e or mdma (methylenedioxymethamphetamine) works by flooding your brain with every drop of seratonin you have. All your seratonin receptors get hit all at the same time, and you have a groovy night. The crash comes when all your receptors get burned out for the night (a temporary state, where your seratonin receptors simply retreat and stop accepting the rest of your seratonin still floating around in your noggin). With all your seratonin receptors down for the next few days, you feel depressed.
E can be neuro toxic. Neuro toxic means that some of your cells are dying in your brain. It works like this. After your seratonin receptors shut down for the day after your trip, you still have extra seratonin floating around. This seratonin is very similar chemically to dopamine, so sometime a dopamine receptor binds the seratonin and tries to break it down chemically. When a dopamine receptor binds seratonin and tries to break it down, the end result is a chemical much like bleach. As you can imagine, bleack in a neuro receptor is a bad thing, and it kills the entire neuron outright. And there you have it... dead brain cells (sort of). BTW, e does not work like acid by residing in the spinal column. It flushes out of your system, same as meth. Also, if you feel especially crappy the next day, its because most mdma these days is not pure, its cut with meth or caffeine or whatever. Mdma is not cut with heroin, as rumor has it. Heroin is much to expensive, and the ammount that you take in pill form wouldnt do jack especially if you eat it.