Cross-generational effects on gender differences in psychoactive drug abuse and dependence

Investigating sex differences and the effect of drug exposure order in the sensory reward-enhancing effects of nicotine and d-amphetamine alone and in combination

Nicotine enhances the rewarding effects of other environmental stimuli; this reward-enhancement encourages and maintains nicotine consumption. Nicotine use precedes other psychostimulant use, but receiving a stimulant prescription also predicts future smoking. Previously, no study has investigated effects of drug exposure order in reward-enhancement, nor with nicotine and d-amphetamine. Thus, we aimed to investigate how drug exposure order impacted the reward-enhancing effects of nicotine and d-amphetamine, alone and in combination. We used 20 male and 20 female Sprague-Dawley rats. Enhancement was investigated within-subjects by examining responding maintained by a visual stimulus reinforcer following a pre-session injection of either d-amphetamine (Sal, 0.1, 0.3, or 0.6 mg/kg) or nicotine (Sal, 0.03, 0.06, 0.1, 0.3 mg/kg). Twenty rats (10 M, 10 F) completed enhancement testing with nicotine before d-amphetamine. The other 20 rats (10 M, 10 F) completed testing with d-amphetamine before nicotine. Following these phases, rats were then given two pre-session injections: one of d-amphetamine (Sal, 0.1, 0.3, or 0.6 mg/kg) and another of nicotine (Sal, 0.03, 0.06, 0.1, or 0.3 mg/kg). Experiencing amphetamine before nicotine increased reward-enhancing effects of nicotine. Females exhibited greater effects of d-amphetamine on reward-enhancement, with no effect of exposure order. During the interaction phase, receiving nicotine before amphetamine enhanced the interaction between nicotine and d-amphetamine for females whereas amphetamine before nicotine heightened this interaction for males. From this, prior and current amphetamine use, in addition to sex, should be considered when treating nicotine dependency and when examining factors driving poly-substance use involving nicotine and d-amphetamine. Keywords: Adderall, ADHD, Dexedrine, operant, smoking, polysubstance use.

Reward-enhancing effects of d-amphetamine and its interactions with nicotine were greater in female rats and persisted across schedules of reinforcement

Nicotine enhances the value of environmental stimuli and rewards, and reward enhancement can maintain nicotine consumption. Stimulants such as d-amphetamine are misused more by women and are commonly co-used with nicotine. d-Amphetamine potentiates nicotine's effects in human and animal research. To date, there are no published studies examining this interaction in a reward-enhancement task. The current study sought to investigate the reward-enhancing effects of nicotine alongside and coadministered with d-amphetamine. Further, we evaluated the persistence of reward enhancement across ratio and temporal schedules of reinforcement. We used 10 male and 10 female Sprague-Dawley rats. Enhancement was assessed within subjects by examining active lever pressing for a visual stimulus reinforcer on variable ratio 3, variable interval 30 s and variable time 30 s - variable ratio 3 schedules. Before 1-h sessions, rats received one injection of saline, 0.1 or 0.3 mg/kg d-amphetamine and one of saline or 0.4 mg/kg nicotine, making six possible drug combinations (saline + saline, saline + nicotine, 0.1 d-amphetamine + aline, 0.1 d-amphetamine + nicotine, 0.3 d-amphetamine + saline and 0.3 d-amphetamine + nicotine) experienced in a randomized order by each rat. When d-amphetamine was coadministered with nicotine, we found an interaction effect on reward enhancement that persisted across schedules of reinforcement. Males and females exhibited reward enhancement by 0.3 d-amphetamine, while only females showed reward enhancement by 0.1 d-amphetamine. Further, females responded more for the visual stimulus than males in all d-amphetamine conditions. Future studies should assess how reward enhancement is involved in high nicotine-amphetamine comorbidity rates and enhanced amphetamine misuse in women.

A co-twin-control analysis of adolescent and young adult drinking effects on learning and memory

BACKGROUND AND AIMS

Existing evidence for a link between alcohol use and memory impairments in adolescents and young adults is largely correlational. We aimed to determine whether associations between drinking and episodic memory were consistent with a causal effect of drinking or accounted for by familial factors confounding such associations. Because cannabis use is associated with a similar pattern of performance on episodic memory measures, we assessed whether any associations might be attributable to concurrent cannabis use.

DESIGN, SETTING AND PARTICIPANTS

Observational study of individuals aged approximately 20-29 years, comprising two independent population-based cohorts of twins. A co-twin-control design permitted an estimate of alcohol exposure effects free of shared genetic and environmental confounding influences. Significant associations were followed-up with twin-difference analyses. Propensity scores derived from measures collected at age 11 were used to adjust for unshared confounders. Participants in both cohorts were assessed from the age of 11 (n = 1251) under the auspices of the Minnesota Center for Twin and Family Research.

MEASUREMENTS

Regression analyses with cumulative alcohol use as the predictor of interest. Multiple measures of attention, learning and memory from a widely used episodic memory task constituted dependent variables.

FINDINGS

Drinking was associated with poorer attention (P ≤ 0.003) and learning (P ≤ 0.008). Results were similar across the two cohorts. The within-pair effect in twin-difference analyses was significant only for measures of learning (P-values ≤ 0.004). Results were not due to measured unshared confounders or cannabis use. Drinking in adolescence (to age 20) and early adulthood (between 20 and 29) exerted independent effects on learning.

CONCLUSIONS

There appears to be a robust and specific association between drinking and learning that can be reproduced across cohorts, is not easily accounted for by confounding factors or concurrent cannabis use and is consistent with a causal influence of drinking.

Illicit drug use by mothers and their daughters in Australia: A comparison of two generations

BACKGROUND

While recent decades have witnessed an increase in the use of illicit drugs in Australia, the extent to which the types of drugs used has changed over a generation of young women has not been documented.

METHODS

Data are from a prospective birth cohort study. Mothers were recruited in early pregnancy (1981-83) and then they and their child were followed up, with mothers interviewed 27 years (2008-2011), and daughters 30 years (2010-14), after the birth. At these most recent interviews both mothers and daughters were administered the Composite International Diagnostic Interview (CIDI III). Comparisons are for mothers and daughters separated by a 25 year period. For this study, we compare levels of lifetime use of a range of illicit drugs and drug use disorders reported by mothers and their daughters (N = 998 mother/daughter pairs) with adjustment for family income, marital status, education and occupation.

RESULTS

There has been a generational increase in the use of illicit substances and prevalence of substance use disorders experienced by Australian women. Mothers' use of illicit drugs was generally restricted to cannabis. By contrast the majority of daughters report lifetime use of an illicit drug with cannabis, club drugs and stimulants the most common. Compared to the mothers, daughters used club drugs 50 times, cocaine 19 times and inhalants 20 times more often. Daughters report experiencing 12 times the rate of cocaine use disorders, 9 times the rate of stimulant disorders and 7 times the rate of cannabis use disorders compared to their mothers.

CONCLUSIONS

Mothers of the current generation of 30 year old Australian women rarely used illicit drugs and few experienced a drug use disorder. The current generation of young women report commonly using one or more illicit drugs with a substantial minority experiencing a drug use disorder. It is unlikely that the use of illicit drugs by young women in Australia will be reversed in the foreseeable future. Government policies and treatment practices need to be calibrated to the reality of the much greater contact with illicit drugs being exhibited by younger women.

The socialization of boys and men in the modern era: An evolutionary mismatch

This paper examines the misalignment between modern human society and certain male phenotypes, a misalignment that has been highlighted and explored in great detail in the work of Tom Dishion. We begin by briefly enumerating the ongoing developmental difficulties of many boys and young men and how these difficulties affect them and those around them. We then suggest that the qualities that have been advantageous for men and their families in our earlier evolution but that are often no longer functional in modern society are a source of these problems. Finally, we provide a brief review of prevention programs that can contribute to preventing this type of problematic development and eliciting more prosocial behavior from at-risk boys and men. We conclude with an overview of research and policy priorities that could contribute to reducing the proportion of boys and young men who experience developmental difficulties in making their way in the world.

