Relationship between abuse and neglect in childhood and diabetes in adulthood: differential effects by sex, national longitudinal study of adolescent health

INTRODUCTION

Few studies have investigated links between child abuse and neglect and diabetes mellitus in nationally representative samples, and none have explored the role of obesity in the relationship. We sought to determine whether child abuse and neglect were associated with diabetes and if so, whether obesity mediated this relationship in a population-representative sample of young adults.

METHODS

We used data from 14,493 participants aged 24 to 34 years from Wave IV of the National Longitudinal Study of Adolescent Health to study associations between self-reported child abuse (sexual, physical, or emotional abuse) and neglect as children and diabetes or prediabetes in young adulthood. We conducted sex-stratified logistic regression analyses to evaluate associations in models before and after the addition of body mass index (BMI) as a covariate.

RESULTS

Although the prevalence of diabetes was similar for men and women (7.0% vs 6.7%), men were more likely than women to have prediabetes (36.3% vs 24.6%; omnibus P < .001). Among men, recurrent sexual abuse (≥3 lifetime incidents) was significantly associated with diabetes (OR, 3.66; 95% CI, 1.31-10.24), but not with prediabetes. There was no evidence of mediation by BMI. No forms of child abuse or neglect were associated with diabetes or prediabetes among women.

CONCLUSIONS

Recurrent sexual abuse is robustly associated with diabetes in young adult men, independently of other forms of child abuse or neglect and BMI. Future research should explore other potential mechanisms for this association to identify avenues for prevention of diabetes among men who have experienced sexual abuse.

Are there common familial influences for major depressive disorder and an overeating-binge eating dimension in both European American and African American female twins?

OBJECTIVE

Although prior studies have demonstrated that depression is associated with an overeating-binge eating dimension (OE-BE) phenotypically, little research has investigated whether familial factors contribute to the co-occurrence of these phenotypes, especially in community samples with multiple racial/ethnic groups. We examined the extent to which familial (i.e., genetic and shared environmental) influences overlapped between Major Depressive Disorder (MDD) and OE-BE in a population-based sample and whether these influences were similar across racial/ethnic groups.

METHOD

Participants included 3,226 European American (EA) and 550 African American (AA) young adult women from the Missouri Adolescent Female Twin Study. An adaptation of the Semi-Structured Assessment for the Genetics of Alcoholism (SSAGA) was administered to assess lifetime DSM-IV MDD and OE-BE. Quantitative genetic modeling was used to estimate familial influences between both phenotypes; all models controlled for age.

RESULTS

The best-fitting model, which combined racial/ethnic groups, found that additive genetic influences accounted for 44% (95% CI: 34%, 53%) of the MDD variance and 40% (25%, 54%) for OE-BE, with the remaining variances due to non-shared environmental influences. Genetic overlap was substantial (rg  = .61 [.39, .85]); non-shared environmental influences on MDD and OE-BE overlapped weakly (re  = .26 [.09, .42]).

DISCUSSION

Results suggest that common familial influences underlie MDD and OE-BE, and the magnitude of familial influences contributing to the comorbidity between MDD and OE-BE is similar between EA and AA women. If racial/ethnic differences truly exist, then larger sample sizes may be needed to fully elucidate familial risk for comorbid MDD and OE-BE across these groups.

Parental separation, parental alcoholism, and timing of first sexual intercourse

PURPOSE

We examined timing of first voluntary sexual intercourse as a joint function of parental separation during childhood and parental history of alcoholism.

METHODS

Data were drawn from a birth cohort of female like-sex twins (n = 569 African ancestry [AA]; n = 3,415 European or other ancestry [EA]). Cox proportional hazards regression was conducted predicting age at first sex from dummy variables coding for parental separation and parental alcoholism. Propensity score analysis was also employed to compare intact and separated families, stratified by predicted probability of separation.

RESULTS

Earlier sex was reported by EA twins from separated and alcoholic families, compared to EA twins from intact nonalcoholic families, with effects most pronounced through the age of 14 years. Among AA twins, effects of parental separation and parental alcoholism were largely nonsignificant. Results of propensity score analyses confirmed unique risks from parental separation in EA families, where consistent effects of parental separation were observed across predicted probability of separation. For AA families, there was poor matching on risk factors presumed to predate separation, which limited interpretability of survival-analytic findings.

CONCLUSIONS

In European American families, parental separation during childhood is an important predictor of early-onset sex, beyond parental alcoholism and other correlated risk factors. To characterize risk for African Americans associated with parental separation, additional research is needed where matching on confounders can be achieved.

