A drug presently used to treat multiple sclerosis could help people to get rid of memories after suffering trauma or pain, scientists reported in the latest issue of Nature Neuroscience, a British scientific journal.

Multiple sclerosis is an inflammatory disease in which the immune system goes wrong and attacks the healthy organizations. The drug, fingolimod, consists of a small molecule which helps to suppress the immune system, thus treating some cases of multiple sclerosis.

In this new study, however, researchers found that this drug has a second molecular function, independent of the immune system. It can inhibit an enzyme called histone deacetylase, a key epigenetic enzyme that regulates gene expression. Mice given fingolimod were faster at extinguishing previously acquired fear memories.

In an experiment, researchers fed mice with the drug and give them a mild electric shock. When their anxiety is high, mice tend to stop moving and fear the chamber where they were given the shock. However, that behaviour reduced much more rapidly when they had taken fingolimod.

The findings, made by American scientists at Virginia Commonwealth University, suggest that this drug could be used to treat post-traumatic stress disorder and other anxiety disorders, if the same finding holds in people.