Parental familial vulnerability, family environment, and their interactions as predictors of depressive symptoms in adolescents

Built and social indices for hazards in Children's environments

Leveraging the capabilities of the Historical Spatial Data Infrastructure (HSDI) and composite indices we explore the importance of children's built and social environments on health. We apply contemporary GIS methods to a set of 2000 historical school records contextualized within an existing HSDI to establish seven variables measuring the relative quality of each child's built and social environments. We then combined these variables to create a composite index that assesses acute (short-term) health risks generated by their environments. Our results show that higher acute index values significantly correlated with higher presence of disease in the home. Further, higher income significantly correlated with lower acute index values, indicating that the relative quality of children's environments in our study area were constrained by familial wealth. This work demonstrates the importance of analyzing multiple activity spaces when assessing built and social environments, as well as the importance of spatial microdata.

Associations between depressive symptom profiles and immunometabolic characteristics in individuals with depression and their siblings

OBJECTIVES

The present study examined associations between immunometabolic characteristics (IMCs) and depressive symptom profiles (DSPs) in probands with lifetime diagnoses of depression and/or anxiety disorders and their siblings.

METHODS

Data were from the Netherlands Study of Depression and Anxiety, comprising 256 probands with lifetime diagnoses of depression and/or anxiety and their 380 siblings. Measured IMCs included blood pressure, waist circumference, and levels of glucose, triglycerides, HDL cholesterol, CRP, TNF-α and IL-6. DSPs included mood, cognitive, somatic and atypical-like profiles. We cross-sectionally examined whether DSPs were associated with IMCs within probands and within siblings, and whether DSPs were associated with IMCs between probands and siblings.

RESULTS

Within probands and within siblings, higher BMI and waist circumference were associated with higher somatic and atypical-like profiles. Other IMCs (IL-6, glucose and HDL cholesterol) were significantly related to DSPs either within probands or within siblings. DSPs and IMCs were not associated between probands and siblings.

CONCLUSIONS

The results suggest that there is a familial component for each trait, but no common familial factors for the association between DSPs and IMCs. Alternative mechanisms, such as direct causal effects or non-shared environmental risk factors, may better fit these results.

Psychosocial stressors and protective factors for major depression in youth: evidence from a case-control study

BACKGROUND

Severe adverse life events, such as traumatic experiences, are well-known stressors implicated in (youth) major depression (MD). However, to date, far less is known about the role of more common psychosocial stressors in the context of MD, which are part of everyday life during youth. In addition, it is not well-understood whether and how distinct stressors interact with protective factors in youths diagnosed with MD. Thus, the present study aimed at examining several specific psychosocial stressors implicated in a first-episode juvenile MD and addressed the question whether protective factors might moderate the relationship between stressors and a diagnosis of MD.

METHODS

One-hundred male and female youths with MD and 101 typically developing (TD) controls (10-18 years) were included. A large number of qualitatively different psychosocial stressors occurring in various areas of life were assessed via self-report. Moreover, we also investigated sociodemographic and pre- and postnatal stressors, as well as the presence of familial affective disorders via parental-report. Social support and a positive family climate were conceptualized as protective factors and were assessed via self-report.

RESULTS

Results showed that the proportion of youths experiencing specific psychosocial stressors was higher in the MD than in the TD group. In particular, the proportion of youths indicating changes at home or at school, experiences of violence, delinquent behavior, as well as the proportion of youths who were exposed to sociodemographic stressors was higher in the MD than in the TD group. Moreover, the percentage of youths with a family history of an affective disorder, or whose mothers experienced psychological burdens during/after pregnancy was elevated in the MD group. Youths with MD experienced less social support and a less positive family climate than their TD peers. These factors, however, did not buffer the influence of specific stressors on MD.

CONCLUSION

We could show that next to more severe adverse life events, more common psychosocial stressors are linked to youth MD. Importantly, by identifying distinct stressors in youth MD, our results can increase treatment and prevention efforts aiming to improve the outcomes in youths affected by MD or in at-risk individuals.

Quantitative monitoring of a panel of stress-induced biomarkers in human plasma by liquid chromatography-tandem mass spectrometry: an application in a comparative study between depressive patients and healthy subjects

Using a metabolomic approach, we have found that stress can induce oxidative damage by disturbing the creatine/phosphocreatine shuttle system and purinergic pathway, leading to an excessive membrane breakdown. To further validate our findings and to monitor the biological impact of stress in research of clinical psychiatry, a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed to simultaneously determine a panel of biomarkers comprising choline, creatine, purinergic metabolites, neurosteroids, lysophosphatidylcholines, and phosphatidylethanolamines in human plasma. After optimization of the extraction protocol, all the 15 analytes plus 4 internal standards with distinct polarities were extracted into an organic phase using methyl tert-butyl ether/methanol (1:1, v/v). A reversed-phase C8 column under gradient elution consisting of aqueous phase A of 5 mM ammonium acetate buffer solution containing 0.1% formic acid and organic phase B of acetonitrile/2-propanol (3:7, v/v) was utilized for separation. Four sequential periods under positive or negative ion mode were combined for the determination of analytes with specific multiple reaction monitoring transitions. For all analytes, this method exhibited good linearity with coefficients of determination (R²) higher than 0.99. The lower limit of quantification (LLOQ) values ranged from 0.05 to 80.0 ng/mL. Recovery between 70.5 and 97.3% was obtained by spiking standards to plasma samples stripped by powdered activated carbon. The intra- and inter-assay relative standard deviations (RSDs) of the analyses varied between 2.0 and 13.3%. The mean accuracy ranged from 90.6 to 109.0%. The matrix effect ranged from 91.2 to 107.3% with variations less than 9.0%. Stability under different conditions was tested, with mean recoveries varying between 90.4 and 109.7%. Finally, the established method was successfully applied to analyze the plasma samples from a small cohort of 30 patients with major depressive disorder and 30 matched healthy controls. Graphical abstract.

Association between mood disorders and BMI/overweight using a family study approach

BACKGROUND

We previously demonstrated the specificity of familial transmission of the atypical subtype of depression, primarily characterized by overeating and oversleeping. However, the specific components of this subtype that are familial have not been established. The aim of this paper is to examine whether the familial specificity of atypical depression can be attributed to the association between Body Mass Index (BMI) and overweight/obesity with mood disorders.

METHODS

The sample included 293 probands recruited from the community and their 544 adult first-degree relatives. Diagnostic assignment was based on a direct semi-structured interview. Mixed effect models were employed to test the familial aggregation and the familial cross-aggregation of mood disorders and BMI/overweight.

RESULTS

There were significant within-individual associations between overweight and the atypical subtype of depression (p-value = 0.003). There was also an association for BMI/overweight between probands and relatives (β = 0.23, p-value < 0.001; odds ratio [OR] = 1.57, 95% confidence interval [CI] = 1.02-2.43, respectively). Atypical depression in probands was significantly associated with BMI and overweight in relatives (β = 0.001, p-value = 0.040; OR = 2.79, 95%CI = 1.20-6.49, respectively).

