Attention Research Update
"Helping parents, professionals and educators stay informed about new research on ADHD"
David Rabiner, Ph.D. Senior Research Scientist, Duke University
medication treatment is helpful for an estimated 70 to 90% of children with
ADHD, the development of effective alternative treatments is important for
several reasons. First, even for children who respond well to medication,
there often remain residual difficulties that need to be addressed.
Second, some children experience intolerable side effects that preclude the
ongoing use of meds. Finally, most studies documenting the beneficial effects
of stimulant medication treatment are relatively short-term, and data showing
that stimulant medication improves the long-term prognosis for children with
ADHD is still scarce.
Dietary supplementation of long-chain fatty acids as an intervention for ADHD has generated considerable interest in recent years. Certain highly unsaturated fatty acids (HUFAs) are known to play an important role in many aspects of physical health, and may also play a role in a wide range of neuro-developmental and psychiatric conditions. For example, children with ADHD have been shown in several studies to have low blood levels of HUFAs. Because HUFAs are important for healthy brain development and functioning, some researchers have suggested that increasing HUFA levels via dietary supplements could enhance brain functioning and reduce ADHD symptoms.
In a prior issue of Attention Research Update - www.helpforadd.com/2002/june.htm - I reviewed 2 studies examining the impact of fatty acid supplementation on ADHD symptoms. In the first study, 63 children who were being treated effectively with stimulant medication were randomly assigned to receive Docasahexaenoic acid (DHA, a type of long-chain fatty acid) or a placebo over a 4-month period. Computerized tests of attention and parents' ratings of children's ADHD symptoms did not differ for treatment vs. placebo groups at 4 months; the authors interpreted this as evidence against the benefit of fatty acid supplementation for children with ADHD.
A problem with this conclusion, however, is that participants remained on medication during the trial. Because these children were all positive medication responders, their symptoms would already have been substantially reduced, thus making it difficult to demonstrate additional benefits of an additional intervention. In children with ADHD who were not being treated with meds, however, DHA supplementation might provide benefits that could not be detected here.
In the second study previously reviewed, 41 8-12 year-old children with developmental dyslexia were randomly assigned to receive either HUFA supplementation, containing both omega 3 and omega 6 fatty acids, or an identical-looking placebo. None had been formally diagnosed with ADHD, although all had above-average scores for high levels of ADHD based on parent responses to the Conners Rating Scale. After 12 weeks, children receiving active treatment had significantly lower ratings for inattention and global ADHD symptoms than children who had received the placebo. Average scores for treated children now fell towards the upper end of the "normal" range while average scores for children in the placebo group remained elevated. The degree to which the results would generalize to children carrying a formal diagnosis of ADHD was not clear.
At the time, my overall conclusion on the effects of fatty acid supplementation on children's ADHD symptoms was the following:
"At this point in our knowledge, it seems premature to conclude either that fatty acid supplementation has no benefits for children with ADHD, or that such benefits are clearly established. Hopefully, research will soon be available that will permit a more definitive evaluation."
A study published in the May 2005 issue of Pediatrics (Richardson, A.J., et al. The Oxford-Durham Study: A randomized, controlled trial of dietary supplementation with fatty acids in children with developmental coordination disorder, Pediatrics, 115, 1360-1366) provides important new data on this interesting issue. This study was conducted in England, and involved 117 5-12 year old children - about one-third were girls - diagnosed with Developmental Coordination Disorder (DCD). Many of these children had elevated levels of ADHD symptoms, although they were not formally diagnosed with ADHD as part of the study.
DCD involves specific impairments of motor coordination that interferes significantly with a child's academic achievement and/or activities of daily living. DCD is believed to affect approximately 5% of children, and frequently overlaps with ADHD dyslexia. Manifestations of the disorder in school-age children frequently include difficulties with the motor aspects of handwriting, playing ball, assembling puzzles, etc. In the school setting, children with DCD frequently struggle with written language and/or problems with organizational skills and attention. Thus, although this is a different disorder from ADHD, children with DCD experience many similar problems in school.
Participants were randomly assigned to receive dietary fatty acid supplementation treatment or a placebo. The initial assignment to treatment vs. placebo lasted for 3 months. At the end of 3 months, those in the treatment group continued to receive fatty acid supplementation for 3 additional months while children who had been receiving placebo were switched to active treatment as well.
Active treatment was a supplement containing 80% fish oil and 20% evening primrose oil in gelatin capsules. The daily dose of 6 capsules (2 capsules in the early morning, at lunch, and in the late afternoon provided both omega-3 fatty acids (Dose received: 558 mg of eicosapentaenoic acid and 174 mg of docosahexaenoic acid) , omega-6 fatty acids (Dose received: 60 mg of y-linoleic acid), plus vitamin E (Dose received: 9.6 mg). Note: Although this information reflects the doses used in the study, the authors specifically comment that the optical dosage and combination of fatty acids remains unknown and that additional studies are required to determined this. Placebo treatment consisted of olive oil capsules that were carefully matched to the active treatment in both appearance and flavor. Capsules were administered by teachers during the week and by parents on the weekend.
Several different measures were collected at baseline, 3 months, and 6 months to determine whether fatty acid supplementation improved children's functioning. First, teachers completed the Conners Rating Scale, a widely used behavior rating scale to assist in the assessment of ADHD and other behavioral/emotional problems in children. Children's reading and spelling achievement was assessed using a standardized measure of academic achievement. This measure of reading achievement focused on the ability to read single words and did not examine reading comprehension. Finally, motor functioning was assessed with the Movement Assessment Battery for Children.
The authors first compared children in the treatment and placebo groups after 3 months to determine whether fatty acid supplementation was associated with improvements in motor and academic functioning and with reductions in ADHD symptoms. Results of these analyses indicated the following:
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