Subjective religiosity, church attendance, and depression in the National Survey of American Life

Studies have consistently indicated that blacks report lower rates of depression than whites. This study examined the association between religion and depression and whether religion explained lower rates of depression among blacks compared to whites. Data were drawn from the National Survey of American Life, a multi-ethnic sample of African Americans, Caribbean Blacks, and non-Hispanic whites (n = 6,082). African Americans and Caribbean Blacks reported higher mean levels of subjective religiosity than whites, but there were no significant differences in levels of church attendance. African Americans (OR 0.54; CI 0.45-0.65) and Caribbean Blacks (OR 0.66; CI 0.48-0.91) reported significantly lower odds of depression than whites. Differences in subjective religiosity and church attendance did not account for the association between major depression and African American and Caribbean Black race/ethnicity relative to whites. More research is needed to examine whether there are other factors that could protect against the development of depression.

Risks for early substance involvement associated with parental alcoholism and parental separation in an adolescent female cohort

BACKGROUND

We examined timing of substance involvement as a joint function of parental history of alcoholism and parental separation during childhood.

METHOD

Data were drawn from a large cohort of female like-sex twins [n=613 African Ancestry (AA), n=3550 European or other ancestry (EA)]. Cox proportional hazards regression was conducted predicting age at first use of alcohol, first alcohol intoxication, first use and regular use of cigarettes, and first use of cannabis and other illicit drugs from dummy variables coding for parental alcoholism and parental separation. Propensity score analysis was also conducted comparing intact and separated families by predicted probability of parental separation.

RESULTS

In EA families, increased risk of substance involvement was found in both alcoholic and separated families, particularly through ages 10 or 14 years, with risk to offspring from alcoholic separated families further increased. In AA families, associations with parental alcoholism and parental separation were weak and with few exceptions statistically nonsignificant. While propensity score findings confirmed unique risks observed in EA families, intact and separated AA families were poorly matched on risk-factors presumed to predate parental separation, especially parental alcoholism, requiring cautious interpretation of AA survival-analytic findings.

CONCLUSION

For offspring of European ancestry, parental separation predicts early substance involvement that is not explained by parental alcoholism nor associated family background characteristics. Additional research is needed to better characterize risks associated with parental separation in African American families.

A twin study of alcohol dependence, binge eating, and compensatory behaviors

OBJECTIVE

Rates of alcohol dependence are elevated in women with eating disorders who engage in binge eating or compensatory behaviors compared with women with eating disorders who do not report binge eating or compensatory behaviors and with healthy controls. Alcohol dependence, binge eating, and compensatory behaviors are heritable; however, it is unclear whether a shared genetic liability contributes to the phenotypic association among these traits, and little information exists regarding this shared liability in men. We investigated genetic and environmental correlations among alcohol dependence, binge eating, and compensatory behaviors in male and female twins.

METHOD

Participants included 5,993 same- and opposite-sex twins from the Australian Twin Registry who completed a modified version of the Semi-Structured Assessment for the Genetics of Alcoholism that assessed lifetime alcohol dependence and binge eating as defined in the Diagnostic and Statistical Manual of Mental Disorders, Third Edition, Revised. Compensatory behaviors were assessed via a general health questionnaire in women only. Biometrical twin models estimated genetic and environmental influences on alcohol dependence, binge eating, and compensatory behaviors.

RESULTS

In women, the multivariate twin model suggested that additive genetic and nonshared environmental effects influenced alcohol dependence, binge eating, and compensatory behaviors, with heritability estimates ranging from 38% to 53%. The best-fitting sex-limitation model was a common effects model that equated all genetic and nonshared environmental influences in men and women. The heritability estimates were 50% and 38% for alcohol dependence and binge eating, respectively. Overall, there were significant genetic correlations between alcohol dependence and binge eating, alcohol dependence and compensatory behaviors, and binge eating and compensatory behaviors.

CONCLUSIONS

These findings indicate that common genetic factors may underlie the vulnerability to alcohol dependence and the liability to binge eating and compensatory behaviors.

Alcohol dependence and reproductive timing in African and European ancestry women: findings in a midwestern twin cohort

OBJECTIVE

We examined associations between reproductive onset and history of alcohol dependence (AD) in 475 African ancestry (AA) and 2,865 European or other ancestry (EA) female twins.

METHOD

Participants were drawn from a U.S. midwestern birth cohort study of like-sex female twin pairs born between 1975 and 1985, ages 21-32 as of last completed assessment. Cox proportional hazards regression models were estimated predicting age at first childbirth from history of AD, separately by race/ethnicity, without and with adjustment for sociodemographic characteristics, body mass index, history of other substance involvement, psychopathology, and family and childhood risks.

RESULTS

Among EA twins, AD predicted early childbearing through age 17 and delayed childbearing from age 25 onward; in adjusted models, AD was associated with overall delayed childbearing. Among AA twins, reproductive timing and AD were not significantly related in either unadjusted or adjusted models.

