Re: what are the long term effects of MDMA on brain chemistry?

Before I answer your question, I want to make a brief comment about your 
use of the word “prove.” My own bias is that I believe scientists rarely 
“prove” anything because research findings are virtually always open to 
revision. I prefer to use terms such as “research suggests” or “supports.” 
Having said that I will get back to your question. 

MDMA (3,4-methylenedioxymethamphetamine) is a popular recreational drug, 
especially among college students. It is also known as “Ecstasy”, “XTC”, 
“ADAM” and “MDM.”   The drug company Merck did some early  research on MDMA 
(circa 1912-14) and was going to market it as a method to reduce appetite, 
but it never actually did so.  In the 1950’s the US army experimented with 
MDMA as a possible “truth serum” drug, but these studies were not 
successful. The drug started to be used recreationally in the 1970’s and 
around the same time, some psychotherapists began experimenting with it as 
an aid to psychotherapy.  There is some evidence that suggests that MDMA 
enhances sociability, but this is mostly based on subjective self-reports. 
In 1985, MDMA was outlawed in the US.  

MDMA appears to increase the secretion of serotonin into the synapses and, 
similar to the SSRI drugs, it also inhibits the reuptake of serotonin (as 
well as noradrenaline).   In terms of your question, there is some animal 
research that suggests that MDMA damages serotonergic nerve endings at drug 
doses that approximate typical human recreational use. I suspect that your 
question may also be related to a recent study published in the medical 
journal Lancet (see http://www.erowid.org/entheogens/x/ricaurte/
ricaurte_study_1098.shtml#summary).  This study used PET scans to 
compare a small group of previously heavy users of MDMA (who now abstained from 
all drug use), with a control group of persons who had never used MDMA.  Similar 
to the animal studies, this report also suggested that MDMA may damage serotonin 
neurons and/or its transmission.   The study did not really address the 
functional implications of these effects, if any.  

I would like to warn you about jumping to any conclusions based on a small 
number of studies such as these.  First of all, human experiments with 
illegal drugs such as MDMA are difficult to carry out because of legal and 
ethical reasons. Thus,  research conclusions are often based on 
correlational data. Remember that cause and effect relationships can only 
be demonstrated with the use of true experiments.  Also, the Lancet study 
above does not address the long term effects of abstinence. For example, 
there is some anecdotal research that suggests that SSRIs do lose their 
therapeutic effects in some subjects who use MDMA, but that these effects 
may return to normal after several years. 

Note that I am not suggesting that MDMA is harmless. if your question is 
motivated by your own MDMA use, I would like to warn you that several 
deaths have been associated with the use of MDMA. Although most of these 
deaths were persons with some type of underlying cardiovascular problems, I 
would not minimize the risks of using MDMA or other illicit drugs.