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ANIDA-supported study has provided the first direct evidence that
chronic use of MDMA, popularly known as "ecstasy," causes brain damage
in people. Using advanced brain imaging techniques, the study found that
MDMA harms neurons that release serotonin, a brain chemical thought to
play an important role in regulating memory and other functions. In a related
study, researchers found that heavy MDMA users have memory problems that
persist for at least two weeks after they have stopped using the drug. Both
studies suggest that the extent of damage is directly correlated with the
amount of MDMA use.
"The message from these studies is that MDMA does change the
brain and it looks like there are functional consequences to these changes,"
says Dr. Joseph Frascella of NIDA's Division of Treatment Research and
Development. That message is particularly significant for young people who
participate in large, all-night dance parties known as "raves," which are
popular in many cities around the Nation. NIDA's epidemiologic studies indicate
that MDMA (3,4-methylenedioxymethamphetamine) use has escalated in
recent years among college students and young adults who attend these social
gatherings.
In
the brain imaging study, researchers used positron emission tomography (PET) to
take brain scans of 14 MDMA users who had not used any psychoactive drug,
including MDMA, for at least three weeks. Brain images also were taken
of 15 people who had never used MDMA. Both groups were similar in age and level
of education and had comparable numbers of men and women.
In
people who had used MDMA, the PET images showed significant reductions in the
number of serotonin transporters, the sites on neuron surfaces that reabsorb
serotonin from the space between cells after it has completed its work. The
lasting reduction of serotonin transporters occurred throughout the brain, and
people who had used MDMA more often lost more serotonin transporters than those
who had used the drug less.
Previous PET studies with baboons also produced images indicating
MDMA had induced long-term reductions in the number of serotonin transporters.
Examinations of brain tissue from the animals provided further confirmation
that the decrease in serotonin transporters seen in the PET images corresponded
to actual loss of serotonin nerve endings containing transporters in the
baboons' brains. "Based on what we found with our animal studies, we maintain
that the changes revealed by PET imaging are probably related to damage of
serotonin nerve endings in humans who had used MDMA," says Dr. George Ricaurte
of The Johns Hopkins Medical Institutions in Baltimore. Dr. Ricaurte is the
principal investigator for both studies, which are part of a clinical research
project that is assessing the long-term effects of MDMA.
"The real question in all imaging studies is what these changes mean
when it comes to functional consequences," says NIDA's Dr. Frascella. To help
answer that question, a team of researchers, which included scientists from
Johns Hopkins and the National Institute of Mental Health who had worked on the
imaging study, attempted to assess the effects of chronic MDMA use on memory.
In this study, researchers administered several standardized memory tests to 24
MDMA users who had not used the drug for at least two weeks and 24 people who
had never used the drug. Both groups were matched for age, gender, education,
and vocabulary scores.
The study found that, compared to the nonusers, heavy MDMA users had
significant impairments in visual and verbal memory. As had been found in the
brain imaging study, MDMA's harmful effects were dose related, the more MDMA
people used, the greater difficulty they had in recalling what they had seen
and heard during testing.
The memory impairments found in MDMA users are among the first
functional consequences of MDMA-induced damage of serotonin neurons to emerge.
Recent studies conducted in the United Kingdom also have reported memory
problems in MDMA users assessed within a few days of their last drug use. "Our
study extends the MDMA-induced memory impairment to at least two weeks since
last drug use and thus shows that MDMA's effects on memory cannot be attributed
to withdrawal or residual drug effects," says Dr. Karen Bolla of Johns Hopkins,
who helped conduct the study.
The Johns Hopkins/NIMH researchers also were able to link poorer
memory performance by MDMA users to loss of brain serotonin function by
measuring the levels of a serotonin metabolite in study participants' spinal
fluid. These measurements showed that MDMA users had lower levels of the
metabolite than people who had not used the drug; that the more MDMA they
reported using, the lower the level of the metabolite; and, that the people
with the lowest levels of the metabolite had the poorest memory performance.
Taken together, these findings support the conclusion that MDMA induced brain
serotonin neurotoxicity may account for the persistent memory impairment found
in MDMA users, according to Dr Bolla.
Research on the functional consequences of MDMA-induced damage of
serotonin-producing neurons in humans is at an early stage, and the scientists
who conducted the studies cannot say definitively that the harm to brain
serotonin neurons shown in the imaging study accounts for the memory
impairments found among chronic users of the drug. However, "that's the
concern, and it's certainly the most obvious basis for the memory problems that
some MDMA users have developed," Dr. Ricaurte says.
Findings from another Johns Hopkins/NIMH study now suggest that
MDMA use may lead to impairments in other cognitive functions besides
memory, such as the ability to reason verbally or sustain attention.
Researchers are continuing to examine the effects of chronic MDMA use on
memory and other functions in which serotonin has been implicated, such as
mood, impulse control, and sleep cycles.
How long MDMA-induced brain damage persists and the long-term
consequences of that damage are other questions researchers are trying to
answer. Animal studies, which first documented the neurotoxic effects of the
drug, suggest that the loss of serotonin neurons in humans may last for many
years and possibly be permanent. "We now know that brain damage is still
present in monkeys seven years after discontinuing the drug," Dr. Ricaurte
says. "We don't know just yet if we're dealing with such a long-lasting effect
in people."
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