genetic epidemiology, epidemiology of tobacco, alcohol and other substances of abuse
Once considered a social problem in society, drug abuse was seldom investigated with respect to genetic and other biological mechanisms. This view has changed dramatically in the past few decades as researchers have gained greater understanding of the dopamine-reward system which forms the basis for all substances of abuse. Dr. Timberlake has focused on three areas related to the use and misuse of licit/illicit substances: 1) associations between drug use and candidate gene polymorphisms in the dopamine pathway system, 2) environmental moderation of genetic influences on substance use, and 3) measurement of nicotine dependence and the factors which predict its development.
The three areas of his research have been addressed using national survey data of drug use among adolescents and young adults. The surveys include the National Longitudinal Study of Adolescent Health (Add Health), the National Survey on Drug Use and Health (NSDUH), and the National Epidemiologic Survey on Alcohol and Related Conditions (NESARC). While Dr. Timberlake's primary research has focused on the genetic basis for adolescent substance use, he has developed a broader interest in the epidemiologic issues of drug use. One issue pertains to the transitions that adolescents make in the use of tobacco products and cannabis, and how these transitions correlate with dependency on nicotine. This is evidenced by adolescents who either smoke tobacco and cannabis in the form of a blunt, or use the two substances interchangeably. A related issue, which has generated controversy among public health professionals, is the advocacy for replacing cigarettes with an alternate tobacco product (i.e. snuff). Researchers have suggested that this substitution would reduce 90% of the mortality associated with tobacco smoking. Yet, little is known about the extent to which alternate tobacco contributes to nicotine dependence, a potential factor hindering smoking cessation.
Sakai JT, Lessem JM, Haberstick BC, Hopfer CJ, Smolen A, Ehringer MA, , Timberlake D, Hewitt JK. Case-control and within-family tests for association between 5HTTLPR and conduct problems in a longitudinal adolescent sample. Psychiatr Genet. 2007, 17(4):207-14.
Haberstick BC, Timberlake D, Smolen A, Sakai JT, Hopfer CJ, Corley RP, Young SE, Stallings MC, Huizinga D, Menard S, Hartman C, Grotpeter J, Hewitt JK. Between- and within-family association test of the dopamine receptor D2 TaqIA polymorphism and alcohol abuse and dependence in a general population sample of adults. J Stud Alcohol Drugs. 2007, 68(3):362-70.
Timberlake DS, Hopfer CJ, Rhee SH, Friedman N, Haberstick BC, Lessem JM, Hewitt JK. College attendance and its effect on drinking behaviors in a longitudinal study of adolescents. Alcohol Clin Exp Res. 2007, 31(6): 1020-1030
Timberlake DS, Haberstick BC, Hopfer CJ, Bricker J, Sakai JT, Lessem JM, Hewitt JK. Progression from marijuana use to daily smoking and nicotine dependence in a national sample of U.S. adolescents. Drug Alcohol Depend. 2007, 88(2-3): 272-281
Haberstick BC, Timberlake D, Ehringer M, Lessem JM, Hopfer CJ, Smolen A, Hewitt JK. Genes, time to first cigarette, and nicotine dependence in a general population sample of young adults. Addiction 2007, 102(4): 655-65
Sakai JT, Hopfer CJ, Hartman C, Haberstick BC, Smolen A, Corley RP, Stallings MC, Young SE, Timberlake D, Hewitt JK, Crowley TJ. Test of association between TaqIA A1 allele and alcohol use disorder phenotypes in a sample of adolescent patients with serious substance and behavioral problems. Drug Alcohol Depend. 2007, 88(2-3): 130-137
Bricker JB, Stallings MC., Corley RP, Wadsworth SJ, Bryan A, Timberlake DS, Hewitt JK, Caspi A., Hofer SM, DeFries JC. Genetic and Environmental Influences on Age at Sexual Initiation in the Colorado Adoption Project. Behav Genet. 2006 , 36(6):820-32
Lessem JM, Hopfer CJ, Haberstick BC, Timberlake D, Ehringer MA, , Smolen A, Hewitt JK. Relationship between Adolescent Marijuana Use and Young Adult Illicit Drug Use. Behav Genet. 2006, 36(4): 498-506
Sakai JT, Young SE, Stallings MC, Timberlake D, Smolen A, Stetler GL, Crowley TJ. Case-Control and Within-Family Tests for an Association Between Conduct Disorder and 5HTT-LPR. Am J Med Genet B Neuropsychiatr. Genet. 2006, 141(8):825-32.
Timberlake DS, Rhee SH, Haberstick BC, Hopfer CJ, Ehringer MA, Lessem JM, Smolen A, Hewitt JK. The moderating effects of religiosity on the genetic and environmental determinants of smoking initiation. Nicotine Tob Res. 2006, 8(1):123-33.
Timberlake DS, Haberstick BC, Lessem JM, Smolen A, Ehringer MA, Hewitt JK. Association between the DAT1 Polymorphism and Smoking Behavior in Young Adults from the National Longitudinal Study of Adolescent Health. Health Psychol. 2006, 25(2):190-7.
Haberstick BC, Lessem JM , Hopfer CJ, Smolen A, Ehringer MA, Timberlake D, Hewitt JK. Monoamine oxidase A (MAOA) and antisocial behaviors in the presence of childhood and adolescent maltreatment. Am J Med Genet B Neuropsychiatr. Genet. 2005, 135(1):59-64.
Hopfer CJ, Timberlake D, Haberstick BC, Lessem JM, Ehringer MA, Smolen A, Hewitt JK. Genetic Influences on Quantity of Alcohol Consumed by Adolescents and Young Adults. Drug Alcohol Depend. 2005, 78(2): 187-93.
Behavior Genetics Association
Genetic Epidemiology Research Institute