 |
| PET
brain scans reveal chemical differences
in the brain between addicts and
non-addicts. The normal images
in the bottom row come from non-addicts;
the abnormal images in the top
row come from patients with addiction
disorders. |
Dopamine, a brain chemical linked
to pleasure and elation, also has
a dark side—a link to addiction.
This link has been explored in detail
by Nora Volkow of Brookhaven National
Laboratory, a world leader in addiction
research. Volkow has shown that that
addicts have fewer than average dopamine
receptors in their brains, so that
weaker dopamine signals are sent between
cells, and life naturally has less
joy. Addicts thus are encouraged to
derive pleasure from dopamine-stimulant
drugs, such as alcohol, cocaine, and
nicotine. This cycle was first identified
in 1990, when Volkow and coworkers
showed that cocaine addiction blunts
the dopamine signaling system. Using
positron emission tomography, an imaging
technique developed with Office of
Science support, they determined the
critical biochemical changes and where
they occur in the brain in response
to addictive drugs. These studies
demonstrated that addictions are associated
with high levels of dopamine in a
pleasure center in the brain. The
findings have been proven again and
again in studies of addictions to
drugs and food/overeating. It is not
yet clear whether a preexisting dopamine
abnormality leads to addiction, or
vice versa.
Scientific Impact:
This work may have uncovered a common
biochemical pathway for addiction.
The findings also opened up new research
areas, including efforts at Brookhaven
and elsewhere to find dopamine-blocking
agents that could be given to addicts
to make drugs less alluring, and Volkow's
studies of the link between addiction
and an area of the brain associated
with higher thinking and obsessive-compulsive
behavior.
Social Impact: Volkow's
work has led the way in debunking
the idea that sheer willpower is a
cure for addictions. Understanding
of the molecular mechanisms underlying
drug addiction could lead to new approaches
for interrupting addictive behavior
and have lasting impacts on how society
copes with this public health problem.
Reference: N.D.,
Volkow, Fowler, J.S., Wolf, A.P.,
Schlyer, D., Shiue, Ch.y., Albert,
R., Dewey, S.L., Logan, J., Bendriem,
B., Christman, D., Hitzemann, R. and
Henn, F., "Effects of chronic cocaine
abuse on postsynaptic dopamine receptors,"
Am. J. Psychiatry 147: 719-724,
1990.
Volkow, N.D., Fowler, J.S., Wang,
G.-J., Hitzemann, R., Logan, J., Schlyer,
D., Dewey, S. and Wolfe, A.P., "Decreased
dopamine D2 receptor availability
is associated with reduced frontal
metabolism in cocaine abusers," Synapse
14: 169-177, 1993.
Volkow, N.D., Wang, G.-J., Fowler,
J.S., Logan, J., Gatley, S.J., Hitzemann,
R., Chen, A.D. and Pappas, N., "Decreased
striatal dopaminergic responsiveness
in detoxified cocaine-dependent subjects,"
Nature 386: 830-833, 1997.
Wang, G.-J., Volkow, N.D., Logan,
J., Pappas, N.R., Wong C.T., Zhu,
W., Netusil, N., and Fowler J.S.,
"Evidence of brain dopamine pathology
in obesity," Lancet 357 :
354-357, 2001.
URL: http://www.bnl.gov/bnlweb/pubaf/pr/bnlpr030701.htm
http://www.chemistry.bnl.gov/bcin.html
http://www.chemistry.bnl.gov/~schretz/PETpage98.html
Technical Contact:
Dr. Prem Srivastava, Medical Sciences
Division, Office of Biological and
Environmental Research, 301-903-4071
Press Contact: Jeff
Sherwood, DOE Office of Public Affairs,
202-586-5806
SC-Funding Office:
Office of Biological and Environmental
Research |
