Common genetic vulnerability for nicotine and alcohol dependence in men.
BACKGROUND
Nicotine and alcohol dependence often occur together. We examined data from male twin pairs to determine whether there are genetic or environmental influences common to nicotine and alcohol dependence, and, if so, to estimate the magnitude and correlation of these influences.


METHODS
Subjects were 3356 male-male twin-pair members of the Vietnam Era Twin Registry who participated in a 1992 telephone administration of the Diagnostic Interview Schedule Version 3 Revised. Genetic model fitting was performed to estimate the magnitude and correlation of genetic and environmental contributions to lifetime nicotine and alcohol dependence.


RESULTS
The heritability of nicotine dependence was 60.3% (95% confidence interval [CI], 55.4%-65.2%); that of alcohol dependence, 55.1% (95% CI, 49.7%-60.5%). The best-fitting model for the co-occurrence of lifetime nicotine and alcohol dependence included a substantial genetic correlation between both disorders (r = 0.68; 95% CI, 0.61-0.74) and a modest unique environmental correlation (r = 0.23; 95% CI, 0.14-0.32).


CONCLUSIONS
These data suggest a common genetic vulnerability to nicotine and alcohol dependence in men. This common genetic influence may partially explain the clinical and epidemiological observations that alcoholics are often dependent smokers.
School of Public Health, St Louis University Health Sciences Center, MO, USA. true@slu.edu
W R
WR
True
H
H
Xian
J F
JF
Scherrer
P A
PA
Madden
K K
KK
Bucholz
A C
AC
Heath
S A
SA
Eisen
M J
MJ
Lyons
J
J
Goldberg
M
M
Tsuang
D000328:Adult; D000437:Alcoholism / Q000453:epidemiology / Q000235:genetics*; D015897:Comorbidity; D004200:Diseases in Twins / Q000453:epidemiology / Q000235:genetics; D020022:Genetic Predisposition to Disease; D006801:Humans; D008297:Male; D008875:Middle Aged; D008957:Models, Genetic; D011569:Psychiatric Status Rating Scales / Q000706:statistics & numerical data; D012737:Sex Factors; D014029:Tobacco Use Disorder / Q000453:epidemiology / Q000235:genetics*; D014429:Twins, Dizygotic; D014430:Twins, Monozygotic