Obviously, the best way to avoid MDMA related memory impairment would be not to take Ecstasy. Clearly not an option for many people.

If you are going to take Ecstasy, we strongly recommend that you take the following precautions:

make E special
only take it occasionally, with lengthy gaps (two or three months at least)

watch the dosage
Never take more than two pills, less if you have a small build. The more MDMA you take, the more likely you are to suffer from the neurotoxic effects and memory impairment.

avoid drinking soft drinks with artifical sweeteners
Aspartame and other sweetners contain phenylalanine, a substance which increases the neurotoxicity of MDMA. Watch for sweeteners in 'alco-pops' and other crappy club drinks. Only drink water and fruit juice.

watch your temperature
The dangers of E and overheating are well known, but heat also increases the neurotoxicity of MDMA. Take breaks, get fresh air, keep cool.

take Vitamin C
Vitamin C is an antioxidant which will prevent MDMA neurotoxicity. Take large amounts of it (500-2000mg) before, during and after, preferably in pill / supplement form, as juice contains relatively low levels of it.

Note: most Vitamin C pills contain artifical sweeteners (see above). Find some that don't.

take 5-HTP afterwards
5-HTP or L-5-Hydroxytryptophan can be found in most health food shops. Your body uses it to make serotonin and it can help build up dimished levels of the neurotransmitter in the brain after an E trip.

Take 50-100mg after your E trip and everyday for a few days afterwards. This will also help prevent the midweek mood swing which often follows a weekend of larging.

Bananas and milk also contain a similar substance (l-tryptophan) so put them in your post-clubbing diet.