behavior problems, and were clinically diagnosed as having hyperkinetic reaction of childhood (now called ADHD) at a child psychiatric research clinic.
Children were not accepted if the primary reason for referral involved aggressive or other antisocial behaviors. Because of this exclusion criterion, we suspect that the children in the study were relatively free of conduct disorder. This is important, in view of our outcome findings regarding antisocial disorder at follow-up.
At 9-year follow-up (mean age, 18 years), 98% were evaluated. At 16-year follow-up (mean age, 25 years), 90% were assessed. A comparison group of 100 individuals with no behavior problems prior to age 13, was also recruited.
We also studied an independent, replication sample of 111 additional children with ADHD and a comparison group of 78 subjects was recruited. The results of both studies combined, are now reported.
At young adult follow-up, more than twice as many subjects as controls had an ongoing mental disorder (50% vs. 19%, p < .001). Three disorders significantly discriminated between groups: attention deficit disorder with or without hyperactivity (ADD, 37% vs. 3%), antisocial personality/conduct disorder (APD, 29% vs. 8%), and non-alcohol substance use disorder (Substance Abuse Disorder, SUD, 13% vs. 2%) which, in nearly all cases, involved marijuana. Anxiety and affective disorders were rare in both groups (1-2%).
Children with ADHD whose disorder persisted into young adulthood were at significantly increased risk for later developing APD and SUD. Specifically, 53% of subjects with persistent ADD vs. 19% of subjects with no ADD at young adult follow-up had ongoing APD or SUD. Furthermore, for those individuals who developed both APD and SUD, in all cases, onset of APD preceded (84%) or coincided with (16%) onset of SUD. These findings describe a developmental progression from ADD to APD to SUD, and underscore the significance of retaining childhood ADD symptoms in later life.
Over half of the children with ADHD were still experiencing clinically significant ADHD symptoms (inattention, impulsivity, hyperactivity) at average age 18 years, and a full 27% had all three of the core symptoms. These results are consistent with those of a young adult follow-up conducted in Montreal (Weiss & Hechtman).
About the author:
Sal Mannuzza, Ph.D. is Professor of Psychiatry at NYU School of Medicine, and Research Scientist at NYU Child Study Center and Nathan S. Kline Institute for Psychiatric Research. For over 20 years, he has collaborated with Dr. Rachel Klein on major prospective follow-up studies of children with ADHD, separation anxiety disorder, and developmental reading disorders; and on high-risk studies of the offspring of parents with anxiety and mood disorders.
This article is courtesy of AboutOurKids.org