Volume 43 | Number 1 | Fall 2012
Fall 2012 Issue
A team of Idaho State University researchers discovered that fish show autism-like gene expression after exposure to water containing psychoactive pharmaceuticals. This study was published in June in the open access journal PLoS ONE and was widely publicized nationally and internationally.
The results may suggest an environmental trigger for autism, although this finding may only apply to genetically predisposed individuals.
"The psychoactive pharmaceuticals were tested at concentrations similar to those found in aquatic systems," said Michael Thomas, ISU associate professor of biological sciences, lead researcher in the project and academic director of the MRCF. "This discovery implies that these drugs might be involved in the increase in autism in the past 30 years."
Thomas said that although these findings are significant, it is too early to draw firm conclusions about the study.
"We've really proposed a new question, but not any new answers," he said. "But asking a new question is the first step towards learning something new, and in many ways, it's the most important step. It is our hope that this new question will prove useful for the autism research community, and eventually lead to fruitful new answers. It is important to remember that much more research on this topic is needed — it's not time to draw any conclusions, yet."
The team discovered that certain psychoactive pharmaceuticals induced gene expression patterns in a fish model that mimic expression patterns in humans with autism. The gene expression patterns are associated with neurological development and growth.
The fish exposed to pharmaceuticals also displayed behavioral characteristics that indicate anxiety-like symptoms. This shows that gene expression induced by drugs had a broader impact on the fish.
The drugs studied include an anti-seizure drug carbamazepine and two anti-depression drugs, fluoxetine (brand names include Prozac) and venlafaxine (brand names incude Effexor). These represent some of the most frequently prescribed pharmaceuticals.
This raises the possibility that pregnant women who drink water containing trace concentrations of these drugs will pass them along to the fetus, according to Thomas. The fetus has a leaky blood-brain barrier, which allows drugs to pass directly into the developing brain.
"The drugs affect activity of serotonin and other neurotransmitters, which are important in the development of neurological networks and, basically, affect how the brain is wired," Thomas said.
Again, Thomas emphasized that his study is early-stage work and more study is needed—at this time there is no reason for pregnant women to be concerned about results of the study.
The ISU research team involved with this project included Loubin Yang, biological sciences research assistant professor, and ISU graduate students Parag Joshi, Victor Ezike and Gauray Kaushik. For the project, Thomas also collaborated with Rebecca Klaper at the University of Wisconsin—Milwaukee School for Freshwater Sciences.
Jason Reynolds and Jamie Mayo
ISU Photographic Services/Bethany Baker