Generational trends and patterns in readmission within a statewide cohort of clients receiving heroin use disorder treatment in Maryland, 2007-2013

The recent rise in opioid-related overdose deaths stresses the importance of understanding how heroin use disorders persist and what interventions are best suited for treating these illnesses. Trends show that there are diverse pathways leading to heroin use disorder that span multiple generations, but little is known about how different generations utilize and respond to treatment. This study provides insight into treatment utilization for young, middle-aged, and older adults by examination of an unusually rich longitudinal dataset of substance use disorder clients in Maryland who were treated for heroin use. Results show that clear patterns of treatment readmission emerge across generations in treatment-naïve clients with regard to gender, ethnicity, employment, geographical region, and treatment type/intensity. In particular, Millennials comprise the majority of the clients receiving heroin use disorder treatment and are the largest contributor to these readmission patterns. Millennials are also given opioid maintenance therapy (OMT) more frequently than other generations, while exhibiting a strong avoidance to treatment. Generational differences in treatment decisions and outcomes over the course of a treatment career are important for understanding the nature of the current opioid epidemic, and can play an important role in directing heroin use disorder treatment efforts and improving models of care.

Sex differences in the anorexigenic effects of dexfenfluramine and amphetamine in baboons

The anorexigenic effects of intramuscular d-amphetamine HCl (0.06-0.50 mg/kg) and dexfenfluramine HCl (0.25-2.0 mg/kg) were determined in experimentally naïve baboons. A group of 8 adult male baboons was tested prior to a group of 7 adult female baboons. A 120-min session occurred at 9:00 a.m. during which baboons could respond for food pellets. Drug was given 30 min prior to the 9:00 a.m. morning session. Beginning at 11:00 a.m., baboons had a 6-hr multiple-meal session during which they could have up to 4 food pellet meals. Food was not available overnight, but food was available for 90 min upon awakening such that drug effects were evaluated in non-food-deprived animals. Under baseline conditions baboons earned between 30 and 70 pellets during the morning session and another 175-225 pellets during the remainder of the day. Amphetamine and dexfenfluramine produced dose-dependent decreases in food pellet intake during both the morning food session and the later multiple-meal session. Whereas there were minimal sex differences in the effects of dexfenfluramine, many of the amphetamine doses produced greater decreases in pellet intake in males than females. These results are discordant with much of the rodent literature on abuse-related drug effects that generally reports greater effects of amphetamine in females than males. Additional work is needed to replicate the current findings in nonhuman primates. (PsycINFO Database Record

Self-administration of methamphetamine aerosol by male and female baboons

The reinforcing efficacy of vaporized methamphetamine HCl (0.3 mg/kg) was determined in baboons with minimal previous drug exposure. A group of 8 adult male baboons was tested prior to a group of 7 adult female baboons. Baboons were initially trained to suck on a brass stem activating a pressure-sensitive relay (i.e., puff), to receive one M&M® candy. Five of the 8 males and 6 of the 7 females learned to activate the relay. 0.05 ml of 95% ethyl alcohol containing 0.3 mg/kg methamphetamine was vaporized and delivered to the mouth of the baboon after he/she completed 2 puffs; a single candy was given after an additional 5 puffs to ensure that baboons continued puffing after the aerosol entered their mouths. Puffing was recorded but not reinforced by candy or drug for 2 min after each aerosol delivery for males and 1 min for females. Males could earn 10 and females could earn 20 aerosol deliveries. Males made between 225 and 650 puffs each session. Females made between 200 and 400 puffs each session. When only candy and placebo aerosol were delivered the number of puffs decreased in all 6 females but increased in all 5 males. When candy was delivered without aerosol, puffing decreased in 4 of 5 males, but this manipulation was not tested in females. Methamphetamine aerosol delivery maintained lower rates of puffing behavior in females than males, but procedural differences weaken interpretation of this sex comparison. Although training non-human primates to inhale drug vapors is time consuming, if successful, their long lifespan could provide years of valuable data justifying further work with non-human primates using models of vaporized drug self-administration.

Codevelopment Between Key Personality Traits and Alcohol Use Disorder From Adolescence Through Young Adulthood

OBJECTIVE

Personality traits related to negative emotionality and low constraint are strong correlates of alcohol use disorder (AUD), but few studies have evaluated the prospective interplay between these traits and AUD symptoms from adolescence to young adulthood.

METHOD

The Minnesota Twin Family Study (N = 2,769) was used to examine the developmental interplay between AUD symptoms and three personality measures of constraint, negative emotionality, and aggressive undercontrol from ages 17 to 29.

RESULTS

Results from random-intercept, cross-lagged panel models showed that low constraint and aggressive undercontrol predicted subsequent rank-order increases in AUD symptoms from ages 17 to 24. AUD symptoms did not predict rank-order change in these traits from ages 17 to 24. There was support for both cross-effects from ages 24 to 29. Biometric analysis of the twin data showed genetic influences accounted for most of the phenotypic correlations over time.

CONCLUSION

Results are consistent with the notion that personality traits related to low constraint and aggressive undercontrol are important vulnerability/predisposition factors for the development of early adult AUD. In later young adulthood, there is more evidence for the simultaneous codevelopment of personality and AUD. Implications are addressed with attention to personality-based risk assessments and targeted AUD prevention approaches.

Associations Between Depression and Obesity in Parents and Their Late-Adolescent Offspring: A Community-Based Study

OBJECTIVE

Major depressive disorder (MDD) and obesity are associated within individuals, but little is known about the association between MDD and obesity within families. We hypothesized that parental MDD would predict increased risk for adolescent obesity and that parental obesity would predict increased risk for adolescent MDD.

METHODS

Participants were drawn from the community-based Minnesota Twin Family Study (N = 7307; 17 years old: n = 3774). Parents and their 17-year-old offspring were assessed for MDD using a structured diagnostic interview, and direct assessments of height and weight were conducted (and diagnoses of obesity were derived from these measurements).

RESULTS

Parental MDD was associated with offspring obesity (odds ratio [OR] = 1.74, 95% confidence interval [CI] = 1.24-2.46). ORs representing the risk associated with maternal and paternal MDD were similar (OR = 1.42, 95% CI = 1.02-1.92; OR = 1.40, 95% CI = 0.88-2.20, respectively). This parental effect remained significant when adjusting for parental obesity and offspring MDD (OR = 1.67, 95% CI = 1.18-2.37). Maternal obesity was associated with increased risk for MDD in offspring (OR = 1.32, 95% CI = 1.06-1.64), but paternal obesity was associated with decreased risk for MDD among offspring (OR = 0.70, 95% CI = 0.54-0.91). These effects remained significant when adjusting for parental MDD and offspring obesity (OR = 1.36, 95% CI = 1.07-1.73; OR = 0.65, CI = 0.49-0.87, respectively). There were no differences in these findings by offspring sex (p values for all tests of a sex interaction term > .374).

CONCLUSIONS

We found general support for hypothesized cross-disorder associations between MDD and obesity in parents and offspring, suggesting that a shared etiology may underlie these associations. Contrary to prediction, paternal obesity was associated with decreased risk for offspring MDD, a finding that requires further investigation.

