There have been over 100 scientific studies examining the effects and side-effects of Ecstasy. Fifteen in particular have studied the effects of MDMA on human memory performance.
However, not all studies are equally well-designed, especially when attempting to measure something as insubstantial and as fluctuating as memory performance. So many factors can influence the results - age, sex, education, intelligence, mood, lifestyle, fitness, sleeping pattern, diet, alcohol, drug use, even time of day.
Of the major studies carried out to date (April 2001) on the effects of Ecstasy on memory performance, only two - Gouzoulis-Mayfrank and Semple - are worth examining closely.