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This is the 6th in a series of blog posts on ADHD. Previous posts in this series reviewed the causes and epidemiology of ADHD, the role of nutrition in ADHD, the evidence for EEG biofeedback. This post is offered as a concise review of the evidence for omega-3 'essential fatty acids' as treatments of ADHD.
Inconsistent research findings on omega-3s in ADHD
Children diagnosed with ADHD have lower plasma concentrations of certain essential fatty acids the so-called 'omega-3' fatty acids compared to the average population suggesting that symptoms of ADHD may be related to dietary deficiencies of these naturally occurring molecules. However, findings of placebo-controlled trials of essential fatty acids in individuals diagnosed with ADHD are inconsistent.
There are two omega-3 fatty acids: docosahexanoic acid (DHA) and ecosapentanoic acid (EPA). Omega-6 fatty acids such as arachadonic acid (AA) have also been studied for their potential benefits in individuals diagnosed with ADHD however most studies examine the efficacy of mixtures of the omega-3 essential fatty acids, DHA and EPA. One study on an omega-3 formula as an add-on therapy to stimulants such as methylphenidate and others found no differential benefit of essential fatty acids compared to stimulants plus a placebo. Another add-on study found only modest improvements over placebo in disruptive behavior and attention. In a placebo-controlled trial on omega-3s as a stand-alone treatment of ADHD, parents of children in the treatment group reported more improvement than parents of children receiving a palm oil placebo. This study has been criticized because a high drop-out rate biases findings in a positive direction. The use of olive oil as a placebo may mask the beneficial clinical effects of essential fatty acids because an active constituent of olive oil is converted into oleamide, which is known to affect brain function.
The short durations and low doses of essential fatty acids used in most studies may not be adequate to result in the long-term changes in neuronal membrane structure required for clinical improvement. The issue of dosing has been addressed by a small open-label study (n = 9) in which ADHD children were supplemented with high dose EPA/DHA concentrates (16.2 g/day) while continuing on stimulant medications. Most children were rated by a blinded psychiatrist as having significant improvements in both inattention and hyperactivity that correlated with reductions in the AA:EPA ratio at the end of an 8-week treatment period. A recent meta-analysis confirmed positive effects of add-on omega-3s in childhood ADHD however therapeutic benefits of this supplement were significantly less than for conventional pharmacologic treatments. A recent study comparing the efficacy of the omega-3 fatty acids DHA and EPA with the omega 6 fatty acid arachidonic acid (AA) found improvement in a few specific areas of behavior and cognition with increasing doses of omega-3s but no improvement in ADHD symptoms overall.
Large prospective trials are needed to replicate these preliminary findings.
