The Effect of Fatty Acid Supplementation on ADHD Symptoms

Although stimulant medication is known to be an effective treatment for an estimated 70 to 90% of children with ADHD, there remains considerable interest in developing alternative treatments for several reasons. First, not all children respond to stimulant medication and, even among children who are positive responders, there often remain residual difficulties that need to be addressed. Second, some children experience intolerable side effects that preclude the ongoing use of stimulants. Third, although stimulants are generally believed to be safe, even when used over long periods of time, conclusive data supporting their long-term safety is not yet available. 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 recently, attention has been focused on their potential 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 in brain development and function, some researchers have suggested that increasing HUFA levels via dietary supplements could enhance brain functioning and reduce ADHD symptoms.

Study 1

This study was a randomized, double-blind, placebo-controlled trial of Docasahexaenoic acid (DHA, a type of long-chain fatty acid) supplementation in 63 ADHD children. (Voight, R.G. et al. (2001). A randomized, double-blind, placebo controlled trial of docosahexaenoic acid supplementation in children with AD/HD. The Journal of Pediatrics, 139, 189-196.) Only children treated effectively with stimulant medication participated, and they continued on medication throughout the four-month study because of ethical concerns about stopping an effective treatment for this duration. Comparisons between treatment and control participants thus determined whether DHA supplementation provided benefits beyond those already provided by medication.

After four months, participants completed a computerized test of attention, and parents completed both a Child Behavior Checklist and the Conners Rating Form, two widely used rating scales that assess parent perceptions of ADHD symptoms along with other behavioral and emotional difficulties. The computerized attention test was administered when participants had been off medication for 24 hours. Behavior ratings, however, were based on parents' observations during ongoing medication treatment.

Results And Summary

Comparisons between children receiving DHA supplementation and those receiving placebo "treatment" revealed no differences on the computerized attention test or parent behavior ratings. Based on this data, the authors conclude that the efficacy of DHA supplementation as an alternative or adjunctive treatment for ADHD is not supported.

The problem with this conclusion is that, because participants remained on medication during the trial, this was not a fair test of DHA supplementation for reducing ADHD symptoms. Since all of the children were positive medication responders, their symptoms would already have been substantially reduced, thus making it difficult to demonstrate additional benefits. In children not being treated with meds, however, DHA supplementation might still provide benefits that could not be detected here.

An analogy would be adding behavioral treatment for children already treated effectively with meds. If no additional benefit was found, one could not conclude that behavioral treatment is not effective for ADHD. A more reasonable explanation would be that, once effective medication treatment is implemented, behavioral treatment does not result in further gains. In the absence of medication treatment, or with children who do not benefit from medication, however, it could still be associated with significant benefits. (In actuality, there is some recent data from the MTA study to suggest that behavioral treatment does yield incremental gains in some areas for ADHD children.)

This concern would not apply to the computerized attention test results -- in which differences between treatment and control differences also were not detected -- because this was completed after meds had been withheld for 24 hours, enough time to clear from the children's systems. These results thus provide a better indication that DHA supplementation may not be efficacious, although computerized attention tests are not generally considered to be the most valid indicator of treatment effectiveness.

The authors also note that supplementation of only a single fatty acid was provided in their study, and suggest that supplementation with a combination of fatty acids (specifically, omega 3 and omega 6 fatty acids) may provide a stronger test of this intervention. In the next study reviewed, this is exactly what was done.

Study 2

The second study was conducted with 41 eight to twelve-year-old children with developmental dyslexia -- i.e. they had a specific learning disability in reading (Richardosn, A., & Puri, B.K. (2002). A radomized double-blind, placebo-controlled study of the effects of supplementation with highly unsaturated fatty acides on ADHD-related symptoms in children with specific learning disabilities. Progress in Neuro-Psychopharmacology & Biological Psychiatry, 26, 233-239). 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.

Children were randomly assigned to receive either HUFA supplementation, containing both omega 3 and omega 6 fatty acids, or an identical-looking placebo. Treatment lasted 12 weeks and neither parents nor the children themselves had any knowledge of which they were receiving. Twenty-nine participants completed the entire trial, with roughly equal numbers of treatment and control children withdrawing prematurely.

Results

After12 weeks, parents completed the Conners Parents Rating Form a second time so that pre- and post-treatment ratings could be compared. Prior to treatment, the treatment and placebo groups did not differ on any of the Conners subscales. In contrast, post-treatment ratings of inattention and global ADHD symptoms were significantly lower in the treatment group than the placebo group. Average scores for the treated children now fell towards the upper end of what would be considered "normal", while average scores for children in the placebo group remained elevated.

Within the placebo group, no significant reductions were found for any of the Conners scales relative to baseline levels. Among treated children, however, statistically significant reductions were found for psychosomatic problems, cognitive problems, anxiety, attention problems, hyperactivity, and a global index measuring a broad range of behavior problems. For several of these scales, the treatment effect sizes exceeded .50, indicating a reasonably robust effect. Thus, there was clearly evidence of clinically significant benefits for the children receiving the supplements.

Summary And Implications

Under carefully controlled double-blind conditions, HUFA supplementation with a combination of fatty acids was significantly better than placebo in reducing a wide range of ADHD symptoms in children with reading disability and elevated ADHD symptoms. This is an impressive result.

There are several limitations, however, that are important to note. First, although all participants had elevated ADHD symptoms at baseline, none had been formally diagnosed with ADHD. Whether similar effects would be found in clinically diagnosed ADHD children, particularly when reading disability was not also present, cannot be known with any certainty.

Second, because practical considerations did not permit blood sampling, it is not clear whether participants had fatty acid deficiencies to start with, or whether supplementation actually raised children's fatty acid levels. No conclusions can thus be made about biochemical mechanisms to explain the improvements observed following HUFA supplementation. However, the fact participants were not selected for low fatty acid status would be expected to weaken any positive effects of HUFA supplementation. This makes the results even more impressive.

Finally, although significant results were obtained, the sample size was relatively small, reflecting the fact that this was a pilot study. Replicating these results with a larger sample is thus required before more definitive claims about the benefits of HUFA supplementation for children with reading disabilities and elevated ADHD symptoms can be made. This is a caution appropriately expressed by the authors.

Overall Conclusion

Study 1 has been widely cited as demonstrating that HUFA supplementation has no benefit for children with ADHD. As indicated in the review, however, this conclusion seems inappropriate given that all participants also were treated with medication throughout the study. In addition, as the authors acknowledge, limiting the supplement treatment to a single fatty acid (i.e. DHA) may also be problematic. Results from Study 2 highlight that HUFA is potentially a helpful intervention for children with ADHD, and points to the need for a larger trial with a clinically diagnosed ADHD population.

At this point in our knowledge, it seems premature to conclude either that HUFA supplementation has no benefits for children with ADHD, or that such benefits are clearly established. The authors of both papers are to be commended for doing the hard work required to move us closer to determining the benefits of this treatment. Hopefully, research will soon be available that will permit a more definitive evaluation.

Note: This article originally appeared in Attention Research Update, an online newsletter written by Dr. David Rabiner, a Duke University psychologist and former member of CHADD's Professional Advisory Board. You can learn more about Attention Research Update and sign up for a free subscription at www.helpforadd.com.

Reproduced with permission of David Rabiner, Ph.D. - HelpforADD.com