Personality Traits Predict the Developmental Course of Externalizing: A Four-Wave Longitudinal Study Spanning Age 17 to Age 29

The objective of the present study was to determine whether and how personality predicts the developmental course of externalizing problems, including antisocial behavior and substance dependence. In a large, population-based longitudinal study (N = 1,252), the 11 personality traits assessed by the Multidimensional Personality Questionnaire were measured at age 17, and DSM diagnoses of adult antisocial behavior, alcohol dependence, and drug dependence were obtained at ages 17, 20, 24, and 29. We fit a quadratic multiple indicator latent growth model where the three diagnoses loaded onto an externalizing factor. This model fit the data well, and externalizing increased until it started to decline at age 24. High aggression and low control were the most significant predictors of the development of externalizing, with aggression playing a significant role in the development of externalizing across the 12-year time span, and control predicting the development from age 17 to 24. The findings highlight the importance of considering the developmental course of externalizing in the context of personality and suggest that the specific personality traits of aggression and control might be targeted in externalizing prevention and intervention programs.

Heritability and molecular genetic basis of electrodermal activity: a genome-wide association study

The molecular genetic basis of electrodermal activity (EDA) was analyzed using 527,829 single nucleotide polymorphisms (SNPs) in a large population-representative sample of twins and parents (N = 4,424) in relation to various EDA indices. Biometric analyses suggested that approximately 50% or more of variance in all EDA indices was heritable. The combined effect of all SNPs together accounted for a significant amount of variance in each index, affirming their polygenic basis and heritability. However, none of the SNPs were genome-wide significant for any EDA index. Previously reported SNP associations with disorders such as substance dependence or schizophrenia, which have been linked to EDA abnormalities, were not significant; nor were associations between EDA and genes in specific neurotransmitter systems. These results suggest that EDA is influenced by multiple genes rather than by polymorphisms with large effects.

Alcohol and drug misuse, abuse, and dependence in women veterans

We conducted a systematic literature review on substance misuse, abuse, and dependence in women veterans, including National Guard/reserve members. We identified 837 articles published between 1980 and 2013. Of 56 included studies, 32 reported rates of alcohol misuse, binge drinking, or other unhealthy alcohol use not meeting diagnostic criteria for abuse or dependence, and 33 reported rates of drug misuse or diagnosed alcohol or drug use disorders. Rates ranged from 4% to 37% for alcohol misuse and from 7% to 25% for binge drinking; among Veterans Health Administration (VA) health-care system outpatients, rates ranged from 3% to 16% for substance use disorder. Studies comparing women veterans and civilians reported no clear differences in binge or heavy drinking. Substance misuse rates were generally lower among women veterans than men veterans. Substance misuse was associated with higher rates of trauma, psychiatric and medical conditions, and increased mortality and suicide rates. Most studies included only VA patients, and many used only VA medical record data; therefore, the reported substance misuse rates likely do not reflect true prevalence. Rates also varied by assessment method, source of data, and the subgroups studied. Further efforts to develop epidemiologically valid prevalence estimates are needed to capture the true health burden of substance misuse in women veterans, particularly those not using VA care.

Genome-wide scans of genetic variants for psychophysiological endophenotypes: a methodological overview

This article provides an introductory overview of the investigative strategy employed to evaluate the genetic basis of 17 endophenotypes examined as part of a 20-year data collection effort from the Minnesota Center for Twin and Family Research. Included are characterization of the study samples, descriptive statistics for key properties of the psychophysiological measures, and rationale behind the steps taken in the molecular genetic study design. The statistical approach included (a) biometric analysis of twin and family data, (b) heritability analysis using 527,829 single nucleotide polymorphisms (SNPs), (c) genome-wide association analysis of these SNPs and 17,601 autosomal genes, (d) follow-up analyses of candidate SNPs and genes hypothesized to have an association with each endophenotype, (e) rare variant analysis of nonsynonymous SNPs in the exome, and (f) whole genome sequencing association analysis using 27 million genetic variants. These methods were used in the accompanying empirical articles comprising this special issue, Genome-Wide Scans of Genetic Variants for Psychophysiological Endophenotypes.

Knowns and unknowns for psychophysiological endophenotypes: integration and response to commentaries

We review and summarize seven molecular genetic studies of 17 psychophysiological endophenotypes that comprise this special issue of Psychophysiology, address criticisms raised in accompanying Perspective and Commentary pieces, and offer suggestions for future research. Endophenotypes are polygenic, and possibly influenced by rare genetic variants. Because they are not simpler genetically than clinical phenotypes, they are unlikely to assist gene discovery for psychiatric disorder. Once genetic variants for clinical phenotypes are identified, associated endophenotypes are likely to provide valuable insights into the psychological and neural mechanisms important to disorder pathology. This special issue provides a foundation for informed future steps in endophenotype genetics, including the formation of large sample consortia capable of fleshing out the many genetic variants contributing to individual differences in psychophysiological measures.

Exploring sex differences in drug use, health and service use characteristics among young urban crack users in Brazil

Introduction

Studies have shown important gender differences among drug (including crack) users related to: drug use patterns; health risks and consequences; criminal involvement; and service needs/use. Crack use is prevalent in Brazil; however, few comparative data by sex exist. We examined and compared by sex key drug use, health, socio-economic indicators and service use in a bi-city sample of young (18–24 years), regular and marginalized crack users in Brazil.

Methods

Study participants (total n = 159; n = 124 males and n = 35 females) were recruited by community-based methods from impoverished neighborhoods in Rio de Janeiro and Salvador. Assessments occurred by an anonymous interviewer-administered questionnaire and serum collection for blood-borne virus testing between November 2010 and June 2011. Descriptive statistics and differences for key variables by sex were computed; in addition, a ‘chi-squared automatic interaction detector’ (‘CHAID’) analysis explored potential primary factors differentiating male and female participants.

Results

Most participants were non-white, and had low education and multiple income sources. More women had unstable housing and income from sex work and/or panhandling/begging, whereas more men were employed. Both groups indicated multi-year histories of and frequent daily crack use, but virtually no drug injection histories. Men reported more co-use of other drugs. More women were: involved in sex-for-drug exchanges; Blood-Borne Virus (BBV) tested and HIV+. Both groups reported similar physical and mental health patterns; however women more commonly utilized social or health services. The CHAID analysis identified sex work; paid work; begging/panhandling; as well as physical and mental health status (all at p < 0.05) as primary differentiating factors by sex.

Conclusions

Crack users in our study showed notable differences by sex, including socio-economic indicators, drug co-use patterns, sex risks/work, BBV testing and status, and service utilization. Results emphasize the need for targeted special interventions and services for males and female crack users in Brazil.

The developmental progression of age 14 behavioral disinhibition, early age of sexual initiation, and subsequent sexual risk-taking behavior

BACKGROUND

Research has demonstrated a consistent relationship between early sexual experience and subsequent sexual risk-taking behaviors. We hypothesized that this relationship is due to a general predisposition toward behavioral disinhibition (BD), and that relationships among BD, early sex, and subsequent risky sexual behavior may be influenced by common genetic influences for males and common environmental influences for females.

METHODS

A prospective sample of 1,512 same-sex adolescent twins (50.2% female) was used. Adolescent BD was measured by clinical symptom counts of conduct disorder, oppositional defiant disorder, and self-reported delinquent behavior (age 14). Age of sexual initiation was defined as first age of consensual oral or penetrative sex (mean age ~17). Adult risky sexual behavior was defined by sexual behaviors under the influence of drugs and alcohol and number of casual sexual partners in the past year (age 24).

RESULTS

Multivariate analyses showed evidence for substantial common genetic variance among age 14 BD, age at sexual initiation, and adult risky sexual behavior for males, but not females. There was no significant difference in the degree of common environmental influence on these variables for females compared to males. Notably, age of sexual initiation was not significantly correlated with age 24 risky sexual behavior for females.

