Web address:
http://www.sciencedaily.com/releases/2011/03/
110302152820.htm
The greater a teen's addiction to nicotine, the less active an area of the
brain called the prefrontal cortex, researchers have found. (Credit:
iStockphoto/Loris Eichenberger)
ScienceDaily (Mar. 2, 2011) Tobacco smoking is the leading preventable cause
of death and disease in the U.S., with more than 400,000 deaths each year
attributable to smoking or its consequences. And yet teens still smoke. Indeed,
smoking usually begins in the teen years, and approximately 80 percent of adult
smokers became hooked by the time they were 18. Meanwhile, teens who don't take
up smoking usually never do.
While studies have linked cigarette smoking to deficits in attention and memory
in adults, UCLA researchers wanted to compare brain function in adolescent
smokers and non-smokers, with a focus on the prefrontal cortex, the area of the
brain that guides "executive functions" like decision-making and that is still
developing structurally and functionally in adolescents.
They found a disturbing correlation: The greater a teen's addiction to
nicotine, the less active the prefrontal cortex was, suggesting that smoking
can affect brain function.
The research appears in the current online edition of the journal
Neuropsychopharmacology.
The finding is obviously not good news for smokers, said the study's senior
author, Edythe London, a professor of psychiatry at the Semel Institute for
Neuroscience and Human Behavior at UCLA.
"As the prefrontal cortex continues to develop during the critical period of
adolescence, smoking may influence the trajectory of brain development and
affect the function of the prefrontal cortex," London said.
In the study, 25 smokers and 25 non-smokers between the ages of 15 to 21 were
asked to perform a test that activated the prefrontal cortex and required them
to inhibit responding.
The test, called the Stop-Signal Task (SST), was done while the participants
were undergoing functional magnetic resonance imaging (fMRI). The Stop-Signal
Task involves pressing a button as quickly as possible every time a lighted
arrow appears -- unless an auditory tone is played, in which case the
participant must prevent himself from pressing the button. It is a test of a
person's ability to inhibit an action.
Prior to the fMRI test, the researchers used the Heaviness of Smoking Index
(HSI) to measure the level of nicotine dependence in the smoking group. The HSI
takes into account how many cigarettes a teen smokes in a day and how soon
after waking he or she takes the first smoke.
The results of the tests, London said, were interesting -- and surprising.
Among smokers, the researchers found that the higher the HSI -- that is, the
more a teen smoked -- the lesser the activity in the prefrontal cortex. And
yet, despite these lower levels of activation, the smoking group and the
non-smoking group performed roughly the same with respect to inhibition on the
Stop-Signal Task.
"The finding that there was little difference on the Stop-Signal Task between
smokers and non-smokers was a surprise," said London, who is also a professor
of molecular and medical pharmacology at the David Geffen School of Medicine at
UCLA and a member of the UCLA Brain Research Institute. "That suggested to us
that the motor response of smokers may be maintained through some kind of
compensation from other brain areas."
Protracted development of the prefrontal cortex has been implicated as a cause
of poor decision-making in teens, London said, caused by immature cognitive
control during adolescence.
"Such an effect can influence the ability of youth to make rational decisions
regarding their well-being, and that includes the decision to stop smoking,"
she said.
The key finding, London noted, is that "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 a healthier life."
On the other hand, the fact that adolescent smokers and non-smokers performed
equally well during a response-inhibition test suggests that early
interventions during the teen years may prevent the transition from a teen
smoking an occasional cigarette in response to peer pressure to addiction in
later adolescence.
In addition to London, study authors included lead author Adriana Galván,
Christine M. Baker and Kristine M. McGlennen of UCLA, and Russell A. Poldrack,
of the University of Texas at Austin.
Funding for this study was provided by Philip Morris USA, an endowment from the
Thomas P. and Katherine K. Pike Chair in Addiction Studies, and a gift from the
Marjorie M Greene Trust. None of the sponsors had any involvement in the
design, collection, analysis or interpretation of data, the writing the
manuscript, or the decision to submit the manuscript for publication.
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Story Source:
The above story is reprinted (with editorial adaptations by ScienceDaily
staff) from materials provided by University of California - Los Angeles.
Journal Reference:
1. Adriana Galván, Russell A Poldrack, Christine M Baker, Kristine M
McGlennen, Edythe D London. Neural Correlates of Response Inhibition and
Cigarette Smoking in Late Adolescence. Neuropsychopharmacology, 2011; DOI:
10.1038/npp.2010.235
Need to cite this story in your essay, paper, or report? Use one of the
following formats:
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University of California - Los Angeles (2011, March 2). Tobacco smoking impacts
teens' brains, study shows. ScienceDaily. Retrieved March 8, 2011, from
http://www.sciencedaily.com /releases/2011/03/110302152820.htm
Note: If no author is given, the source is cited instead.
Disclaimer: This article is not intended to provide medical advice, diagnosis
or treatment. Views expressed here do not necessarily reflect those of
ScienceDaily or its staff.
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