Skin Color Clue To Nicotine Dependence
Skin Color Clue To Nicotine Dependence
University Park, Pa. -- Higher concentrations of melanin -- the color
pigment in skin and hair -- may be placing darker pigmented smokers
at increased susceptibility to nicotine dependence and
tobacco-related carcinogens than lighter skinned smokers, according
to scientists.
"We have found that the concentration of melanin is directly
related to the number of cigarettes smoked daily, levels of nicotine
dependence, and nicotine exposure among African Americans," said Gary
King, professor of biobehavioral health, Penn State.
King states that previous research shows that nicotine has a
biochemical affinity for melanin. Conceivably, this association could
result in an accumulation of the addictive agent in
melanin-containing tissues of smokers with greater amounts of skin
pigmentation.
"The point of the study is that, if in fact, nicotine does
bind to melanin, populations with high levels of melanin could
indicate certain types of smoking behavior, dependence, and health
outcomes that will be different from those in less pigmented
populations," explained King. "And the addiction process may very
well be longer and more severe."
The team's findings appear in the June issue of the journal
Pharmacology, Biochemistry and Behavior.
To investigate the factors linking tobacco use, nicotine
exposure, and skin pigmentation, the researchers recruited 150 adult
African American smokers from three sites in inner city Harrisburg
during summer 2007. Participants provided researchers with the
average number of cigarettes smoked each day and answered a
questionnaire that measured nicotine dependence -- the Fagerstrom
Test of Nicotine Dependence (FTND).
Researchers also measured the smokers' cotinine levels.
Cotinine is a metabolic byproduct of nicotine that can be used as a
biomarker for tobacco use. King and colleagues surmise that
nicotine's half-life may, along with tobacco toxicants, be extended
due to the accumulation in melanin-containing tissues.
Statistical analyses of data on the three measures of
smoking -- cigarettes per day, FTND score, and cotinine levels --
along with a host of other variables including age, education and
social demographics of the smokers, reveal that facultative melanin
-- the total amount of melanin acquired genetically plus the amount
from the tanning effect of sunlight -- is significantly linked to the
number of cigarettes smoked per day as well as the FTND score. This
link was not observed with constitutive melanin, which is the amount
of melanin solely acquired genetically.
However, the Penn State researcher cautions that additional
studies with larger samples of smokers with varying levels of skin
pigmentation will be required to provide a clearer picture of the
link between skin color and nicotine addiction.
"We also think that studies conducted at different times of
the year and in different geographic regions would help avoid
seasonal variations such as the effect of tanning during summer,"
King explained. "Additionally, nicotine levels could also be
influenced by factors such as consumption of alcohol, amount of
exercise, diet, body fat and stress. Future studies will have to
control for these factors as well."
According to King, findings from the study could have
potential health implications for African American smokers, who tend
to have darker skin, are disproportionately burdened with
tobacco-related diseases, and report greater difficulty quitting smoking.
"One of the questions we want to address is why African
Americans have lower quit rates than whites," King said. "This avenue
of research may help us explore that question more definitively."
Previous studies indicate that even though African Americans
smoke fewer cigarettes than some other groups, they have a higher
intake of nicotine from each cigarette.
Other researchers on the paper include Valerie B. Yerger,
Assistant Adjunct Professor, University of California, San Francisco;
Guy-Lucien Whembolua, recent doctoral graduate, Penn State; Robert B.
Bendel, biostatistician, Washington State University; Rick Kittles,
geneticist, University of Chicago; and Eric T. Moolchan, research
physician, Alkermes, Inc. (formerly of the National Institute of Drug Abuse).
Penn State's Africana Research Center and the Social Science
Research Institute funded this work.
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EDITOR: Dr. King may be reached at gxk14@psu.edu.
A'ndrea Elyse Messer
Sr. Science & Research Information Officer
Penn State Public Information
1 College Avenue Annex
University Park, Pa 16802
814-865-9481
814-865-9421
aem1@psu.edu
