Janice Juraska, Ph.D.
University of Illinois
NIEHS grantees found that adult rats exposed to phthalates early in life had a smaller medial prefrontal cortex region of the brain and performed worse on attention-switching tasks than rats who were not exposed. The study provided new evidence of the neurological effects of phthalates, a chemical commonly used in plastics, on a region of the brain important for behavior and cognition.
Throughout pregnancy and lactation, researchers fed female rats a daily mixture of phthalates at two different levels within the range of estimated daily human exposures. Compared with offspring of females not exposed to phthalates, they found the adult offspring of exposed rats had a smaller medial prefrontal cortex that contained fewer neurons and synapses. They also observed a deficit in cognitive flexibility, which is the ability to switch between thinking about two different concepts and to think about multiple concepts simultaneously. Rats with fewer overall synapses were less cognitively flexible than those with more synapses.
According to the authors, the study is unique in demonstrating the effects of early-life exposure to environmentally relevant phthalate levels on cognitive regions of the brain. The effects were independent of sex, which suggests a common neurotoxic effect of phthalates on the developing cortex of both males and females.
Citation: Kougias DG, Sellinger EP, Willing J, Juraska JM. 2018. Perinatal exposure to an environmentally relevant mixture of phthalates results in a lower number of neurons and synapses in the medial prefrontal cortex and decreased cognitive flexibility in adult male and female rats. J Neurosci 38(31):6864−6872.