CONCLUSION

The relationship between early sex and later risky sex can be better understood through a general liability toward BD, which is influenced primarily by genetic factors for males. The association between age 14 BD and age of sexual initiation was influenced through a combination of genetic and environmental factors for females; however, age of sexual initiation does not appear to be a salient predictor of adult women’s sexual risk-taking behavior. Findings suggest that prevention programs aimed at reducing sexual risk behavior might target youth exhibiting BD by age 14, particularly males. More research is needed on what predicts adult sexual risk-taking behavior for females.

Obesity and depression in adolescence and beyond: reciprocal risks

Objective

Obesity and Major Depressive Disorder (MDD) are associated, but evidence about how they relate over time is conflicting. The goal of this study was to examine prospective associations between depression and obesity from early adolescence through early adulthood.

Methods

Participants were drawn from a statewide, community-based, Minnesota sample. MDD and obesity with onsets by early adolescence (by age 14), late adolescence (between 14 and 20), and early adulthood (ages 20 to 24) were assessed via structured interview (depression) and study-measured height and weight.

Results

Cross-sectional results indicated that depression and obesity with onsets by early adolescence were concurrently associated, but the same was not true later in development. Prospective results indicated that depression by early adolescence predicted the onset of obesity (odds ratio=3.76, confidence interval= 1.33–10.59) during late adolescence among females. Obesity that developed during late adolescence predicted the onset of depression (odds ratio=5.89, confidence interval= 2.31–15.01) during early adulthood among females.

Conclusions

For girls, adolescence is a high risk period for the development of this comorbidity, with the nature of the risk varying over the course of adolescence. Early adolescent-onset depression is associated with elevated risk of later onset obesity, and obesity, particularly in late adolescence, is associated with increased odds of later depression. Further investigation into the mechanisms of these effects and the reasons for the observed gender and developmental differences is needed. Prevention programs focused on early-onset cases of depression and adolescent-onset cases of obesity, particularly among females, may help in reducing risk for this form of comorbidity.

Age, period and cohort trends in drug abuse hospitalizations within the total Swedish population (1975-2010)

BACKGROUND

The societal consequences of drug abuse (DA) are severe and well documented, the World Health Organization recommending tracking of population trends for effective policy responses in treatment of DA and delivery of health care services. However, to correctly identify possible sources of DA change, one must first disentangle three different time-related influences on the need for treatment due to DA: age effects, period effects and cohort effects.

METHODS

We constructed our main Swedish national DA database (spanning four decades) by linking healthcare data from the Swedish Hospital Discharge Register to individuals, which included hospitalisations in Sweden for 1975-2010. All hospitalized DA cases were identified by ICD codes. Our Swedish national sample consisted of 3078,129 men and 2921,816 women. We employed a cross-classified multilevel logistic regression model to disentangle any net age, period and cohort effects on DA hospitalization rates.

RESULTS

We found distinct net age, period and cohort effects, each influencing the predicted probability of hospitalisation for DA in men and women. Peak age for DA in both sexes was 33-35 years; net period effects showed an increase in hospitalisation for DA from 1996 to 2001; and in birth cohorts 1968-1974, we saw a considerable reduction (around 75%) in predicted probability of hospitalisation for DA.

CONCLUSIONS

The use of hospital admissions could be regarded as a proxy of the population's health service use for DA. Our results may thus constitute a basis for effective prevention planning, treatment and other appropriate policy responses.

Lifetime prevalence and co-morbidity of externalizing disorders and depression in prospective assessment

BACKGROUND

Epidemiological research is believed to underestimate the lifetime prevalence of mental illness due to recall failure and a lack of rapport between researchers and participants.

METHOD

In this prospective study, we examined lifetime prevalence and co-morbidity rates of substance use disorders, antisocial personality disorder (ASPD) and major depressive disorder (MDD) in a representative, statewide Minnesota sample (n = 1252) assessed four times between the ages of 17 and 29 years with very low attrition.

RESULTS

Lifetime prevalence rates of all disorders more than doubled between the ages of 17 and 29 years in both men and women, and our prospective rates at the age of 29 years were consistently higher than rates from leading epidemiological surveys. Although there was some variation, the general trend was for lifetime co-morbidity to increase between the ages of 17 and 29 years, and this trend was significant for MDD-alcohol dependence, MDD-nicotine dependence, and ASPD-nicotine dependence.

CONCLUSIONS

Overall, our results show that emerging adulthood is a high-risk period for the development of mental illness, with increases in the lifetime prevalence and co-morbidity of mental disorders during this time. More than a quarter of individuals had met criteria for MDD and over a fifth had experienced alcohol dependence by the age of 29 years, indicating that mental illness is more common than is estimated in cross-sectional mental health surveys. These findings have important implications for the measurement of economic burden, resource allocation toward mental health services and research, advocacy organizations for the mentally ill, and etiological theories of mental disorders.

Disentangling the relative contribution of parental antisociality and family discord to child disruptive disorders

A number of familial risk factors for childhood disruptive disorders have been identified. However, many of these risk factors often co-occur with parental antisociality, which by itself may account for both the familial risk factors and the increased likelihood of offspring disruptive behavior disorders (DBDs). The current study aimed to examine the association of parenting behaviors, marital conflict, and divorce with child DBDs while accounting for (a) coparent parenting behaviors, and (b) parental adult antisocial behavior (AAB). A series of regressions tested the association between family-level variables (namely, parent-child relationship quality, parental willingness to use physical punishment, marital adjustment, and history of divorce) and DBDs (attention deficit hyperactivity disorder, conduct disorder, and oppositional defiant disorder) alone and after statistically adjusting for coparent variables and parental AAB. Results indicated that parents with AAB were more likely to engage in various forms of maladaptive parenting, to divorce, and to have conflictual marriages. Maladaptive parenting, marital conflict, and divorce were associated with heightened rates of child DBDs, and these associations persisted after adjusting for coparent parenting and parental AAB. Finally, the mother's parenting behaviors had a higher impact on child DBDs than the father's parenting behaviors. Thus, familial variables continue to have an effect on childhood DBDs even after accounting for confounding influences. These variables should be a focus of research on etiology and intervention.

Decreased frontal lobe phosphocreatine levels in methamphetamine users

BACKGROUND

Mitochondria-related mechanisms have been suggested to mediate methamphetamine (METH) toxicity. However, changes in brain energetics associated with high-energy phosphate metabolism have not been investigated in METH users. Phosphorus-31 ((31)P) magnetic resonance spectroscopy (MRS) was used to evaluate changes in mitochondrial high energy phosphates, including phosphocreatine (PCr) and β-nucleoside triphosphate (β-NTP, primarily ATP in brain) levels. We hypothesized that METH users would have decreased high-energy PCr levels in the frontal gray matter.

METHODS

Study participants consisted of 51 METH (age=32.8±6.7) and 23 healthy comparison (age=31.1±7.5) subjects. High-energy phosphate metabolite levels were compared between the groups and potential gender differences were explored.

RESULTS

METH users had lower ratios of PCr to total pool of exchangeable phosphate (PCr/TPP) in the frontal lobe as compared to the healthy subjects (p=.001). The lower PCr levels in METH subjects were significantly associated with lifetime amount of METH use (p=.003). A sub-analysis for gender differences revealed that female METH users, who had lower daily amounts (1.1±1.0g) of METH use than males (1.4±1.7g), had significantly lower PCr/TPP ratios than male METH users, controlling for the amount of METH use (p=.02).

CONCLUSIONS

The present findings suggest that METH compromises frontal lobe high-energy phosphate metabolism in a dose-responsive manner. Our findings also suggest that the abnormality in frontal lobe high-energy phosphate metabolism might be more prominent in female than in male METH users. This is significant as decreased PCr levels have been associated with depressive symptoms, and poor responses to antidepressant treatment have been reported in those with decreased PCr levels.

