Jon Randolph Haber

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.

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.

Measured environmental contributions to cannabis abuse/dependence in an offspring of twins design

Genetic and environmental factors are known to contribute to cannabis abuse/dependence (CAD). We sought to determine the magnitude of the contribution from measured environmental variables to offspring cannabis dependence in a design that controls for familial vulnerability. Data come from a study of 725 twin members of the Vietnam Era Twin Registry, 720 of their biological offspring (age 18-32 years) and 427 mothers. Data were obtained on offspring perception of family and peer support and substance use behaviors and offspring CAD. After adjusting for familial risk, and environmental covariates, CAD was significantly more likely among male offspring (OR=2.73; 95% CI: 1.69-4.41). Offspring CAD was associated with reporting: siblings used illicit drugs (OR=3.40; 95% CI: 1.81-6.38), a few friends used drugs (OR=2.72; 95% CI: 1.04-7.09), a quarter or more friends used drugs (OR=8.30; 95% CI: 3.09-22.33) and one-half or more 12th grade peers used drugs (OR=3.17; 95% CI: 1.42-7.08). Perceived sibling, friend and school peer substance use are strongly associated with CAD in young adults even after accounting for latent familial risk and for multiple measured intra-family and extra-family environmental influences.

Patterns of use, sequence of onsets and correlates of tobacco and cannabis

BACKGROUND While most individuals initiate their use of tobacco prior to onset of cannabis use, recent reports have identified a smaller subset of youth who report onset of cannabis use prior to tobacco use. In this study, we characterize patterns of cannabis and tobacco use (tobacco but not cannabis, cannabis but not tobacco or both) and compare the factors associated with onset of tobacco before cannabis and cannabis before tobacco. METHODS Data on 1812 offspring aged 12-32 years, drawn from two related offspring of Vietnam Era twin studies, were used. Individuals were divided into tobacco but not cannabis (T), cannabis but not tobacco (C) and users of both substances (CT). Those who used both could be further classified by the timing of onset of tobacco and cannabis use. Multinomial logistic regression was used to characterize the groups using socio-demographic and psychiatric covariates. Furthermore, data on parental smoking and drug use was used to identify whether certain groups represented greater genetic or environmental vulnerability. RESULTS 22% (N=398) reported T, 3% (N=55) reported C and 44% reported CT (N=801). Of the 801 CT individuals, 72.8% (N=583), 9.9% (N=77) and 17.3% (N=139) reported onset of tobacco before cannabis, cannabis before tobacco and onsets at the same age. C users were as likely as CT users to report peer drug use and psychopathology, such as conduct problems while CT was associated with increased tobacco use relative to T. Onset of tobacco prior to cannabis, when compared onset of cannabis before tobacco or reporting initiation at the same age was associated with greater cigarettes smoked per day, however no distinct factors distinguished the group with onset of cannabis before tobacco from those with initiation at the same age. CONCLUSION A small subset of individuals report cannabis without tobacco use. Of those who use both cannabis and tobacco, a small group report cannabis use prior to tobacco use. Follow-up analyses that chart the trajectories of these individuals will be required to delineate their course of substance involvement.

Dimensions of Religion/Spirituality and Relevance to Health Research

This study aimed to identify unique religion/ spirituality (R/S) factors that account for variation in R/S measures of interest to health research. A 127-item questionnaire that included R/S items from classic, personality, clinical, and recent R/S-health research was administered to California state college students (n = 846) and to members of two California churches (n = 425). A seven-factor solution emerged that explained 61.5% of total variance that replicated across independent samples and that was highly stable across diverse subgroups. A large primary factor (28% of explained variance) included a number of key R/S measures assessing R/S motivation, devotion, and coping. Six other factors, each accounting for 6% to 9%, supported the discriminant validity of social support, existential well-being, extrinsic motivation, religious proscription, and two personality factors (spiritual and self transcendence). The link between current results and literature on health is discussed in terms of current causal models.

Parent, sibling and peer associations with subtypes of psychiatric and substance use disorder comorbidity in offspring.

