Biomedical subjects

Robin P Corley

Publications and source records attributed to Robin P Corley.

24 records · Page 2Linked to original sources

PubMed2003

Genetic and environmental influences on substance initiation, use, and problem use in adolescents.

BACKGROUND: We conducted a sibling/twin/adoption study of substance initiation, use, and problem use, estimating the relative contribution of genetic and environmental influences on these phenotypes in adolescents. METHODS: The participants were 345 monozygotic twin pairs, 337 dizygotic twin pairs, 306 biological sibling pairs, and 74 adoptive sibling pairs assessed by the Colorado Center for the Genetics and Treatment of Antisocial Drug Dependence, Denver and Boulder. The initiation, use, and problem use of tobacco, alcohol, marijuana, and other illicit drugs were assessed. Tetrachoric correlations were computed for each group, and univariate model-fitting analyses were conducted. RESULTS: There were moderate to substantial genetic influences, with the exception of alcohol use and any drug use, and modest to moderate shared environmental influences on substance initiation, use, and problem use. For alcohol and any drug, heritability was higher and the magnitude of shared environmental influences was lower for problem use than for initiation or use. Environmental influences shared only by twin pairs had a significant effect on tobacco initiation, alcohol use, and any drug use. For tobacco use, tobacco problem use, and marijuana initiation, heritability was higher and the magnitude of shared environmental influences was lower in female than in male adolescents. There was no evidence for sex-specific genetic or shared environmental influences on any variable. CONCLUSIONS: The moderate to substantial heritabilities found for adolescents in the present study are comparable to those found in twin studies of adult substance use and substance use disorders. The finding that problem use is more heritable than initiation and use is also consistent with the results of adult twin studies. The significance of environmental influences shared only by twin pairs on tobacco initiation, alcohol use, and any drug use suggests the influences of peers, accessibility of substances, and sibling interaction.

Adolescent↗

PubMed2003

The validity of analyses testing the etiology of comorbidity between two disorders: comparisons of disorder prevalences in families.

Klein and Riso proposed several alternative models explaining the causes of comorbidity between two disorders (KR models). For each comorbidity model, they also presented a set of predictions for comparing the prevalence of disorder A-only, disorder B-only, and disorder AB (i.e., both disorders) among the relatives of probands with A-only, B-only, AB and controls (i.e., the KR predictions). Neale and Kendler provided the quantitative expectations for these prevalences (i.e., the NK models) and suggested biometric model fitting as an alternative way of testing comorbidity models. Neale and Kendler also suggested that the KR predictions have limited use because variations in the model parameters may lead to different predictions. We tested the KR predictions on two sets of data simulated under the assumptions of the KR/NK models. The results predicted by Klein and Riso and the results derived from the simulated datasets matched in most cases, but there were several notable discrepancies between the two sets of results. First, these discrepancies may be due to variations in the model parameters although the KR predictions are valid tests of the model for some model parameter sets. Second, several KR predictions may not be valid because they do not consider the necessary conditions for the diagnosis of A-only and B-only or alternative routes to comorbidity that are not hypothesized in their comorbidity model, including the fact that some comorbid cases will result by chance in all comorbidity models.

Comorbidity↗

PubMed2003

Relationships between personality and preferred substance and motivations for use among adolescent substance abusers.

This study examined the utility of Cloninger's tridimensional personality theory (1986, 1987a) in predicting preferred substance of abuse and self-reported motivations for use among a sample of 200 adolescent substance abusers and 200 matched community control adolescents. Two primary hypotheses were tested: (1) Cloninger's type II profile is more strongly associated with stimulant use, and his type I profile is more strongly associated with substances having sedative-hypnotic effects; and 2) type II individuals will report motivations for use that focus primarily on obtaining positive rewards, whereas type I individuals will report motivations primarily concerning negative reinforcement or the avoidance of problems and negative life experiences. Our results did not show strong associations between Cloninger's Harm Avoidance and Reward Dependence dimensions and preferred substance or motivations for use. However, in partial support of the hypotheses examined here, we did find that individuals low in novelty seeking (NS) tended to prefer alcohol and marijuana, whereas those high in NS endorsed a wider range of preferred substances. High NS was associated with significantly greater stimulant use and motivations focused on obtaining positive rewards, whereas low NS was associated with greater sedative use and motivations related to avoiding negative emotions or negative life experiences.