LIMITATIONS

The cross-sectional design impedes our ability to evaluate the direction of these associations. Other potential risk factors, such as diabetes, physical activity and unhealthy diet were not considered.

CONCLUSIONS

These findings imply that overweight may be either a precursor or consequence of atypical depression rather than a manifestation of a common diathesis underlying depression in families. Clinicians should pay particular attention to this subtype that could be at increased risk for the development of cardiovascular risk factors and diseases.

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.

Family and College Environmental Exposures Mediate the Relationship between Parental Education and Depression among College Students

Background

Depression is a major health concern for college students due to its substantial morbidity and mortality. Although low parental education has been identified as a factor in depression in college students, the mechanisms through which parental educational achievement affects students’ depression are not well understood. We tested whether adverse family and college environments mediate the relationship between parental educational level and depression among Chinese college students.

Methods

A total of 5180 respondents were selected using a cross-sectional survey. We examined the association of parental education, adverse family and college environments with depression in college students using the Adolescent Self-Rating Life Events Checklist, Beck Depression Inventory and socio-demographic questionnaires.

Results

Lower parental educational level is significantly correlated with depression in college students in our sample. Additionally, low family economic status, paternal or maternal unemployment, long periods spent apart from family, family conflicts, having been scolded and beaten by parents, poor or dissatisfying test performance, conflict with friends, heavy course load and failure in selection processes are also associated with parental education. Low family economic status, paternal or maternal unemployment, long periods spent apart from family, family conflicts, poor or dissatisfying test performance, conflict with friends and heavy course load mediated the relationship between parental education and depression in college students.

Conclusions

Adverse family and college environments could explain the influence of parental educational level on depression in college students.

Associations among within-litter differences in early mothering received and later emotional behaviors, mothering, and cortical tryptophan hydroxylase-2 expression in female laboratory rats

This article is part of a Special Issue "Parental Care". The effects of differential maternal care received on offspring phenotype in rodents has been extensively studied between litters, but the consequences of differential mothering within litters on offspring neurobehavioral development have been rarely examined. We here investigated how variability in maternal care received among female rat siblings (measured four times daily on postnatal days 4, 6, 8, and 10) relates to the siblings' later emotional and maternal behaviors. As previously reported, we found that some female pups received up to three times more maternal licking bouts compared to their sisters; this difference was positively correlated with the pups' body weights. The number of maternal licking bouts that females received was negatively correlated with their later neophobic behaviors in an open field during periadolescence, but positively correlated with their anxiety-related behavior in an elevated plus maze during adulthood. Licking received was also positively correlated with females' later likelihood to retrieve pups in a maternal sensitization paradigm. In addition, females' neophobia during adolescence and anxiety-related behavior during adulthood predicted some aspects of both postpartum and sensitized maternal responsiveness. Medial prefrontal cortex expression of tryptophan hydroxylase-2 (TPH2; enzyme necessary for serotonin synthesis) was negatively associated with early maternal licking received. Interestingly, cortical TPH2 was positively associated with the maternal responsiveness of sensitized virgins but negatively associated with it in postpartum females. These results indicate that within-litter differences in maternal care received is an often neglected, but important, contributor to individual differences in offspring socioemotional behaviors as well as to the cortical serotonin neurochemistry that may influence these behaviors.

Self-reported sleep quality, weight status and depression in young adult twins and siblings

Background

Research supporting relationships between sleep quality, weight, depression and anxiety has typically examined the relationships separately rather than simultaneously, potentially hampering insights into the characteristics of reported links. This study aimed to fill this gap in the research to provide further insight into the factors associated with sleep.

Methods

Data from wave 4 of the G1219 cohort were used in cross-sectional analyses. The sample comprised 1392 adult twins and siblings aged 18–27 years. Participants completed a self-report questionnaire which included the Pittsburgh Sleep Quality Index as a measure of sleep quality, the Short Mood and Feelings Questionnaire as a measure of depression symptoms and the Revised Symptoms of Anxiety Scale as a measure of anxiety symptoms. Participants were asked to self-report general health and weight and height so researchers could derive weight status from measures of body mass index.

Results

An analysis of covariance including weight status, depression, anxiety and general health as predictors and sleep quality as the outcome revealed main effects of depression (F(3,1163) = 10.93, p < 0.001) and general health (F(4,1163) = 5.72, p < 0.001) only.

Conclusions

A direct relationship between weight and sleep should not be assumed as it is possible that the relationship is at least in part accounted for by depression symptoms or general health. Depression symptoms and general health may also account for the association between sleep quality and anxiety symptoms in young adults.

Brief report: Explaining differences in depressive symptoms between African American and European American adolescents

African American adolescents report more depressive symptoms than their European American peers, but the reasons for these differences are poorly understood. This study examines whether risk factors in individual, family, school, and community domains explain these differences. African American and European American adolescents participating in the Birmingham Youth Violence Study (N = 594; mean age 13.2 years) reported on their depressive symptoms, pubertal development, aggressive and delinquent behavior, connectedness to school, witnessing violence, and poor parenting. Primary caregivers provided information on family income and their education level, marital status, and depression, and the adolescents' academic performance. African American adolescents reported more depressive symptoms than European American participants. Family socioeconomic factors reduced this difference by 29%; all risk factors reduced it by 88%. Adolescents' exposure to violence, antisocial behavior, and low school connectedness, as well as lower parental education and parenting quality, emerged as significant mediators of the group differences in depressive symptoms.

Genes, environments and depressions in young people

Among the common mental illnesses in childhood and adolescence, the unipolar depressions are the most concerning. These mental illnesses are aetiologically and clinically heterogeneous and little is known about their pathophysiology. This selected review considers the contribution of genetic and environmental factors in the emergence of these illnesses in the second decade of life.

Depressive Symptoms in a Trial Behavioral Family Systems Therapy for Diabetes: A Post Hoc Analysis of Change

OBJECTIVE

The objective was to test whether Behavioral Family Systems Therapy for Diabetes (BFST-D), an evidence-based family therapy, produces individual changes in depressive symptoms for adolescents with type 1 diabetes in suboptimal glycemic control (HbA(1c) ≥9.0% [≥74.9 mmol/mol]).

RESEARCH DESIGN AND METHODS

Data were from a randomized controlled trial (RCT) comparing two modes of BFST-D delivery: in clinic versus Internet videoconferencing. There were no significant differences between groups in the RCT, so groups were collapsed into a within-group prepost design for secondary analyses. A multiple regression analysis was performed to test for mediation of treatment outcomes by changes in family processes.

