|NIDA Research Uncovers the Neurobiology of Dread
In what is the first brain imaging study of dread, new research supported by
the National Institute on Drug Abuse (NIDA), National Institutes of Health, has
shown that people who experience substantial dread about an adverse experience
can be biologically distinguished from those who can better tolerate the experience.
Understanding how the brains of nonaddicted people guide them in selecting what
actions to take when the outcome of a decision is unpleasant lays the foundation
for further investigations that can compare how drug abusers’ brains make such
choices. The study is published in the May 5, 2006 issue of the journal Science.
“Brain imaging technology offers unique insight into the biological mechanisms
involved in decision-making, which is invaluable in developing tailored treatment
strategies for addiction and drug abuse,” says NIH Director Dr. Elias Zerhouni.
“There is substantial evidence that drug abusers place more value on short-term,
rather than long-term outcomes,” says NIDA Director Dr. Nora D. Volkow. “Past
investigations that have looked at how drug abusers make choices have used positive
rewards. But this study looked at how people made choices when faced with unpleasant
In the study, Dr. Gregory Berns of Emory University School of Medicine and his
colleagues used functional magnetic resonance imaging (fMRI) to create images
of brain activity in 32 nondrug-abusing participants awaiting brief electrical
shocks to their feet. By charting which regions experience increased blood flow
over time, fMRI helps scientists understand the relationship between particular
types of mental activity and specific areas of the brain.
They observed that activity patterns associated with the dread of waiting involved
areas of the brain that govern human pain perception. Specifically, the responses
were seen in brain areas that appear to be ruled by attention more than regions
associated with fear.
The scientists determined each participant’s maximal pain threshold and then
presented them with a series of choices from 36 possibilities. For example, each
person could elect to receive a shock that was 30 percent of their threshold
in 27 seconds or one that was 60 percent in 9 seconds.
“We noted that normal, healthy subjects could be divided into two groups — extreme
dreaders, who could not tolerate a delay and preferred an immediate (and stronger)
painful stimulus; and mild dreaders, who could tolerate a delay for a milder
shock,” says Dr. Berns. “We saw that the extreme dreaders could be distinguished
from the mild dreaders by virtue of the information captured on the brain scans.
The findings suggest that dread derives, in part, from the attention devoted
to the expected physical response and is not simply a fear or anxiety reaction.”
“Continuing to use drugs despite the expectation of the practice’s negative
effects is a hallmark of addiction,” says Dr. Volkow. “The results of this study
form the foundation for future research to determine whether drug abusers exhibit
disruption in the brain systems that process the anticipation of unpleasant consequences.”
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 ensure the rapid dissemination
of research information and its implementation in policy and 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 http://www.drugabuse.gov.
The National Institutes of Health (NIH) — The Nation's 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.