MDMA exposure during a period equivalent to the late human third trimester causes lasting learning and memory impairments in rats, while exposure during the early third trimester has little effect. Rats given MDMA on days 11–20 after birth showed dose-related difficulties in sequential learning and spatial learning and memory, but not in swimming or cued learning. Body weight temporarily dropped but recovered to 90–95% of controls. Brain chemical changes were small and did not explain the learning deficits. These findings suggest MDMA may pose a previously unrecognized risk to the developing brain.
Rats given MDMA from postnatal days 11 to 20 showed lasting deficits in spatial learning and memory, even when growth restriction from the drug was matched by raising rats in larger litters. Males exposed to MDMA took longer and made more errors in the Cincinnati water maze than control males. In the Morris water maze, MDMA-treated rats of both sexes were impaired during initial learning. Only females showed deficits when the platform was first moved, but both sexes were impaired after a second move with a smaller platform. No differences appeared in swimming ability, cued navigation, or stress hormone responses. Growth retardation, injections, or litter size did not account for the learning impairments.