RESULTS

Significant improvements in glycemic control, depressive symptoms, and family functioning were found from pre- to posttreatment. A multiple regression analysis for within-subject mediation indicated that improvements in depressive symptoms were partially mediated by improvements in parent-youth conflict; however, family process changes did not mediate diabetes health outcomes.

CONCLUSIONS

In addition to improving treatment adherence and glycemic control, BFST-D has collateral benefits on depressive symptoms.

Familial factors associated with development of alcohol and mental health comorbidity

BACKGROUND AND AIMS

Co-occurring mental health and alcohol problems appear to be associated with greater health burdens than either single disorder. This study compares familial and individual contributions to development of comorbid alcohol/mental problems and tests whether these differ from single disorders.

DESIGN

Women (n = 6703) were recruited during pregnancy to the longitudinal Mater-University of Queensland Study of Pregnancy (MUSP). Mother/offspring dyads were followed over 21 years.

SETTING

Mater-Misericordiae Public Hospital, Brisbane, Australia.

PARTICIPANTS

Primary offspring from the MUSP with full psychiatric information at 21 years and maternal information at age 14 (n = 1755).

MEASUREMENTS

Structured interviews at age 21 yielded a four-category outcome using mental health and alcohol modules of the Composite International Diagnostic Interview (no disorder, alcohol only, mental health only and comorbid alcohol/mental health). Multinomial logistic regression models were adjusted for gender, maternal mental health and substance use, family environment and adolescent behaviour.

FINDINGS

Maternal smoking [odds ratio (OR) = 1.56; 95% confidence interval (CI) = 1.09-2.22 versus no-disorder] and low mother-offspring warmth (OR = 3.19; 95% CI = 1.99-5.13) were associated with mental health/alcohol comorbidity in young adults, as were adolescent drinking (OR = 2.22; 95% CI = 1.25-3.96), smoking (OR = 2.24; 95% CI = 1.33-3.77) and attention/thought problems (OR = 2.04; 95% CI = 1.18-3.52). Some differences were seen from single disorders. In a subsample with paternal data, fathers' drinking problems (OR = 2.41; 95% CI = 1.10-5.29) were more associated strongly with offspring mental health/alcohol comorbidity than both single disorders (P < 0.05).

CONCLUSIONS

Maternal smoking and low mother-child warmth appear to be related to alcohol, mental health and comorbid disorders at age 21, possibly via constituent alcohol and mental health disorders. Adolescent drinking and attention/thought problems appear to be associated with comorbid disorders but not with individual alcohol and mental health disorders.

Genome-wide methylomic analysis of monozygotic twins discordant for adolescent depression

BACKGROUND

Adolescent depression is a common neuropsychiatric disorder that often continues into adulthood and is associated with a wide range of poor outcomes including suicide. Although numerous studies have looked at genetic markers associated with depression, the role of epigenetic variation remains relatively unexplored.

METHODS

Monozygotic (MZ) twins were selected from an adolescent twin study designed to investigate the interplay of genetic and environmental factors in the development of emotional and behavioral difficulties. There were 18 pairs of MZ twins identified in which one member scored consistently higher (group mean within the clinically significant range) on self-rated depression than the other. We assessed genome-wide patterns of DNA methylation in twin buccal cell DNA using the Infinium HumanMethylation450 BeadChip from Illumina. Quality control and data preprocessing was undertaken using the wateRmelon package. Differentially methylated probes (DMPs) were identified using an analysis strategy taking into account both the significance and the magnitude of DNA methylation differences. The top differentially methylated DMP was successfully validated by bisulfite-pyrosequencing, and identified DMPs were tested in postmortem brain samples obtained from patients with major depressive disorder (n = 14) and matched control subjects (n = 15).

RESULTS

Two reproducible depression-associated DMPs were identified, including the top-ranked DMP that was located within STK32C, which encodes a serine/threonine kinase, of unknown function.

CONCLUSIONS

Our data indicate that DNA methylation differences are apparent in MZ twins discordant for adolescent depression and that some of the disease-associated variation observed in buccal cell DNA is mirrored in adult brain tissue obtained from individuals with clinical depression.

Polymorphisms in the circadian expressed genes PER3 and ARNTL2 are associated with diurnal preference and GNβ3 with sleep measures

Sleep and circadian rhythms are intrinsically linked, with several sleep traits, including sleep timing and duration, influenced by both sleep homeostasis and the circadian phase. Genetic variation in several circadian genes has been associated with diurnal preference (preference in timing of sleep), although there has been limited research on whether they are associated with other sleep measurements. We investigated whether these genetic variations were associated with diurnal preference (Morningness-Eveningness Questionnaire) and various sleep measures, including: the global Pittsburgh Sleep Quality index score; sleep duration; and sleep latency and sleep quality. We genotyped 10 polymorphisms in genes with circadian expression in participants from the G1219 sample (n = 966), a British longitudinal population sample of young adults. We conducted linear regressions using dominant, additive and recessive models of inheritance to test for associations between these polymorphisms and the sleep measures. We found a significant association between diurnal preference and a polymorphism in period homologue 3 (PER3) (P < 0.005, recessive model) and a novel nominally significant association between diurnal preference and a polymorphism in aryl hydrocarbon receptor nuclear translocator-like 2 (ARNTL2) (P < 0.05, additive model). We found that a polymorphism in guanine nucleotide binding protein beta 3 (GNβ3) was associated significantly with global sleep quality (P < 0.005, recessive model), and that a rare polymorphism in period homologue 2 (PER2) was associated significantly with both sleep duration and quality (P < 0.0005, recessive model). These findings suggest that genes with circadian expression may play a role in regulating both the circadian clock and sleep homeostasis, and highlight the importance of further studies aimed at dissecting the specific roles that circadian genes play in these two interrelated but unique behaviours.

Does early socio-economic disadvantage predict comorbid alcohol and mental health disorders?

BACKGROUND

Alcohol and mental health disorders are highly prevalent in the general population, with co-occurrence recognised as a major public health issue. Socio-economic factors are frequently associated with both disorders but their temporal association is unclear. This paper examines the association between prenatal socio-economic disadvantage and comorbid alcohol and mental health disorders at young adulthood.

METHODS

An unselected cohort of women was enrolled during early pregnancy in the large longitudinal Mater-University of Queensland Study of Pregnancy (MUSP), at the Mater Misericordiae Public Hospital in Brisbane, Australia. The mothers and their offspring were followed over a 21 year period. Offspring from the MUSP birth cohort who provided full psychiatric information at age 21 and whose mothers provided socioeconomic information at baseline were included (n=2399). Participants were grouped into no-disorder, mental health disorder only, alcohol disorder only or comorbid alcohol and mental health disorders according to DSM-IV diagnoses at age 21 as assessed by the Composite International Diagnostic Interview. We used multivariate logistic regression analysis to compare associations of disorder group with single measures of prenatal socio-economic disadvantage including family income, parental education and employment, and then created a cumulative scale of socioeconomic disadvantage.

