The following are some key findings from their work. Some of the statistics may be troubling, especially those having to do with substance abuse or criminal behavior. To parents questioning whether taking their ADHD child off medication will increase the adverse risks associated with ADHD, Dr. Klein says, "First, the question should only be posed in relation to adolescents who are still symptomatic. There is no reason to keep treating those who no longer have ADHD symptoms. Among the symptomatic adolescents, no one knows the answer. But we do know that treatment is effective in adolescence; therefore it makes sense to continue treatment if it's indicated. However, it would be premature to promise a positive outcome as a result."

Other, smaller follow-up studies have shown consistently that hyperactivity or ADHD is a highly persistent disorder from childhood into adolescence.[1] Short term studies have shown fairly consistently that children diagnosed with ADHD continue to experience significant academic, cognitive, and behavioral difficulties into their early to mid teens (13 - 15).[2] Between 30 and 50 percent may continue to have the full disorder into late adolescence (16 to 19).[3]

Klein and Mannuzza found that 37% of the ADHD subjects[4] continued to have ADHD into adolescence, compared to only 3% of the controls. It seemed to drop off in adulthood to 7%.

However, the extent to which ADHD is likely to persist into adulthood is not easily determined from the long term studies, largely because the methods of measuring symptoms usually change as subjects grow up. Children and teenagers are more likely to be evaluated based in part on interviews with teachers and parents, while adult diagnoses are often based on self-reports, which tend to result in much lower rates of diagnosis. (For more discussion on the methodological problems with longitudinal ADHD research, see this overview by Russell Barkley).

Academic difficulties

Many studies have shown that ADHD subjects often experience academic difficulties into adolescence. In one ten year follow-up study, researchers found that at age 19, ADHD subjects "completed less formal schooling, achieved lower grades, failed more courses and were more often expelled" than control subjects.[5] Klein and Mannuzza found that ADHD children were less likely than control subjects to have graduated college or attained a graduate degree. (14% vs. 52%).

Other mental disorders

ADHD children may be at greater risk for developing other mental disorders later in life. Klein and Mannuzza found that ADHD children were more likely to have any psychiatric disorder in adolescence than control subjects. (50% of hyperactive children v. 19% of controls).

Thirty percent of the ADHD subjects in their study later developed Conduct Disorder, compared to 8 percent of the controls. Those subjects whose ADHD continued into adolescence were more likely than either the controls or those whose ADHD remitted by adolescence to develop CD.

ADHD subjects were no more likely than the control subjects to develop mood or anxiety disorders, however.

Substance Abuse

Klein and Mannuzza found that in adolescence, the ADHD subjects were more likely than the controls to develop Substance Use Disorder. (SUD) (17% v. 2%). Interestingly, however, it was only those who subsequently developed Conduct Disorder who showed this increased risk, so it was not the ADHD itself that predicted the SUD.

It is also interesting to note that the discrepancy between the ADHD subjects and the controls only existed for substances other than alcohol; they were no more likely than the control subjects to have a problem with drinking.

Criminal behavior

ADHD children may be at higher risk for criminal behavior. Klein and Mannuzza found that 39% of their ADHD subjects had been arrested in adolescence or early adulthood, compared to 20% of the controls. Conviction rates for the former ADHD children were also higher, 28% v. 11%. However, as with substance abuse, the arrest and conviction rates among the ADHD subjects were higher only for those who also had developed Conduct Disorder or Anti-Social Personality Disorder later in life.

Four percent of the ADHD subjects were incarcerated in adulthood, while none of the controls were.

"Longitudinal Course of Childhood ADHD," Rachel Klein, Ph.D.
Presentation at New York University Medical School, March 30, 2001.

"Longterm Prognosis in Attention-Deficit/Hyperactivity Disorder," Mannuzza, Salvatore and Klein, Rachel; Child and Adolescent Psychiatric Clinics of North America, Volume 9, Number 3, July 2000

"Attention Deficit Hyperactivity Disorder: Long-Term Course, Adult Outcome, and Comorbid Disorders," Russell A. Barkley, Ph.D.

"Adolescent and Adult Outcomes in Attention Deficit/Hyperactivity Disorder," Mannuzza, Salvatore and Klein, Rachel in H.C. Quay and AE Hogan (Eds) Handbook of Disruptive Behavior Disorders. New York: Klumer Academic/Plenum Publishers. 1999 pp. 279-294

[1] http://add.about.com/health/add/library/weekly/aa1119f.htm

[2] "Adolescent and Adult Outcomes in Attention Deficit/Hyperactivity Disorder," Mannuzza, Salvatore and Klein, Rachel in H.C. Quay and AE Hogan (Eds) Handbook of Disruptive Behavior Disorders. New York: Klumer Academic/Plenum Publishers. 1999 pp. 279-294

[3] http://add.about.com/health/add/library/weekly/aa1119f.htm

[4] The subjects of the study were all boys diagnosed with "hyperkinetic reaction of childhood" under the DSM-II criteria. They had been referred by their school for behavior problems, but not for primarily aggressive or anti-social behaviors. They were followed up 6 and 9 years after the initial study.

[5] "Adolescent and Adult Outcomes in Attention Deficit/Hyperactivity Disorder," Mannuzza, Salvatore and Klein, Rachel in H.C. Quay and AE Hogan (Eds) Handbook of Disruptive Behavior Disorders. New York: Klumer Academic/Plenum Publishers. 1999 pp. 279-294