Led by Duke-NUS Medical School, a team of researchers has discovered a possible link between autistic-like behavior in adult mice and exposure to a conventional antidepressant in the womb. In the new study published in the journal Molecular Brain, also identified by the researchers is a treatment that helped improve memory loss and social interactions.
A regular prescription for treatment of major depression and post-traumatic stress disorder is antidepressant, including in pregnant women. One of the most commonly prescribed antidepressants is fluoxetine, a serotonin reuptake inhibitor.
Fluoxetine has the power to cross the placenta and is also detected in breast milk. The researchers have little knowledge about its safety during pregnancy, and not enough studies have been conducted on its long-term effects on offspring.
A senior and corresponding author of the study Hyunsoo Shawn Je, Associate Professor from Duke-NUS' Neuroscience and Behavioral Disorder (NBD) Programme, said that many human association studies had been conducted to investigate connections between antidepressant exposure during pregnancy and children with autism and attention deficit disorder (ADHD). But they have not been able to pinpoint a causal relationship.
Along with their collaborators in South Korea and Singapore, the Duke-NUS team investigated adult mice born to mothers treated with fluoxetine, sold under the brand names Prozac and Sarafem, over a 15-day time period that corresponds to the second trimester in humans, in comparison with those born to mothers given normal saline as controls.
The researchers found key differences in behavior. One instance of it is the unexposed mice frequently explored all three arms of a Y-shaped maze over a ten-minute and, throughout multiple arm entries, mice usually enter a less recently visited arm, while the fluoxetine-exposed ones were less inclined to explore unvisited arm.
The second experiment of the team was where they introduced the mice to two juvenile mice, one after the other. When the second new mouse was introduced, mice that were not exposed to fluoxetine were more likely only to sniff the newly introduced mouse, recognizing that they had already met the first mouse. But the fluoxetine-exposed group smelled both mice, indicating that they have impaired social novelty recognition.
Next, the researchers intend to investigate autistic children born to mothers treated with antidepressants using positron emission tomography (PET) scans, an imaging technique used to observe metabolic processes in the body. If they also show enhanced serotonin receptor activity in the same area of the brain, the team plans to test whether FDA-approved serotonin receptor blockers can normalize their behaviors.
The Senior Vice Dean for Research at Duke_NUS, Professor Patrick Casey noted that the consensus among experts is that the rise in the number of individuals diagnosed with autism around the world is likely due to more awareness and testing rather than an increase in the prevalence of autism.