CONCLUSIONS

Findings for twins of European ancestry are consistent with well-documented links between early alcohol mis/use and teenage parenting as well as delays in childbearing associated with drinking-related reproductive and relationship difficulties. Extension of analyses to other racial/ethnic groups of sufficient sample size remains important.

Gut microbiota from twins discordant for obesity modulate metabolism in mice

The role of specific gut microbes in shaping body composition remains unclear. We transplanted fecal microbiota from adult female twin pairs discordant for obesity into germ-free mice fed low-fat mouse chow, as well as diets representing different levels of saturated fat and fruit and vegetable consumption typical of the U.S. diet. Increased total body and fat mass, as well as obesity-associated metabolic phenotypes, were transmissible with uncultured fecal communities and with their corresponding fecal bacterial culture collections. Cohousing mice harboring an obese twin's microbiota (Ob) with mice containing the lean co-twin's microbiota (Ln) prevented the development of increased body mass and obesity-associated metabolic phenotypes in Ob cage mates. Rescue correlated with invasion of specific members of Bacteroidetes from the Ln microbiota into Ob microbiota and was diet-dependent. These findings reveal transmissible, rapid, and modifiable effects of diet-by-microbiota interactions.

Investigating the association between childhood sexual abuse and alcohol use disorders in women: does it matter how we ask about sexual abuse?

OBJECTIVE

The purpose of this study was to determine whether the type of questions used to assess childhood sexual abuse (CSA) introduces systematic bias into estimations of the magnitude of the association between CSA and alcohol use disorders (AUDs).

METHOD

The Semi-Structured Assessment for the Genetics of Alcoholism was administered by telephone to 3,787 female twins ages 18-29 years (14.6% African American, 85.4% White). Interviews included questions regarding sexual abuse experiences described in behavioral terms and a standard trauma checklist (in a separate section) with the items "rape" and "sexual molestation," with definitions provided in respondent booklets. Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, diagnoses of alcohol abuse and dependence, parental history of alcohol-related problems, and psychiatric conditions associated with AUDs were also assessed.

RESULTS

The majority of women who endorsed one question type also endorsed the other type. Rates of psychiatric risk factors for AUDs did not vary by pattern of CSA question endorsement. Separate Cox proportional hazards regression analyses using CSA variables derived from behavioral questions (hazard ratio [HR] = 1.67, 95% CI [1.27, 2.19]) and checklist items (HR = 1.41,95% CI [1.08, 1.84]) each revealed elevated risk for AUDs associated with CSA, and HRs did not differ significantly across models. However, a Cox proportional hazards regression analysis predicting AUD from the pattern of CSA question endorsements revealed a significantly higher risk for AUDs among women who endorsed only behavioral questions (HR = 3.26, 95% CI [1.72, 6.21]) than for all other groups.

CONCLUSIONS

Findings underscore the importance of querying CSA in studies of alcohol-related problems and highlight some of the limitations of assessment methods that can be integrated into studies covering a wide range of psychosocial domains.

Childhood sexual abuse and early substance use in adolescent girls: the role of familial influences

AIM

To assess the extent to which the association between childhood sexual abuse (CSA) and early use of alcohol, cigarettes and cannabis in adolescent girls is mediated by risk factors that tend to cluster in families where CSA occurs.

DESIGN

An abridged version of the Semi-Structured Assessment for the Genetics of Alcoholism (SSAGA) was administered by telephone.

PARTICIPANTS

A total of 3761 female twins aged 18-29 (14.6% African American, 85.4% European American).

MEASUREMENTS

CSA experiences and history of substance use were queried in the SSAGA-based interviews.

FINDINGS

After controlling for familial influences on early substance use by including co-twin early use status in models, separate Cox proportional hazards regression analyses predicting onset of alcohol, cigarette and cannabis use revealed a significant association with CSA. The effect was observed to age 19 years for cigarettes and to age 21 years for cannabis, but was limited to age 14 years or younger for alcohol, with the most pronounced risk before age 10 [hazard ratio (HR) = 4.59; confidence interval (CI): 1.96-10.74]. CSA-associated risk for initiation of cigarette and cannabis use was also highest in the youngest age range, but the decline with age was much more gradual and the hazard ratios significantly lower (HR: 1.70; CI: 1.13-2.56 for cigarettes and HR: 2.34, CI: 1.57-3.48 for cannabis).

CONCLUSIONS

Childhood sexual abuse history is a distinct risk factor for use of cigarettes and cannabis, and a very strong predictor of early age at first drink.