RESULTS

Greater socio-economic disadvantage was more strongly associated with comorbidity (OR 3.36; CI95 1.37, 8.24) than with single disorders. This relationship was not fully accounted for by maternal mental health, smoking and drinking during pregnancy.

CONCLUSION

Multiple domains of socio-economic disadvantage in early life are associated with comorbid alcohol and mental health disorders.

A meta-analysis of the risk of major affective disorder in relatives of individuals affected by major depressive disorder or bipolar disorder

BACKGROUND

To conduct a meta-analysis to estimate the incidence of major depressive disorder (MDD) and bipolar disorder (BD) in first-degree relatives (FDRs) of probands affected by MDD or BD. The risk for MDD in FDR of BD probands and vice versa is also investigated.

METHODS

A systematic review of case-control and cohort studies, which were published between 1977 and 2012; reported relative risks (RR) or odd ratios (OR) or equivalent raw data; made an explicit distinction between MDD and BD; used operational diagnostic criteria; and reported systematic proband recruitment and ascertainment of relatives. Studies were obtained by electronic MEDLINE and EMBASE searches and hand-searching. Estimates were derived from pooled data using random effects methods.

RESULTS

Of an initial sample of 241 articles, 22 were eligible for inclusion. For FDRs of one proband with MDD compared to healthy control probands, estimates for MDD were OR=2.14 (95% CI 1.72-2.67), increasing to OR=3.23 (95% CI 2.11-4.94) for two MDD probands. For FDRs of one BD proband compared to healthy control probands, estimates for BD were OR=7.92 (95% CI 2.45-25.61), and OR=6.58 (95% CI 2.64-16.43) for FDRs of two BD probands.

CONCLUSIONS

These findings support previously published data indicating strong familiality for both MDD and BD. Data will be useful in providing individuals with a family history of MDD or BPD with tailored risk estimates.

Stress, Inflammation, and Cellular Vulnerability during Early Stages of Affective Disorders: Biomarker Strategies and Opportunities for Prevention and Intervention

The mood disorder prodrome is conceptualized as a symptomatic, but not yet clinically diagnosable stage of an affective disorder. Although a growing area, more focused research is needed in the pediatric population to better characterize psychopathological symptoms and biological markers that can reliably identify this very early stage in the evolution of mood disorder pathology. Such information will facilitate early prevention and intervention, which has the potential to affect a person's disease course. This review focuses on the prodromal characteristics, risk factors, and neurobiological mechanisms of mood disorders. In particular, we consider the influence of early-life stress, inflammation, and allostatic load in mediating neural mechanisms of neuroprogression. These inherently modifiable factors have known neuroadaptive and neurodegenerative implications, and consequently may provide useful biomarker targets. Identification of these factors early in the course of the disease will accordingly allow for the introduction of early interventions which augment an individual's capacity for psychological resilience through maintenance of synaptic integrity and cellular resilience. A targeted and complementary approach to boosting both psychological and physiological resilience simultaneously during the prodromal stage of mood disorder pathology has the greatest promise for optimizing the neurodevelopmental potential of those individuals at risk of disabling mood disorders.

Replication of Genome-Wide Association Studies (GWAS) loci for sleep in the British G1219 cohort

Sleep is a critical behavior shared by most higher animals. Sleep disturbances are comorbid with numerous psychiatric disorders, most notably symptoms of depression. Twin studies have suggested that genetic influences partially underlie the variation seen for numerous sleep-related traits across individuals. Recently, two Genome-Wide Association Studies (GWAS) conducted for sleep traits have revealed new candidate genes for sleep-related measures. We attempted to replicate the two most significant associations from these two studies, CACNA1C (a l-type calcium channel) with sleep latency and quality and ABCC9 (an ATP-sensitive potassium channel) with sleep duration, using the G1219 British population sample. We genotyped single-nucleotide polymorphisms (SNPs) for each of the two different sleep GWAS loci. Linear regression analyses were conducted to assess main effects of these SNPs on their corresponding sleep measures, as well as for depressive symptoms. We successfully replicated an association of a genetic variant in the CACNA1C gene (rs16929277) with sleep quality using an additive model of inheritance. A significant association of the ABCC9 gene (rs11046209) with sleep duration was seen only in a recessive models based upon a rare homozygous genotype (n = 2). There was also a significant association between a different ABCC9 gene variant (rs11046205) and depressive symptoms. These findings add further support for the involvement of calcium channels in the mechanisms regulating sleep function and suggest a possible role of the ABCC9 gene in depression.

The Genesis 12–19 (G1219) Study: A Twin and Sibling Study of Gene–Environment Interplay and Adolescent Development in the UK

The Genesis 12–19 (G1219) Study is an ongoing longitudinal study of a sample of UK twin pairs, non-twin sibling pairs, and their parents. G1219 was initially designed to examine the role of gene–environment interplay in adolescent depression. However, since then data have continued to be collected from both parents and their offspring into young adulthood. This has allowed for longitudinal analyses of depression and has enabled researchers to investigate multiple phenotypes and to ask questions about intermediate mechanisms. The study has primarily focused on emotional development, particularly depression and anxiety, which have been assessed at multiple levels of analysis (symptoms, cognitions, and relevant environmental experiences). G1219 has also included assessment of a broader range of psychological phenotypes ranging from antisocial behaviors and substance use to sleep difficulties, in addition to multiple aspects of the environment. DNA has also been collected. The first wave of data collection began in the year 1999 and the fifth wave of data collection will be complete before the end of 2012. In this article, we describe the sample, data collection, and measures used. We also summarize some of the key findings to date.

Friendship context matters: examining the domain specificity of alcohol and depression socialization among adolescents

Driven by existing socialization theories, this study describes specific friendship contexts in which peer influence of alcohol misuse and depressive symptoms occurs. In the fall and spring of the school year, surveys were administered to 704 Italian adolescents (53 % male, M (age) = 15.53) enrolled in Grades 9, 10 and 11. Different friendship contexts were distinguished based on two dimensions referring to the level (i.e., best friendships and friendship networks) and reciprocity (i.e., unilateral and reciprocal) of the relationships. Social network and dyadic analyses were applied in a complementary manner to estimate peer socialization effects across the different friendship contexts. Results showed that within friendship networks both male and female adolescents' alcohol misuse was affected by friends' alcohol misuse, regardless of whether the relationship was reciprocated or not. Conversely, peer socialization of depressive symptoms only emerged within very best friendship dyads of female adolescents. Findings suggest that the effects of peer socialization depend on the friendship context and specific types of behaviors. The theoretical and methodological implications of the findings are discussed.