The changing gender gap in substance use disorder: a total population-based study of psychiatric in-patients

AIMS

To study changes over a 25-year period in the gender gap in discharge diagnoses of alcohol use disorder (AUD) and other substance use disorder (SUD) in psychiatric in-patients.

DESIGN, SETTING AND PARTICIPANTS

 A register-based study of all admissions to psychiatric hospitals in Iceland between January 1983 and December 2007.

MEASUREMENTS

Annual rate of admissions to psychiatric hospitals, adjusted for changes in the size of the population. Furthermore, gender-specific analysis of changes in discharge diagnoses of AUD solely and other SUD (including AUD with other SUDs).

FINDINGS

Of all psychiatric admissions, the proportion of any SUD admissions increased considerably during the study period. This increase was most pronounced in SUDs other than solely AUD. AUD increased for women and decreased for men. The male to female ratio of AUD alone decreased from 4.2 to 1.5 (P < 0.001). There was no significant change in the gender gap for other SUDs (P = 0.96).

CONCLUSIONS

There has been a marked convergence of the gender gap in discharge diagnosis of alcohol use disorder among psychiatric in-patients in Iceland over the last decades. For other substance use disorders, the change was not as pronounced. Our results emphasize the importance of monitoring changes in substance use disorder diagnosis as this may uncover different treatment needs in this group of vulnerable individuals.

Gender, brain-derived neurotrophic factor Val66Met, and frequency of methamphetamine use

BACKGROUND

Frequency of pretreatment methamphetamine (MA) use is an important predictor of outcomes of treatment for MA dependence. Preclinical studies suggest females self-administer more MA than males, but few clinical studies have examined potential sex differences in the frequency of MA use. Estrogen increases expression of brain-derived neurotrophic factor (BDNF), which has effects on MA-induced striatal dopamine release and protects against MA-induced neurotoxicity.

OBJECTIVE

We examined potential effects of sex, the Val66Met polymorphism in BDNF, and their interaction on frequency of MA use among 60 Caucasian MA-dependent volunteers screening for a clinical trial.

METHODS

Data was taken from 60 Caucasian MA-dependent volunteers screening for a clinical trial.

RESULTS

Females reported significantly more pretreatment days with MA use in the past 30 days than males. There was a significant interaction between sex and BDNF Val66Met, with the highest frequency of MA use among females with Val/Val genotype.

CONCLUSIONS

These results, although preliminary, add to the literature documenting sexual dimorphism in response to stimulants, including MA, and suggest a potential biological mechanism involving BDNF that might contribute to these differences. Additional research characterizing the biological basis of altered response to MA among females is warranted.

Minnesota Center for Twin and Family Research

The Minnesota Center for Twin and Family Research (MCTFR) houses a collection of longitudinal, community-based twin-family and adoptee-family projects that focus on the mental health outcomes of adolescent youth with a special focus on the development of substance use and related behavior disorders. The Minnesota Twin Family Study includes epidemiological investigations of 11- and 17-year-old twins, an examination of 11-year-old twins selected for being at high risk for having a childhood disruptive behavior disorder, and a supplemental registry of young adult twins age 18 years and older who are not enrolled in these longitudinal studies. Also, part of the MCTFR is the Sibling Interaction and Behavior Study, a complementary prospective investigation of adolescent sibling pairs in families with adoptive and biological offspring. MCTFR participants from these various projects are assessed in person and through multiple informants to provide comprehensive coverage of psychological adjustment, mental health, and psychosocial risk/protective factors. Measurement of EEG and autonomic nervous system reactivity is also part of the assessment battery for twin families. This article provides an overview of study design and includes a review of recent MCTFR findings.

An age-period-cohort analysis of cannabis use prevalence and frequency in Germany, 1990-2009

BACKGROUND

In order to better understand trends in cannabis use, this study estimates independent and non-confounded age, period and cohort effects on 12-month cannabis use prevalence and frequency.

METHODS

Data from seven waves of the German Epidemiological Survey of Substance Abuse (ESA) conducted between 1990 and 2009 were used. The total sample included 29,836 men and 34,877 women aged 18-65 years. Cross-classified random effects models were conducted to estimate fixed effects of age and random effects of periods and birth cohorts. Analyses were stratified by gender.

RESULTS

With regard to 12-month prevalence, substantial age variations were identified with a peak of cannabis use in young adulthood. The overall effects of periods and birth cohorts were not significant. With regard to frequency of use, there were no significant influences of either variable. The results were largely identical for men and women.

CONCLUSIONS

This study identified little variation in trend data of current cannabis use. When confounding influences of period and ageing are controlled, the widely reported increases in cannabis consumption in recent birth cohorts cannot be demonstrated.

Genetic and environmental influences on personality trait stability and growth during the transition to adulthood: a three-wave longitudinal study

During the transition to adulthood individuals typically settle into adult roles in love and work. This transition also involves significant changes in personality traits that are generally in the direction of greater maturity and increased stability. Competing hypotheses have been offered to account for these personality changes: The intrinsic maturation hypothesis suggests that change trajectories are endogenous, whereas the life-course hypothesis suggests that these changes occur because of transactions with the social environment. This study investigated the patterns and origins of personality trait changes from ages 17 to 29 using 3 waves of Multidimensional Personality Questionnaire data provided by twins. Results suggest that (a) trait changes were more profound in the first relative to the second half of the transition to adulthood; (b) traits tend to become more stable during the second half of this transition, with all the traits yielding retest correlations between .74 and .78; (c) Negative Affectivity declined over time, and Constraint increased over time; minimal change was observed on agentic or communal aspects of Positive Emotionality; and (d) both genetic and nonshared environmental factors accounted for personality changes. Overall, these genetically informed results support a life-course perspective on personality development during the transition to adulthood.

Stability and Invariance of Psychopathic Traits from Late Adolescence to Young Adulthood

The current study examined the longitudinal stability and invariance of psychopathic traits in a large community sample of male twins from ages 17 to 23. Participants were assessed across six years to gauge the stability and measurement invariance of the Minnesota Temperament Inventory (MTI), a Cleckley-based measure of psychopathic personality traits, and how family functioning and externalizing behavior were linked to these traits. A latent variable approach was used to model the structure of the MTI and provide a statistical test of measurement invariance across time. The results revealed support for invariance and moderate to strong stability of the MTI factors, which showed significant associations with the external correlates in late adolescence but not early adulthood.

Initiation to drug injection among street youth: a gender-based analysis

OBJECTIVE(S)

To estimate the incidence rate of initiation into drug injection and to identify predictors of initiation into drug injection separately among street girls and boys.

DESIGN

Data from two consecutive prospective street youth cohort studies (1995-2001 and 2001-2005) were used to conduct these analyses, stratified by gender.

METHODS

Data were collected using semi-annual interviewer-administered questionnaires. Variables from the following domains were considered in Cox regression models: socio-demographic characteristics, early and current substance abuse, marginalization, childhood traumatic sexual events and injection exposure.

RESULTS

Of the 946 youth who had never injected drugs at study entry, 86.4% completed at least two questionnaires representing 243 girls and 574 boys. Incidence rates of injection of 7.0 and 5.9 per 100 person-years were observed among these girls and boys respectively. Among girls, cocaine or crack use (adjusted hazard ratio (AHR)=1.97), heroin use (AHR=2.86), homelessness (AHR=2.49) and hanging out regularly with people who inject (AHR=4.46) all independently increased risk of first injection. Among boys, age decreased risk of initiating injection (AHR=0.90/year), while cocaine or crack use (AHR=2.14), heroin use (AHR=3.56), homelessness before age 16 (AHR=1.68), incest or rape before age 14 (AHR=1.98) and hanging out regularly with people who inject (AHR=1.66) all independently increased this risk.

