Antidepressants in water activate autism-like genes in fish
Signs of autism have shown up in fish swimming in anti-depressent-laden waters.
Researchers at the Idaho State University exposed fathead minnows to three psychoactive pharmaceuticals - two antidepressants called fluoxetine and venlafaxine, and carbamazepine, which is used to control seizures - and then analyzed the genes being expressed in the fishes' brains.
After 18 days of exposure, the researchers had expected gene expression for several neurological disorders. But they found that the only gene expression patterns affected were those associated with the autism in humans.
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The pathways affected are those associated with idiopathic autism spectrum disorders, which are caused by both genetic susceptibility and environmental triggers.
New Scientist reports that around 80 percent of each antidepressant drug passes through the human body without being broken down, which is why they are found in waste water. If they're not filtered out in purification systems, they can end up in the water supply.
"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," said lead researcher Michael A. Thomas of Idaho State University.
The study suggests that these results could point to potential environmental triggers for autism spectrum disorders in vulnerable populations, but it may not be that cut and dry.
"The study has shown that the drugs affect the expression of genes in fish, and that the fish may behave differently afterwards. This is not the same as 'drugs cause autism in fish'," writes Tom Chivers at The Telegraph, in a piece that warns readers to use caution when studies like this are released.
"Even if it were the same as 'drugs cause autism in fish', it is not the same as 'drugs cause autism in humans', and even if that were the same, it would not be the same as 'the trace amounts of drugs in drinking water can cause autism in humans'," he continues.
Chivers isn't the only one who says people should be careful not to draw too quick a conclusion from these findings.
'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," said Caroline Hattersley, Head of Information, Advice and Advocacy at The National Autistic Society, according to The Daily Mail.
"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."
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