Preschoolers who are diagnosed with ADHD are not likely to respond to treatment with the stimulant methylphenidate, regardless of dosage, if they also have three or more coexisting disorders, according to a recent analysis of data from the Preschoolers with ADHD Treatment Study (PATS). PATS was funded by the National Institutes of Health?s National Institute of Mental Health (NIMH).

Previously reported PATS results http://www.nimh.nih.gov/science-news/2006/preschoolers-with-adhd-improve-with-low-doses-of-medication.shtml showed that overall, low doses of methylphenidate were safe and effective in treating 3-5-year-olds diagnosed with ADHD. This most recent study, one of seven new PATS articles published November 5, 2007, in the Journal of Child and Adolescent Psychopharmacology, sought to identify individual characteristics that may affect how a child would respond to treatment. The other articles examine topics such as the effectiveness of methylphenidate over a follow-up phase, the effects of the medication on functional outcomes for the preschoolers, and others.

"This new data is an important step forward in bridging the gap between research results and clinical practice, bringing potentially valuable information to clinicians about ways to better customize treatments for their patients," said NIMH Director Thomas R. Insel, M.D. "It also identifies a group of young children who have significant and multiple problems, and for whom more research is needed to identify effective treatments."

Analyzing data from 165 children, Jaswinder Ghuman, M.D., of the University of Arizona, and colleagues examined demographic and family characteristics that may predict response to ADHD treatment. Among the children, 29 percent had no coexisting disorders, 42 percent had one coexisting disorder, 21 percent had two coexisting disorders, and 9 percent had three or more coexisting disorders. Oppositional defiant disorder, conduct disorder and anxiety disorders were the most common coexisting disorders.

The researchers found that children with no or only one coexisting disorder were most likely to respond to methylphenidate, while those with two coexisting disorders were moderately likely to respond. Children with three or more coexisting disorders did not respond at all to the treatment.

They also found no demographic characteristics (e.g., gender, age, ethnicity) that predicted how a child would respond to methylphenidate. However, children with three or more coexisting disorders were more likely to have a lower socioeconomic status, and lived with parents who were less educated and unemployed. In addition, these children also were more likely to live in a single-parent household.

"These results need to be replicated before they can be translated into practical recommendations," said Dr. Ghuman. "But they are a solid reminder that we need to find better treatments for children with multiple disorders and challenging circumstances."

The findings are consistent with the NIMH-funded Multimodal Treatment Study of Children with ADHD (MTA), <http://www.nimh.nih.gov/health/trials/nimh-research-on-treatment-for-attention-deficit-hyperactivity-disorder-adhd-questions-and-answers-about-the-multimodal-treatmen.shtml> which found that school-aged children with more coexisting disorders were less likely to respond to ADHD treatment.

The National Institute of Mental Health (NIMH) mission is to reduce the burden of mental and behavioral disorders through research on mind, brain, and behavior. More information is available at the NIMH website, http://www.nimh.nih.gov.

The National Institutes of Health (NIH) — The Nation's Medical Research Agency — includes 27 Institutes and Centers and is a component of the U.S. Department of Health and Human Services. It is the primary federal agency for conducting and supporting basic, clinical and translational medical research, and it investigates the causes, treatments, and cures for both common and rare diseases. For more information about NIH and its programs, visit www.nih.gov.