McGill research team to investigate possible mercury/vaccine/autism connection

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Medical Post
November 09, 2004 Volume 40 Issue 42

CANADIAN ACADEMY OF CHILD AND ADOLESCENCE PSYCHIATRY

CACAP: McGill research team looking for cause of rise in autism cases

Will investigate theory that mercury in vaccinations may be involved

By Susannah Benady

MONTREAL � After a decade that has witnessed an exponential increase in the number of cases of autism, a specialist team from McGill University is in the throes of a Quebec government-funded study to try to identify some of the possible causes.

Numerous theories have been advanced to explain the rise in pervasive developmental disorders (PDD), including mumps, measles, rubella (MMR) vaccine, toxic metals in the environment, food allergies, and thimerosol or mercury used in many countries to stabilize vaccines. (See related story on page 48.)

These theories are now being put to the test by autism expert Dr. Eric Fombonne, whose recent paper published in the Lancet�a case-control study of more than 5,000 children�found no association between MMR vaccination and increased risk of autism or other PDD.

The epidemiologist said the new study will pay particular attention to testing the mercury hypothesis�whether the increase in intensity of infants' vaccination schedules could be causing mercury accumulation, resulting in poisoning.

But other theories, including whether there is immune system or gastrointestinal dysfunction, will also be examined.

Dr. Fombonne is conducting the new study on behalf of families with affected children�parents desperate to understand the cause of their child's disorder�and as a public health measure to help allay suspicion about vaccines in general.

Fears that vaccination is contributing to the rise in PDD, now generally agreed to be 69 cases per 10,000 children, are undermining one of the mainstays of the public health system, and that has implications for the whole population, he told the conference here of the Canadian Academy of Child and Adolescent Psychiatry.

"This problem has an impact beyond families with autistic children," he said.

The far-reaching effect of the debate over MMR vaccination, for example, had been that the uptake of MMR vaccine had fallen to 82% in the U.K. and much lower in some parts of that country. The lower uptake has led to some deaths of unprotected children in Ireland and in the Netherlands.

"It is possible that vaccine uptake levels will fall to the point where, we predict, we will see epidemics of these nasty infectious diseases," said Dr. Fombonne, who holds a Canada Research Chair in Child and Adolescent Psychiatry at McGill University.

The team has so far completed data collection on 73 children in the randomized study and is now working to get data on all the controls. The PDD children attend the autism clinic at the Montreal Children's Hospital. The controls are children attending the hospital for benign medical reasons.

Both groups of children are ages three or four years and are from similar ethnic and socioeconomic backgrounds, although the PDD children tend to be in more stable family situations than the controls, said Dr. Fombonne.

The PDD children all function roughly with two standard deviations below the mean on standardized measures. Of the 73 PDD subjects, 70% have the diagnosis of autistic disorder and 30% have the diagnosis of non-specific PDD.

The children have their blood, hair and nail analysed to check for dietary deficiencies and levels of heavy metal toxicity. They have immune function tests. Information is collected on their diet, sleep patterns and behaviour, immunization history, family history and GI symptoms.

These tests will allow the researchers to evaluate almost all the autism hypotheses currently in circulation, including the vaccine-mercury link, the essential fatty acid deficiency question and whether the syndrome is a result of an autoimmune disease.

Heavy metal toxicity is being measured with mass spectroscopy using the specialist toxicology lab in Quebec City. Dr. Fombonne's team has also paired with McGill lab, where experts in the virology of measles will try to replicate some of Dr. Andrew Wakefield's findings that prompted him to question the safety of MMR vaccination.

What is unique about the new study is that it will be able to examine the interrelationship between the behaviour of the child, his sleep and his diet; between his behaviour and biological parameters that involve immune function/dysfunction; and between behaviour and exposure to various neurotoxins.

"We will be able to really look at everything�anything unusual, raised or abnormal. We can look at whether or not it affects the children's behaviour or how it relates to other aspects of his development."

Preliminary results on the first data set from 32 PDD children and 15 controls show that other than one child with PDD who, with his mother, stands out as having extremely high mercury levels, no significant differences have been found between the two groups.

The child with the very high mercury levels, who also had high levels of lead, was however no different from all the other PDD children in his behaviour. Neither did he have more cognitive deficits, added Dr. Fombonne.

"If we find no difference, and no correlation between levels of mercury and the PDD children's behaviour�which is what we find so far�this will go a long way to rule out the mercury hypothesis."

Analysis of the children's immune systems has also failed to show up any major distinctions between the two groups.

"We have tested all the children's immunoglobulins, and the PDD children do not appear to be deficient in either IgA, IgE, IgG or IgMs.

"If anything, the mean of the PDD group is slightly higher for IgA. And a significantly raised proportion of the PDD children had high levels of IgE. This concurs with a seprate study of children whose parents were concerned about their immune function. The only abnormal finding at the time was that six of 24 had high levels of IgE. It's about the same proportion here."

All these children with abnormal results have been referred to the immunologist who works with the team. The children manifest benign atopic conditions that appear to have no relationship with their autism, he added.

Full results from the study will not be available for another year, but if they follow the pattern set by the first set of patients analysed, they could throw a number of hypotheses out the window, including, Dr. Fombonne suspects, the mercury hypothesis.

If the theories are all shot down, it will leave a gaping void for the thousands of parents convinced their child's disorder has been triggered by some environmental mishap. And after researching autism for more than 13 years, Dr. Fombonne said he has no hunch about what might be causing the epidemic.

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