|
Watching Nicotine at Work in the Brain
Nearly 80% of the smokers who try to quit relapse within six months, and nicotine
is the main reason why. A new brain imaging study supported in part by NIH's
National Institute on Drug Abuse (NIDA) shows how the nicotine in just a few
puffs of a cigarette can drive someone to continue smoking.
 |
|
| Tracking nicotine in the brain. Image courtesy of NIH's
National Institute on Drug Abuse. |
|
Dr. Arthur Brody of the David Geffen School of Medicine at UCLA and his colleagues
used positron emission tomography (PET) to scan the brains of 11 smokers and
assess nicotine's activity. They used a recently-developed radiotracer that binds
nicotine receptors but can be displaced when nicotine comes in to bind the receptors
instead. During scanning, the participants smoked different amounts. Their craving
was measured with the Urge to Smoke scale, which assesses responses to 10 craving-related
questions.
In the August 2006 issue of the Archives of General Psychiatry, the
researchers report that the amount of nicotine in just one puff of a cigarette
occupied about 30% of the brain's most common type of nicotine receptors, while
three puffs of a cigarette occupied about 70%. Smoking a whole cigarette filled
more than 88% of the receptors and alleviated craving to some extent. Only when
nearly all of the receptors were occupied, however, after smoking at least 2
and a half cigarettes, did the smokers becomes satiated, or satisfied, for a
time. Soon, however, this level of satiation wore off, driving the smoker to
continue smoking throughout the day to satisfy their cigarette cravings.
"The central findings of the study suggest that typical daily smokers need to
have these nicotine receptors almost completely saturated throughout the day,
which drives the almost uncontrollable urge to keep smoking," says Dr. Nora D.
Volkow, Director of NIDA. "A more complete understanding of how nicotine affects
the brain can help us develop better therapies for people looking to quit."
|
