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Special Needs Research and News
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Thursday, September 07, 2006
Medical Research News
Published: Thursday, 24-Aug-2006
According to new research the common medical belief that young children with autism have accelerated brain growth is not the case even though their brains may appear enlarged.
The results of a study by researchers at the University of Washington School of Medicine, has found that the abnormality seen in the brains of autistic children in magnetic resonance imaging (MRI) scans is clearly not because of accelerated brain growth.
The findings while they confirm some earlier reports also conflict with others.
Dr. Stephen Dager and his colleagues compared 60 autistic children to 16 children with developmental delay and 10 children with typical development by using MRI scans to measure how much water was moving around inside the brain tissue, which gives clinicians an indirect measure of brain maturation.
The researchers found the autistic children had differences in the gray matter of their brains compared to the children with typical development.
A number of earlier studies have suggested the brains of younger children with autism are 10 percent larger, but Dager says their research focussed on tissue chemistry and found the abnormality wasn't due to lack of "pruning," which is how the normal developing brain rids itself of unnecessary neurons.
Dager suggests an alternative hypothesis could be an inflammatory process.
He says that would be consistent with adult studies that found higher levels of cytokines, associated with inflammation, in postmortem studies.
The popular theory that autistic children experience a more rapid brain growth that plateaus out at the age of 5 or 6 was not evident and in fact says Dager the opposite appeared to be true.
Dager says the processes that go hand in hand with brain maturation were slower in the autistic brains, particularly in gray matter.
Experts in the field say the findings are interesting and support other studies which suggest that autism could be a premature development leading to disorganized circuitry so that synaptic pruning didn't occur, and noise became predominant over signal itself.
But Dager's study suggests gray matter development in autism involves the same volume as normal brains, but fewer neurons and that gray matter abnormality could be inflammatory.
He says the scans appear to suggest there is more water in autistic children's brains.
This differences in gray matter was found only in the brains of autistic children, while both gray and white matter differences were found in the brains of children with learning delays.
For children with learning delays, the findings suggest slowed neuronal development is to blame.
Gray matter consists of the brain's neurons, while white matter is the brain's wiring system.
According to a recent study from the U.S. Centers for Disease Control and Prevention, autism affects up to one in every 175 school-age children and boys are nearly four times more likely to be diagnosed with autism than girls.
The study is published in the Aug. 22 issue of Neurology.
James Randerson Monday September 4, 2006
A study linking autism with bacteria in the gut today raised hopes that the condition could be treated using probiotics.
The result are very preliminary, but the scientist responsible, Professor Glenn Gibson of the University of Reading, said he was "cautiously optimistic" about them. He added that the study did not suggest any connection between autism and childhood vaccinations.
Prof Gibson told the annual British Association Festival of Science in Norwich that autistic children often suffered with bowel problems such as diarrhoea and constipation, suggesting that they may not have a normal collection of microbes in their guts.
His team compared the bacteria in faeces samples taken from 50 autistic children with those taken from 50 non-autistic subjects, and found that the samples from autistic children had raised levels of the bacterium clostridium.
"Whatever is going on there, [it] is not doing these children any good, and I think almost certainly explains their gastro problems," said Prof Gibson.
More speculatively, he said that some species of clostridium could produce toxins that affected the brain, possibly causing autistic symptoms. But he warned: "The problem with these kinds of studies is, you never know whether it is cause or effect."
To find out, the team set up a trial of a probiotic treatment to reduce the level of clostridium. The trial involved 40 autistic children aged between four and eight. Half were given a harmless bacterium naturally present in the gut, called lactobacillus lantarum; half were given a placebo.
The probiotic was administered as a gramme of powder each day containing around 1bn bacteria. Without being told which group their children were in, parents were asked to record their symptoms.
The results are inconclusive because around half of children dropped out. Some parents withdrew their kids because they did not want them to be swapped on to the placebo.
"Some of the parents worked out that their child was on the [probiotic] and didn't want to move on to the placebo because they were seeing some positive results," said Prof Gibson.
Parents reported that their child's concentration and behaviour had improved, and one mother said it was "heartbreaking" to be told to move on to the placebo.
The Times September 05, 2006
By David Rose
OLDER men are far more likely to father autistic children, according to new research.
A study involving more than 100,000 children found that those born to fathers aged 40 and over were nearly six times more likely to suffer from autism and related disorders than those with a father under 30.
Scientists from the Institute of Psychiatry at King’s College, London and Mount Sinai School of Medicine in New York, said that their research supported the theory that men also have a “biolog-ical clock” when it comes to producing healthy babies.
They described the findings as “the first convincing evidence that advanced paternal age is a risk factor for autism spectrum disorder”. However the authors could not find a link between a mother’s advancing age and autism.
The exact causes of autism remain unknown, but cases of it and related conditions such as Asperger’s syndrome — known collectively as autism spectrum disorders (ASDs) — have increased tenfold in the past two decades. They now affect the lives of more than half a million families in Britain. A recent study suggested that the rate could be as high as 116 ASD cases per 10,000 children.
According to the Office of National Statistics, the number of new fathers aged over 40 rose by about a third in the five years to 2004, when 75,810 older men became parents. Only 32,000 men aged over 40 became fathers in 1983.
Abraham Reichenberg, lead researcher in the latest study, said that genetic mutations in the sperm of older men may be responsible for the increased risk of their children developing ASDs.
Autism is a lifelong disability affecting the way that a person communicates and relates to others. People with autism have impaired social interactions, communication and imagination, including repetitive patterns of behaviour.
Better diagnosis has contributed to the rising rates of autism, but experts also believe that there may be more cases. Scientists have dismissed suggestions that the increase might be linked to the use of MMR, the combined childhood vaccine given to protect against measles, mumps and rubella.
The latest study, published in the Archives of General Psychiatry, analysed 132,271 Jewish children born during the 1980s in Israel. The researchers found that, if the father was aged 15 to 29 when the child was born, the risk of autism was 6 in every 10,000 children. If the father was 30 to 39, then 9 in 10,000 children suffered autism (1.6 times higher), going up to 32 in 10,000 (5.75 times higher) for fathers aged 40 to 49. The risk was even higher for older fathers.
“This research adds to our knowledge that men also have a biological clock when it comes to reproducing,” Dr Reichenberg said. “The sample size for the over-50s was small, so we added it to the results for fathers aged over 40, but our research suggests that very old fathers have around nine times the risk. “The research shows a linear effect — with every ten years, the risk doubles.”
The researchers emphasised that the results related to autism and could not necessarily be generalised to apply to related disorders such as Asperger’s syndrome. But they added: “This data suggests a significant association between advancing paternal age and risk of ASD.”
They said that there were several genetic factors which could be at play, including spontaneous mutations in sperm-producing cells, or discrepancies in how genes are expressed.
Although the fact that all the children were Jewish was a limitation of the study, Dr Reichenberg did not believe it affected the results. More research was needed to see if the findings were replicated across other racial and ethnic backgrounds.
ASDs have been linked with abnormalities in children’s brain development which occur before, during, or soon after birth. The advancing age of parents has also been linked to brain development.
Dr Reichenberg and his team discuss several possible genetic mechanisms to explain the paternal age effect but add: “It is important to keep in mind, however, that age at paternity is influenced by the sociocultural environment and varies across societies and over time.”
The National Autistic Society (NAS), Britain’s leading charity for the condition, said yesterday that the causes of autism were complex and required further investigation.
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