Psychiatric outcomes of bullying victimization: a study of discordant monozygotic twins.

BACKGROUND: Bullying victimization in childhood is associated with a broad array of serious mental health disturbances, including anxiety, depression, and suicidal ideation and behavior. The key goal of this study was to evaluate whether bullying victimization is a true environmental risk factor for psychiatric disturbance using data from 145 bully-discordant monozygotic (MZ) juvenile twin pairs from the Virginia Twin Study of Adolescent Behavioral Development (VTSABD) and their follow-up into young adulthood. METHOD: Since MZ twins share an identical genotype and familial environment, a higher rate of psychiatric disturbance in a bullied MZ twin compared to their non-bullied MZ co-twin would be evidence of an environmental impact of bullying victimization. Environmental correlations between being bullied and the different psychiatric traits were estimated by fitting structural equation models to the full sample of MZ and DZ twins (N = 2824). Environmental associations were further explored using the longitudinal data on the bullying-discordant MZ twins. RESULTS: Being bullied was associated with a wide range of psychiatric disorders in both children and young adults. The analysis of data on the MZ-discordant twins supports a genuine environmental impact of bullying victimization on childhood social anxiety [odds ratio (OR) 1.7], separation anxiety (OR 1.9), and young adult suicidal ideation (OR 1.3). There was a shared genetic influence on social anxiety and bullying victimization, consistent with social anxiety being both an antecedent and consequence of being bullied. CONCLUSION: Bullying victimization in childhood is a significant environmental trauma and should be included in any mental health assessment of children and young adults.

Siblings of individuals with Smith-Magenis syndrome: an investigation of the correlates of positive and negative behavioural traits.

BACKGROUND: Smith-Magenis syndrome (SMS) is a neurodevelopmental disorder that affects approximately one out of 25,000 births worldwide. To date, no research has been conducted to investigate how having an individual with SMS in a family is a positive or negative influence on siblings. METHODS: To investigate this question we conducted a study involving 79 siblings and 60 parents of individuals with SMS to assess perceptions of how having a sibling with SMS positively and negative influence siblings' behavioural traits. RESULTS: Our findings show that age of siblings of individuals with SMS was associated with a significant increase in positive behavioural traits and a significant decrease in negative behavioural traits. Additionally, siblings who perceive benefits from having a sibling with SMS demonstrate significantly more positive behavioural traits and significantly fewer negative behavioural traits. Parents accurately assess the changes in sibling behavioural traits with age, and parents who perceive their child as having experienced benefits from the sibling relationship report that siblings demonstrate significantly more positive behavioural traits and significantly fewer negative behavioural traits. CONCLUSIONS: Our research shows that although individuals experience difficulties as a result of having a sibling with SMS, overall, siblings tend to fare well and parents appreciate both the positive and negative behavioural effects that result from having a sibling with SMS.

Fatigue in a community sample of twins.

BACKGROUND: Fatigue is a complex symptom associated with many physiological, psychological and pathological processes. Its correlates and typology remain inadequately understood. METHOD: These data were from two large, longitudinal twin studies. Trained interviewers enquired as to the presence of a > or = 5 day period in the previous year of fatigue or tiredness that interfered with daily activities. A range of potential correlates was assessed in a structured interview: demography; health beliefs; the presence of nine physical disorders; mood, anxiety and addictive disorders; neuroticism and extraversion; recollections of parental rearing; and nine stressful life events. Statistical analyses included logistic regression, CART, MARS, latent class analysis and univariate twin modelling. RESULTS: Data were available for interfering fatigue (IF) on 7740 individual twins (prevalence 9.9% in the previous year). IF was significantly associated with 42 of 52 correlates (most strongly with major depression, generalized anxiety disorder, reported major health problems and neuroticism). Multivariate analyses demonstrated that IF is a highly complex construct with different sets of correlates in its subtypes. There were two broad clusters of correlates of IF: (a) major depression, generalized anxiety disorder and neuroticism; and (b) beliefs of ill health coexisting with alcoholism and stressful life events. Twin analyses were consistent with aetiological heterogeneity--genetic effects may be particularly important in women and shared environmental effects in men. CONCLUSIONS: IF is a complex and common human symptom that is highly heterogeneous. More precise understanding of the determinants of IF may lead to a fuller understanding of more extreme conditions like chronic fatigue syndrome.

Common disease analysis using Multivariate Adaptive Regression Splines (MARS): Genetic Analysis Workshop 12 simulated sequence data.

A newly developed modern analytic approach, Multivariate Adaptive Regression Splines (MARS), was used to identify both genetic and non-genetic factors involved in the etiology of a common disease. We tested this method on the simulated data provided by the Genetic Analysis Workshop (GAW) 12 in problem 2 for the isolated population. MARS simultaneously analyzes all inputs, in this case DNA sequence variants and non-genetic data, and selectively prunes away variables contributing insignificantly to fit by internal cross-validation to arrive at a generalizable predictive model of the response. The relevant factors identified, by means of an importance value computed by MARS, were assumed to be associated with risk to the disease. The application of a series of subsequent models identified the quantitative traits and a single major gene contributing directly to risk liability using five sets of 7,000 individuals.