CONCLUSIONS

Our findings suggest similar rates of initiation among girls and boys; however, factors associated with initiation vary by gender. This might lead to the design of more effective programs to prevent initiation into drug injection.

Parental divorce and disordered eating: an investigation of a gene-environment interaction

OBJECTIVE

We investigated gene-environment interactions (GxE) for associations between parental divorce and disordered eating (DE).

METHOD

Participants were 1,810 female twins from the Michigan State University Twin Registry and the Minnesota Twin Family Study. The Minnesota Eating Behaviors Survey was used to assess DE. We tested for GxE by comparing the heritability of DE in twins from divorced versus intact families. It was hypothesized that divorce would moderate the heritability of DE, in that heritability would be higher in twins from divorced than twins from intact families.

RESULTS

As expected, the heritability of body dissatisfaction was significantly higher in twins from divorced than intact families. However, genetic influences were equal in twins from divorced and intact families for all other forms of DE.

DISCUSSION

Although divorce did not moderate heritability of most DE symptoms, future research should replicate GxEs for body dissatisfaction and identify factors underlying this unique relationship.

Dietary restraint moderates genetic risk for binge eating

Dietary restraint is a prospective risk factor for the development of binge eating and bulimia nervosa. Although many women engage in dietary restraint, relatively few develop binge eating. Dietary restraint may increase susceptibility for binge eating only in individuals who are at genetic risk. Specifically, dietary restraint may be a behavioral exposure factor that activates genetic predispositions for binge eating. We investigated this possibility in 1,678 young adolescent and adult same-sex female twins from the Minnesota Twin Family Study and the Michigan State University Twin Registry. Twin moderation models were used to examine whether levels of dietary restraint moderate genetic and environmental influences on binge eating. Results indicated that genetic and nonshared environmental factors for binge eating increased at higher levels of dietary restraint. These effects were present after controlling for age, body mass index, and genetic and environmental overlap among dietary restraint and binge eating. Results suggest that dietary restraint may be most important for individuals at genetic risk for binge eating and that the combination of these factors could enhance individual differences in risk for binge eating.

The effects of progesterone pretreatment on the response to oral d-amphetamine in Women

Stimulant abuse continues to be a problem, particularly for women. There is increasing preclinical and clinical evidence showing that the hormone progesterone attenuates the behavioral effects of cocaine, and this effect is primarily observed in females. The purpose of the present study was to determine if progesterone would also alter the behavioral effects of another stimulant, oral d-amphetamine (AMPH) in women. Eighteen normal non-drug abusing women completed eight outpatient sessions over two menstrual cycles. During the follicular phase of each cycle, women were administered AMPH (0, 10, 20 mg); in one cycle they were pretreated with oral micronized progesterone (200 mg) and in another cycle they were pretreated with placebo progesterone. Each session, participants completed a range of tasks including subjective measures of abuse liability, cognitive performance tasks, and behavioral measures of impulsivity and risk-taking. AMPH produced dose-related increases in positive subjective effects and these effects were enhanced by progesterone pretreatment. AMPH alone, or in combination with progesterone, had little effect on performance or behavioral measures of impulsivity. These results are in contrast with previous studies showing that progesterone attenuates the subjective response to cocaine and nicotine. Additional studies are needed to explore the modulatory role of progesterone on the effects of AMPH to determine whether progesterone has any clinical utility for AMPH abuse.

Puberty and the genetic diathesis of disordered eating attitudes and behaviors

Twin studies from the Minnesota Twin Family Study (MTFS) suggest negligible genetic effects on eating pathology before puberty but increased genetic effects during puberty. However, an independent study found no pubertal differences in genetic and environmental effects (R. Rowe, A. Pickles, E. Simonoff, C. M. Bulik, & J. L. Silberg, 2002). Discrepant results may be due to methodological differences. The MTFS studies divided twins at mid-puberty, whereas R. Rowe et al. (2002) divided twins based on menarche alone. In the present study, the authors aimed to reconcile discrepant findings by examining differences in etiologic effects for disordered eating attitudes and behaviors (i.e., levels of weight preoccupation, body dissatisfaction, binge eating, compensatory behaviors) using both classification methods in a new sample of 656 female twins. Using the MTFS method (i.e., K. L. Klump, M. McGue, & W. G. Iacono, 2003), the authors observed nominal genetic effects in prepubertal twins but significant genetic effects in pubertal and young adult twins. Conversely, genetic effects were moderate and equal in all groups using the R. Rowe et al. (2002) method. Findings highlight the potentially important role of puberty in the genetic diathesis of disordered eating attitudes and behaviors and the need to use early indicators of pubertal status in studies of developmental effects.

Longitudinal associations between depression and substance dependence from adolescence through early adulthood

AIMS

The association between depression and substance dependence is poorly understood; examinations of these two disorders over time during key developmental periods can provide insight into how these problems relate to each other. The goal of the present study was to examine longitudinal associations between depression and substance (alcohol and illicit drug) dependence during the period from adolescence through early adulthood.

PARTICIPANTS

Participants in the Minnesota Twin Family Study, a community-based sample of 1252 youth and their families, were used. Youth were first assessed at age 17; they returned to the study at ages 20 and 24.

MEASUREMENTS

Major depression and drug and alcohol dependence were assessed via structured interviews. Gender was examined as a possible moderator.

FINDINGS

The results indicated that both substance dependence and depression showed stability over time--that is, each disorder was associated with increased risk for the same disorder later. Substance dependence between ages 17 and 20 predicted increased risk of depression between ages 20 and 24. These associations did not differ significantly by gender.

CONCLUSIONS

Substance dependence during late adolescence predicts the subsequent occurrence of major depression.

Parental psychopathology and migraine headaches among adolescent girls

Migraine headaches and depression often co-occur within individuals, and both syndromes run in families. However, knowledge about how these disorders relate across generations, as well as how migraine relates to other forms of psychopathology, is sparse. This study examined risk for migraine among female adolescent offspring of parents with different types of psychopathology. The sample was drawn from the Minnesota Twin Family Study, a community-based study of adolescents and their families (n = 674, 17-year-old female adolescents and their biological parents). Diagnoses of maternal, paternal and offspring major depression, antisocial behaviour, alcohol dependence and drug dependence were based on structured interviews. Migraine headaches in each family member were assessed via interviews with the mother. Parental depression, antisocial behaviour and drug dependence were associated with offspring migraine. These associations mostly remained significant even when parental migraine and the corresponding type of psychopathology in offspring were adjusted for. In contrast, there were no significant associations between parental psychopathology and offspring stomach problems, indicating that these associations did not extend to all offspring somatic symptoms. These results emphasize the need to look at antisocial behaviour and substance-related problems when examining associations between migraine and psychopathology, and indicate that more research on inter-generational links between migraine and psychopathology is needed.

Deviant P300 amplitude development in males is associated with paternal externalizing psychopathology

Boys at risk for alcoholism show deviant P300 amplitude development. Genetic influences on P300, however, are related to a range of externalizing disorders. This study examined whether P300 development from adolescence to early adulthood differed between groups varying in severity of paternal externalizing. Parietal P300 was assessed during the "rotated heads" task on up to 3 times between the ages of 17 and 24 years. Participants were divided into 3 paternal externalizing groups: (a) severe (father has adult antisocial behavior), (b) intermediate (father has alcohol dependence but not a more severe disorder), and (c) low (father has no externalizing disorders or substance treatment and is not extreme in alcohol use). Mixed models were used to evaluate linear change in amplitude. P300 decreased with age. The severe-risk group had smaller P300 initially and changed less with time than did the low-risk group. The intermediate-risk group did not differ significantly from the low-risk group, but differed marginally from the severe-risk males. Externalizing and early-onset substance disorders in the sons were associated with smaller initial values of P300. Measures of deviant P300 development may be vulnerability markers for externalizing psychopathology.

