A new US study has confirmed a sharp but unexplained rise in the number of childhood autism cases being reported by health centres in California. The research also rules out suggested reasons for the 273 per cent increase in cases, including more accurate diagnosis and an influx of children from outside the study area.
The MMR three-in-one vaccination and measles virus in the intestinal tract have both been put forward as reasons for an increase in autism reported by health services in many Western countries, including the Republic. In some instances this has led to a drop in the uptake of the vaccine.
The research team at the MIND Institute at the University of California, Davis, does not attempt to give reasons for the increase, however.
The California study was prompted by a reported 273 per cent increase between 1987 and 1998 in the number of autistic children entering the state's 21 regional centres handling developmental disorders.
The state provided funding for the UC Davis study that involved 684 children aged seven to nine and 17 to 19 years of age. Of the 684 children assessed, 375 were diagnosed as autistic and 309 were grouped as suffering mental disability without a definitive diagnosis of autism.
Some had attempted to "explain away" the increase, according to Dr Robert Byrd, the epidemiologist that led the study.
"Instead we found that autism is on the rise in the state and we still do not know why. The results of this study are, without a doubt, sobering."
The rise could not be explained by more accurate diagnosis. Nor could it be attributed to children migrating into California because 90 per cent of the children in the survey were native to the state, Dr Byrd said. The researchers also said that parents in the younger age grouping more commonly reported gastrointestinal symptoms in the first 15 months.
Dr Mary Grehan, a Dundalk-based GP who provides alternative vaccinations to the MMR, viewed the findings as significant. Her own practice had seen a steady rise in autism cases. "In the 1980s we would seldom see autism cases. They were very, very rare.
"We don't know if the MMR is to blame, but the jury is still very much out on it," she said yesterday.