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Thomas J Crowley

Publications and source records attributed to Thomas J Crowley.

26 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

Review of twin and adoption studies of adolescent substance use.

OBJECTIVE: To review studies of adolescent substance use and abuse with genetically informative designs. METHOD: Twin and adoption studies of adolescent substance use were searched in Medline using keywords. RESULTS: Of 19 studies that used adolescent samples, 18 examined initiation or use of substances and 1 examined abuse. Of the 7 retrospective studies using adult samples, 6 examined problematic behaviors such as substance dependence. Genetic and shared environmental influences on adolescent substance use are moderated by the specific substance, age, gender, specific contexts, religiousness, and region. There is some evidence for a common genetic influence on substance use across substances. Genetic influences on adolescent substance use may act through an influence on disinhibited behavior. Shared environment contributed to adolescent substance use consistently across all adolescent samples and common shared environmental influences influenced initiation into tobacco and alcohol use. While parental alcohol use had a small influence on adolescent shared environment, sibling influences were substantial. CONCLUSIONS: Twin and adoption studies have increased our understanding of genetic and environmental influences on adolescent substance use and its initiation; however, more studies focusing on clinical syndromes of abuse and dependence are needed.

Adolescent↗
PubMed2003

Family transmission of marijuana use, abuse, and dependence.

OBJECTIVE: To examine the familial aggregation of marijuana use, abuse, and dependence. METHOD: Adolescents recruited from residential and day treatment programs for youths with conduct and substance problems, matched controls, and all available family members were interviewed with structured research instruments. A total of 2,546 individuals from 781 families were interviewed. Risk ratios of relatives of clinical cases were calculated, compared with controls, for marijuana use, abuse, or dependence. Spousal, parent-offspring, and sibling correlations and the proportion of variance attributable to parent-offspring transmission were estimated using structural equation modeling. RESULTS: For all three measures, the risk ratios were elevated in the family members of clinical probands, with estimates ranging from 1.5 to 3.3. Spousal correlations ranged from 0.33 to 0.70. Parent-offspring correlations ranged from 0.17 to 0.30. Sibling correlations ranged from 0.34 to 0.44. The proportion of variance attributable to factors transmitted from parents to children ranged between 25% and 44%. CONCLUSIONS: Familial aggregation of marijuana use, abuse, and dependence is present for all three measures. The results suggest significant parent-offspring transmission of risk, sibling environmental influences, and assortative mating for all three levels of marijuana use.

Adolescent↗
PubMed2003

Discriminative validity and clinical utility of an abuse-neglect interview for adolescents with conduct and substance use problems.

OBJECTIVE: Many youths with conduct and substance use problems experience abuse and neglect. A valid measure of the severity of abuse-neglect events could facilitate research and clinical care. The authors' goal was to examine the discriminative validity, clinical utility, and severity correlations of the Colorado Adolescent Rearing Inventory, a structured, 20-45-minute abuse-neglect interview in the assessment of adolescents with conduct and substance use problems. METHOD: Ninety-eight adolescent patients with conduct and substance use problems and 102 comparison subjects (about 40% of the subjects in each group were female) completed the Colorado Adolescent Rearing Inventory, the Diagnostic Interview Schedule for Children, and the Composite International Diagnostic Interview-Substance Abuse Module. RESULTS: Although the subjects were advised that reports of abuse-neglect would be communicated to child welfare agencies, nearly two-thirds of the patients with conduct and substance use problems endorsed items indicating probable abuse-neglect, compared with about a third of the comparison subjects, a highly significant difference. Clinicians judged that 68%-80% of the cases of the patients and comparison subjects who endorsed such items warranted reporting to child welfare agencies. Scores on the Colorado Adolescent Rearing Inventory correlated significantly with severity of substance involvement, conduct disorder, and major depression. Compared to males, significantly more females (including 15% of comparison females) reported sexual abuse. Patients were significantly more likely than comparison subjects to attribute adverse life effects to their reported abuse-neglect experiences. CONCLUSIONS: Colorado Adolescent Rearing Inventory scores revealed many cases of serious abuse-neglect, generated many reports to child welfare agencies, demonstrated discriminative validity, correlated with clinical measures, and reflected important gender differences. The Colorado Adolescent Rearing Inventory can contribute to clinical evaluation and research involving youths with conduct and substance use problems.

Adolescent↗
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↗
PubMed2002

Adolescent heroin use: a review of the descriptive and treatment literature.

The prevalence of heroin use is rising among young people. We reviewed descriptive and treatment studies of heroin-using youth. Medline and Psychinfo were searched with the following kewords: heroin or opiate; and adolescent or young or juvenile. Nine articles describing treatment and five articles describing clinical characteristics of youth with heroin use were reviewed. Descriptive studies of heroin-using youth demonstrate substantial polysubstance use and psychiatric comorbidity. The largest treatment study found that, of four different treatment modalities, methadone maintenance had the highest retention rate. For youth who stayed in treatment for at least 6 months, therapeutic communities or drug-free treatment resulted in better outcomes compared with methadone maintenance. No controlled treatment trials were found. Length of time in treatment, regardless of modality, was the best predictor of outcome. The rise of heroin use among adolescents and young adults calls for descriptive studies as well as controlled treatment studies.

Adolescent↗