Evaluating longitudinal relationships between parental monitoring and substance use in a multi-year, intensive longitudinal study of 670 adolescent twins

Introduction

Parental monitoring is a key intervention target for adolescent substance use, however this practice is largely supported by causally uninformative cross-sectional or sparse-longitudinal observational research designs.

Methods

We therefore evaluated relationships between adolescent substance use (assessed weekly) and parental monitoring (assessed every two months) in 670 adolescent twins for two years. This allowed us to assess how individual-level parental monitoring and substance use trajectories were related and, via the twin design, to quantify genetic and environmental contributions to these relationships. Furthermore, we attempted to devise additional measures of parental monitoring by collecting quasi-continuous GPS locations and calculating a) time spent at home between midnight and 5am and b) time spent at school between 8am-3pm.

Results

ACE-decomposed latent growth models found alcohol and cannabis use increased with age while parental monitoring, time at home, and time at school decreased. Baseline alcohol and cannabis use were correlated (r = .65) and associated with baseline parental monitoring (r = -.24 to -.29) but not with baseline GPS measures (r = -.06 to -.16). Longitudinally, changes in substance use and parental monitoring were not significantly correlated. Geospatial measures were largely unrelated to parental monitoring, though changes in cannabis use and time at home were highly correlated (r = -.53 to -.90), with genetic correlations suggesting their relationship was substantially genetically mediated. Due to power constraints, ACE estimates and biometric correlations were imprecisely estimated. Most of the substance use and parental monitoring phenotypes were substantially heritable, but genetic correlations between them were not significantly different from 0.

Discussion

Overall, we found developmental changes in each phenotype, baseline correlations between substance use and parental monitoring, co-occurring changes and mutual genetic influences for time at home and cannabis use, and substantial genetic influences on many substance use and parental monitoring phenotypes. However, our geospatial variables were mostly unrelated to parental monitoring, suggesting they poorly measured this construct. Furthermore, though we did not detect evidence of genetic confounding, changes in parental monitoring and substance use were not significantly correlated, suggesting that, at least in community samples of mid-to-late adolescents, the two may not be causally related.

Etiological Overlap Between Sex Under the Influence and Number of Lifetime Sexual Partners

Drug and alcohol use is associated with risky sexual behavior (RSB). It is unclear whether this association is due to correlated liabilities (e.g., third variables influencing both traits), or whether use of drugs and alcohol during sexual decision making increases RSB. This study addresses this question by fitting a series of biometrical models using over 800 twin pairs assessed in early adulthood (m = 25.21 years). Measures included an index of sex under the influence (e.g., frequency that drugs or alcohol affect sexual decision making), number of lifetime sexual partners, and a general measure of substance use. Analyses suggest the covariance among these measures is explained by both genetic and environmental correlated liabilities. The overlap was not specific to sex under the influence, but was shared with a measure of general substance use. Models testing necessary but not sufficient parameters for direction of causation suggest that sex under the influence is unlikely to cause an increase in RSB; more evidence for reverse causation was found.

Independent predictors of mortality in adolescents ascertained for conduct disorder and substance use problems, their siblings and community controls

BACKGROUND AND AIMS

Adolescents with conduct and substance use problems are at increased risk for premature mortality, but the extent to which these risk factors reflect family- or individual-level differences and account for shared or unique variance is unknown. This study examined common and independent contributions to mortality hazard in adolescents ascertained for conduct disorder (CD) and substance use disorder (SUD), their siblings and community controls, hypothesizing that individual differences in CD and SUD severity would explain unique variation in mortality risk beyond that due to clinical/control status and demographic factors.

DESIGN

Mortality analysis in a prospective study (Genetics of Antisocial Drug Dependence Study) that began in 1993.

SETTING

Multi-site sample recruited in San Diego, California and Denver, Colorado, USA.

PARTICIPANTS

A total of 1463 clinical probands were recruited through the juvenile correctional system, court-mandated substance abuse treatment programs and correctional schools, along with 1399 of their siblings, and 904 controls.

MEASUREMENTS

Mortality and cause-of-death were assessed via National Death Index search (released October, 2017).

FINDINGS

There were 104 deaths documented among 3766 (1168 female) adolescents and young adults (average age 16.79 years at assessment, 32.69 years at death/censoring). Mortality hazard for clinical probands and their siblings was 4.99 times greater than that of controls (95% confidence interval = 2.40-10.40; P < 0.001). After accounting for demographic characteristics, site, clinical status, familial dependence and shared contributions of CD and SUD, CD independently predicted mortality hazard, whereas SUD severity did not.