Alcohol and illicit drug dependence among parents: associations with offspring externalizing disorders

BACKGROUND

Previous research indicates that alcohol and drug dependence constitute aspects of a general vulnerability to externalizing disorders that accounts for much of the parent-offspring resemblance for these and related disorders. This study examined how adolescent offspring risk for externalizing psychopathology varies with respect to parental alcoholism and illicit drug dependence.

METHOD

Data from the Minnesota Twin Family Study, a community-based investigation of adolescents (age 17 years, n=1252) and their parents, were used. Lifetime diagnoses of alcohol and drug dependence (among both parents and offspring) and offspring attention deficit hyperactivity disorder, oppositional defiant disorder, conduct disorder, adult antisocial behavior, and nicotine dependence were assessed via structured interviews.

RESULTS

Parental alcohol dependence and parental drug dependence were similarly associated with increased risk for nearly all offspring disorders, with offspring of alcohol and drug-dependent parents having approximately 2-3 times the odds for developing a disorder by late adolescence compared to low-risk offspring. Compared to parental dependence on other illicit drugs, parental cannabis dependence was associated with weaker increased risk for offspring externalizing disorders.

CONCLUSIONS

Both parental alcohol and drug dependence are independently associated with an increased risk for a broad range of externalizing psychopathology among late-adolescent offspring.

Strengthening the case: prenatal alcohol exposure is associated with increased risk for conduct disorder

OBJECTIVE

The purpose of this study was to examine the relationship between alcohol exposure in pregnancy and offspring conduct disorder symptoms in adolescence and to examine how much this increasingly known association may be mediated by maternal and paternal externalizing diagnoses, including lifetime maternal and paternal alcohol and drug abuse/dependence diagnoses as well as antisocial disorders. Few other studies have examined the contribution of these diagnoses across both parents.

METHOD

A population sample of 1252 adolescents (53.8% female; drawn from the Minnesota Twin Family Study) as well as both of their parents completed structured diagnostic interviews to generate lifetime psychiatric diagnoses; mothers were also retrospectively interviewed about alcohol and nicotine use during pregnancy. Linear regression models were used to test the effects of prenatal alcohol exposure on adolescents' conduct-disorder symptoms.

RESULTS

Prenatal exposure to alcohol was associated with higher levels of conduct-disorder symptoms in offspring, even after statistically controlling for the effects of parental externalizing disorders (illicit substance use disorders, alcohol dependence, and antisocial/behavioral disorders), prenatal nicotine exposure, monozygosity, gestational age, and birth weight.

CONCLUSIONS

Prenatal alcohol exposure contributes to increased risk for conduct disorder in offspring.

The heritability of life events: an adolescent twin and adoption study

Although life events are often conceptualized as reflecting exogenous risk factors for psychopathology, twin studies have suggested they are heritable. We undertook a mixed twin/adoption study to further explore genetic and environmental contributions to individual differences in the experience of life events. Specifically, a sample of 618 pairs of like-sex adolescent twins, 244 pairs of like-sex adopted adolescent and young adult siblings, and 128 pairs of like-sex biological siblings completed a life events interview. Events were classified as independent (not likely to have been influenced by respondent's behavior), dependent (likely to have been influenced by respondent's behavior), or familial (experienced by a family member), and then summed to form three life event scales. Variance on the scales was assumed to be a function of four factors: additive genetic effects (a2), shared environmental effects (c2), twin-specific effects (t2), and nonshared environmental effects (e2). Data were analyzed using standard biometrical models. Shared environmental effects were found to be the largest contributor to variance in familial events (c2 = .71; 95% confidence interval of .65, .76); additive genetic effects were the largest contributor to dependent events (a2 = .45; CI = .31, .58); and nonshared environmental effects were found to be the largest contributor independent events (e2 = .57; CI = .51, .64). A significant twin-specific effect was also found for independent life events, indicating that twins are more likely to be exposed to such events than non-twin biological siblings. Findings are discussed in terms of their implication for understanding the nature of psychosocial risk.

Gender Differences in the salience of psychosocial mediators of the impact of acculturation on substance abuse among Hispanic youth in Florida

OBJECTIVES

A number of psychosocial factors have been identified as mediators of the impact that acculturation exerts on adolescent drug use. We sought to evaluate gender differences in mediators of the impact of acculturation on substance abuse.

METHODS

We used t-test and logistic regression to analyze data collected from 8,200 adolescent students who self-identified as Hispanic during the 2004 Florida Youth Substance Abuse. The dependent variable was past 30 day use of marijuana and the key independent variable was language spoken at home. The covariates were 32 risk and protective (R/P) factors for drug use as defined by the Social Development Strategy framework.

RESULTS

For boys, the ORs associated with language changed significantly with the addition of any of the R/P factors to their basic model, while for girls only the addition of the Individual domain factors significantly changed the ORs.

DISCUSSION AND CONCLUSION

These findings suggest that among boys the interventions that target any or all of the R/P factors may be able to positively alter the drug using behaviors among boys. In contrast, only the interventions that reinforce girls' innate strengths may succeed in dissuading them from initiating and perpetuating drug use. This information can be used to develop policies and interventions geared toward preventing drug problems among the growing group of adolescent of immigrant descent.

Alcohol and drug use among university students: gender differences

OBJECTIVE

This study compared the pattern of alcohol, legal and illegal drugs use among students of the Universidade de São Paulo (Brazil) in 1996 and 2001.

METHOD

Samples of 2.564 (1996) and 2.837 (2001) students answered a questionnaire proposed by the World Health Organization, which characterizes the consumption of alcohol, legal and illegal drugs in lifetime, in the last 12 months and in the last 30 days.

RESULTS

Men showed a significant increase in lifetime use of tobacco (44.8% to 50.9%), marijuana (33.7% to 39.5%) and hallucinogens (6.6% to 14.1%) between 1996 and 2001. No significant change was observed among women between 1996 and 2001 in tranquilizer use. Concerning the consumption reported in the last 12 months, both genders displayed significant increases in the consumption of marijuana (22.3% to 27.1% for men and 12.9% to 16.9% for women), amphetamines (1.9% to 5.0% for men and 3.4% to 5.6% for women), and inhalants (9.8% to 15.7% for men and 5.4% to 10.6% for women). The greatest gender difference was observed in consumption reported in the last 30 days with significant increases in male use of tobacco (19.6% to 23.5%), marijuana (15.8% to 20.5%), amphetamines (1.1% to 3.2%), and inhalants (4.0% to 7.9%). Substance use reported in the last 30 days remained stable among women between the 2 surveys.

CONCLUSION

Rates of substance use among university students increased. These gender differences in substance consumption should be taken into account in the development of preventive and treatment strategies for undergraduate university students.

Father-child transmission of antisocial behavior: the moderating role of father's presence in the home

OBJECTIVE

To demonstrate an environmental effect of being raised by an antisocial father and to test whether the transmission of antisocial behavior from father to child is moderated by the father's presence in the home.

METHOD

A community sample of male and female 11- and 17-year-old twins and their biological parents participating in the Minnesota Twin Family Study was used. A series of hierarchical linear regression models was used to examine the relationship between father antisociality and his children's externalizing psychopathology and to determine whether the father's time spent in the home moderated this relationship. Models controlled for the child's sex.

