Babies born with EITHER parent over the age of 30 are more likely to suffer from autism
Children are more likely to have autism if either of their parents is older than 35 at the time of conception, according to a major study.
The risk is up to 27 per cent higher than for those with younger parents, according to researchers from Denmark working alongside Cambridge University.
Initially it had been thought that the mother’s age was far more important in affecting whether a child developed the condition.
Older parents are now believed to increase the risk of autism in children
The academics claim that the risk
posed by the mother’s and father’s age are virtually the same. However,
they also found that if both parents are in their late 30s, the child’s
risk of having autism is no higher than if only one of them is.
They studied 1.3million children born
in Denmark between 1980 and 2003. Their findings were published in the
journal Annals of Epidemiology.
It had been thought that it was only the mother's age that mattered.
Around one in 100 children in Britain is thought to have some form of autism.
Last week research from the NHS
Information Centre found that one in 50 men had a type of the condition
compared to one in 300 women.
Caroline Hattersley, of the National
Autistic Society, said: ‘While this research suggests that there is a
link between parental age and autism, more studies are needed. We know
little about the biological chain of events that gives rise to autism.’
If both parents are in their late 30s, the risk does not increase any further than if only one of them is.
However, if one parent is under 35
and the other 40 or over, the extra risk of autism is greater with an
older mother (65 per cent) compared with an older father (44 per cent).
Autism was thought to be linked to natural changes that occur to both eggs and sperm as people age.
The study examined 1.3million children born in Denmark between January 1980 and December 2003
The new study suggests that while age still plays a role, there must also be some other explanation which is not yet known.
The researchers said that they ‘could
not rule out’ the effect of other environmental factors such as
infections, medication or fertility treatment, and added that more work
was needed to see if this was the case.
But they also suggested their
findings could reflect the fact that older parents may seek help for
children with developmental delays sooner.
The
study examined 1.3 million children born in Denmark between January
1980 and December 2003. Of those, 9,556 were later diagnosed with a
disorder on the autistic spectrum by a child psychiatrist after being
referred for treatment. This includes autism, Asperger’s syndrome and
other developmental conditions.
The
study, published in the journal Annals Of Epidemiology, was led by
Professor Erik Thorlund Parner at the University of Aarhus in Denmark,
but also included work by Professor Simon Baron-Cohen at Cambridge
University.
Prof Parner said: ‘The [old] explanation was that new mutations in the sperm increase the risk for autism, and that new mutations in the egg increase the risk for autism.
‘One would then expect that if a couple had these particular mutations in both the sperm and the egg, then they would have a higher risk for autism than if only one parent had the particular mutation. We don’t see this pattern.’
Caroline Hattersley of The National Autistic Society said: ‘While this research suggests that there is a link between parental age and autism, more studies are needed to understand the factors.
‘Much research has posited risk factors, but we know little about the biological chain of events that gives rise to autism.’
Autistic spectrum disorders affect about one per cent of all children. After that, Ms Stewart, who is dating her Twilight co-star Robert Pattinson, will be seen in a big-screen version of Jack Kerouac’s classic Beat Generation book On The Road and Snow White And The Huntsman, a reworking of the familiar fairy tale.