Drug may reduce bad memories
31 May 2011
Recalling painful memories while under the influence of the
drug metyrapone reduces the brain’s ability to re-record the negative
emotions associated with them, according to researchers at the
Centre for Studies on Human Stress of Louis-H. Lafontaine Hospital,
University of Montreal.
The team’s study challenges the theory that memories cannot be
modified once they are stored in the brain. “Metyrapone is a drug
that significantly decreases the levels of cortisol, a stress
hormone that is involved in memory recall,” explained lead author
Manipulating cortisol close to the time of forming new memories
can decrease the negative emotions that may be associated with them.
“The results show that when we decrease stress hormone levels at the
time of recall of a negative event, we can impair the memory for
this negative event with a long-lasting effect,” said Dr. Sonia
Lupien, who directed the research.
Thirty-three men participated in the study, which involved
learning a story composed of neutral and negative events. Three days
later, they were divided into three groups – participants in the
first group received a single dose of metyrapone, the second
received double, while the third were given placebo. They were then
asked to remember the story.
heir memory performance was then evaluated again four days later,
once the drug had cleared out.. “We found that the men in the group
who received two doses of metyrapone were impaired when retrieving
the negative events of the story, while they showed no impairment
recalling the neutral parts of the story,” Marin explained. “We were
surprised that the decreased memory of negative information was
still present once cortisol levels had returned to normal.”
The research offers hope to people suffering from syndromes such
as post-traumatic stress disorder. “Our findings may help people
deal with traumatic events by offering them the opportunity to
‘write-over’ the emotional part of their memories during therapy,”
Marin said. One major hurdle, however, is the fact that metyrapone
is no longer commercially produced.
Nevertheless, the findings are very promising in terms of future
clinical treatments. “Other drugs also decrease cortisol levels, and
further studies with these compounds will enable us to gain a better
understanding of the brain mechanisms involved in the modulation of