Why, after 30 years, is diet and ADHD still controversial?

From a presentation at the Dietitians Association of Australia –  Workshop on Food Intolerance June 2009 by Joan Breakey Specialist Food Sensitivity Dietitian.

The blind men and the elephant a verse by John Godfrey Saxe

There was six men of Hindostan, To learning much inclined

Who went to see the elephant, (Though all of them were blind);

That each by observation Might satisfy his mind.

This old verse is an apt one for this discussion as it reminds us that when viewing anything it is important not to have limited vision.

Why is the controversy about diet and ADHD still relevant today?

In fact diet and ADHD is not controversial at all to many people. Changes with diet are blindingly obvious to those whose symptoms improve with diet and then reoccur with challenges. These changes are also obvious to clinical dietitans who regularly see improvements in many families who have trialled diet. Scientists, including dietitians who have read much of the research showing statistically significant connections in double-blind, placebo-controlled trials, know the issue need not be controversial. Many of the public are concerned about the level of additive in the food supply and aim to avoid them in their diet. The health food industry and alternative medicine support the connection between diet factors and behaviour change in children. And media articles present the issue as complex but not controversial.

However there are groups to who the issue is still controversial. These include some paediatricians who have placed diet with unproven and alternative treatments. Some dermatologists say that those who say they have ‘allergies’ without postitive skin prick tests are hypochondriacs! There are met-analysis writers who say the level of evidence is not as good as may be desired. Many health and education professionals see behaviour as only due to other factors. There are even dietitians, usually outside this clinical practice and often unaware of the full extent of the research, who say ’restrictive diets are not supported by the evidence’. The Australian and NZ Foods Standards body [ANZFA] in responding to requests for some dyes to be banned, provided a comment that related only to the amount of dye being consumed, not acknowledging the research showing their role in behaviour, and the importance of ingredient labelling.

Why does the controversy matter? It matters as it affects how health professionals are viewed by other health professionals who may see them as working in what they believe is a less respected area. It matters as FSANZ  does not act as if suspect additives should be seen as a problem particularly compared to allergies. But above all it matters that this valuable treatment that changes attention, impulsivity, restlessness, mood, sleep and many physical symptoms, is not used as much as it should be.

An interesting aspect is that there is no problem providing diet therapy for diet investigation. The range of suspect substances is known. The Family Sensitivity History can show which suspect substances should be the focus, and also the likelihood of successful outcome. Allergens and suspect environmental factors can be incorporated. The level of restriction to match severity of symptoms and motivation can be decided. Behaviours likely to change are known and a questionnaire to record changes with diet has been developed. Time taken to reach the baseline of minimum symptoms for various age groups is known. Challenge and washout time frames are known, and individual variation can be incorporated.

If the research is controversial to some how is it that we can be so secure about the practice? We can because of the way the research developed. In the 1970s research tested Feingold’s hypothesis that diet caused hyperactivity. This was disproved, but the double blind placebo controlled trials showed that some children reacted, so ingredient labelling laws were introduced.

In the 1980s and 1990s several clinicial research teams applied the treatment and reported their findings. This broad approach showed the complexity of the issues involved including the variety of suspect substances that needed to be considered, as well as some individual variation in tolerance. From these and further monitoring of food intolerance the successful clinical practice has developed.

With the variety of people involved in this complex issue it is not really surprising that some have limited vision about what is involved. Following is a rewritten verse applied to diet and ADHD with thanks and apologies to John Godfrey Saxe.

The blind men and the elephant [diet and ADHD]

There were six men of Hindostan,     To learning much inclined,

Who went to see the elephant ,     (though all of them were blind);

That each by observation     Might satisfy his mind.

The first approached the Elephant,     And happening to fall

Against one firmly worded article,     At once began to bawl:

‘Bless me there is no elephant:     There’s nothing there at all!

The second, feeling of the work,     Cried, ‘Ho! What have we here

So very like just what I thought?     To me ‘tis mighty clear

I know about this Elephant     It’s white sugar acting here.’

The third approached the animal,     And happening to take

The many foods he found around,     That most seem to tolerate

‘I see,’ quoth he, ‘The Elephant     Is very much a fake!’

The fourth stretched out his eager hand     And felt that he could see,

‘What most this mighty beast is like     Is mighty plain,’ quoth he:

‘Tis clear enough the Elephant     Affects everyone you see.’

The fifth who chanced to touch a child     Said, ‘Even the blindest man

Can tell what this resembles most;   Deny the fact who can,

This marvel of an Elephant     We’ll solve it with a ban!’

The sixth no sooner had begun     About the beast to grope,

Then, seizing on the stats he found       That fell within his scope,

‘The Elephant exists’ he cried     ‘But not well enough, I note.’

And so these men of Hindostan     Disputed loud and long,

Each in his own opinion     Exceeding stiff and strong,

Though each was partly in the right     And all were in the wrong.

Why are there so many views of diet and ADHD? It is because it is a very complicated issue. This idea needs to be appreciated. Unfortunately since 2000  researchers have hoped for a relatively uncomplicated way to clarify the role of diet in ADHD using simplified hypotheses.  Because of this, and because of the passage of time, a separation of this newer experimental research from the earlier useful complex clinical research has occurred.

Recent researchers, without consulting clinical researchers, chose some suspect substances, chose some dose, chose some age group, chose some symptoms to assess [e.g ADHD]. They chose some amount of change wanted, chose some time frame for challenge, chose some time frame for washout, and chose some preferred statistical method. Despite these decisions affecting the quality of the research they still found statistically significant results. But some of these decisions – especially those relating to dose and washout – affected the level of significance desired by some critics. Met analysis writers selected studies on the basis of statistical aspects of methodology and in so doing have excluded studies which have made important contributions to this complex issue. Valid statistical methodology is not sufficient if other important aspects of methodology have been neglected. One example is the removal and challenge with artificial colours only when around 75% of those who react to these also react to chocolate and tomato sauce.

Diet and ADHD is not the only topic in science that is complex. Consider the effects of alcohol. We all recognise and accept the wide variation in time, intensity and symptoms with alcohol between people and even in one individual. Adjusting to the pharmacological effect of food chemicals should not be a whole new idea to incorporate but it obviously is for some.

This is not research into a treatment that is introduced and tested as a new medication is.

To adequately test the hypothesis that there is a role for diet factors in ADHD researchers first need to exclude sufficient suspect substances to ensure they have not retained a confounding chemical which will affect the results of any challenge. They need to do this for four weeks expecting some withdrawal in food sensitive children. They then need to challenge with doses of suspect chemicals which reflect the amounts of all excluded suspect chemicals typically ingested. Remember that artificial flavours are used in ten times the dose of colours. They need to measure all the symptoms reported to change: ADHD symptoms, mood [especially irritability], settling and sleep, motor and speech development and physical symptoms. They need to incorporate time for withdrawal, diet response, challenge effect and washout. Overall double-blind placebo controlled trials are not useful unless they are actually testing the clinicians’ hypothesis.

To add to the complexity of this issue we still do not know exactly who are diet responders. We still do not know the mechanism so there are no laboratory tests that show who will respond. The symptoms that change vary greatly. Food sensitivity is a multisystem disorder. The amount of improvement varies, and individuals also vary in their tolerance within the group of suspect substances and whole foods. We don’t have all the answers. Think about the elephant. The more we learn about elephants the more we realise we have more to learn to really understand them. More field work is needed!

Having said all of that I can now say that the controversy does not need to matter to you if you are food sensitive or suspect you are, and want to investigate diet. You can be a scientist for your own individual situation. It is wise to have the help and support of your doctor and a dietitian, preferably one experienced in the area. The diet investigation process is known. You can record the symptoms, run a diet trial and do challenges. If there is no change then diet is not relevant. But in those who find the hypothesis confirmed the controversy is solved.  If you are a health professional you are in a position to learn about the elephant and, over time, to learn even more. You can deal with those who have a limited view of the elephant knowing that it will be years before what is know clinically from diet responsive families is accepted broadly.