MDMA is not old enough to show it's long term effects the way smoking or drinking has.
One study of 52 users that where hand selected out of 1500 that showed no cognitive impairment. http://www.addictionjournal.org/viewpressrelease.asp?pr=147 Others studies both before and after have demonstrated issues. The problem is it's hard to find good data on individuals before they started heavy use, and sleep deprivation and dehydration are linked to long term cognitive impairment.
However, if you look at the existing literature there is no large scale and long term study's demonstrating it's safety. And a lot of evidence that MDMA is dangerous.
You keep repeating "MDMA is not old enough..." but MDMA has been around since 1912, and used recreationally since the 60s. While there are certainly risks (mostly due to sourcing issues), negative effects are certainly subtle enough that after 40+ years of fairly widespread use, we haven't seen major epidemiological issues.
Furthermore, these risks must be balanced against the very tangible and easily observable psychological benefits. There's a reason psychotherapists used this drug.
You know what we're sure will ruin your future chances of holding down a job, will stunt your development, and might well lead to severe harm or even death?
Going to prison.
Putting people in prison for harming themselves is the height of absurdity.
One study of 52 users that where hand selected out of 1500 that showed no cognitive impairment. http://www.addictionjournal.org/viewpressrelease.asp?pr=147 Others studies both before and after have demonstrated issues. The problem is it's hard to find good data on individuals before they started heavy use, and sleep deprivation and dehydration are linked to long term cognitive impairment.
However, if you look at the existing literature there is no large scale and long term study's demonstrating it's safety. And a lot of evidence that MDMA is dangerous.