Post by Okwes on Feb 24, 2006 11:34:06 GMT -5
Alcoholism, smoking and genetics among Plains American Indians
Alcoholism, smoking and genetics among Plains American Indians
www.eurekalert.org/pub_releases/2006-02/ace-asa021406.php
<http://www.eurekalert.org/pub_releases/2006-02/ace-asa021406.php>
Alcoholism and smoking have a high rate of co-occurrence in the general
population. Yet little is known about the co-morbidity of alcoholism and
smoking among American Indians. In the March issue of Alcoholism:
Clinical & Experimental Research, researchers examine patterns of
alcohol and tobacco use among Plains American Indians, as well as the
influence that a catechol-O-methyltransferase (COMT) functional
polymorphism called Val158Met may have on these behaviors.
"The shared heritability between smoking and alcoholism, particularly in
heavy smokers and heavy drinkers, indicates that some genes predispose
individuals to both smoking and drinking," said Mary-Anne Enoch, a staff
scientist in the Laboratory of Neurogenetics at the National Institute
on Alcohol Abuse and Alcoholism and corresponding author for the study.
"Nicotine's effects on the brain occur mainly through nicotinic
acetylcholine receptors, and alcohol acts on these same receptors to
release dopamine, the 'pleasure' hormone in the brain's reward pathway."
Enoch added that the enzyme COMT plays an important role in the
breakdown of dopamine and norepinephrine in the brain, its activity
varying according to a common COMT polymorphism, Val158Met. "The Met
allele results in a less efficient enzyme and therefore probably more
dopamine and norepinephrine in the brain," she said. "The Met allele has
also been associated with increased anxiety and neuroticism, increased
emotionality in response to pain, and greater brain activation in
response to unpleasant visual images."
Whereas studies of European men have shown that the Met allele is
associated with late onset alcoholism and increased alcohol intake in
social drinkers, Enoch and her colleagues have found that in American
Indians the Met allele was protective against alcoholism, and the Val
allele was the risk allele.
"The answer to this paradox may lie in the relationship between anxiety
and drinking patterns," she said. "In societies where regular, daily
drinking is the norm, such as in Europe, anxious Met individuals may be
more vulnerable to alcoholism through using alcohol as a coping
mechanism. In societies where heavy, periodic drinking bouts are the
norm, such as in some American Indian tribes, anxious Met individuals
may be less likely to participate in this kind of risky behavior and may
be protected from alcoholism."
Enoch and her colleagues also found that the Val allele was a risk
factor for smoking, but only in women.
For the current study, researchers recruited 342 (201 women, 141 men)
community-based Plains American Indians, establishing their lifetime
drinking and smoking histories. Additionally, five COMT loci –
including Val158Met – were genotyped.
"There are three key findings," said Enoch. "One, Plains Indians have
very different drinking patterns. Alcoholics drink heavily, but
episodically … yet they still meet the criteria for alcoholism."
Two, she continued, "they have a very different comorbidity. They don't
smoke heavily." In statistical terms, although 62 percent of the male
alcoholics and 40 percent of the female alcoholics were smokers, only 12
percent of the alcoholic men and eight percent of the alcoholic women
smoked heavily.
"And three," she noted, "at least one third are social smokers who never
progress to 'real' smoking, they just smoke in social settings. This may
be a throwback to the traditional use of tobacco amongst American
Indians."
Enoch said that this study shows how there is no such thing as an
"alcoholism gene" or "alcoholism allele."
"Here you've got one gene, and in one population one allele of the gene
is associated with a disease, alcoholism, yet in another population, the
gene's other allele is associated with that disease," she said. "You've
really got to look at the gene-environment interaction when you've got a
gene like this, with two common variants."
Furthermore, she said, researchers cannot extrapolate findings from one
group to another. "The vast majority of alcoholism studies are conducted
among male alcoholics, and also among treatment alcoholics. The
assumption has always been 'everything you find in Caucasian men can be
applied to everyone else,' but this study shows that you cannot."
###
Alcoholism: Clinical & Experimental Research (ACER) is the official
journal of the Research Society on Alcoholism and the International
Society for Biomedical Research on Alcoholism. Co-authors of the ACER
paper, "Sex Differences in the Influence of COMT Val158Met on Alcoholism
and Smoking in Plains American Indians," were: Juwaria F. Waheed,
Claudia R. Harris, and David Goldman of the Laboratory of Neurogenetics
at the National Institute on Alcohol Abuse and Alcoholism; and Bernard
Albaugh of the Center for Human Behavior Studies, Inc. of Weatherford,
Oklahoma. The study was funded by the National Institute on Alcohol
Abuse and Alcoholism, the National Institutes of Health, and the Office
of Research on Minority Health.
