Parent-offspring similarity for drinking: a longitudinal adoption study.

Parent-offspring resemblance for drinking was investigated in a sample of 409 adopted and 208 non-adopted families participating in the Sibling Interaction and Behavior Study. Drinking data was available for 1,229 offspring, assessed longitudinally up to three times in the age range from 10 to 28 years. A single drinking index was computed from four items measuring quantity, frequency and density of drinking. As expected, the mean drinking index increased with age, was greater in males as compared to females (although not at the younger ages), but did not vary significantly by adoption status. Parent-offspring correlation in drinking did not vary significantly by either offspring or parent gender but did differ significantly by adoption status. In adopted families, the parent-offspring correlation was statistically significant at all ages but decreased for the oldest age group (age 22-28). In non-adopted families, the parent-offspring correlation was statistically significant at all ages and increased in the oldest age group. Findings imply that genetic influences on drinking behavior increase with age while shared family environment influences decline, especially during the transition from late-adolescence to early adulthood.

A genome-wide association study of behavioral disinhibition.

We report results from a genome wide association study (GWAS) of five quantitative indicators of behavioral disinhibition: nicotine, alcohol consumption, alcohol dependence, illicit drugs, and non-substance related behavioral disinhibition. The sample, consisting of 7,188 Caucasian individuals clustered in 2,300 nuclear families, was genotyped on over 520,000 SNP markers from Illumina's Human 660W-Quad Array. Analysis of individual SNP associations revealed only one marker-component phenotype association, between rs1868152 and illicit drugs, with a p value below the standard genome-wide threshold of 5 × 10(-8). Because we had analyzed five separate phenotypes, we do not consider this single association to be significant. However, we report 13 SNPs that were associated at p < 10(-5) for one phenotype and p < 10(-3) for at least two other phenotypes, which are potential candidates for future investigations of variants associated with general behavioral disinhibition. Biometric analysis of the twin and family data yielded estimates of additive heritability for the component phenotypes ranging from 49 to 70%, GCTA estimates of heritability for the same phenotypes ranged from 8 to 37%. Consequently, even though the common variants genotyped on the GWAS array appear in aggregate to account for a sizable proportion of heritable effects in multiple indicators of behavioral disinhibition, our data suggest that most of the additive heritability remains "missing".

The structure of DSM-IV ADHD, ODD, and CD criteria in adolescent boys: a hierarchical approach.

Numerous studies have examined the structure of the childhood externalizing disorder symptoms of Attention Deficit Hyperactivity Disorder (ADHD), Oppositional Defiant Disorder (ODD), and Conduct Disorder (CD), both separately as well as simultaneously. The present study expanded on previous findings by implementing a multi-level hierarchical approach to investigating the component structure of ADHD, ODD, and CD criteria in 487 14-year-old boys from the Minnesota Twin Family Study (MTFS). We found support for a hierarchical conceptualization of externalizing behavior criteria in early adolescent boys by specifying how one-, two-, three-, four-, five- and six-factor models of externalizing criteria can be integrated. These results suggest that it may be more beneficial to conceptualize different levels of this hierarchy as relevant to different issues in case conceptualization and research design, from the broad level of an overall externalizing spectrum, to the level of finer-grained subtypes within specific disorders.

The impact of attention-deficit/hyperactivity disorder on preadolescent adjustment may be greater for girls than for boys.

Whether gender differences exist in the impairment associated with attention-deficit/hyperactivity disorder (ADHD) is still largely unknown, because most samples have few affected girls or include only one sex. The current study evaluated whether ADHD affects adjustment differently for girls than boys in a population-based cohort of 11-year-olds (520 girls, 478 boys). Those with a DSM-IV diagnosis of ADHD (predominantly inattentive, hyperactive-impulsive, or combined) were compared to those without ADHD on teacher, parent, and child reports of academics, peer relationships, self-concept, clinical symptoms, and treatment. Although boys and girls with ADHD experienced difficulties in all areas, girls with ADHD, especially the inattentive subtype, were more negatively affected in academics and peer relationships. Inattentive girls were less popular and more likely to be bullied than girls without ADHD, whereas inattentive boys were not. The social isolation experienced by many girls with ADHD deserves greater attention.

The effect of parental alcohol and drug disorders on adolescent personality.

OBJECTIVE: The relationship of parental alcohol or drug diagnosis to offspring personality was examined in a population-based sample of 17-year-old twins (568 girls and 479 boys) participating in the Minnesota Twin Family Study. Whether offspring personality characteristics 1) are specific to the type of substance use disorder in parents (alcohol versus drug) and 2) are found in high-risk offspring without substance use disorders as well as in offspring with substance use disorders was investigated. METHOD: Personality was assessed with the Multidimensional Personality Questionnaire; substance use disorders were assessed in person through diagnostic interviews. RESULTS: In both male and female offspring, parental history of alcohol dependence was associated with greater negative emotionality, aggression, stress reaction, and alienation but lower well-being; parental history of drug disorders was associated with lower constraint, control, harm avoidance, and traditionalism but higher social potency. Excluding offspring with a substance use disorder had virtually no effect on the statistical significance of these findings. CONCLUSIONS: In contrast to findings in some adult samples, personality characteristics associated with a family history of substance use disorders are found even in adolescent offspring who have not yet developed these disorders themselves, suggesting that personality might be one indicator of familial risk for substance use disorders during this developmental stage. Personality profiles of offspring of parents with substance use disorders also show some diagnostic specificity, with constraint associated with parental drug abuse and negative emotionality with parental alcoholism.

Development of substance dependence in two delinquency subgroups and nondelinquents from a male twin sample.

OBJECTIVE: The effect of delinquency subtype on the development of substance dependence symptoms was examined. It was proposed that early-onset delinquents possess characteristics that increase their likelihood of developing substance dependence problems earlier and more rapidly than late-onset delinquents and nondelinquents. METHOD: The development of alcohol, nicotine, and cannabis dependence symptoms (DSM-III-R) was examined over a 6-year period of adolescence (age 11-17) among 36 early-onset delinquent, 86 late-onset delinquent, and 25 nondelinquent boys from a large epidemiological twin sample. Multilevel/random coefficients models were used to compare groups on the rate of growth in number of symptoms over time. RESULTS: As expected, early-onset delinquents showed an earlier onset and a faster rate of increase in the number of cannabis and nicotine dependence symptoms than late-onset delinquents and controls. Both delinquent groups had a more rapid increase in alcohol dependence symptoms than controls. CONCLUSIONS: The data showed that early-onset delinquency is associated with earlier onset of substance use disorder symptoms and more rapid acceleration of problems with drugs than late-onset delinquency. Treatments for boys with early-onset delinquency should account for their increased risk for drug use problems in adolescence and the potential effects of those problems on the course of antisocial behavior.

Cascadia tremor located near plate interface constrained by S minus P wave times.

Nonvolcanic tremor is difficult to locate because it does not produce impulsive phases identifiable across a seismic network. An alternative approach to identifying specific phases is to measure the lag between the S and P waves. We cross-correlate vertical and horizontal seismograms to reveal signals common to both, but with the horizontal delayed with respect to the vertical. This lagged correlation represents the time interval between vertical compressional waves and horizontal shear waves. Measurements of this interval, combined with location techniques, resolve the depth of tremor sources within +/-2 kilometers. For recent Cascadia tremor, the sources locate near or on the subducting slab interface. Strong correlations and steady S-P time differences imply that tremor consists of radiation from repeating sources.