Browsing by Author "Brooks, Andrew"

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    Association of substance dependence phenotypes in the COGA sample
    (Wiley, 2015-05) Wetherill, Leah; Agrawal, Arpana; Kapoor, Manav; Bertelsen, Sarah; Bierut, Laura J.; Brooks, Andrew; Dick, Danielle; Hesselbrock, Michie; Hesselbrock, Victor; Koller, Daniel L.; Le, Nhung; Nurnberger Jr., John I.; Salvatore, Jessica E.; Schuckit, Marc; Tischfield, Jay A.; Wang, Jen-Chyong; Xuei, Xiaoling; Edenberg, Howard J.; Porjesz, Bernice; Bucholz, Kathleen; Goate, Alison M.; Foroud, Tatiana; Department of Medical & Molecular Genetics, IU School of Medicine
    Alcohol and drug use disorders are individually heritable (50%). Twin studies indicate that alcohol and substance use disorders share common genetic influences, and therefore may represent a more heritable form of addiction and thus be more powerful for genetic studies. This study utilized data from 2322 subjects from 118 European-American families in the Collaborative Study on the Genetics of Alcoholism sample to conduct genome-wide association analysis of a binary and a continuous index of general substance dependence liability. The binary phenotype (ANYDEP) was based on meeting lifetime criteria for any DSM-IV dependence on alcohol, cannabis, cocaine or opioids. The quantitative trait (QUANTDEP) was constructed from factor analysis based on endorsement across the seven DSM-IV criteria for each of the four substances. Heritability was estimated to be 54% for ANYDEP and 86% for QUANTDEP. One single-nucleotide polymorphism (SNP), rs2952621 in the uncharacterized gene LOC151121 on chromosome 2, was associated with ANYDEP (P = 1.8 × 10(-8) ), with support from surrounding imputed SNPs and replication in an independent sample [Study of Addiction: Genetics and Environment (SAGE); P = 0.02]. One SNP, rs2567261 in ARHGAP28 (Rho GTPase-activating protein 28), was associated with QUANTDEP (P = 3.8 × 10(-8) ), and supported by imputed SNPs in the region, but did not replicate in an independent sample (SAGE; P = 0.29). The results of this study provide evidence that there are common variants that contribute to the risk for a general liability to substance dependence.
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    CYP2A6 metabolism in the development of smoking behaviors in young adults
    (Wiley, 2018-01) Olfson, Emily; Bloom, Joseph; Bertelsen, Sarah; Budde, John P.; Breslau, Naomi; Brooks, Andrew; Culverhouse, Robert; Chan, Grace; Chen, Li-Shiun; Chorlian, David; Dick, Danielle M.; Edenberg, Howard J.; Hartz, Sarah; Hatsukami, Dorothy; Hesselbrock, Victor M.; Johnson, Eric O.; Kramer, John R.; Kuperman, Samuel; Meyers, Jacquelyn L.; Nurnberger, John; Porjesz, Bernice; Saccone, Nancy L.; Schuckit, Marc A.; Stitzel, Jerry; Tischfield, Jay A.; Rice, John P.; Goate, Alison; Bierut, Laura J.; Biochemistry and Molecular Biology, School of Medicine
    Cytochrome P450 2A6 (CYP2A6) encodes the enzyme responsible for the majority of nicotine metabolism. Previous studies support that slow metabolizers smoke fewer cigarettes once nicotine dependent but provide conflicting results on the role of CYP2A6 in the development of dependence. By focusing on the critical period of young adulthood, this study examines the relationship of CYP2A6 variation and smoking milestones. A total of 1209 European American young adults enrolled in the Collaborative Study on the Genetics of Alcoholism were genotyped for CYP2A6 variants to calculate a previously well-validated metric that estimates nicotine metabolism. This metric was not associated with the transition from never smoking to smoking initiation nor with the transition from initiation to daily smoking (P > 0.4). But among young adults who had become daily smokers (n = 506), decreased metabolism was associated with increased risk of nicotine dependence (P = 0.03) (defined as Fagerström Test for Nicotine Dependence score ≥4). This finding was replicated in the Collaborative Genetic Study of Nicotine Dependence with 335 young adult daily smokers (P = 0.02). Secondary meta-analysis indicated that slow metabolizers had a 53 percent increased odds (OR = 1.53, 95 percent CI 1.11-2.11, P = 0.009) of developing nicotine dependence compared with normal metabolizers. Furthermore, secondary analyses examining four-level response of time to first cigarette after waking (>60, 31-60, 6-30, ≤5 minutes) demonstrated a robust effect of the metabolism metric in Collaborative Study on the Genetics of Alcoholism (P = 0.03) and Collaborative Genetic Study of Nicotine Dependence (P = 0.004), illustrating the important role of this measure of dependence. These findings highlight the complex role of CYP2A6 variation across different developmental stages of smoking behaviors.
