Memories can be erased using a drug commonly prescribed for high blood pressure, research has shown.

The discovery could lead to new ways of treating people suffering from the emotional after effects of traumatic experiences such as terrorist attacks or natural disasters.

But one British expert questioned the ethics of meddling with a person’s mind in this way.

Previous research on animals had shown fear memories are susceptible to being altered at the time they are recalled.

At this crucial stage the memories are “reconsolidated” in the brain. Studies suggested beta-blockers, a family of drugs normally used to treat high blood pressure, may interfere with the reconsolidation process.

A team of Dutch researchers artificially created a fearful memory by associating pictures of spiders with a mild electric shock delivered to the wrists of the 60 participants.

When the volunteers were shown the spider pictures 24 hours later their “startle” response — a measure of fear — was assessed by testing eyeblink reactions.

Administering the beta-blocker drug propranolol before reactivation of the fearful memory led to a marked reduction in the startle response.

After taking the drug, volunteers were much less disturbed by the spider pictures.

The findings, reported today in the journal Nature Neuroscience, raise the possibility of a new approach to tackling emotional problems and post-traumatic stress disorder.

Study leader Professor Merel Kindt and colleagues from the University of Amsterdam wrote: “Our findings may have important implications for the understanding and treatment of persistent and self-perpetuating memories in individuals suffering from emotional disorders.”