BACKGROUND Parental substance use disorder (SUD) is associated with a range of negative offspring outcomes and psychopathology, but the clustering of these outcomes into subtypes has seldom been examined, nor have the familial and environmental contexts of these subtypes been reported. The present study examines the clustering of offspring lifetime substance use and psychiatric disorders into subtypes and characterizes them in terms of familial and non-familial influences using an offspring-of-twins design. METHOD Telephone-administered diagnostic interviews were used to collect data on psychiatric disorders and SUD from 488 twin fathers, 420 biological mothers and 831 offspring. Latent class analysis (LCA) was used to derive subtypes of lifetime comorbidity in offspring. Familial risk and environmental variables associated with each subtype (i.e., parenting, childhood physical or sexual abuse, perceived sibling and peer substance use) were identified using multinomial logistic regression. RESULTS Four classes identified by LCA were characterized as (1) unaffected, (2) alcohol abuse/dependence, (3) alcohol abuse/dependence comorbid with anxiety and depression, and (4) alcohol, cannabis abuse/dependence and nicotine dependence comorbid with conduct disorder. Inconsistent parenting, childhood physical/sexual abuse, and perceived sibling and peer substance use were significantly associated with profiles of offspring comorbidity after adjusting for familial vulnerability. Some associations were specific (i.e., perceived peer alcohol use to the AUD class), while others were general (peer smoking to all 3 comorbidity classes). CONCLUSIONS We observed distinct subtypes of psychiatric and SUD comorbidity in adolescents and young adults. Subtypes of offspring psychopathology have varied associations with parental psychopathology, family environment, and sibling and peer behaviors.

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.

Alcoholism, Personality, and Religion/Spirituality: An Integrative Review

A review of the literature on the relationships between alcoholism, personality, and religion identified patterns that may help explain the inverse association between alcoholism and religion/spirituality (R/S). Personality plays a central role in two etiological models of alcoholism. The personality traits of high behavioral undercontrol (low Agreeableness and low Conscientiousness) and high negative affect (high Neuroticism) are both significantly related to higher alcohol use. Religiosity is also correlated with these traits, but in the opposite direction (e.g., with low behavioral undercontrol and low negative affect). Thus, the personality profiles associated with alcoholism and religion are the inverse of one another. In addition, evidence suggests that R/S moderates genetic variation on both Neuroticism and Disinhibition (part of behavioral undercontrol). Implications are discussed in terms of competing explanatory models: a basic research model which argues for genetically-determined stability in personality and alcoholism risk, and a clinical treatment model which argues for the primacy of environmental interventions in treatment and the possibility of personality change as a pathway to recovery.

Testing the Equal Environments Assumption in the Children of Twins Design

In a Children of Twins (COT) design, the environmental and genetic risk of a child is, in part, dependent upon the status of the father and the father’s cotwin. The logic of the COT method breaks down if the zygosity of the twin pair is confounded with the environment provided to the child (a version of the Equal Environment Assumption, EEA). If MZ twin fathers see each other more often than DZ twin fathers, and a child’s uncle is the affected twin in discordant pairs, this could increase the environmental risk of children of MZ over that of DZ discordant twins. The current study was designed to test the EEA in the COT design, specifically in children of alcohol and drug dependent fathers. Results indicated that MZ twins did have more contact than DZ twins. Regression analyses were conducted to predict child externalizing symptom counts from father’s zygosity group status, level of contact with father’s cotwin, and their interaction. Results found no significant interaction between father’s zygosity and the higher level of cotwin contact (seen in MZ twins) in predicting several measures of offspring externalizing risk. The results of this study suggested that the COT design does not confound zygosity with differences in environmental risk exposure, findings that support the validity of the EEA within this research context.

Parental Separation and Offspring Alcohol Involvement: Findings from Offspring of Alcoholic and Drug Dependent Twin Fathers.

BACKGROUND We examined associations between parental separation during childhood and offspring alcohol involvement, adjusting for genetic and environmental risks specific to parental alcohol (AD) and cannabis/other illicit drug dependence (DD). METHODS The sample consisted of 1,828 offspring of male twins from the Vietnam Era Twin (VET) Registry, who completed a telephone diagnostic interview. Cox proportional hazards regression analyses were conducted predicting onset of first use, transition from first use to first AD symptom, and transition from first use to AD diagnosis from paternal and avuncular AD and DD history, parental separation, and offspring and family background characteristics. Paternal/avuncular DD/AD was based on the DSM-III-R; offspring and maternal AD were based on DSM-IV criteria. RESULTS Paternal DD/AD predicted increased offspring risk for all transitions, with genetic effects suggested on rate of transitioning to AD diagnosis. Parental separation was predictive of increased risk for early alcohol use, but a reduced rate of transition to both AD symptom onset and onset of AD. No interactions between separation and familial risk (indexed by paternal or avuncular DD/AD) were found. CONCLUSIONS Findings highlight the contribution of both parental separation and paternal substance dependence in predicting timing of offspring alcohol initiation and problems across adolescence into early adulthood.