Canadian Research Team Looking For Cause of Rise In Autism Cases
Canadian Academy Of Child And Adolescence Psychiatry will investigate theory that mercury in vaccinations may be involved
By Susannah Benady
Montreal – After a decade that has witnessed an exponential increasein the number of cases of autism, a specialist team from McGill Universityis in the throes of a Quebec government-funded study to try to identify someof the possible causes.
Numerous theories have been advanced to explain the rise in pervasivedevelopmental disorders (PDD), including mumps, measles, rubella (MMR)vaccine, toxic metals in the environment, food allergies, and thimerosol ormercury used in many countries to stabilize vaccines. (See related story onpage 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-controlstudy of more than 5,000 children-found no association between MMRvaccination and increased risk of autism or other PDD.
The epidemiologist said the new study will pay particular attentionto testing the mercury hypothesis-whether the increase in intensity of infants’vaccination schedules could be causing mercury accumulation, resulting inpoisoning. But other theories, including whether there is immune system orgastrointestinal dysfunction, will also be examined. Dr. Fombonne is conducting the new study on behalf of families withaffected children-parents desperate to understand the cause of their child’s disorder-and as a public health measure to help allay suspicion aboutvaccines in general. Fears that vaccination is contributing to the rise in PDD, nowgenerally agreed to be 69 cases per 10,000 children, are undermining one ofthe mainstays of the public health system, and that has implications for thewhole population, he told the conference here of the Canadian Academy ofChild 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, forexample, 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 ledto some deaths of unprotected children in Ireland and in the Netherlands.
“It is possible that vaccine uptake levels will fall to the pointwhere, we predict, we will see epidemics of these nasty infectiousdiseases,” 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 therandomized study and is now working to get data on all the controls. The PDDchildren attend the autism clinic at the Montreal Children’s Hospital. Thecontrols are children attending the hospital for benign medical reasons. Both groups of children are ages three or four years and are fromsimilar ethnic and socioeconomic backgrounds, although the PDD children tendto 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% havethe diagnosis of autistic disorder and 30% have the diagnosis ofnon-specific PDD. The children have their blood, hair and nail analysed to check fordietary deficiencies and levels of heavy metal toxicity. They have immunefunction tests. Information is collected on their diet, sleep patterns andbehaviour, immunization history, family history and GI symptoms.
These tests will allow the researchers to evaluate almost all theautism hypotheses currently in circulation, including the vaccine-mercurylink, the essential fatty acid deficiency question and whether the syndromeis a result of an autoimmune disease. Heavy metal toxicity is being measured with mass spectroscopy usingthe specialist toxicology lab in Quebec City. Dr. Fombonne’s team has alsopaired with McGill lab, where experts in the virology of measles will try toreplicate some of Dr. Andrew Wakefield’s findings that prompted him toquestion 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 hisdiet; between his behaviour and biological parameters that involve immunefunction/dysfunction; and between behaviour and exposure to variousneurotoxins.
“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’sbehaviour or how it relates to other aspects of his development.”
Preliminary results on the first data set from 32 PDD children and 15controls show that other than one child with PDD who, with his mother,stands out as having extremely high mercury levels, no significantdifferences have been found between the two groups. The child with the very high mercury levels, who also had high levelsof lead, was however no different from all the other PDD children in hisbehaviour.
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 upany major distinctions between the two groups.
“We have tested all the children’s immunoglobulins, and the PDDchildren 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 ofIgE. This concurs with a separate study of children whose parents wereconcerned about their immune function. The only abnormal finding at the timewas that six of 24 had high levels of IgE. It’s about the same proportionhere.”
All these children with abnormal results have been referred to theimmunologist who works with the team. The children manifest benign atopicconditions 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 forthe thousands of parents convinced their child’s disorder has been triggeredby some environmental mishap. And after researching autism for more than 13years, Dr. Fombonne said he has no hunch about what might be causing theepidemic.