So there they are, "Tom" and "Tara," sitting on
their back porch and lighting up their first cigarettes of the day. The mellow
sun rays and fresh morning breeze are forgotten as the nicotine and other
chemicals in the cigarettes turbocharge their brains.
Blood rushes to the visual cortex and cerebellum, blood flowing to the
anterior cingulate and right hippocampus declines, and as blood flow to the
latter two regions ebbs, Tom's and Tara's craving for a cigarette is snuffed
out as well.
This anecdote illustrates the outcome of a study exploring the brain impact
of the first smoke of the day. The study was headed by Jon-Kar Zubieta, M.D.,
Ph.D., an associate professor of psychiatry at the University of Michigan.
Findings appeared in the March American Journal of Psychiatry.
Nineteen cigarette smokers who smoked seven to 30 cigarettes a day for
seven years on average were selected to participate in the study. On the night
before the study, they abstained from smoking, then reported the next morning
to the hospital's positron emission tomography (PET) suite. In the suite, PET
scans tracked blood flow to various parts of their brains, and they were asked
to rate, on a scale of 0 (not at all) to 10 (most ever), how they felt
regarding cigarette craving. Then they lit up their first cigarettes of the
day. Once again PET scans were used to track blood flow to various parts of
their brains, and once again subjects were asked to rate how they felt
regarding cigarette craving.
Subjects' baseline PET scan results and craving reports were then compared
with their PET scan results and craving reports after lighting up.
The first smoke, Zubieta and his colleagues learned, resulted in increases
in blood flow to two regions located in the back of the brain—the visual
cortex and the cerebellum—and in decreases in blood flow to a region
located in the front of the brain and in another region located in the
midbrain—the anterior cingulate and right hippocampus,
After subjects smoked their first cigarette of the day, PET scans of
their brains revealed decreased cerebral blood flow in the anterior cingulate
and right hippocampus.
Of course, the visual cortex is crucial for vision; the cerebellum for
movement; the anterior cingulate for motivation, executive control, and
decision making; and the hippocampus for memory and emotion. But the anterior
cingulate has also been implicated in drug craving, and the hippocampus in
associating drugs with certain environmental cues. Even more noteworthy, the
researchers found, as blood flow to subjects' anterior cingulate and right
hippocampus ebbed, their craving for a cigarette diminished
Thus, both the anterior cingulate and the right hippocampus "seem
quite involved in the [cigarette] addiction process," Zubieta said in an
interview. And when smokers have not used nicotine for a while, the left
anterior cingulate and the right hippocampus "may actually be
overactivated, only going down in their function after receiving a nicotine
The implication of these findings for cigarette smokers, Zubieta added, is
that cigarette smoking is simply another form of drug addiction—in fact,
the most frequent form of substance abuse.
The study was funded by the National Institute on Drug Abuse.
The study, "Regional Cerebral Blood Flow Responses to Smoking
in Tobacco Smokers After Overnight Abstinence," is posted online at<http://ajp.psychiatryonline.org/cgi/content/full/162/3/567>.▪
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