CONCLUSIONS

In the United States, youth with conduct and substance use disorders and their siblings face far greater risk of premature death than demographically similar community controls. In contrast to substance use disorder severity, conduct disorder is a robust predictor of unique variance in all-cause mortality hazard beyond other risk factors.

Stability and change in executive function abilities from late adolescence to early adulthood: A longitudinal twin study

Executive functions (EFs)-the higher level cognitive abilities that enable us to control our own thoughts and actions-continue to develop into early adulthood, yet no longitudinal study has examined their stability during the important life transition from late adolescence to young adulthood. In this twin study (total N = 840 individuals from 424 families), we examined the stability of individual differences in 3 EF components across a 6-year period, from approximately age 17 years (Wave 1) to 23 years (Wave 2). Specifically, we address the following questions: (a) How stable are individual differences in multiple EFs across this time period? and (b) What (genetic and/or environmental) influences affect stability and change in EFs? Results indicated that individual differences in EFs are quite stable across this 6-year period (phenotypic latent variable correlations ranged from 0.86 to 1.0). However, there was evidence for change, particularly in the factor common to multiple EFs (Common EF). Multivariate twin models suggested that stability was due almost entirely to high genetic correlations across time; there was no new genetic variance at Wave 2. Change in Common EF was due to small but significant nonshared environmental influences at Wave 2 (15%). The results suggest that individual differences in EFs are quite heritable and stable by late adolescence, yet are still sensitive to environmental influences.

Relations between Preschool Attention Span-Persistence and Age 25 Educational Outcomes

This study examined relations between children's attention span-persistence in preschool and later school achievement and college completion. Children were drawn from the Colorado Adoption Project using adopted and non-adopted children (N = 430). Results of structural equation modeling indicated that children's age 4 attention span-persistence significantly predicted math and reading achievement at age 21 after controlling for achievement levels at age 7, adopted status, child vocabulary skills, gender, and maternal education level. Relations between attention span-persistence and later achievement were not fully mediated by age 7 achievement levels. Logistic regressions also revealed that age 4 attention span-persistence skills significantly predicted the odds of completing college by age 25. The majority of this relationship was direct and was not significantly mediated by math or reading skills at age 7 or age 21. Specifically, children who were rated one standard deviation higher on attention span-persistence at age 4 had 48.7% greater odds of completing college by age 25. Discussion focuses on the importance of children's early attention span-persistence for later school achievement and educational attainment.

Design, Utility, and History of the Colorado Adoption Project: Examples Involving Adjustment Interactions

This paper describes the Colorado Adoption Project (CAP), a longitudinal study in behavioral development, and discusses how adoption studies may be used to assess genetic and environmental etiologies of individual differences for important developmental outcomes. Previous CAP research on adjustment outcomes in childhood and adolescence which found significant interactions, including gene-environment interactions, is reviewed. New research suggests mediating effects of menarche and religiosity on age at first sex in this predominantly middle-class, Caucasian sample.

Bivariate analysis of disordered eating characteristics in adolescence and young adulthood

OBJECTIVE

We examined the etiology of two disordered eating characteristics.

METHOD

Participants included 1,470 female adolescent and young adult twins and their female nontwin siblings. Phenotypic factor analyses of a seven-item eating pathology screening tool yielded two factors: weight and shape concerns and behaviors (WSCB) and binge eating (BE). Univariate and bivariate extended twin analyses (including cotwins and nontwin siblings) were used to estimate the magnitude of genetic and environmental influences on these characteristics.

RESULTS

Analyses indicated that individual differences in WSCB and BE could be explained by additive genetic influences (a² = 0.43 (95% CI: 0.33-0.52) and 0.49 (95% CI: 0.36-0.58), respectively), with the remaining variance due to nonshared environmental influences. The genetic correlation between WSCB and BE was estimated at 0.64; the nonshared environmental correlation was estimated at 0.27.

DISCUSSION

These results corroborate previous findings on genetic and environmental influences on disordered eating characteristics and suggest that findings can be extended to nontwin populations.

Genetic and shared environmental influences on children's 24-h food and beverage intake: sex differences at age 7 y

BACKGROUND

The genetics of habitual food and beverage intake in early childhood is poorly understood.

OBJECTIVE

The objective was to test the magnitude of genetic and environmental influences on 24-h food and beverage intake in 7-y-old children. The association between intake of specific food-beverage categories and child body mass index (BMI; in kg/m(2)) was also tested.