Cannabis or alcohol first? Differences by ethnicity and in risk for rapid progression to cannabis-related problems in women

BACKGROUND

Initiation of cannabis use typically follows alcohol use, but the reverse order does occur and is more common for African-Americans (AAs) than European-Americans (EAs). The aim of this study was to test for differences in the order of initiation of cannabis and alcohol use between AA and EA women and to determine whether order and ethnicity contribute independently to risk for rapid progression to cannabis-related problems. Method Data were drawn from structured psychiatric interviews of 4102 women (mean age = 21.6 years), 3787 from an all-female twin study and 315 from a high-risk family study; 18.1% self-identified as AA, 81.9% as EA. Ethnicity and order of initiation of cannabis and alcohol use were modeled as predictors of transition time from first use to onset of cannabis use disorder symptom(s) using Cox proportional hazards regression analyses.

RESULTS

AA women were nearly three times as likely as EA women to initiate cannabis use before alcohol use. Using cannabis before alcohol [hazard ratio (HR) 1.44, 95% confidence interval (CI) 1.08-1.93] and AA ethnicity (HR 1.59, 95% CI 1.13-2.24) were both associated with rapid progression from first use to cannabis symptom onset even after accounting for age at initiation and psychiatric risk factors.

CONCLUSIONS

The findings indicate that AA women are at greater risk for rapid development of cannabis-related problems than EA women and that this risk is even higher when cannabis use is initiated before alcohol use. Prevention programs should be tailored to the various patterns of cannabis use and relative contributions of risk factors to the development of cannabis-related problems in different ethnic groups.

Differences in time to onset of smoking and nicotine dependence by race/ethnicity in a Midwestern sample of adolescents and young adults from a high risk family study

OBJECTIVE

The objective of this study was to determine whether race/ethnicity was associated with time to smoking initiation and time from first cigarette to onset of DSM-IV nicotine dependence (ND) after adjusting for familial and individual psychosocial risk factors.

METHODS

Cox proportional hazards models with time-dependent covariates were used to analyze data from 1376 offspring aged 12-33 years from 532 families at high risk for substance use problems due to paternal alcohol problems and 235 low risk families. Fifty-six percent of the sample self-identified as African-American (AA) and 44% were mainly of European descent.

RESULTS

Controlling for covariates, AAs began smoking at older ages (HR=0.58; 95% CI: 0.48-0.70) and had longer times between smoking initiation and onset of ND compared to non-AAs (HR=0.25, 95% CI: 0.16-0.39 for ND onset occurring <18 years and HR=0.49, 95% CI: 0.30-0.80 for ND onsets ≥ age 18). After additionally controlling for number of cigarettes smoked daily, the racial/ethnic effects for onset of ND were attenuated, but remained statistically significant for ND onset <18 (HR=0.34, 95% CI: 0.19-0.61); however, the estimate was no longer significant for later ND onset (HR=0.84, 95% CI: 0.50-1.41).

CONCLUSIONS

AA adolescents and young adults initiate smoking at older ages and have longer transition periods between initiation and onset of ND compared to non-AAs, even after controlling for many relevant psychiatric and psychosocial covariates; however, racial/ethnic differences in time to onset of nicotine dependence in late adolescence and young adulthood may be explained by differences in daily quantity smoked.

The impact of a consortium of fermented milk strains on the gut microbiome of gnotobiotic mice and monozygotic twins

Understanding how the human gut microbiota and host are affected by probiotic bacterial strains requires carefully controlled studies in humans and in mouse models of the gut ecosystem where potentially confounding variables that are difficult to control in humans can be constrained. Therefore, we characterized the fecal microbiomes and metatranscriptomes of adult female monozygotic twin pairs through repeated sampling 4 weeks before, 7 weeks during, and 4 weeks after consumption of a commercially available fermented milk product (FMP) containing a consortium of Bifidobacterium animalis subsp. lactis, two strains of Lactobacillus delbrueckii subsp. bulgaricus, Lactococcus lactis subsp. cremoris, and Streptococcus thermophilus. In addition, gnotobiotic mice harboring a 15-species model human gut microbiota whose genomes contain 58,399 known or predicted protein-coding genes were studied before and after gavage with all five sequenced FMP strains. No significant changes in bacterial species composition or in the proportional representation of genes encoding known enzymes were observed in the feces of humans consuming the FMP. Only minimal changes in microbiota configuration were noted in mice after single or repeated gavage with the FMP consortium. However, RNA-Seq analysis of fecal samples and follow-up mass spectrometry of urinary metabolites disclosed that introducing the FMP strains into mice results in significant changes in expression of microbiome-encoded enzymes involved in numerous metabolic pathways, most prominently those related to carbohydrate metabolism. B. animalis subsp. lactis, the dominant persistent member of the FMP consortium in gnotobiotic mice, up-regulates a locus in vivo that is involved in the catabolism of xylooligosaccharides, a class of glycans widely distributed in fruits, vegetables, and other foods, underscoring the importance of these sugars to this bacterial species. The human fecal metatranscriptome exhibited significant changes, confined to the period of FMP consumption, that mirror changes in gnotobiotic mice, including those related to plant polysaccharide metabolism. These experiments illustrate a translational research pipeline for characterizing the effects of FMPs on the human gut microbiome.

Associations of alcohol, nicotine, cannabis, and drug use/dependence with educational attainment: evidence from cotwin-control analyses

BACKGROUND

Although substance use is associated with reduced educational attainment, this association may be owing to common risk factors such as socioeconomic disadvantage. We tested whether alcohol, nicotine, and illicit drug use and dependence were associated with lifetime educational attainment after controlling for familial background characteristics.

METHODS

Data were from a 1987 questionnaire and a 1992 telephone diagnostic interview of 6,242 male twins (n = 3,121 pairs; mean age = 41.9 years in 1992) who served in the U.S. military during the Vietnam era and therefore, were eligible for educational benefits after military service. Reduced educational attainment (<16 years) was examined in twin pairs discordant for substance use history. Substance use and dependence risk factors assessed were early alcohol and cannabis use, daily nicotine use, lifetime cannabis use, and alcohol, nicotine, cannabis, and any illicit drug dependence.

RESULTS

Three significant differences were observed between at-risk twins and their cotwins: Compared to their low-risk cotwins, likelihood of completing <16 years of education was significantly increased for the following: (i) twins who used alcohol before age 18 (adjusted OR = 1.44; 95% CI: 1.02 to 2.05), (ii) twins with a lifetime alcohol dependence diagnosis (adjusted OR = 1.76; 95% CI: 1.27 to 2.44), and (iii) twins who had used nicotine daily for 30 or more days (adjusted OR = 2.54, 95% CI: 1.55 to 4.17). However, no differences in education were observed among twin pairs discordant for cannabis initiation, early cannabis use, or cannabis, nicotine, or any illicit drug dependence.

CONCLUSIONS

Even in a veteran population with access to military educational benefits, early alcohol use, alcohol dependence, and daily nicotine use remained significantly associated with years of education after controlling for shared familial contributions to educational attainment. The association between other substances and educational attainment was explained by familial factors common to these substance use phenotypes and adult educational attainment.

Posttraumatic stress disorder and alcohol dependence in young women

OBJECTIVE

The aim of the current study is to characterize the relationship between posttraumatic stress disorder (PTSD) and alcohol dependence (AD) in women, distinguishing PTSD-specific influences on AD from the contribution of co-occurring psychiatric conditions and from the influences of trauma more generally.

METHOD

Trauma histories and DSM-IV lifetime diagnoses, including PTSD and AD, were obtained via telephone interview from 3,768 female twins. Based on PTSD status and trauma history, participants were categorized as no trauma (43.7%), trauma without PTSD (52.6%), or trauma with PTSD (3.7%). Cox proportional hazards regression analyses were conducted using trauma/PTSD status to predict AD, first adjusting only for ethnicity and parental problem drinking, then including conduct disorder, major depressive disorder, regular smoking, and cannabis abuse.

RESULTS

Before accounting for psychiatric covariates, elevated rates of AD were evident in both trauma-exposed groups, but those with PTSD were at significantly greater risk for AD than those without PTSD. This distinction was no longer statistically significant when psychiatric covariates were included in the model, but both trauma-exposed groups continued to show elevated odds of developing AD compared with the no trauma group.

CONCLUSIONS

The elevated rates of AD in women who have experienced trauma are not accounted for in full by psychiatric conditions that commonly co-occur with AD and trauma exposure. The greater likelihood of developing AD in the subset of trauma-exposed individuals who develop PTSD may reflect higher levels of distress and/ or higher rates of psychopathology associated with traumas that lead to PTSD rather than PTSD-specific influences.

A latent class analysis of DSM-IV and Fagerström (FTND) criteria for nicotine dependence

BACKGROUND

Nicotine dependence is associated with considerable morbidity and mortality. Two predominant classification systems, the Diagnostic and Statistical Manual (DSM-IV) and Fagerström Test for Nicotine Dependence (FTND), have been used to measure liability to nicotine dependence, yet few studies have attempted to simultaneously examine both sets of criteria.

METHODS

Using a sample of 624 regular smoking individuals who are offspring of Vietnam Era Twin fathers ascertained for an offspring of twin study, we applied latent class analysis to the 7 DSM-IV and the 6 FTND criteria to classify individuals by their nicotine dependence symptom profiles. Post-hoc across-class comparisons were conducted using a variety of smoking-related variables and aspects of psychopathology. Whether a single class identified offspring at high genetic and environmental vulnerability was also investigated.

RESULTS

The cross-diagnosis kappa was .30. A 4-class solution fit these data best. The classes included a low DSM-low FTND class and a high DSM-high FTND class; a moderate DSM-moderate FTND class, which was distinguished by moderate levels of smoking and intermediate levels of comorbid psychopathology; and a light smoking-moderate FTND class consisting primarily of lighter smokers with a more recent onset of regular smoking. High genetic and environmental vulnerability to nicotine dependence was noted in all classes with no statistically significant across-class differences.

CONCLUSIONS

In general, the DSM-IV and FTND criteria performed similarly to define a continuum of risk for nicotine dependence. The emerging class of light smokers should be further investigated to assess whether they transition to another class or remain as such.

Smoking outcome expectancies in young adult female smokers: individual differences and associations with nicotine dependence in a genetically informative sample

Outcome expectancy is a central construct in models of addiction. Several outcome expectancies associated with smoking cigarettes have been identified, and studies suggest that individual differences in smoking expectancies are related to important aspects of tobacco use, including levels of smoking, nicotine dependence and smoking cessation. In the present study, we used a novel analytic method, exploratory structural equation modeling (ESEM), to quantify smoking expectancies from a subset of items adapted from the Smoking Consequences Questionnaire (SCQ; Brandon and Baker, 1991) and SCQ-Adult (Copeland et al., 1995). In our sample of 1262 monozygotic and dizygotic young adult, female twins who were regular smokers, we quantified six smoking expectancy factors similar to those reported in previous studies. These included Negative Affect Reduction, Boredom Reduction, Weight Control, Taste Manipulation, Craving/Addiction and Stimulation-state Enhancement. We used genetic model-fitting to examine the extent to which individual differences in the expectancies were influenced by latent genetic, shared environmental and non-shared environmental factors. We also examined the validity of the expectancy factors by examining their associations with nicotine dependence (ND) before and after adjusting for comorbid diagnoses of drug dependence and alcohol use disorder. Results of the validity analysis indicated that all of the expectancies were associated with ND after covariate adjustment. Although we lacked the statistical power to distinguish between genetic and shared environmental sources of variance, our results suggest that smoking outcome expectancies aggregate in families, but the majority of variance in these expectancies is due to environmental factors specific to the individual.

Common genetic and environmental contributions to post-traumatic stress disorder and alcohol dependence in young women

BACKGROUND

The few genetically informative studies to examine post-traumatic stress disorder (PTSD) and alcohol dependence (AD), all of which are based on a male veteran sample, suggest that the co-morbidity between PTSD and AD may be attributable in part to overlapping genetic influences, but this issue has yet to be addressed in females.MethodData were derived from an all-female twin sample (n=3768) ranging in age from 18 to 29 years. A trivariate genetic model that included trauma exposure as a separate phenotype was fitted to estimate genetic and environmental contributions to PTSD and the degree to which they overlap with those that contribute to AD, after accounting for potential confounding effects of heritable influences on trauma exposure.

RESULTS

Additive genetic influences (A) accounted for 72% of the variance in PTSD; individual-specific environmental (E) factors accounted for the remainder. An AE model also provided the best fit for AD, for which heritability was estimated to be 71%. The genetic correlation between PTSD and AD was 0.54.

CONCLUSIONS

The heritability estimate for PTSD in our sample is higher than estimates reported in earlier studies based almost exclusively on an all-male sample in which combat exposure was the precipitating traumatic event. However, our findings are consistent with the absence of evidence for shared environmental influences on PTSD and, most importantly, the substantial overlap in genetic influences on PTSD and AD reported in these investigations. Additional research addressing potential distinctions by gender in the relative contributions of genetic and environmental influences on PTSD is merited.

Deconstructing the architecture of alcohol abuse and dependence symptoms in a community sample of late adolescent and emerging adult women: an item response approach

The objective of this study was to examine the underlying factorial architecture of lifetime DSM-IV alcohol use disorder (AUD) criteria in a population-based sample of adolescent and emerging adult female twins who had ever used alcohol (n=2832; aged 18-25 years), and to determine whether thresholds and factor loadings differed by age. Item response modeling was applied to DSM-IV AUD criteria. Compound criteria (e.g., persistent desire or unsuccessful attempts to quit or cut down) were included as separate items. Of the remaining 16 items, tolerance and use despite physical problems were the most and least commonly endorsed items, respectively. Underlying the items was a single factor representing liability to AUDs. Factor loadings ranged from 0.67 for blackouts to 0.90 for time spent using/recovering from effects. Some items assessing different DSM-IV criteria had very similar measurement characteristics, while others assessing the same criterion showed markedly different thresholds and factor loadings. Compared to that of women aged 21-25 years, the threshold for hazardous use was higher in women aged 18-20 years, but lower for used longer than intended and persistent desire to cut down. After accounting for threshold differences, no variations in discrimination across age groups were observed. In agreement with the extant literature, our findings indicate that the factorial structure of AUD is unidimensional, with no support for the abuse/dependence distinction. Individual components of compound criteria may differ in measurement properties; therefore pooling information from such divergent items will reduce information about the AUD construct.

Effect of paternal alcohol and drug dependence on offspring conduct disorder: gene-environment interplay

OBJECTIVE

Not only are substance-use disorders and externalizing disorders frequently comorbid, they often co-occur in families across generations. The current study examined the role of genetic and environmental influences in the relationship between paternal histories of drug dependence or alcohol dependence and offspring conduct disorder using an offspring-of-twins design.

METHOD

Participants were male twins (n = 1,774) from the Vietnam Era Twin Registry, their offspring (n = 1,917), and mothers of the offspring (n = 1,202). Twins had a history of drug dependence, alcohol dependence, or neither. Based on the father's and his co-twin's drug-dependence or alcohol-dependence history and zygosity, risk groups were constructed to reflect different levels of genetic and environmental risk that were then used to predict offspring conduct disorder.

RESULTS

After controlling for potentially confounding variables, the offspring of men with a history of drug dependence or alcohol dependence had significantly higher rates of conduct disorder, compared with offspring of men without this history. Offspring at higher genetic risk had higher rates of conduct disorder. High-risk offspring at lower environmental risk had lower rates of conduct disorder but only in the case of paternal drug-dependence risk. Lower environmental risk did not influence rates of offspring conduct disorder when the father had an alcohol-dependence history.

CONCLUSIONS

Genetic risk associated with both paternal drug-dependence and paternal alcohol-dependence histories predicted offspring conduct-disorder risk, but only risk associated with paternal drug-dependence history was mitigated by having a low-risk environment. These results demonstrated a significant gene-environment interaction effect.

Body mass index and regular smoking in young adult women

Little is known about the relationship between relative body weight and transition from experimentation to regular smoking in young adult women. In the current study, data from 2494 participants in wave 4 of the Missouri Adolescent Female Twin Study (aged 18-29years) who reported ever smoking a cigarette were analyzed using logistic regression. Body mass index (BMI) at time of interview was categorized according to CDC adult guidelines, and regular smoking was defined as having ever smoked 100 or more cigarettes and having smoked at least once a week for two months in a row. Since the OR's for the overweight and obese groups did not differ significantly from one another in any model tested, these groups were combined. Forty-five percent of women who had ever smoked had become regular smokers. Testing of interactions between potential covariates and levels of the categorical BMI variable revealed a significant interaction between overweight/obesity and childhood sexual abuse (CSA; p<0.001) associated with regular smoking. Among women reporting CSA, the association between overweight/obesity and having become a regular smoker was negative (n=374; OR=0.48, 95% CI: 0.28-0.81). Both underweight and overweight/obesity were positively associated with transition to regular smoking among women who did not report CSA (n=2076; OR=1.57, 95% CI: 1.05-2.35 and OR=1.73, 95% CI: 1.35-2.20, respectively). These results suggest that experiencing CSA alters the association between BMI and regular smoking in women who have experimented with cigarettes.

The effects of maternal smoking during pregnancy on offspring outcomes

OBJECTIVE

To evaluate the possible association between maternal smoking during pregnancy and offspring outcomes of birth weight, pre-term birth, remediation, low scholastic achievement, regular smoking, attention deficit hyperactivity disorder and conduct problems while controlling for similar behaviors in parents.

METHODS

Using telephone interviews, data were collected, in 2001 and 2004, as a part of two United States offspring-of-twins projects. Fathers, who were twins participating in the Vietnam Era Twin Registry, their female spouse and their offspring were interviewed - information on 1,342 unique pregnancies in mothers with a history of regular smoking was utilized for these analyses. The association between maternal smoking during pregnancy and birth weight, pre-term birth, remediation, low scholastic achievement, regular smoking, attention deficit hyperactivity disorder and conduct disorder while controlling for similar behaviors in parents, was examined using regression.

RESULTS

Maternal smoking during pregnancy was associated with decreased birth weight, low scholastic achievement, regular smoking and attention deficit hyperactivity disorder. However, the association between maternal smoking during pregnancy and offspring attention deficit hyperactivity disorder was explained by maternal attention deficit hyperactivity disorder. Maternal smoking during pregnancy was also associated with earlier age of offspring initiation of smoking and onset of regular smoking.

CONCLUSIONS

Maternal smoking during pregnancy may influence certain offspring outcomes via mechanisms that are independent from genetic risk attributable to comorbid conditions. Assisting expecting mothers with their smoking cessation efforts will likely provide widespread health benefits to both mother and offspring.

