London, study leader and a professor of psychiatry at the Semel Institute for
Neuroscience and Human Behavior at UCLA, along with a team of researchers from
UCLA and the University of Texas at Austin, have found that teenage smokers have
reduced brain activity compared to non-smokers.
team determined these results by measuring the level of nicotine dependence
in 25 smokers and 25 non-smokers that ranged from ages 15 to
21 through the use of the Heaviness of Smoking Index (HSI). The HSI looks
at how many cigarettes the teen smokes per day and how soon they begin smoking
each day to determine their dependence.
then performed a test called the Stop-Signal Task (SST) on the
participants. While being subjected to functional magnetic resonance
imaging (fMRI), the test subjects were asked to press a button as quickly as
they could when a lighted arrow appeared. The only time they were not to press
the button was when an auditory cue was played. This tested each participant’s
ability to inhibit an action.
described the results as "interesting." Higher HSI measurements, or
the more a teen smoked, resulted in reduced activity in
a part of the brain known as the prefrontal cortex, which is responsible for
decision-making. But despite this reduced activity, both smokers and
non-smokers performed about the same in the Stop-Signal Task.
finding that there was little difference on the Stop-Signal Task between
smokers and non-smokers was a surprise," said London. "That suggested
to us that the motor response of smokers may be maintained through some kind of
compensation from other brain areas."
to the study, the fact that both smokers and non-smokers performed the same in
the Stop-Signal Task "suggests that early interventions during the teen
years" may prevent teens from smoking occasionally to smoking
also noted that protracted development of the prefrontal cortex may cause poor
decision-making in teenagers, due to immature cognitive control during the time
an effect can influence the ability of youth to make rational decisions
regarding their well-being, and that includes the decision to stop
smoking," said London. "As the prefrontal cortex continues to develop
during the critical period of adolescence, smoking may influence the trajectory
of brain development,
affecting the function of the prefrontal cortex. In turn, if the prefrontal
cortex is negatively impacted, a teen may be more likely to start smoking and
to keep smoking - instead of making the decision that would favor in a
This study was
published in Neuropsychopharmacology.