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Is Age-at-Onset Criterion Relevant for
the Response to Methylphenidate in
Attention-Deficit/Hyperactivity Disorder?

Marcelo C. Reinhardt, M.D.; Lucia Benetti; Marcelo M. Victor, M.D.;
Eugenio H. Grevet, M.D.; Paulo Belmonte-de-Abreu, M.D.;
Stephen V. Faraone, Ph.D.; and Luis A. Rohde, M.D.

Objective: Since DSM-IV criteria for attention-deficit/hyperactivity disorder (ADHD) require that some symptoms causing impairment must be present before 7 years of age, clinicians are faced with a diagnostic and treatment dilemma on how to proceed with late-onset ADHD patients. We aimed to compare the response to methylphenidate between a group
of patients fulfilling all DSM-IV ADHD criteria (full ADHD diagnosis) and a group of patients fulfilling all DSM-IV criteria except the age-at-onset criterion (late-onset ADHD).

Method: We evaluated 180 children and adolescents (4-17 years old) and 111 adults from our ADHD unit. All ADHD diagnoses were assessed using DSM-IV criteria. Methylphenidate was administered twice daily (8 a.m. and noon), but an extra dose was allowed between 5 and 6 p.m. for children and adolescents needing extra coverage in the evening. The minimum dose was 0.30 mg/kg/day. Response to treatment was assessed in methylphenidate-naive subjects using the Swanson, Nolan, and Pelham Scale-version IV (SNAP-IV) at baseline and after 1 month of treatment. Data were collected from January 2000 to January 2006.

Results: In both samples, subjects with the full ADHD diagnosis did not have a better response to methylphenidate at doses around 0.5 mg/kg/day than the late-onset ADHD subjects. In fact, adults with late-onset ADHD had a better response to methylphenidate than adults with the full diagnosis, even after adjustment for confounders (baseline SNAP-IV total score and ADHD types) (children and adolescents: F = 0.865, p = .354; adults: F = 5.760, p = .018).

Conclusion: These results concur with recent literature questioning the validity of the DSM-IV age-at-onset criterion for the diagnosis of ADHD and suggest that clinicians should consider implementing methylphenidate treatment for subjects with late-onset ADHD.

(J Clin Psychiatry 2007;68:1109–1116)

Received Sept. 1, 2006; accepted Dec. 7, 2006. From the ADHD Outpatient Program, Federal University of Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil (Drs. Reinhardt, Victor, Grevet, Belmonte-de-Abreu, and Rohde and Ms. Benetti) and Departments of Psychiatry and Behavioral Sciences and Neuroscience and Physiology, Upstate Medical University, Syracuse, N.Y. (Dr. Faraone).

This work was partially supported by research grants from Conselho Nacional de Desenvolvimento Científico e Tecnológico, Brasília, DF, Brazil (Grant 307780/2004-0), and Hospital de Clínicas de Porto Alegre, Rio Grande do Sul, Brazil. The ADHD Outpatient Program receives research support from the following pharmaceutical companies: Bristol-Myers Squibb, Eli Lilly, Janssen-Cilag, and Novartis.

Dr. Belmonte-de-Abreu has received grant/research support from Bristol-Myers Squibb, Pfizer, and Janssen-Cilag. Dr. Faraone has received grant/research support from McNeil Consumer & Specialty Pharmaceuticals, Shire, Eli Lilly, National Institute of Mental Health, National Institute on Drug Abuse, National Institute of Child Health and Human Development, and National Institute of Neurological Diseases and Stroke; has served on the speakers bureaus of Eli Lilly, McNeil Consumer & Specialty Pharmaceuticals, and Shire; and has served as a consultant for or on the advisory boards of McNeil Consumer & Specialty Pharmaceuticals, Noven Pharmaceuticals, Shire, and Eli Lilly. Dr. Rohde has served as a consultant for or on the speakers bureaus of Bristol-Myers Squibb, Eli Lilly, Janssen-Cilag, and Novartis and has served on the advisory board of Eli Lilly. Drs. Reinhardt, Victor, and Grevet and Ms. Benetti report no other financial affiliations relevant to the subject of this article.

Corresponding author and reprints: Luis A. Rohde, M.D., Serviço de Psiquiatria da Infância e Adolescência, Hospital de Clínicas de Porto Alegre, Rua Ramiro Barcelos, 2350, Porto Alegre, Rio Grande do Sul, Brazil 90035-003 (e-mail: