It's taken in a pill form, generally. It can also be taken as pressed powder, in capsules, intranasally, or injected. Studies indicate there is potential neurotoxicity in the drug as well. MDMA may precipitate heart attacks or strokes depending on the age of the person, etc. It's so impairing that if a person is driving, it can be very dangerous.
Depth perception is affected.
In addition to this, there's the possibility that what the drug is cut with isn't necessarily controlled, and therefore, it is very unpredictable. I'm not familiar with that study. Yes, testing has been done. There is a belief among certain psychotherapists that MDMA could be useful and there were studies done around that to determine an underlying diagnosis with many of the patients they were testing. Because MDMA does take away the inhibitions and defense structure, their thinking was that it could access some of the underlying issues that might be going on for a patient.