|Does the Desire for Drugs Begin Outside Awareness?
NIDA Research Reveals Subconscious Signals Can Trigger Drug Craving
Using a brain imaging technology called functional magnetic resonance
imaging (fMRI), scientists have discovered that cocaine-related
images trigger the emotional centers of the brains of patients
addicted to drugs — even when the subjects are unaware they've
seen anything. The study, published Jan. 30 in the journal PLoS
One, was funded by the National Institute on Drug Abuse (NIDA),
part of the National Institutes of Health (NIH).
A team of researchers at the University of Pennsylvania, led by
Dr. Anna Rose Childress and Dr. Charles O'Brien, showed cocaine
patients photos of drug-related cues like crack pipes and chunks
of cocaine. The images flashed by in just 33 milliseconds — so
quickly that the patients were not consciously aware of seeing
them. Nonetheless, the unseen images stimulated activity in the
limbic system, a brain network involved in emotion and reward,
which has been implicated in drug-seeking and craving.
"This is the first evidence that cues outside one's awareness
can trigger rapid activation of the circuits driving drug-seeking
behavior," said NIDA director Dr. Nora Volkow. "Patients
often can't pinpoint when or why they start craving drugs. Understanding
how the brain initiates that overwhelming desire for drugs is essential
to treating addiction."
To verify that the patterns of brain activity triggered by the
subconscious cues reflected the patients' feelings about drugs,
Childress and her colleagues gave the patients a different test
two days later, allowing them to look longer at the drug images.
The patients who demonstrated the strongest brain response to unseen
cues in the fMRI experiment also felt the strongest positive association
with visible drug cues. Childress notes, "It's striking that
the way people feel about these drug-related images is accurately
predicted by how strongly their brains respond within just 33 milliseconds."
Childress and her colleagues also found that the regions of the
brain activated by drug images overlapped substantially with those
activated by sexual images. This finding supports the scientific
consensus that addictive drugs usurp brain regions that recognize
natural rewards needed for survival, like food and sex.
According to Childress, these results could improve drug treatment
strategies. "We have a brain hard-wired to appreciate rewards,
and cocaine and other drugs of abuse latch onto this system. We
are looking at the potential for new medications that reduce the
brain's sensitivity to these conditioned drug cues and would give
patients a fighting chance to manage their urges."
For more information about cocaine, go to: http://www.drugabuse.gov/DrugPages/Cocaine.html
The National Institute on Drug Abuse is a component of the National
Institutes of Health, U.S. Department of Health and Human Services.
NIDA supports most of the world's research on the health aspects
of drug abuse and addiction. The Institute carries out a large
variety of programs to inform policy and improve practice. Fact
sheets on the health effects of drugs of abuse and information
on NIDA research and other activities can be found on the NIDA
home page at www.drugabuse.gov.
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Medical Research Agency — includes 27 Institutes and
Centers and is a component of the U.S. Department of Health and
Human Services. It is the primary federal agency for conducting
and supporting basic, clinical and translational medical research,
and it investigates the causes, treatments, and cures for both
common and rare diseases. For more information about NIH and
its programs, visit www.nih.gov.