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    A GABRA2 Polymorphism Improves a Model for Prediction of Drinking Initiation
    (Elsevier, 2017-09) Kuperman, Samuel; Chan, Grace; Kramer, John; Wetherill, Leah; Acion, Laura; Edenberg, Howard J.; Foroud, Tatiana M.; Nurnberger, John, Jr.; Agrawal, Arpana; Anokhin, Andrey; Brooks, Andrew; Hesselbrock, Victor; Hesselbrock, Michie; Schuckit, Marc; Tischfield, Jay; Liu, Xiangtao; Department of Biochemistry & Molecular Biology, IU School of Medicine
    Background Survival analysis was used to explore the addition of a single nucleotide polymorphism (SNP) and covariates (sex, interview age, and ancestry) on a previously published model's ability to predict onset of drinking. A SNP variant of rs279871, in the chromosome 4 gene encoding gamma-aminobutyric acid receptor (GABRA2), was selected due to its associations with alcoholism in young adults and with behaviors that increased risk for early drinking. Methods A subsample of 674 adolescents (ages 14–17) participating in the Collaborative Study on the Genetics of Alcoholism (COGA) was examined using a previously derived Cox proportional hazards model containing: 1) number of non-drinking related conduct disorder (CD) symptoms, 2) membership in a high-risk alcohol-dependent (AD) family, 3) most best friends drank (MBFD), 4) Achenbach Youth Self Report (YSR) externalizing score, and 5) YSR social problems score. The above covariates along with the SNP variant of GABRA2, rs279871, were added to this model. Five new prototype models were examined. The most parsimonious model was chosen based on likelihood ratio tests and model fit statistics. Results The final model contained four of the five original predictors (YSR social problems score was no longer significant and hence dropped from subsequent models), the three covariates, and a recessive GABRA2 rs279871 TT genotype (two copies of the high-risk allele containing thymine). The model indicated that adolescents with the high-risk TT genotype were more likely to begin drinking than those without this genotype. Conclusions The joint effect of the gene (rs279871 TT genotype) and environment (MBFD) on adolescent alcohol initiation is additive, but not interactive, after controlling for behavior problems (CD and YSR externalizing score). This suggests that the impact of the high-risk TT genotype on the onset of drinking is affected by controlling for peer drinking and does not include genotype-by-environment interactions.
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    ssociations of Parental Alcohol Use Disorders and Parental Separation with Offspring Initiation of Alcohol, Cigarette, and Cannabis Use and Sexual Debut in High-Risk Families
    (Wiley, 2017) McCutcheon, Vivia V.; Agrawal, Arpana; Kuo, Sally I-Chun; Su, Jinni; Dick, Danielle M.; Meyers, Jacquelyn L.; Edenberg, Howard J.; Nurnberger, John I.; Kramer, John R.; Kuperman, Samuel; Schuckit, Marc A.; Hesselbrock, Victor M.; Brooks, Andrew; Porjesz, Bernice; Bucholz, Kathleen K.; Department of Biochemistry and Molecular Biology, School of Medicine
    Background and Aims Parental alcohol use disorders (AUDs) and parental separation are associated with increased risk for early use of alcohol in offspring, but whether they increase risks for early use of other substances and for early sexual debut is under-studied. We focused on associations of parental AUDs and parental separation with substance initiation and sexual debut to (1) test the strength of the associations of parental AUDs and parental separation with time to initiation (age in years) of alcohol, tobacco and cannabis use and sexual debut and (2) compare the strength of association of parental AUD and parental separation with initiation. Design Prospective adolescent and young adult cohort of a high-risk family study, the Collaborative Study on the Genetics of Alcoholism (COGA). Setting Six sites in the United States. Participants A total of 3257 offspring (aged 14–33 years) first assessed in 2004 and sought for interview approximately every 2 years thereafter; 1945 (59.7%) offspring had a parent with an AUD. Measurements Diagnostic interview data on offspring substance use and sexual debut were based on first report of these experiences. Parental life-time AUD was based on their own self-report when parents were interviewed (1991–2005) for most parents, or on offspring and other family member reports for parents who were not interviewed. Parental separation was based on offspring reports of not living with both biological parents most of the time between ages 12 and 17 years. Findings Parental AUDs were associated with increased hazards for all outcomes, with cumulative hazards ranging from 1.19 to 2.71. Parental separation was also an independent and consistent predictor of early substance use and sexual debut, with hazards ranging from 1.19 to 2.34. The strength of association of parental separation with substance initiation was equal to that of having two AUD-affected parents, and its association with sexual debut was stronger than the association of parental AUD in one or both parents. Conclusions Parental alcohol use disorders (AUDs) and parental separation are independent and consistent predictors of increased risk for early alcohol, tobacco and cannabis use and sexual debut in offspring from families with a high risk of parental AUDs.