A recent NIMH-funded survey tracking the prevalence of attention deficit/hyperactivity symptoms found that an estimated 4.4 percent of adults ages 18-44 in the United States experience symptoms and some disability. The survey is known as the National Comorbidity Survey Replication (NCS-R) and is part of a series of tracking surveys supported by NIMH and conducted by researchers at Harvard Medical School to assess the state of mental health of the nation. The NCS-R is a nationally representative survey of English-speaking residents ages 18 and older.

The results of the survey raise awareness about the possibility that many children who have ADHD continue to have related symptoms as adults. It points to the need for long-term, follow-up assessments of children diagnosed with ADHD to determine if the disorder lingers past adolescence and into adulthood.

In the survey, those with attention deficit/hyperactivity symptoms were more likely to be white males who were divorced and unemployed or unable to work. They also tended to have more problems with alcohol and drug abuse—problems that are known to be associated with ADHD. In addition, the study found that while many people with ADHD problems are in treatment for other mental disorders and substance abuse, a smaller proportion receive treatment for their ADHD symptoms.

Adult ADHD symptoms often coexist with other mental and emotional disorders, such as depression or anxiety, and can significantly impair a person's ability to function productively. The researchers also note that because ADHD assessments have been traditionally targeted to children, ADHD is difficult to diagnose in adults.

Moreover, the symptoms tend to be more varied and subtler in adults than in children, suggesting that clinicians may need to consider a wider variety of possible symptoms for the condition to allow for better assessment in adults. Until biomarkers for ADHD are identified that will allow clinicians to differentiate between ADHD and non-ADHD conditions with similar symptoms, diagnosis must depend on careful and comprehensive clinical evaluation. Treatment decisions are best left to individual patients and their doctors, taking into account the potential risks and benefits posed by the various treatment options.

The study was published in the American Journal of Psychiatry April 1, 2006. Ronald C. Kessler, PhD, professor of health care policy at Harvard Medical School, led the study. Also participating in the study were: Lenard Adler, MD, of New York University Medical Center; Russell Barkley, PhD, of Medical University of South Carolina; Joseph Biederman, MD, of Massachusetts General Hospital; C. Keith Conners, PhD, of Duke University Medical Center; Olga Demler, MA, MPH, of Harvard Medical School; Stephen V. Faraone, PhD, of SUNY Upstate Medical University; Laurence L. Greenhill, MD, of Columbia University and New York State Psychiatric Institute; Mary J. Howes, PhD, of Harvard Medical School; Kristina Secnik, PhD, of Eli Lilly and Company; Thomas Spencer, MD, of Massachusetts General Hospital; T. Bedirhan Ustun, MD, of World Health Organization; Ellen E. Walters, MS, of Harvard Medical School; and Alan M. Zaslavsky, PhD, of Harvard Medical School