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BABIES who go on to develop autism or learning difficulties have
significantly raised levels of key brain growth factors when they鈥檙e born, say
researchers in the US.

The discovery might lead to an early diagnostic test for autism, allowing
special care to start at a very young age. It could even make it possible to
treat or even prevent autism and learning difficulties.

Karin Nelson and her colleagues at the National Institute of Neurological
Disorders and Stroke in Maryland analysed blood samples from 69 children with
autism, 60 with learning difficulties, 63 with cerebral palsy and 54 healthy
children. The samples were taken at birth, before any problems became evident,
between 1983 and 1985.

The researchers looked at the levels of several neural growth factors in
their blood. They found that 99 per cent of children with autism and 97 per cent
of children with learning difficulties had abnormal levels of these factors at
birth. The levels of some neural growth factors were on average three times as
high in the blood of these children.

But although autism and learning difficulties are different disorders, the
blood analysis did not distinguish between them. 鈥淲e would never suggest that
altered levels of these factors are the whole story behind the
disorders鈥攂ut the findings are certainly intriguing,鈥� says Nelson.

鈥淭his is a fascinating study,鈥� agrees Francesca Happe of the Institute of
Psychiatry in London, who studies autism. 鈥淏ut it鈥檚 not entirely clear that the
blood markers are linked to autism per se, or just to mental retardation,鈥� she
says.

The work supports the growing consensus among researchers that there are
basic biological causes of autism, says Nelson. 鈥淭he head size of children who
develop autism is normal at birth and accelerates [compared with healthy
children] in the first two to three years of life. If there is a biological
reason for this, there might be a way to intervene,鈥� she says. In animal
studies, researchers have already managed to alter levels of at least one of the
most important markers, adds Nelson.

Other attempts to identify clear biological markers for autism have failed.
The disorder is not normally spotted until a child starts to show behavioural
symptoms at around 18 months. But more research is necessary to show that
increased levels of neural factors could be used to diagnose autism at birth.
But at the moment it鈥檚 not clear what can be done. Behavioural treatments have
limited success.