Adolescent↗

PubMed2003

The validity of analyses testing the etiology of comorbidity between two disorders: a review of family studies.

BACKGROUND: Knowledge regarding the causes of comorbidity between two disorders has a significant impact on research regarding the classification, treatment, and etiology of the disorders. Two main analytic methods have been used to test alternative explanations for the causes of comorbidity in family studies: biometric model fitting and family prevalence analyses. Unfortunately, the conclusions of family studies using these two methods have been conflicting. In the present study, we examined the validity of family prevalence analyses in testing alternative comorbidity models. METHOD: We reviewed 42 family studies that used family prevalence analyses to test three comorbidity models: the alternate forms model, the correlated liabilities model, or the three independent disorders model. We conducted the analyses used in these studies on datasets simulated under the assumptions of 13 alternative comorbidity models including the three models tested most often in the literature. RESULTS: Results suggest that some analyses may be valid tests of the alternate forms model (i.e., two disorders are alternate manifestations of a single liability), but that none of the analyses are valid tests of the correlated liabilities model (i.e., a significant correlation between the risk factors for the two disorders) or the three independent disorders model (i.e., the comorbid disorder is a third, independent disorder). CONCLUSION: Family studies using family prevalence analyses may have made incorrect conclusions regarding the etiology of comorbidity between disorders.

Adolescent↗

PubMed2003

Sibling-based association analyses of the serotonin transporter polymorphism and internalizing behavior problems in children.

BACKGROUND: Childhood internalizing problems are often precursors in the development of more serious psychiatric syndromes including anxiety and depressive disorders. Twin studies of the etiology of these disorders suggest that the genetic risk factors underlying anxiety and depression are highly correlated. However, the specific genetic mechanisms responsible for this risk have not yet been identified. METHODS: We examined the association between childhood internalizing problems and a functional polymorphism in the serotonin transporter gene (5-HTTLPR) in 711 children participating in a longitudinal twin study of behavioral and emotional development. Internalizing problems were measured at ages 4, 7, 9, 10, 11 and 12 years using the Child Behavior Checklist (CBCL) parent report form. We applied a sibling-based methodology for estimating allelic association with quantitative traits, while controlling for population stratification. RESULTS: No associations were found for CBCL Internalizing problems at any age, including the subscales for Somatic Complaints, Withdrawn and Anxiety/Depression. CONCLUSIONS: Thus, although our results did not support the hypothesis that the 5-HTTLPR contributes to a dimensional expression of internalizing behavior problems, this does not rule out the possibility that it is an interesting polymorphism to pursue in the search for genetic risk factors related to major depressive and/or anxiety disorders.

Anxiety Disorders↗

PubMed2002

Dopamine transporter polymorphism associated with externalizing behavior problems in children.

Early childhood externalizing behavior is a stable and heritable pattern of aggressive and delinquent behavior that often leads to the development of serious psychiatric disorders such as conduct disorder and attention deficit hyperactivity disorder. We examined the relationship between parent reported externalizing behavior (assessed at ages 4, 7, and 9 years) and the VNTR polymorphism of the 3' untranslated region of SLC6A3 (DAT1) in a community sample of 790 children ascertained as part of our longitudinal twin and adoption studies. We applied the sibling-based methodology developed by Fulker et al. [1999: Am J Hum Genet 64:259-267] for estimating allelic association with quantitative traits, while controlling for population stratification. An extension of these methods allowed for the inclusion of monozygotic twins, dizygotic twins, siblings, and singletons. We have demonstrated that the 9-repeat variant of the DAT1 is a significant risk allele for externalizing behavior at ages 4 (P=0.001) and 7 years (P=0.02). Although the effect size was negligible at age 9 (P=0.92), a formal test of the developmental decrease in effect across the three ages was non-significant (P=0.70).

Adolescent↗