Because studies have suggested possible roles for diet and immunoglobulin (Ig) in attention deficit hyperactivity disorder (ADHD), these researchers compared two diets in children with ADHD (age range, 4–8 years), who were recruited via advertisements.
In the multiphase study, 100 unmedicated children (mean age, 6.5) were randomized to an individually tailored, restricted diet or a normal diet for 5 weeks. Restricted-diet responders continued these diets and were rerandomized in a crossover design to challenge with foods that induced low or high IgG levels. Parents were not blinded to diets except for IgG-related foods; behavioral assessments were obtained by physicians, from their own observations and from parent reports, and occurred on different schedules for the two groups.
Of 41 patients who completed the restricted diet, 32 met improvement criteria for ADHD or oppositional defiant disorder. Of 30 children entering the second phase, 63% relapsed with a food challenge, but outcomes did not differ by the IgG level of the challenge.
Comment: Nonmedication therapies are especially important to study in developing children. This study, however, had several features that may have biased the findings. Physicians administered the assessments to parent informants who knew the diet contents, volunteered for a diet study, and provided a highly tailored diet to their children. Thus, parental objectivity might have been less than if teachers or other informants, who were blind to the diet but able to observe the children, had been used. Combining preschool and school-age children may be problematic, as they respond differently to methylphenidate (J Am Acad Child Adolesc Psychiatry 2006; 45:1284). Even if these findings are replicated, it is not known whether dietary restriction would normalize neurodevelopment, as seen with methylphenidate in imaging studies (e.g., Am J Psychiatry 2010; 167:977). Potential problems with dietary regimens include the psychological effects of nonparticipation in numerous age-appropriate activities (e.g., cake at birthday parties, peer outings to fast food places, same diet as siblings). Practitioners who offer dietary trials to families need to discuss the complicated logistics of tailored diets and lack of knowledge about neurodevelopmental and psychological effects of dietary therapy for ADHD.
— Barbara Geller, MD
Published in Journal Watch Psychiatry February 28, 2011
