The brain is built to adapt to changing circumstances. One of the ways your brain adapts is through the up-and-down regulation of receptors. What this means is that if your serotonin receptors get hyper-activated by serotonin molecules, they may retreat into the membrane of the dendrite, essentially shutting themselves down for a while. One theory says they do this in order to avoid getting damaged from over-stimulation. Another theory says that it is just a way for your brain to maintain a balanced, normal state. Whichever one of these theories is true, it has been proven conclusively that serotonin receptors will down-regulate over time if bombarded with large amounts of serotonin.

This may lead to depression, even after your brain serotonin levels have been restored, because the serotonin cannot bind to downregulated receptors. Many ecstasy users we have interviewed have reported periods of depression lasting months or even a year or more following a period of heavy use. Keep in mind, however, that most evidence of MDMA-induced depression is anecdotal, based on reports by MDMA users. Since many people experience depression it is difficult to know for sure whether the depression experienced by MDMA users is really related to their MDMA use. While MDMA is known to reduce serotonin levels, serotonin levels varies greatly among healthy, non-depressed, non-MDMA users. Until more research is done, we cannot know for sure whether MDMA users actually have a greater risk of experiencing depression than non-users. (Of course, it is wise to be cautious, and so we have included a section on our health and safety page about ecstasy-related depression.)

Let's now turn to the issue of neurotoxicity . . .