The research in your article "Proof positive. Taking ecstasy
permanently alters your brain" (6 November) proves no such thing.
What it shows is that taking illegally procured "pills" causes
changes in the brain. Because Ecstasy is illegal, the content of
illegal pills is hardly ever MDMA, the substance which clubbers
seek.

So, if this research was conducted on real life clubbers, it
certainly cannot be concluded that MDMA causes any such effect.
Illegal pills are often related chemicals, such as MDEA or MDA or
cocktails of these and other drugs. No conclusions can be drawn
about the health effects of using dance drugs whilst they remain
illegal.

Derek Williams
Norwich