The research was the work of Dr Merel Kindt, a professor in the Faculty of Social and Behavioural Sciences – Clinical Psychology at the University of Amsterdam and other colleagues from the university and was published in the advanced online issue of Nature Neuroscience on 15 February.
Animal studies have shown that memories involving fear can change when recalled, a process that psychologists term reconsolidation.
In this study Kindt and colleagues found that giving human subjects propranolol pills before getting them to recall fear memories erased the behavioural expression of the fear 24 hours later and prevented the return of the fear.
Propranolol is a widely available generic beta-adrenergic receptor antagonist (beta-blocker) that is normally used in the treatment of high blood pressure.
For the study, the researchers recruited 60 healthy male and female volunteers. According to a report in BBC news, on day 1 they got them to learn to associate spiders with fear by giving them mild electric shocks to their wrists while they looked at pictures of spiders.
On day 2 the participants were randomly assigned to either a treatment group or a placebo group. The treatment group was given propranolol and the placebo group was given a dummy drug before they were all shown the spider pictures again.
In each case, the participant’s startle response (how much they blink when a sudden noise occurs) was measured, this is a standard way of measuring how fearful a person is at a certain point in time.
The results showed that the startle response was significantly lower in the treatment group compared to the placebo group.
On day 3, by which time the drug would no longer be in their bodies, the participants were retested. The results were largely similar: the treatment group showed lower startle responses compared to the placebo group.
The researchers concluded that disrupting the reconsolidation of fear memory could be a route to new treatments for patients with emotional disorders.
Kindt told Reuters news agency in a telephone interview that:
“We could show that the fear response went away, which suggests the memory was weakened.”
BBC news reported that Kindt said the drug had dampened the emotional intensity of the fear memories and that animal studies had shown that beta blockers can interfere with how the brain makes sense of fear memories.
She did however caution that it was too early to say if such a procedure would work for complex conditions like post traumatic stress.
The current therapy for helping people cope with bad memories, for instance in post traumatic stress disorder, is to teach them to build new associations and extinguish the bad memory link. The problem with such approaches, Kindt told Reuters, is that people relapse and the memories don’t become extinguished.
The BBC said some British experts were sceptical and questioned the ethics of treating the mind by using drugs to alter memory.
Paul Farmer, chief executive of mental health charity Mind, told BBC news that he was worried about the “fundamentally pharmacological” approach for the treatment of phobias and anxiety.
And medical ethics expert, Dr Daniel Sokol said we need to reflect on the effects of approaches like erasing memories may have on people. What if they also affect the “good memories” and we end up with cases of “accelerated Alzheimer’s”?
“Beyond extinction: erasing human fear responses and preventing the return of fear.”
Merel Kindt, Marieke Soeter and Bram Vervliet.
Nature Neuroscience Published online: 15 February 2009.
Sources: Journal abstract, Reuters, BBC News.
Written by: Catharine Paddock, PhD