Here's what Alexander Shulgin[1] had to say[2] in response to a similar question on the subject:

  Dear Dr. Shulgin:

  Lately I've been hearing a lot of talk about how every
  time you take ecstasy it does permanent damage to the
  brain. I've also heard that ecstasy puts holes in the
  brain. Are these statements true?

    -- Road Dog

  Dear Road Dog:

  No, they are not. The "permanent brain damage" is based
  totally on studies done with experimental animals, with
  the findings extrapolated to encompass the human subject.
  In a simple statement, there have been no studies in man
  that have indicated brain damage.

  The "holes in the brain" is an even more outrageous
  deception. These popular holes are areas in brain scans
  that appear less active in attracting radiolabelled agents
  that are agonists for certain receptor site areas. The
  pictures that are shown for comparison are not of the same
  person with or without MDMA in them, but of different
  people, one of whom has used a lot of ecstasy and the
  other one without any such history. The quintessence of
  this line of mythology is an article that appeared
  recently in the Willamette Week. It not only assured the
  reader that there were holes generated by serotonin loss,
  but that they became flooded with dopamine (the default
  neurotransmitter) and, being attacked by hydrogen
  peroxide, produced rust.

  Sorry, drug warriors. No damage, no holes, no rust.

    -- Dr. Shulgin

I can also strongly recommend reading the information on MDMA (and other psychoactive substances) on erowid.org[3]

[1] - https://en.wikipedia.org/wiki/Alexander_Shulgin

[2] - http://www.cognitiveliberty.org/shulgin/adsarchive/brainhole...

[3] - https://www.erowid.org/chemicals/mdma/mdma.shtml