Subjective effects to cannabis are associated with use, abuse and dependence after adjusting for genetic and environmental influences

BACKGROUND

Previous reports in adults have suggested that the effects experienced after cannabis use can be described in terms of positive and negative subtypes that are heritable and are associated with abuse and dependence. This study extends existing research by inclusion of adolescents and young adults in an offspring of twins design which makes it possible to take into account genetic and environmental risks for substance use disorder.

METHODS

Data were collected from 725 twin members of the Vietnam Era Twin Registry, 839 of their 12-32 year old biological offspring and 427 mothers. Offspring who had ever used cannabis (n=464) were asked the degree to which they typically experienced 13 subjective effects shortly after using cannabis. Latent class analysis (LCA) was used to derive subjective effect classes and logistic regression models were computed to test associations between subjective effect class and heavy cannabis use, abuse and dependence after adjusting for familial risk and psychopathology and sociodemographics.

RESULTS

The best fitting LCA model included 4 classes of responders which were characterized as 'high responders' (39%), 'positive responders' (28%), 'mixed/relaxed' (22%), and 'low responders' (11%). Compared to low responders, members of other classes were heavier users (OR range 3.0-11.8). Compared to mixed/relaxed responders and positive responders, high responders were more likely to have cannabis abuse and dependence.

CONCLUSIONS

Subjective reactions to cannabis use are associated with use to heavy use, abuse and dependence in adolescents and young adults. This association exists above and beyond the genetic vulnerability for problem cannabis use.

Relationship between body mass index, alcohol use, and alcohol misuse in a young adult female twin sample

OBJECTIVE

The aim of this study was to examine the relationships between body mass index (BMI) and alcohol use and misuse in young adulthood in a sample of black and white female twins.

METHOD

Cox proportional hazards and logistic regression models were used to examine the relationships between BMI category and first alcohol use, current weekly alcohol use, and current weekly heavy episodic drinking in 3,514 (14.06% black) young adult female twins. Analyses were conducted separately in black and white women.

RESULTS

After adjusting for relevant covariates, in white women obesity was protective against alcohol use (hazard ratio = 0.83; 95% confidence interval [CI]: 0.73-0.93) and against weekly drinking (odds ratio [OR] = 0.36; 95% CI: 0.24-0.53) and weekly heavy episodic drinking (OR = 0.51; 95% CI: 0.31-0.82) among ever drinkers compared with women of ideal weight. Overweight women living with their parents were less likely to be weekly drinkers (OR = 0.31; 95% CI: 0.16-0.61), whereas overweight women who were not living with their parents were less likely to be weekly heavy episodic drinkers (OR = 0.51; 95% CI: 0.31-0.82). Among black women, obesity was not associated with any of the drinking outcomes; however, black women who were overweight and who reported that the majority of their friends were not weekly drinkers had greater odds of reporting weekly drinking than those of ideal weight (OR = 2.91; 95% CI: 1.33-6.39).

CONCLUSIONS

Obese white women were less likely to ever use alcohol, be weekly drinkers, or be weekly heavy episodic drinkers than their ideal-weight peers. Body weight may affect drinking behavior in young women, and this effect may differ by race. Future research is needed to identify mediators and moderators of this relationship as well as to explore racial differences in the effect of body weight on drinking behavior.

Genetic and environmental contributions to BMI in adolescent and young adult women

The objective of this study was to determine the genetic and environmental contributions to variation in BMI over time in European-American (EA) and African-American (AA) adolescent and young adult women. Self-reported BMI (kg/m(2)) data from 2,816 EA (1,306 twin pairs, 56.5% monozygotic (MZ)) and 404 AA (178 twin pairs, 42.7% MZ) women at baseline (T1; median age 15 years) and 3,225 EA (1,511 twin pairs, 55.3% MZ) and 539 AA (252 pairs, 43.3% MZ) women at follow-up (T2; median age 22 years) from a Midwestern US, population-based twin registry were used to construct biometrical genetic models. For EA women, the majority of the variance in BMI was attributable to additive genetic effects at both time points (82% for each), with the remaining variance attributable to nonshared environment. Genetic and nonshared environment correlations between adolescent and young adult BMI were 0.87 and 0.23, respectively. Among AA women, nonadditive genetic effects comprised 68% of the variance at T1 and 73% at T2, and were highly correlated (r(D) = 0.94). The proportions of variance attributable to nonshared environment at T1 (29%) and T2 (25%) were more modestly correlated (r(E) = 0.31). The remaining variance in AA women could be attributed to additive genetic effects. Additive vs. nonadditive genetic effects contribute differentially to BMI in AA vs. EA adolescent and young adult women. Additional research is needed to better characterize the environmental and genetic factors related to BMI in persons of different races to aid understanding of the complex determinants of body weight in individuals.