DESIGN

A classic twin design was conducted, using the MacArthur Longitudinal Study of Twins. There were 792 children, including 396 boys from 102 monozygotic and 96 dizygotic twin pairs and 396 girls from 112 monozygotic and 86 dizygotic twin pairs; Children's 24-h dietary intake was estimated by parental recall, from which 9 composite food-beverage categories were derived. Height and weight were converted to BMI. Biometrical analyses of children's daily intake of food-beverage categories and BMI were conducted.

RESULTS

There was consistent evidence of genetic influences on children's 24-h intake of food and beverages (servings/d), especially among boys. Seven categories showed significant heritability estimates among boys, ranging from 12% (fish and lemon) to 79% (peanut butter and jelly). Only 3 categories showed significant heritability estimates among girls, ranging from 20% (bread and butter) to 56% (fish and lemon). BMI showed a genetic correlation only with bread and butter intake in girls.

CONCLUSION

The magnitude of genetic and environmental influences on children's 24-h food and beverage intake differed for boys and girls, which suggests sex differences in the development of eating patterns. Heritability estimates were generally large, although other eating phenotypes may be necessary for identifying genetic correlations with adiposity.

Genetic and environmental influences on age at sexual initiation in the Colorado Adoption Project

Whereas the majority of research on adolescent sexual initiation has focused solely on environmental factors, the present study used behavioral genetic analyses to investigate the relative contributions of genetic and environmental influences. Structural equation models were fitted to data from adoptive and non-adoptive sibling pairs (231 biologically related pairs and 169 unrelated pairs) from the Colorado Adoption Project. Information from censored individuals who had not yet experienced sexual initiation was maximized by adapting the twin survival analysis method of Pickles et al. (Behav Genet 24(5):457-468, 1994) to accommodate adoptive and non-adoptive siblings. Point estimates of variance components from an ACE model, including additive genetic (A), shared environmental (C), and non-shared environmental (E) influences were 28%, 24%, and 48%, respectively. Despite the lower point estimate for shared environmental effects than additive genetic effects, a CE model provided the best fit to the data. However, because adoptive siblings provide a direct estimate of shared environmental influences there is greater power to detect shared environmental effects in adoption designs. Evidence for genetic influences from our data were somewhat lower than those obtained in previous twin studies, possibly reflecting a return to more socially conservative sexual attitudes, changing sexual behaviors, or ambiguities in the wording of questions commonly used in research on adolescent sexuality.

Reliability of sibling reports on parental drinking behaviors

Questionnaire data from the Colorado Alcohol Research on Twins and Adoptees (CARTA) were analyzed to explore the reliability of sibling responses to items from the CARTA Family Alcoholism History Questionnaire (FHQ) concerning parental drinking behaviors. Subjects included 142 pairs of male and female, twin and nontwin siblings who reported on paternal and maternal problem drinking. FHQ items were summed to produce drinking-problem scales for fathers and mothers. There was generally good concordance across sibling reports of parental problem-drinking symptoms. There was a significant gender difference in that male offspring were more in agreement about their mothers' drinking behavior, while female offspring were more in agreement about their fathers' drinking behavior. For the most part, objective items, such as having two or more drunk-driving arrests, were more reliable (paternal kappa total = .56, maternal = .66) than subjective items, such as being happy only when drinking (paternal = .24, maternal = -.03). This evidence for reliability of sibling reports about parental drinking does seem to validate the use of such questionnaire data in alcohol studies.

Anticipated and subjective sensitivities to alcohol

The development and maintenance of alcohol use patterns may depend, in part, on differences between how an individual anticipates he will respond to alcohol and how he appears to others when he is drinking. Such differences may introduce bias in decisions regarding which activities are safe while under the influence of an intoxicating amount of alcohol. This study of 387 participants of the Colorado Alcohol Research on Twins and Adoptees project examined the interrelationships of anticipated, subjective and observer-judged sensitivity to a blood alcohol concentrations of about 0.1 g/dl (approximated by breath alcohol concentration). Differences among the sensitivity measures were dependent upon recent alcohol drinking history and individual differences in actual sensitivity (as observer-rated). The results were consistent with hypotheses that people with little drinking experience may overestimate how intoxicated they will be, that heavier drinkers may develop chronic tolerance to the intoxicating effects and that denial may play a role in both subjective and anticipated sensitivity.