It implies the possibility of long-term effects which may not be reversible

Dr Philip Murphy, Edge Hill College of Higher Education

The psychologists compared groups of non-users, current ecstasy users and people who had not touched the drug for at least six months.

The tests involved the 'working memory' which is concerned with common tasks such interpreting visual and audio information and understanding language.

Everyday tasks

Deficiencies in such tests typically indicate potential problems on a range of everyday tasks.

Performing under time pressure, the users and former users made significantly more mistakes than the non-users.

Researcher Dr Philip Murphy said: "The poor performance on these tasks of former ecstasy users is potentially worrying as it implies the possibility of long-term effects which may not be reversible."

Former users rated themselves as significantly more mentally alert than current users.

Dr Murphy said: "One speculative interpretation is that this may be indicative of the abnormal regeneration of nerve fibres in the brain containing serotonin, after initial damage caused by the toxic effects of ecstasy (MDMA).

"Such abnormal regeneration has been found in studies of laboratory animals given ecstasy."

Serotonin is a chemical that enables messages to be passed around the brain.