The boldest of the brain blood flow experiments was done by researchers from UCLA's Neurology, Radiology, and Psychiatry departments. They studied the amount of blood flow in current and former 'ecstasy' user's brains and found that recent users (within the past few weeks) had slightly lower blood flow to parts of the brain, but people who hadn't used for four weeks had perfectly normal levels of total and regional blood flow within their brains.[8] That wasn't the bold part, however: Not content simply to test volunteers who had used 'ecstasy' on their own, they gave recreational doses of MDMA to a number of the volunteers after their initial scan, then re-scanned their brains afterwards. As expected, there was a decrease in blood flow immediately after MDMA use, but it returned to normal within 3-4 weeks. In their final report, the researchers concluded that "Low-dose recreational MDMA use does not cause detectable persistent rCBF (regional cerebral blood flow) changes in humans."
Further research has only confirmed their findings, so the answer is...yes and no. Yes, there is a modest change to your brain after using MDMA that seems to last for about three to four weeks, give or take. It's not permanent, and there's no reason to believe it involves damage; rather, it appears to be a sort of 'hangover' effect caused by your brain's reaction to being exposed to a drug.