MDMA is one of the few psychedelics known to actually cause long term changes to the brain: "Numerous studies in animals have shown that MDMA can produce long-lasting decreases in brain functions involving the neurotransmitter serotonin", “Consistent reports link repeated ecstasy use to depressed mood”, “there are a number of case reports of psychiatric disorders, such as psychosis, depression, and panic attacks in ecstasy users”. That’s all quoted from Erowid, and there are a lot more of these negative long term effects shown here: Erowid MDMA (Ecstasy) Vault : Does MDMA Cause Brain Damage?, by Matthew Baggott & John Mendelson

In the early days, SWIM stayed away from MDMA because it didn't have a long history of use. Now he's glad he did. It seems there are a lot of tests out there showing very negative long term effects.

Considering all the negative long term effects related to MDMA use, I highly recommend NOT using it. Long term mescaline use has shown NO negative effects in humans. It’s been used for hundreds of years by millions of people. I recommend all MDMA users switch to using mescaline. It’s much less harmful.