Catastrophic worries in mothers of adolescents with internalizing disorders

OBJECTIVES

This study investigates worrying in mothers of adolescents with internalizing disorders, and tests the hypothesis that these mothers will produce a greater number of worries with higher catastrophic content compared to control groups.

DESIGN

Differences in worry steps and in catastrophic content of worries were investigated in a cross-sectional, between groups design, employing a clinical internalizing group, a clinical control, and a non-referred control group.

METHODS

Twenty-five mothers of adolescents with internalizing disorders, 24 mothers of adolescents with externalizing disorders, and 28 mothers with non-referred adolescents participated in two interviews about their 'real' pre-existing worries and their worries in response to a hypothetical situation.

RESULTS

The internalizing group produced both a greater number of worry steps and a higher catastrophic content when they talked about their 'real' worries, compared to both control groups. They also produced a greater number of worry steps in response to a hypothetical situation compared to the other two groups. The number of worry steps and the level of catastrophic content of 'real' worries were associated with adolescent depression and anxiety. Additionally, the number of worry steps and the level of catastrophic content of worries in response to a hypothetical situation were related to adolescent depression. The number of worry steps in 'real' worries and the level of catastrophic content in hypothetical worries were also associated with maternal depressive symptoms.

CONCLUSIONS

Mothers of adolescents with internalizing disorders may worry more catastrophically about their children than other mothers.

Associations between sleep quality and anxiety and depression symptoms in a sample of young adult twins and siblings

OBJECTIVES

Little is known about the aetiology of the links between sleep disturbance and anxiety and depression symptoms. The aim of this study was to estimate genetic and environmental influences on these associations.

METHODS

Questionnaires were completed by 1556 young adults from twin and sibling pairs (61.5% female).

RESULTS

Sleep disturbance was moderately correlated with symptoms of anxiety (r=.39) and depression (r=.50). There was substantial overlap between genes influencing sleep disturbance and those influencing symptoms of anxiety (rA=.58) and depression (rA=.68). Overall, the associations between sleep and symptoms of both anxiety and depression were mainly due to genes (explaining 74% and 58% of the covariances respectively), with the remainder due to nonshared environmental factors.

CONCLUSIONS

Moderate phenotypic and genetic correlations between the phenotypes support the view that sleep disturbance is related to the presence of various psychiatric difficulties, but also warrants independent consideration and treatment.

Sleep quality and diurnal preference in a sample of young adults: associations with 5HTTLPR, PER3, and CLOCK 3111

Research investigating associations between specific genes and individual differences with regards to the quality and timing of sleep has primarily focussed on serotonin-related and clock genes. However, there are only a few studies of this type and most of those to date have not considered the possibility of gene-environment interaction. Here, we describe associations between sleep quality and diurnal preference and three functional polymorphisms: 5HTTLPR, PERIOD3, and CLOCK 3111. Furthermore, we assessed whether associations between genotypes and sleep phenotypes were moderated by negative life events-a test of gene-environment interaction. DNA from buccal swabs was collected from 947 individuals [mean age = 20.3 years (SD = 1.77), age range = 18-27 years; 61.8% female] and genotyped for the three polymorphisms. Participants completed the Pittsburgh Sleep Quality Index and the Morningness-Eveningness Questionnaire. There was a significant main effect of 5HTTLPR on sleep quality, indicating that "long-long" homozygotes experienced significantly poorer sleep quality (mean = 6.35, SD = 3.36) than carriers of at least one "short" allele (mean = 5.67, SD = 2.96; β = -0.34, P = 0.005). There were no main effects of 5HTTLPR on diurnal preference; no main effects of PERIOD3 or CLOCK on sleep quality or diurnal preference; and no significant interactions with negative life events. The main effect of the "long" 5HTTLPR allele contradicts previous research, suggesting that perhaps the effects of this gene are heterogeneous in different populations. Failure to replicate previous research in relation to PERIOD3 and CLOCK concurs with previous research suggesting that the effects of these genes are small and may be related to population composition.

Genetic risk by experience interaction for childhood internalizing problems: converging evidence across multiple methods

BACKGROUND

Identifying how genetic risk interacts with experience to predict psychopathology is an important step toward understanding the etiology of mental health problems. Few studies have examined genetic risk by experience interaction (G×E) in the development of childhood psychopathology.

METHODS

We used both co-twin and parent mental health as markers of genetic risk to test whether G×E predicted internalizing problems in a sample of 8-year-old twins. Multi-instrument composites were used to characterize both parent and child psychopathology, and five experiential risk factors (socioeconomic status, single parent upbringing, negative parent-child interactions, number of negative life events, negative impact of negative life events) composed a cumulative risk index.

RESULTS

We found consistent evidence for G×E for child internalizing problems, with significant interaction effects emerging both when genetic risk was indexed by co-twin mental health and when it was based on parent mental health. When co-twin mental health was used to estimate genetic risk, child internalizing problems were more heritable for children at low rather than high experiential risk. When parent mental health was used to estimate genetic risk, the association between genetic risk and internalizing problems was stronger for children at elevated experiential risk. Consideration of the interaction effect sizes helps to reconcile these findings.

CONCLUSIONS

Our results suggest that the processes involved in both diathesis-stress and bioecological models of development may operate for child internalizing problems. Effect sizes indicated that the main effects of genetic and experiential risk were much better predictors of child internalizing problems than was their interaction.

Associations between diurnal preference, sleep quality and externalizing behaviours: a behavioural genetic analysis

BACKGROUND

Certain aspects of sleep co-occur with externalizing behaviours in youth, yet little is known about these associations in adults. The present study: (1) examines the associations between diurnal preference (morningness versus eveningness), sleep quality and externalizing behaviours; (2) explores the extent to which genetic and environmental influences are shared between or are unique to these phenotypes; (3) examines the extent to which genetic and environmental influences account for these associations. method: Questionnaires assessing diurnal preference, sleep quality and externalizing behaviours were completed by 1556 young adult twins and siblings.

RESULTS

A preference for eveningness and poor sleep quality were associated with greater externalizing symptoms [r=0.28 (95% CI 0.23-0.33) and 0.34 (95% CI 0.28-0.39), respectively]. A total of 18% of the genetic influences on externalizing behaviours were shared with diurnal preference and sleep quality and an additional 14% were shared with sleep quality alone. Non-shared environmental influences common to the phenotypes were small (2%). The association between diurnal preference and externalizing behaviours was mostly explained by genetic influences [additive genetic influence (A)=80% (95% CI 0.56-1.01)], as was the association between sleep quality and externalizing behaviours [A=81% (95% CI 0.62-0.99)]. Non-shared environmental (E) influences accounted for the remaining variance for both associations [E=20% (95% CI -0.01 to 0.44) and 19% (95% CI 0.01-0.38), respectively].

