Fatty Acids in Dyslexia

Fatty Acids in Dyslexia, Dyspraxia and ADHD

Dr Alex Richardson is Senior Research Fellow in Neuroscience, Mansfield College, Oxford

There is a wide spectrum of conditions in which deficiencies of highly unsaturated fatty acids (HUFA) appear to play a role. This includes ‘allergic’ conditions such as eczema and asthma as well as psychiatric disorders such as schizophrenia and depression. The focus here is on the role of HUFA in three common developmental disorders of learning and behaviour - dyslexia, dyspraxia and ADHD, although similar issues are also relevant to the autistic spectrum.

Dyslexia alone affects at least 5% of the general population in a severe form, as does ADHD, although estimates rise when milder forms are included. Dyspraxia remains less well-known, but prevalence appears to be similar. There is considerable overlap between all three as well as autistic spectrum disorders, and each can occur with differing degrees of severity.

Current evidence suggests that up to 20% of the population may be affected by one or more of these conditions which usually persist into adulthood, causing serious problems not only for those affected, but for society as a whole.

Essential Fats and Brain Function

To understand how fatty acid abnormalities could play a role in these conditions one needs to understand their essential role in brain structure and function. Two fatty acids (AA and DHA) make up 20% of the dry weight of the brain and more than 30% of the retina. Two others (EPA and DGLA) play a more minor structural role but are also crucial for normal brain function.

The truly essential fatty acids (EFAs) cannot be synthesised by the body and must therefore be provided in the diet. They are linoleic acid (omega-6 series) and alpha-linolenic acid (omega-3 series). The brain can usually synthesise the longer-chain highly unsaturated fatty acids (HUFA) that it needs from these EFAs.

Unfortunately, various dietary, lifestyle and disease factors can interfere with this conversion process - viz. excess saturated fats, hydrogenated fats or ‘trans’ fatty acids in the diet; deficiency of vitamins and minerals (notably zinc); excessive consumption of alcohol or coffee; smoking; diabetes, eczema, asthma and other allergic conditions, and ‘stress’.

Thus many individuals may be deficient in HUFA despite having EFAs in their diet. Individuals will also differ in their constitutional ability to convert EFA to HUFA, and this is the suggestion in dyslexia, dyspraxia and ADHD.

Evidence for FATTY ACID DEFICIENCY

ADHD

Colquhoun & Bunday of the Hyperactive Children’s Support Group conducted a survey of hyperactive children in 1981 and found the expected excess of males, associations with asthma, eczema and other allergic conditions, and evidence of zinc deficiency. They also noted various clinical signs of possible EFA deficiency in these children, including excessive thirst, frequent urination, and dry skin and hair.

They proposed that the problem might lie in the conversion of EFA to HUFA, because they saw no evidence of a dietary deficiency of the ‘parent’ EFA. They also hypothesised that this could explain both the higher numbers of ADHD boys (males are more vulnerable than females to EFA deficiency) and the apparent intolerance of many ADHD children to certain foods such as salicylates (because they can block the further conversion of HUFAs). Blood biochemical studies also provided some supporting evidence for deficiencies of certain fatty acids in ADHD.

Dyspraxia & Dyslexia

In children with dyspraxia, so far only ‘open’ trials of fatty acid supplementation have been carried out which did find evidence of improvements in manual dexterity etc. The first randomised,double-blind plabebo-controlled trial in dyspraxia is now underway.

However visual function in dyslexia appears to be improved by fatty acid treatment. The role of omega-3 fatty acids in visual function is well recognised, and the evidence for visual problems in dyslexia is now substantial.

Abnormal brain lipid (fat) metabolism in dyslexia was also revealed by brain imaging studies carried out at Hammersmith Hospital (Richardson et al., 1997).

In a large sample of dyslexic and non-dyslexic adults, clinical signs of fatty acid deficiency were significantly higher in the dyslexic group (Taylor et al., 2000). Within dyslexic children, those with more clinical signs of fatty acid deficiency had more severe difficulties in reading, spelling and working memory (Richardson et al, 2000).

In view of the mounting evidence for fatty acid abnormalities in dyslexia, several double-blind clinical trials were set up to assess whether treatment with fatty acids can be of benefit. These studies are now approaching completion, and some preliminary results are already available:

Trial 1: In a school-based study, 41 dyslexic children with ADHD features took either a fatty acid supplement or a placebo for three months. Compared with the placebo group, those dyslexic children who had received the fatty acid supplement showed significant reductions in a range of ADHD symptoms, particularly cognitive problems (inattention, learning and memory problems) and anxiety.

In a second stage of the study, those children who had received the placebo treatment were then switched to the fatty acid supplement under single-blind conditions and followed for a further 3 months. In these children, significant improvements were observed for a wide range of ADHD measures, in striking contrast to the lack of improvement they had shown on placebo treatment. Numbers in this study were small, so these results need to be confirmed in larger double-blind trials still underway.

