ADHD Subtypes and Subgroups at Risk for Substance Use Disorders
Naimah Weinberg, M.D.

SUMMARY: Dr. Naimah Weinberg, as chair of this session, opened the discussion with a brief presentation outlining the relationship between substance use disorders (SUD) and ADHD. Weinberg began by distinguishing between SUD and substance use, and moved to examining the implication that ADHD is indeed a risk factor for SUD. She pointed out that the limitations of existing clinical studies and reports weaken the suggested link between ADHD and SUD, and stressed that further, more encompassing studies are needed to disentangle the etiologic role of ADHD in risk for drug abuse.

Subtypes of ADHD Youth at Risk for Substance Abuse
Timothy E. Wilens, M.D.

SUMMARY: Dr. Timothy Wilens evaluated existing literature depicting the developmental relationship of substance use disorders (SUD) in ADHD males and females. Prospective studies of boys, girls, and their siblings and parents as well as retrospective studies of adults with ADHD were evaluated for the relationship between SUD and ADHD. Specific developmental issues, with an emphasis on the role of psychiatric comorbidity, were evaluated, as well as data from epidemiologic and clinic samples. Wilens showed that studies of ADHD children and adults demonstrate an increased risk of SUD in those with persistent ADHD, and that psychiatric comorbidity with conduct disorder continues to be the most robust risk factor for SUD in ADHD. ADHD with comorbid bipolar disorder also poses a major risk for SUD.

Childhood ADHD, Comorbidity, and Risk for Late-Adolescent Drug Abuse
Ken C. Winters, Ph.D.

SUMMARY: Dr. Ken Winters presented findings from a young adult (mean age 20) followup assessment as part of the University of Minnesota ADHD Prospective Study. Community-recruited ADHD and control children were regularly assessed during an 8-year span. Winters’ presentation focused on the drug use behavior outcomes of the subjects with respect to several measures of drug use behaviors, including SUDs. The findings indicated reliable elevations in drug use behaviors for the ADHD + Externalizing group when compared with controls, but no group differences were found for the other comparisons (ADHD alone vs. controls and ADHD + Internalizers vs. controls). Implications of the findings in light of the community-based ADHD sample also were discussed.

Developmental Twin Studies of Relations Between Substance Use and ADHD
James J. Hudziak, M.D.

SUMMARY: Dr. James Hudziak combined two approaches, a developmental twin study of 25,000 Dutch twin pairs followed since birth to determine the contributions of maternal smoking and drinking behavior to offspring with ADHD, ODD, and other psychopathologies; to determine the genetic and environmental contributions to these phenotypes; and lastly, to determine the stability of these behavioral problems across the 12 years of development. The MOTWIN data set was presented in order to shed light on the relations between ADHD and its subtypes and substance use. Data also were presented that indicate natural age of onset for substance use behavior and how inattention, delinquency, and aggressive behavior problems of childhood both precede and predict later substance use behavior.

Variability in Risk for Substance Use and Disorder Among Children Diagnosed with ADHD
Brooke S.G. Molina, Ph.D.

[Slides not available.]

SUMMARY: Dr. Brooke Molina addressed questions regarding the persistent risk of vulnerability to adult substance use for those diagnosed with ADHD in childhood. She reported results from her team’s longitudinal study on children with ADHD (Pittsburgh ADHD Longitudinal Study, Co-Pls Molina and William E. Pelham, Jr., Ph.D., funded by NIAAA/NIDA), in which they followed more than 350 children diagnosed with ADHD and 240 without ADHD through adolescence into early adulthood. Unique features of this study include a wealth of standardized and objective childhood data that characterize the probands in childhood, a large sample size that allows previously underpowered examinations of comorbidity, and a comprehensive assessment at followup of alcohol, tobacco, and drug use/disorder through adolescence and early adulthood with annual interviews. Molina reported variability in characteristics in their sample and relations to risk for later substance-related outcomes such as frequency and quantity of consumption and substance-related impairment. Implications for clinicians and future research also were discussed.

Behavioral and Cognitive Predictors of Adolescent Substance Use in Children with ADHD
Jeffrey M. Halperin, Ph.D.

SUMMARY: Children with ADHD are at heightened risk for substance use during adolescence. However, the degree to which this association is specific to ADHD or whether it is more closely linked to (1) the presence of early conduct disorder (CD); (2) the persistence of CD into adolescence; and/or (3) the manifestation of ADHD symptoms during adolescence remains unclear. Further, it is unknown how this risk is affected by level of cognitive function. Dr. Jeffrey Halperin presented data from an ongoing longitudinal study of youth who were evaluated and diagnosed with ADHD combined type, when they were 7 to 11 years old. These patients, along with controls, are being re-evaluated at age 16 to 21 years. Preliminary analyses indicate that adolescent substance use in ADHD is best accounted for by an interaction between early CD and Full Scale IQ. Among patients with ADHD + CD, those with high IQ scores were most likely to use drugs and alcohol. In contrast, among those without early CD, increased adolescent substance use was associated with low IQ scores.

Long-Term Followup of Childhood ADHD: Development of Adult Substance Abuse
F. Xavier Castellanos, M.D.

SUMMARY: Dr. F. Xavier Castellanos presented study results consistent with basic science studies suggesting that low doses of methylphenidate may have enduring effects, which are greatest in younger individuals. From 1970 to 1977, 226 cross-situationally hyperactive children were enrolled in a long-term followup study after undergoing standardized treatment with methylphenidate. Based on data available for 171 male probands and 178 male contemporaneously recruited comparisons, Castellanos’ team observed significantly greater rates of substance abuse in probands, along with a significant relationship between age of first treatment with stimulants and the lifetime prevalence of drug abuse disorders (OR=2.3; p=.01). Younger age at first treatment predicted lower risk, independently of potential confounds such as severity of hyperactivity, social class, or intelligence. In an independent sample of children and adolescents with ADHD who had longitudinal anatomic MRI scans, Castellanos observed strikingly low white matter volumes in previously untreated ADHD children, and an apparent increase in white matter volume in those children once they began stimulant treatment.