Steven M. Wilson1, & John K. Hewitt1
It is well known that lifestyle choices such as use of alcohol, tobacco, or illicit drugs can have major effects on the health of individuals. Further, experimentation and decisions to use such substances are often initiated in adolescence. The present report investigates patterns of use of various substances, individually and jointly, in MZ and DZ adolescent twins. The Colorado Adolescent Twin Study (CATS) is a longitudinal investigation which is seeking to explore the initiation of use as well as transition to regular or problem use of alcohol, tobacco, marijuana, and other illicit drugs in adolescent twins between the ages of 11 and 18. Poly-substance use is also investigated, as are relationships to substance use and personality, health traits, and eating disorders. Presently, data have been collected for 1104 twins. The mean age of our sample is 14.4 years, with a standard deviation of 1.8 years. Looking at the sample by reported substance use: Alcohol: 426 respondents reported having ever consumed alcohol (more than just a taste of someone else's drink), while 314 reported having consumed alcohol in the past month; mean age of this 'ever' group was 15.5 years (sd=1.6), and mean number of drinks consumed at a time was in the 3-5 drink range. Tobacco: 334 subjects reported having used tobacco; the mean age of these subjects was 15.3 (sd=1.6), and the mean number of cigarettes smoked on an average day was between 3-9. Marijuana: 224 subjects reported ever having tried marijuana, and all of these subjects reported that they had used marijuana within the past month; the mean age of this group was 15.7 years (sd=1.5); the mean number of times that these individuals reported having smoked marijuana in the past month was 1 to 2 times. Genetic and environmental influences on the use of these substances individually and jointly will be presented.
Address: Steven.Wilson@Colorado.EDU
1Institute for Behavioral Genetics, University of Colorado, Boulder, CO 80309