CONCLUSIONS

A preference for eveningness and poor sleep quality are moderately associated with externalizing behaviours in young adults. There is a moderate amount of shared genetic influences between the phenotypes and genetic influences account for a large proportion of the association between sleep and externalizing behaviours. Further research could focus on identifying specific genetic polymorphisms common to both sleep and externalizing behaviours.

A systematic evaluation and validation of subtypes of adolescent alcohol use motives: genetic and environmental contributions

BACKGROUND

Alcohol use motives are closely associated with specific profiles of alcohol use and reflect a subjectively derived decisional framework based on a motivational style of responding. Adult twin studies typically estimate the heritability of alcohol use motives to be between 7 and 42%, although relatively little is known about genetic and environmental influences upon alcohol use motives in adolescence.

METHODS

Latent class analysis (LCA) models containing 1 through 5 classes were fitted to the data derived from 1,422 adolescent twin and siblings self-reported alcohol use motives. Using twin models, we estimated the genetic, shared, and nonshared environmental influences to the class membership data derived from the LCA.

RESULTS

Four drinking motives classes were identified (family-oriented, social, enhancement/social, and coping/social). The coping/social and enhancement/social classes were differentiated from the social class on measures of depression, delinquency, and aggressive behavior. Analyses indicated that nonadditive genetic factors accounted for 76% of the variance in the coping/social motives class and additive genetic influences accounted for 66% of the variance in the social motives class. There was a moderate contribution of genetic factors and shared environmental factors influencing class membership of enhancement/social motivated drinkers (28 and 20% explained variance, respectively). Substantial shared environmental influences were revealed for membership of the family-oriented class (75%).

CONCLUSIONS

Heritable influences may predispose individuals to drink to cope with negative affect, for social reasons, and to a lesser extent for enhancement. Familial environmental influences shape family-oriented motives for drinking in adolescents.

Childhood and adolescent anxiety and depression: beyond heritability

OBJECTIVE

To review the methodology of behavior genetics studies addressing research questions that go beyond simple heritability estimation and illustrate these using representative research on childhood and adolescent anxiety and depression.

METHOD

The classic twin design and its extensions may be used to examine age and gender differences in the genetic determinants of complex traits and disorders, the role of genetic factors in explaining comorbidity, the interaction of genes and the environment, and the effect of social interaction among family members. An overview of the methods typically employed to address such questions is illustrated by a review of 34 recent studies on childhood anxiety and depression.

RESULTS

The review provides relatively consistent evidence for small to negligible sex differences in the genetic etiology of childhood anxiety and depression, a substantial role of genetic factors in accounting for the temporal stability of these disorders, a partly genetic basis of the comorbidity between anxiety and depression, a possible role of the interaction between genotype and the environment in affecting liability to these disorders, a role of genotype-environment correlation, and a minor, if any, etiological role of sibling interaction.

CONCLUSION

The results clearly demonstrate a role for genetic factors in the etiology and temporal stability of individual differences in childhood anxiety and depression. Clinical implications of the findings are discussed.

The genetics of mood disorders

Studying the genetics of mood disorders has never been more exciting. We have moved rapidly from establishing the genetic basis of depression to asking questions about how genes are expressed. This has been made possible by the capacity to collect and sequence DNA for large samples cheaply. But "multidisciplinary" approaches investigating interrelationships between risk factors have also been increasingly adopted, encouraging collaborations between those studying genes and those studying the brain, cognition, and/or the social environment. In this review, we first describe findings from quantitative and molecular studies investigating the genetic basis of depression. Second, we present overviews of three hot topics of genetic research: gene-environment interplay, which considers how genetic factors shape exposure and responses toward the social environment; endophenotypic research, which identifies neurophysiological and psychological mediators of genetic risk; and epigenetics, which explain how early environments can foster changes in gene expression, altering subsequent emotional development.

Genetic influences on the cognitive biases associated with anxiety and depression symptoms in adolescents

BACKGROUND

There is a substantial overlap between genes affecting anxiety and depression. Both anxiety and depression are associated with cognitive biases such as anxiety sensitivity and attributional style. Little, however, is known about the relationship between these variables and whether these too are genetically correlated.

METHODS

Self-reports of anxiety sensitivity, anxiety symptoms, attributional style and depression symptoms were obtained for over 1300 adolescent twin and sibling pairs at two time points. The magnitude of genetic and environmental influences on the measures was examined.

RESULTS

Strongest associations were found between anxiety sensitivity and anxiety ratings at both measurement times (r=.70, .72) and between anxiety and depression (r=.62 at both time points). Correlations between the cognitive biases were modest at time 1 (r=-.12) and slightly larger at time 2 (r=-.31). All measures showed moderate genetic influence. Generally genetic correlations reflected phenotypic correlations. Thus the highest genetic correlations were between anxiety sensitivity and anxiety ratings (.86, .87) and between anxiety and depression ratings (.77, .71). Interestingly, depression ratings also showed a high genetic correlation with anxiety sensitivity (.70, .76). Genetic correlations between the cognitive bias measures were moderate (-.31, -.46).

LIMITATIONS

The sample consists primarily of twins, there are limitations associated with the twin design.

CONCLUSIONS

Cognitive biases associated with depression and anxiety are not as genetically correlated as anxiety and depression ratings themselves. Further research into the cognitive processes related to anxiety and depression will facilitate understanding of the relationship between bias and symptoms.

Genetic and environmental influences on different components of the Pittsburgh Sleep Quality Index and their overlap

STUDY OBJECTIVES

To examine the extent to which genetic and environmental factors influence components of sleep quality; the degree to which these components co-occur; and genetic and environmental influences on this co-occurrence.

DESIGN

Twin study.

SETTING

Population based twin registry across the U.K.

PATIENTS OR PARTICIPANTS

Four hundred twenty monozygotic twins, 773 dizygotic twins, and 363 siblings (mode age = 20 years; range 18 to 27 years).

INTERVENTIONS

N/A.

MEASUREMENTS AND RESULTS

The Pittsburgh Sleep Quality Index (PSQI) assessed 7 components of sleep quality which overlap to varying degrees. Genetic influence on individual components ranged from 0% to 47%. The remaining source of variance was non-shared environment, except for "sleep duration", for which shared environmental influences were important. Phenotypic correlations between components ranged from 0.22 to 0.61. Bivariate analyses indicated substantial overlap between genes influencing phenotypes (10 of 15 correlations were > or = 0.69); and in general, genetic influence accounted for roughly half the association (> 40% in 9 of 15 correlations). Non-shared environmental influences were in general less correlated across variables (11 of 15 were < 0.4), but owing to their greater influence on each variable, still accounted for roughly half of each association (> or = 40% in 12 of 15 correlations).

CONCLUSIONS

Genetic and non-shared environmental factors are most important in explaining individual differences with regards to different components of sleep quality, although shared environment may influence sleep duration. The pattern of overlap in the genetic and environmental influences accounting for the associations between components of sleep quality is consistent with that seen in other areas of developmental psychopathology of general genes and specific non-shared environmental influences.

