asianfreek: here's a quote taken from our forthcoming MDMA mega-FAQ, from the 'ecstasy myths' section - it basically answers your question

- feel free to ask more if you don't understand it
5. Ecstasy burns holes in your brain
Status: myth
Source: MTV's Special on Ecstasy, 11/28/2000.
Rebuttal: Rick Doblin, PhD – see
http://www.maps.org/media/mtvclarify.html
MTV presented a brain scan of a woman named Lynn Smith, who had consumed a large amount of MDMA. This brain scan was described as showing ‘holes in her brain’, similar to the brain of an elderly woman who had had many strokes. However, the scan actually measures the amount of blood flow in the brain. The ‘holes’ merely demonstrate a lower blood flow in some regions of her brain. These lower figures are relative, not absolute – they are lower relative to her own brain, not to anyone else’s. Not to a “normal” standard. In other words, you could scan anyone’s brain and get the same results, if you wanted to.
Another study, which used more sophisticated techniques to compare MDMA users and non-users, found no significant difference in brain blood flow between the two groups.
More information at the above hyperlink.