RESULTS

A significant main effect of both father's antisociality and father's presence on the children's externalizing psychopathology was found: Children born to antisocial fathers evidenced higher rates of externalizing behavior, and children raised without their biological father in the home exhibited more externalizing behaviors. The interaction was also significant such that the association between father and child antisociality was stronger when the father was present for a longer period of the child's life. Furthermore, when fathers show high levels of antisociality, fathers' presence appears to have deleterious rather than beneficial effects on child behavior.

CONCLUSIONS

The present results suggest the transmission of antisociality from father to child is at least partially environmentally moderated.

Stability and change in personality traits from late adolescence to early adulthood: a longitudinal twin study

We conducted a longitudinal-biometric study examining stability and change in personality from ages 17 to 24 in a community sample of male and female twins. Using Tellegen's (in press) Multidimensional Personality Questionnaire (MPQ), facets of Negative Emotionality (NEM) declined substantially at the mean and individual levels, whereas facets of Constraint (CON) increased over time. Furthermore, individuals in late adolescence who were lowest on NEM and highest on CON remained the most stable over time, whereas those exhibiting the inverse profile (higher NEM, lower CON) changed the most in a direction towards growth and maturity. Analyses of gender differences yielded greater mean-level increases over time for women as compared to men on facets of CON and greater mean-level increases for men than women on facets of Agentic Positive Emotionality (PEM). Biometric analyses revealed rank-order stability in personality to be largely genetic, with rank-order change mediated by both the nonshared environment (and error) as well as genes. Findings correspond with prior evidence of a normative trend toward growth and maturity in personality during emerging adulthood.

Personality in Middle Childhood: A Hierarchical Structure and Longitudinal Connections With Personality in Late Adolescence

Research on the structure of personality in middle childhood, while advancing, is still in the early stages of development. In this study, we employed a group of 1563 twins to elucidate the hierarchical structure of personality in middle childhood and provide connections to established personality traits in adult populations. Our results provide evidence for a higher-order structure of personality in middle childhood that maps on to recent findings in adult populations supporting hierarchical relationships among 2-, 3-, 4-, and 5-factor models of personality. In addition, primary higher-order personality traits rated by parents at age 11 showed substantial predictive validity for analogous traits rated by self at age 17. We discuss our results within the context of developing a convergent hierarchical taxonomy of personality in middle childhood and the importance of multiinformant investigations.

Looking Beyond Nativity: The Relation of Age of Immigration, Length of Residence, and Birth Cohorts to the Risk of Onset of Psychiatric Disorders for Latinos

Past studies yield inconsistent results regarding risk of psychopathology for U.S. Latinos by nativity possibly due to differences across immigrants in their age of arrival to the U.S., their length of residence in the U.S., or birth-cohort differences. This paper seeks to document the relation of age of arrival, time in the U.S., and cohort effects on the risk of onset of psychiatric disorders using a nationally representative sample of 2554 Latinos in the coterminous United States. Risk of onset of psychiatric disorders was assessed using the World Health Organization Composite International Diagnostic Interview (WMH-CIDI, Kessler & Ustun, 2004). Findings indicate that Latino immigrants have lower risks of onset for some psychiatric disorders in their country of origin, but once in the U.S., Latino immigrants appear to experience similar risks of onset as U.S.-born Latinos of the same age. The longer Latino immigrants remain in their country of origin, the less cumulative risk of onset they experience, resulting in lower lifetime rates of disorders. These findings could potentially be due to variation in cultural and social norms and expectations across geographical contexts, differences in family structure and gender roles, as well as artifactual-level explanations.

Gender differences in DUI offenders in treatment in Texas

OBJECTIVE

This is a study of 8,464 adult women and 21,155 adult males who entered substance abuse treatment in Texas between 2000 and 2005. Participants were either on probation for driving under the influence (DUI), were referred to treatment by DUI probation, or had been arrested for DUI in the past year.

METHODS

The female and male clients were compared on demographic characteristics, substance use patterns, DSM-IV diagnoses, and levels of impairment. T tests and chi square tests were used to determine significance and multivariate logistic regression identified predictors of completing treatment and being abstinent at follow-up.

RESULTS

The proportion of females who were sent to treatment as a result of DUI increased from 27% in 2000 to 32% in 2005. Females were significantly more likely than males to be White (73% vs. 56%), to have used substances a shorter period of time (17 vs. 19 years), to be seeking custody to regain their children (11% vs. 2%), to meet the DSM criteria for drug dependence (32% vs. 23%), to have injected drugs (31% vs. 23%), to have used substances daily (42% vs. 40%), to have a depressive disorder (16% vs. 7%) or bipolar disorder (12% vs. 5%), and to be have been in treatment before (60% vs. 49%). In contrast, males were more likely to be alcohol dependent (49% vs. 44%). Females were less likely to complete treatment (67% vs. 72%) and reported significantly more days of problems on the 6 domains of the ASI at both admission and at 60-day follow-up. Furthermore, at follow-up, they were more likely to be living with someone who abused alcohol or used drugs (9% vs.7%).

CONCLUSIONS

Although females comprised only 29% of the DUI treatment admissions, they were more impaired and experienced more problems than their male counterparts. The findings indicate that additional resources, including treatment for co-occurring mental health problems and living in sober households, may be keys to helping these women achieve abstinence and prevent additional DUI episodes.

Investigating Gender Differences in Alcohol Problems: A Latent Trait Modeling Approach

BACKGROUND

Inconsistent results have been found in research investigating gender differences in alcohol problems. Previous studies of gender differences used a wide range of methodological techniques, as well as limited assortments of alcohol problems.

METHODS

Parents (1,348 men and 1,402 women) of twins enrolled in the Minnesota Twin Family Study answered questions about a wide range of alcohol problems. A latent trait modeling technique was used to evaluate gender differences in the probability of endorsement at the problem level and for the overall 105-problem scale.

RESULTS

Of the 34 problems that showed significant gender differences, 29 were more likely to be endorsed by men than women with equivalent overall alcohol problem levels. These male-oriented symptoms included measures of heavy drinking, duration of drinking, tolerance, and acting out behaviors. Nineteen symptoms were denoted for removal to create a scale that favored neither gender in assessment.

CONCLUSIONS

Significant gender differences were found in approximately one-third of the symptoms assessed and in the overall scale. Further examination of the nature of gender differences in alcohol problem symptoms should be undertaken to investigate whether a gender-neutral scale should be created or if men and women should be assessed with separate criteria for alcohol dependence and abuse.

Substance abuse treatment entry, retention, and outcome in women: a review of the literature

This paper reviews the literature examining characteristics associated with treatment outcome in women with substance use disorders. A search of the English language literature from 1975 to 2005 using Medline and PsycInfo databases found 280 relevant articles. Ninety percent of the studies investigating gender differences in substance abuse treatment outcomes were published since 1990, and of those, over 40% were published since the year 2000. Only 11.8% of these studies were randomized clinical trials. A convergence of evidence suggests that women with substance use disorders are less likely, over the lifetime, to enter treatment compared to their male counterparts. Once in treatment, however, gender is not a significant predictor of treatment retention, completion, or outcome. Gender-specific predictors of outcome do exist, however, and individual characteristics and treatment approaches can differentially affect outcomes by gender. While women-only treatment is not necessarily more effective than mixed-gender treatment, some greater effectiveness has been demonstrated by treatments that address problems more common to substance-abusing women or that are designed for specific subgroups of this population. There is a need to develop and test effective treatments for specific subgroups such as older women with substance use disorders, as well as those with co-occurring substance use and psychiatric disorders such as eating disorders. Future research on effectiveness and cost-effectiveness of gender-specific versus standard treatments, as well as identification of the characteristics of women and men who can benefit from mixed-gender versus single-gender treatments, would advance the field.