Association of monoamine oxidase A (MAOA) polymorphisms and clinical subgroups of major depressive disorders in the Han Chinese population

It has been proposed that an MAOA abnormality may be an important factor in the development of major depressive disorder (MDD). Various polymorphisms of the MAOA gene have been investigated for possible associations with mood disorders, but results have been inconsistent. The goal of the present study was to investigate whether polymorphisms of the MAOA gene are associated with MDD or alternatively with different clinical subgroups of MDD. A total of 590 Han Chinese subjects in Taiwan (312 controls and 278 MDD patients) were recruited. Among the males, there were no associations with MAOA polymorphisms. Among the females, an association was found between MAOA polymorphisms and severe MDD (P=0.041 for uVNTR and 0.017 for EcoRV (rs1137070), respectively). However, in analyses of haplotype frequencies and multiple logistic regression, MAOA polymorphisms were not associated with either MDD or its subgroups. The results suggest that MAOA polymorphisms do not play a major role in the pathogenesis of MDD or its subgroups. However, a potential role for a minor association with some specific subgroups and with different ethnic samples needs to be explored further.

Assessment of parental experiential avoidance in a clinical sample of children with anxiety disorders

This investigation seeks to establish the psychometric properties of an adapted measure of experiential avoidance (EA) in the parenting context by assessing its relation to other parenting constructs and psychosocial correlates of child anxiety in a clinical sample. Participants were 154 children (90 female, 64 male) diagnosed with anxiety disorders and their parents (148 mothers, 119 fathers). The newly developed Parental Acceptance and Action Questionnaire (PAAQ) was administered to parents along with self-report measures of adult experiential avoidance, parental psychopathology, affective expression, and parental control behaviors. A subsample of participants, n = 35, were re-administered the PAAQ to assess temporal stability. Factor analysis of the PAAQ yielded a two-factor solution with factors labeled Inaction and Unwillingness. Temporal stability of the PAAQ was found to be moderate, r = .68-.74. Internal consistency was fair across subscales of the PAAQ, alpha = .64-.65. Correlational analysis of the PAAQ and parent-report measures support the criterion validity of the PAAQ, suggesting that the PAAQ correlates with parent-report measures of parental locus of control, affective expression, and controlling parental behaviors as well as child psychopathology symptoms. Finally, the clinical applicability of the PAAQ is indicated by the PAAQ's ability to predict a significant amount of variance in parent- and clinician-rated levels of child anxiety and related psychopathology.

Longitudinal precursors of young adult light smoking among African Americans and Puerto Ricans

INTRODUCTION

Studies have consistently documented the importance of examining light smoking among African American and Latino adolescent and adult smokers. Little is known, however, about the psychosocial antecedents of adolescent and young adult light smoking in these racial/ethnic minority groups.

METHODS

This study examined the longitudinal interrelationships and pathways leading to light smoking among African Americans (n = 288) and Puerto Ricans (n = 262). Specifically, we assessed parental factors, perceived discrimination, peer smoking, personality factors, and light smoking in late adolescence as precursors to light smoking among African American and Puerto Rican young adults.

RESULTS

The results of structural equation modeling showed that a history of greater parental smoking, less parental educational attainment, and more perceived discrimination were each mediated by peer smoking and the youth's maladaptive personality and behavior in late adolescence. The youth's maladaptive personality and behavioral characteristics and light smoking in late adolescence, in turn, predicted light smoking in young adulthood. There were no significant racial/ethnic or gender differences in the pathways to light smoking.

DISCUSSION

Findings highlight the longitudinal pathways to light smoking among African Americans and Puerto Ricans. The results suggest that effective prevention and cessation programs must address peer and parental social influences, perceived discrimination, and especially, emotional and behavioral problems in late adolescence to reduce light smoking among late adolescents and young adults in these racial/ethnic groups.

A Comparative Study of Parental Behaviors and Children's Eating Habits

Childhood obesity poses a serious threat to the health of our nation. Specifically, the preschool years (3-5 years of age) have been identified as a crucial time to study the determinants of childhood nutrition and obesity. This study investigated the body mass index (BMI) of children ages 3 to 5 years, as well as parenting behaviors and parenting styles and how they possibly influenced children's eating habits and overall BMIs. Results indicated there was a significant difference between parenting styles and children's eating habits, with authoritative parents labeling their children's eating habits as either very good or good and permissive parents labeling their children's eating habits as fair. In addition, results indicated a significant difference between parents' educational levels and personal BMIs. As parents' educational level increased, their BMI levels decreased.

Links between parenting and extra-familial relationships: nature or nurture?

The current paper examined associations between parenting and both peer group characteristics and friendship quality within a genetically sensitive design. Participants were aged 12-19 years (approximately equal numbers of males and females), including 424 sibling pairs and 1185 twin pairs, of whom 328 were MZ, 311 were DZ same-sex, 463 were DZ opposite-sex and 83 were of unknown zygosity. The adolescents provided self-report questionnaire measures of parental discipline, friendship quality, and peer group characteristics. All three relationship measures were moderately to substantially heritable. The novel and provocative finding, that adolescents' genetic propensities are largely responsible for the overlap seen between parental discipline strategies and friendship quality, is discussed in terms of its implications for socialization theory and understanding of adolescent relationships.

The Behavioral Genetics of Personality Disorder

Behavioral genetics research has opened a new window on understanding personality disorder. The earliest studies were focused on establishing the relative contributions of genes and the environment in these disorders. Although these studies provided solid evidence of the importance of genetic and environmental influences on personality disorder and showed that all aspects of personality disorder are subject to genetic influence, heritability studies are limited because they are not helpful in explicating causal mechanisms. More recent research has focused on the relative contributions of the covariation of personality disorder diagnoses and traits, which allows one to examine etiological relationships. These developments are leading to major changes in ideas about what constitutes the environment and nature of the interplay between genes and environment. The present review examines major themes in this growing body of research in the context of current issues in the personality disorders.

The interplay of familial depression liability and adverse events in predicting the first onset of depression during a 10-year follow-up

BACKGROUND

The aim of the present article is to explore interaction and correlation effects between familial depression liability and selected adverse (separation and traumatic) events in predicting the first onset of a major depressive episode (MDE) in a 10-year prospective longitudinal community survey.

METHODS

Analyses are based on 1982 subjects (14 to 24 years at baseline) without baseline MDE who participated during the whole study period and for whom diagnostic information about psychopathology in both parents was available. The offspring's familial depression liability was determined by aggregating information on parental depressive symptoms obtained from family history data and direct interviews with parents. Data were assessed with the Munich-Composite International Diagnostic Interview according to its DSM-IV algorithms.

