Autism 'could be triggered by very low doses of anti-depressants or other chemicals found in water supply'Just traces of drugs appear to bring on disorderScientists test fish swimming in water contaminated with low levels of medicationDisorder appears to be combination of environmental and genetic factors

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UPDATED:

10:28 GMT, 7 June 2012

Autism in genetically vulnerable people could be triggered by very low levels of chemicals found in the water supply, researchers have discovered.

Experts from the University of Idaho in the US were 'astonished' to find that just traces of common medication such as anti-depressants can bring on the disorder.

They made the discovery by observing the changes in the genetic pathways of fish swimming in water contaminated with psychoactive drugs.

Flushed away: Traces of psychoactive drugs found in our water supply could trigger developmental disorders, scientists believe

Flushed away: Traces of psychoactive drugs found in our water supply could trigger developmental disorders, scientists believe

Lead scientist Dr Michael Thomas said: 'While others have envisioned a causal role for psychotropic drugs in idiopathic autism, we were astonished to find evidence that this might occur at very low dosages, such as those found in aquatic systems.'

The fish were exposed to two kinds of
anti-depressants – Prozac and venlafaxine – and a drug used to control
seizures, called carbamazepine.

Concentrations were comparable with the highest estimated environmental levels.

Fascinating find: Scientists examined fish swimming in water contaminated with small doses of anti-depressants or anti-seizure drugs

Fascinating find: Scientists examined fish swimming in water contaminated with small doses of anti-depressants or anti-seizure drugs

They
found patterns of gene activity in the fathead minnows that mimicked
those seen in humans susceptible to the developmental disorder.

WHAT IS AUTISM AND HOW IS IT TREATED

Autistic spectrum disorders begin in childhood and last through adulthood.

Symptoms include problems with social interaction, an impaired ability to communicate and unusual patterns of thought and physical behaviour.

There is no cure for ASD but a wide range of treatments can help improve symptoms.

The number of cases of ASD has increased over the past 20 years, but many believe this is due to improved rates of diagnosis.

The
findings, published in the online journal Public Library of Science ONE, suggest a potential environmental trigger for autism in
genetically vulnerable people, the authors of the study claim.

It could radically change treatment for the one in 100 children in England who have autism, improving doctors' understanding of how to prevent or treat the disorder.

The genetic pathways affected were
the same as those associated with 'idiopathic' autism spectrum
disorders, whose cause is unknown.

Experts suspect the disorders were brought about by a combination of genetic and environmental factors.

Caroline Hattersley, Head of Information, Advice and Advocacy at The National Autistic Society, said: 'It’s important that we expand research into the causes of autism. We know that environmental and genetic factors have some role to play, but our understanding is still very limited as it’s such a complex disability.

'However, we need to be cautious when looking at these particular findings. There’s simply not enough evidence to draw any firm conclusions and so people should not be alarmed by this research.'