Trial 2: In a larger clinic-based study, 102 dyslexic children took either the same fatty acid supplement or placebo for six months under double-blind conditions. Supplementation was associated with significant improvements in reading, especially for children with fatty acid deficiency signs or visual symptoms. (Richardson et al, in preparation).

How can we best identify people who can be helped by fatty acid supplements?

Clearly, supplementation is most likely to help if there is already some evidence of a deficiency in highly unsaturated fatty acids. Unfortunately, objective biochemical measures of fatty acid status are not usually a practical option but the following provides some provisional guidelines for identifying those who may be most likely to benefit from fatty acid supplements.

• Physical signs of fatty acid deficiency (all of which could have other causes and if persistent, should be discussed with the GP) e.g. excessive thirst, frequent urination, rough, dry patches on the skin (especially if this is ‘bumpy’ in appearance and feel), dull or dry hair, tendencies to dandruff, and soft or brittle nails.

• ‘Allergic’ tendencies - tendencies towards eczema,asthma or hay fever seem to be more common in people with dyslexia, dyspraxia or ADHD and their relatives. Fatty acid deficiencies can play a role in these allergic conditions.

• Visual perceptual problems - visual perceptual problems seem to be a good predictor of a positive response to HUFA supplementation. Despite having no visual problems that an ordinary eye test would detect, many dyslexic people report blurring or apparent movement of letters and words, eye strain, or ‘glare’ from text on the page. They also have unusual sensitivity to bright light in general and poor night vision.

• Attention/concentration problems. A good response to HUFA supplementation seems more likely if there are genuine problems with attention and concentration. Many children (and adults) have real difficulties in ‘screening out’ things that are irrelevant to the task in hand. Or they find that their minds ‘wander’ very easily, and they have to make extraordinary efforts to focus so tire very quickly.

• Mood swings/undue anxiety/low ‘frustration tolerance’. Some individuals are particularly susceptible to stress or criticism (real or perceived) and they take any ‘failure’ very much to heart. Omega-3 supplementation has been shown to reduce susceptibility to stress-aggression-frustration in placebo-controlled trials.

• Sleep problems. Certain molecules derived from HUFA play an important part in determining sleep onset and offset. Subjective reports from participants in treatment trials strongly suggest that fatty acid supplementation may help to improve sleep for some people, especially for those who had difficulty in getting to sleep at night and waking up in the morning.

What Kind of Supplements will Work Best?

First, it should be re-emphasised that fatty acid supplements will not ‘work’ for everyone. Some people already get all the HUFA they need via their diet and/or their own metabolism. Individual differences in constitution, diet and lifestyle are all important, so there can be no universal answers.

Omega-3 fatty acids play a crucial role in eye and brain function, yet these are the ones most likely to be lacking from modern diets. The only way to get the complex omega-3 fatty acids (EPA and DHA) directly from the diet is by consuming large amounts of oily fish and seafood on a regular basis. This is often impractical, so fish or marine oil supplements are sometimes the only realistic option.

Omega-6 fatty acids are also important, with evening primrose oil being the best-known. Evening primrose alone often helps with the dry skin problems and allergies common in people with ADHD, dyslexia and dyspraxia (and often found in their relatives).

Omega 3: EPA versus DHA?

Fish oil contains two major omega-3 fatty acids: EPA and DHA. Both are necessary, but until recently, it wasn’t at all clear which of these was more important in producing the benefits reported for ADHD and related conditions. However, the latest research makes clear that it is EPA, not DHA, which is more effective in reducing the problems with attention, perception and memory that are associated with ADHD, dyslexia and dyspraxia. So supplements with a high ratio of EPA to DHA are likely to be most effective.

A note of caution should also be sounded about any fish liver oils. They do provide an excellent source of omega-3 fatty acids but also contain significant levels of Vitamin A, which can be harmful in excess.

A final point concerns the quality of oils used. The popularity of both evening primrose and fish oils has led to a huge number of different supplements becoming available. Unfortunately, not all of these are of good quality. Any reputable supplier should be able to provide information on both the source of their oils and their manufacturing methods, but do not assume that the cheapest oils are the best value.

Are there any Negative Side-Effects and What Dose is Appropriate?

Highly unsaturated fatty acids are safe even in extremely large doses, and their regular consumption carries a wide range of positive health benefits. They are foodstuffs, not drugs. Indeed they used to form an important part of our natural diet for centuries, but have been disappearing from our food in recent decades.

The appropriate dosage will vary between individuals and it is very important to recognise that it can sometimes take up to three months for the maximum benefits to become apparent although some individuals report clear benefits as rapidly as two weeks after starting supplementation.

Informing the GP is strongly recommended before embarking on any kind of dietary supplementation, and this is obviously essential if someone is already taking any medications or being treated for any other condition.

As emphasised throughout, not everyone can expect noticeable benefits from taking fatty acid supplements. If no improvements are apparent within three months then it is reasonable to conclude that fatty acid deficiency is not a major factor for that individual.