RESULTS

Adverse events predicted a substantially increased incidence of MDE among respondents with familial liability but not in those without familial liability. There was a significant interaction between familial liability and traumatic events with the strongest effect for the number of severe traumatic events (risk difference = 11.3%; 95% confidence interval = 3.55-19.15). Associations with familial liability were most pronounced for separation events.

CONCLUSIONS

Adverse events are particularly pathogenic in individuals with familial liability. The involvement of interactions and correlations between familial liability and adversity might depend on type, severity, and number of events. Both processes are suggested to be concomitant rather than exclusive.

Parental punitive discipline, negative life events and gene-environment interplay in the development of externalizing behavior

BACKGROUND

To investigate the extent to which three putative 'environmental' risk factors, maternal punitive discipline (MPD), paternal punitive discipline (PPD) and negative life events (NLEs), share genetic influences with, and moderate the heritability of, externalizing behavior.

METHOD

The sample consisted of 2647 participants, aged 12-19 years, from the G1219 and G1219Twins longitudinal studies. Externalizing behavior was measured using the Youth Self-Report, MPD, PPD and exposure to NLEs were assessed using the Negative Sanctions Scale and the Life Event Scale for Adolescents respectively.

RESULT

Genetic influences overlapped for externalizing behavior and each 'environmental' risk, indicating gene-environment correlation. When controlling for the gene-environment correlation, genetic variance decreased, and both shared and non-shared environmental influences increased, as a function of MPD. Genetic variance increased as a function of PPD, and for NLEs the only interaction effect was on the level of non-shared environment influence unique to externalizing behavior.

CONCLUSION

The magnitude of the influence of genetic risk on externalizing behavior is contextually dependent, even after controlling for gene-environment correlation.

Stressful life events and depressive problems in early adolescent boys and girls: the influence of parental depression, temperament and family environment

BACKGROUND

Stressful life events increase the probability of depressive problems in early adolescence. Several genetic and environmental risk factors may change individual sensitivity to the depressogenic effect of these events. We examined modification by parental depression and gender, and mediation of the former by temperament and family environment.

METHODS

Data were collected as part of a longitudinal cohort study of (pre)adolescents (n = 2127). During the first assessment wave at approximately age 11, we assessed parental depression, family functioning, perceived parenting behaviours, and temperamental frustration and fearfulness. At the second wave, about two and a half years later, stressful life events between the first and second assessment were assessed. Depressive problems were measured at both waves.

RESULTS

Adolescents with parents who had a (lifetime) depressive episode were more sensitive to the depressogenic effect of stressful events than adolescents without depressed parents. Furthermore, girls are more sensitive to these effects than boys. The modifying effect of parental depression was not mediated by temperament, family functioning and perceived parenting.

LIMITATIONS

Life events were assessed without consideration of contextual information. Depressive problems were measured by questionnaires that did not directly represent DSM-IV criteria. The measure of parental depression was unspecific regarding severity and timing of depressive episodes.

CONCLUSION

The results suggest that gender and parental depression are associated with increased sensitivity to depression after experiencing stressful life events during adolescence.

I think, therefore I am: a twin study of attributional style in adolescents

BACKGROUND

Parenting factors may be important to the development of attributional style in adolescence, which in turn relates to depression symptoms. These relationships have mainly been considered in terms of social risk mechanisms, and little is known about the role of genetic influences.

METHOD

Self-reported measures of attributional style, depression symptoms and parental disciplinary styles were administered to over 1300 adolescent twin and sibling pairs. Model-fitting techniques were used to examine the role of genetic and environmental influences.

RESULTS

Moderate genetic influences on attributional style were demonstrated, and furthermore, its association with depression reflected considerable genetic effects. Familial factors were implicated in the association between attributional style and punitive parenting, although genetic from shared environmental causes could not be distinguished.

CONCLUSIONS

Our results demonstrate that attributional style is influenced by genetic, as well as social factors. Implications for aetiological pathways integrating cognitive, genetic and social factors on adolescent depression are discussed.

Family conflict interacts with genetic liability in predicting childhood and adolescent depression

OBJECTIVE

To test for gene-environment interaction with depressive symptoms and family conflict. Specifically, to first examine whether the influence of family conflict in predicting depressive symptoms is increased in individuals at genetic risk of depression. Second, to test whether the genetic component of variance in depressive symptoms increases as levels of family conflict increase.

METHOD

A longitudinal twin design was used. Children ages 5 to 16 were reassessed approximately 3 years later to test whether the influence of family conflict in predicting depressive symptoms varied according to genetic liability. The conflict subscale of the Family Environment Scale was used to assess family conflict and the Mood and Feelings Questionnaire was used to assess depressive symptoms. The response rate to the questionnaire at time 1 was 73% and 65% at time 2. Controlling for initial symptoms levels (i.e., internalizing at time 1), primary analyses were conducted using ordinary least-squares multiple regression. Structural equation models, using raw score maximum likelihood estimation, were also fit to the data for the purpose of model fit comparison.

RESULTS

Results suggested significant gene-environment interaction specifically with depressive symptoms and family conflict. Genetic factors were of greater importance in the etiology of depressive symptoms where levels of family conflict were high. The effects of family conflict on depressive symptoms were greater in children and adolescents at genetic risk of depression.

CONCLUSIONS

The present results suggest that children with a family history of depression may be at an increased risk of developing depressive symptoms in response to family conflict. Intervention programs that incorporate one or more family systems may be of benefit in alleviating the adverse effect of negative family factors on children.

A monozygotic twin differences study of nonshared environmental influence on adolescent depressive symptoms

The monozygotic (MZ) twin differences method was used to examine nonshared environmental aspects of the association of parenting (punitive and constructive discipline), negative life events (independent and dependent), and peers (antisocial and prosocial) with adolescent depressive symptoms in terms of sequelae, risk, and maintaining factors. Two self-report booklets were completed by 328 MZ twin pairs aged 12-19 years, 6 months apart. Increased punitive discipline and negative life events were found to be relevant nonshared environmental factors that followed depression. Negative life events were the only factor that had a direct nonshared environmental association with concurrent depressive symptoms in adolescents independent of previous depressive symptoms, and all other study variables.

Gene-environment interplay and psychopathology: multiple varieties but real effects

Gene-environment interplay is a general term that covers several divergent concepts with different meanings and different implications. In this review, we evaluate research evidence on four varieties of gene-environment interplay. First, we consider epigenetic mechanisms by which environmental influences alter the effects of genes. Second, we focus on variations in heritability according to environmental circumstances. Third, we discuss what is known about gene-environment correlations. Finally, we assess concepts and findings on the interaction between specific identified genes and specific measured environmental risks. In order to provide an understanding of what may be involved in gene-environment interplay, we begin our presentation with a brief historical review of prevailing views about the role of genetic and environmental factors in the causation of mental disorders, and we provide a simplified account of some of the key features of how genes 'work'.