BPA impairs synapses formation in brain, new study finds

The U of G research has been covered by media outlets across the world, including the Globe and Mail, National Post, Ottawa Citizen, Canadian Press, Washington Post, Times of India, Global television and CTV.

The study reveals that continuous low doses of Bisphenol A (BPA) hinders the formation of synapses in the brain, which allow neurons to communicate with one another and are critical to the way we interpret and remember experiences.

"It dramatically impairs the formation of synapses in the regions of the brain important to learning," said biomedical sciences professor Neil MacLusky. "These findings are worrisome because BPA is one of the most widely used chemicals in the world."

BPA is used in plastic water bottles and some baby bottles, dental prostheses and sealants, and in the lining inside of food cans. It has been proven that this chemical can leach from these products and be absorbed through human consumption.

Although previous research has been done on the harmful effects of BPA, MacLusky's study, set to be published this week in the Proceedings of the National Academy of Sciences, is the first to mimic continuous environmental exposure levels.

Using the dose level declared safe by the U.S. Environmental Protection Agency for daily consumption by humans, the researchers exposed African green monkeys living on the Island of St. Kitts to BPA for a month.

Results showed that even at this low dose, BPA turns off increases in synapses density in the brain normally induced by estrogen, said MacLusky.

"Estrogen is more than just a female reproductive hormone. It enhances the rate at which some types of synapses are formed and is vital in maintaining normal neuronal structure in regions of the brain that control learning, memory and mood state. When we have BPA in our systems, it seriously impairs this process."

Although further research is needed, these results support the possibility that BPA may be involved in human neurological conditions such as Alzheimer's disease, depression and schizophrenia, which all feature aberrant synapse formation and are also sensitive to sex hormone levels, he said.

This study was funded by the U.S. National Institutes of Health and the Natural Sciences and Engineering Research Council of Canada.