Alcoholism, smoking and genetics among Plains American Indians
www.eurekalert.org/pub_releases/2006-02/ace-asa021406.php
<http://www.eurekalert.org/pub_releases/2006-02/ace-asa021406.php>
Alcoholism and smoking have a high rate of co-occurrence in the general
population. Yet little is known about the co-morbidity of alcoholism and
smoking among American Indians. In the March issue of Alcoholism:
Clinical & Experimental Research, researchers examine patterns of
alcohol and tobacco use among Plains American Indians, as well as the
influence that a catechol-O-methyltransferase (COMT) functional
polymorphism called Val158Met may have on these behaviors.
"The shared heritability between smoking and alcoholism, particularly in
heavy smokers and heavy drinkers, indicates that some genes predispose
individuals to both smoking and drinking," said Mary-Anne Enoch, a staff
scientist in the Laboratory of Neurogenetics at the National Institute
on Alcohol Abuse and Alcoholism and corresponding author for the study.
"Nicotine's effects on the brain occur mainly through nicotinic
acetylcholine receptors, and alcohol acts on these same receptors to
release dopamine, the 'pleasure' hormone in the brain's reward pathway."
Enoch added that the enzyme COMT plays an important role in the
breakdown of dopamine and norepinephrine in the brain, its activity
varying according to a common COMT polymorphism, Val158Met. "The Met
allele results in a less efficient enzyme and therefore probably more
dopamine and norepinephrine in the brain," she said. "The Met allele has
also been associated with increased anxiety and neuroticism, increased
emotionality in response to pain, and greater brain activation in
response to unpleasant visual images."
Whereas studies of European men have shown that the Met allele is
associated with late onset alcoholism and increased alcohol intake in
social drinkers, Enoch and her colleagues have found that in American
Indians the Met allele was protective against alcoholism, and the Val
allele was the risk allele.
"The answer to this paradox may lie in the relationship between anxiety
and drinking patterns," she said. "In societies where regular, daily
drinking is the norm, such as in Europe, anxious Met individuals may be
more vulnerable to alcoholism through using alcohol as a coping
mechanism. In societies where heavy, periodic drinking bouts are the
norm, such as in some American Indian tribes, anxious Met individuals
may be less likely to participate in this kind of risky behavior and may
be protected from alcoholism."
Enoch and her colleagues also found that the Val allele was a risk
factor for smoking, but only in women.
For the current study, researchers recruited 342 (201 women, 141 men)
community-based Plains American Indians, establishing their lifetime
drinking and smoking histories. Additionally, five COMT loci –
including Val158Met – were genotyped.
"There are three key findings," said Enoch. "One, Plains Indians have
very different drinking patterns. Alcoholics drink heavily, but
episodically … yet they still meet the criteria for alcoholism."
Two, she continued, "they have a very different comorbidity. They don't
smoke heavily." In statistical terms, although 62 percent of the male
alcoholics and 40 percent of the female alcoholics were smokers, only 12
percent of the alcoholic men and eight percent of the alcoholic women
smoked heavily.
"And three," she noted, "at least one third are social smokers who never
progress to 'real' smoking, they just smoke in social settings. This may
be a throwback to the traditional use of tobacco amongst American
Indians."
Enoch said that this study shows how there is no such thing as an
"alcoholism gene" or "alcoholism allele."
"Here you've got one gene, and in one population one allele of the gene
is associated with a disease, alcoholism, yet in another population, the
gene's other allele is associated with that disease," she said. "You've
really got to look at the gene-environment interaction when you've got a
gene like this, with two common variants."
Furthermore, she said, researchers cannot extrapolate findings from one
group to another. "The vast majority of alcoholism studies are conducted
among male alcoholics, and also among treatment alcoholics. The
assumption has always been 'everything you find in Caucasian men can be
applied to everyone else,' but this study shows that you cannot."
###
Alcoholism: Clinical & Experimental Research (ACER) is the official
journal of the Research Society on Alcoholism and the International
Society for Biomedical Research on Alcoholism. Co-authors of the ACER
paper, "Sex Differences in the Influence of COMT Val158Met on Alcoholism
and Smoking in Plains American Indians," were: Juwaria F. Waheed,
Claudia R. Harris, and David Goldman of the Laboratory of Neurogenetics
at the National Institute on Alcohol Abuse and Alcoholism; and Bernard
Albaugh of the Center for Human Behavior Studies, Inc. of Weatherford,
Oklahoma. The study was funded by the National Institute on Alcohol
Abuse and Alcoholism, the National Institutes of Health, and the Office
of Research on Minority Health.