BPA makes mice anxious, forgetful.

Apr 15, 2010

Tian, YH, JH Baek, SY Lee and CG Jang. 2010. Prenatal and postnatal exposure to bisphenol A induces anxiolytic behaviors and cognitive deficits in mice. Synapse 64: 432-439. doi:10.1002/syn.20746.

Synopsis by Laura Vandenberg

Memory and anxiety behavior were affected in mice that were exposed to low levels of BPA as youngsters, adding more concrete evidence that early life exposure to the synthetic estrogen can alter brain function.

Mice exposed to low levels of bisphenol A (BPA) during early development had impaired memory and altered levels of anxiety later in life, finds a study published in the journal Synapse. These behavioral effects could be related to the changes seen in certain regions of the rodents' brains that control cognition and impulsiveness.

The results support a growing body of research that suggests exposure to BPA early in life alters brain development and affects behaviors in a number of ways. It also adds more evidence to concerns about exposure of humans to BPA during fetal development and infancy. The period of exposure in this study is similar to the third trimester and right after birth in people.

BPA is a widely-used chemical used to make polycarbonate plastics and epoxy resins. It is found in food and drink can linings, some plastic bottles, dental sealants, carbonless paper and many other products. Human exposure through food, air and water is widespread. This, coupled with evidence of an array of health effects, has raised concerns about its safety. Animal studies indicate that exposure during development and early life can alter reproductive organs, the central nervous system and other organs and systems.

In the study, researchers compared mice fed one of two low doses of BPA – either 100 micrograms per kilogram per day or 500 ug/kg/day – from gestation through puberty with untreated mice. These doses were chosen because they are well below the safe dose level of 50 milligrams/kilogram/day identified by the U.S. Environmental Protection Agency.

Several different tests determined the rodents' levels of anxiety and ability to form memories. The animals exposed to the higher dose were more anxious when placed on a raised platform, and the animals exposed to the lower dose were more anxious when in an unfamiliar environment. Animals exposed to either dose had decreased memory recall when exploring a Y-shaped maze.

They also examined the how exposure altered neuron development and activity in specific areas of the brain.  Both doses changed regions of the brain that are important for controlling impulses and making memories.