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Background Resilience has been shown to be protective against alcohol use disorders (AUDs), but the magnitude and nature of the relationship between these 2 phenotypes are not clear. The aim of this study was to examine the strength of this relationship and the degree to which it results from common genetic or common environmental influences. Methods Resilience was assessed on a 9-point scale during a personal interview in 1,653,721 Swedish men aged 17 to 25 years. AUD was identified based on Swedish medical, legal, and pharmacy registries. The magnitude of the relationship between resilience and AUD was examined using logistic regression. The extent to which the relationship arises from common genetic or common environmental factors was examined using a bivariate Cholesky decomposition model. Results The 5 single items that comprised the resilience assessment (social maturity, interest, psychological energy, home environment, and emotional control) all reduced risk for subsequent AUD, with social maturity showing the strongest effect. The linear effect by logistic regression showed that a 1-point increase on the resilience scale was associated with a 29% decrease in odds of AUD. The Cholesky decomposition model demonstrated that the resilience-AUD relationship was largely attributable to overlapping genetic and shared environmental factors (57 and 36%, respectively). Conclusions Resilience is strongly associated with a reduction in risk for AUD. This relationship appears to be the result of overlapping genetic and shared environmental influences that impact resilience and risk of AUD, rather than a directly causal relationship. [ABSTRACT FROM AUTHOR]

Background Evidence from twin and molecular genetic studies is accumulating that Autism Spectrum Disorder ( ASD) shares substantial etiological factors with other disorders. This is mirrored in clinical practice where ASD without coexisting disorders is rare. The present study aims to examine the range of coexisting disorders in ASD in a genetically informative cohort. Methods Parents of all Swedish 9-year-old twins born between 1992 and 2001 ( n = 19,130) underwent a telephone interview designed to screen for child psychiatric disorders, including ASD. To ensure full coverage of child psychiatric disorders, data were also retrieved from population-based health registers. We investigated the coexistence of eight psychiatric disorders known to coexist with ASDs in probands and their co-twins. Results Half of the individuals with ASDs (50.3%) had four or more coexisting disorders and only 4% did not have any concomitant disorder. The 'healthy co-twin' in ASD discordant monozygotic twin pairs was very often (79% of boys and 50% of girls) affected by at least one non- ASD disorder. The corresponding figures for ASD discordant dizygotic twin pairs were significantly lower (46% of males and 30% of females). Conclusions Detailed phenotypic descriptions including symptoms of problems associated with a wide range of child psychiatric disorders may aid in unraveling the genetic architecture of ASD and should guide the development of intervention strategies addressing each problem type specifically. [ABSTRACT FROM AUTHOR]

Background Studies have found an association between low birth weight and ADHD, but the nature of this relation is unclear. First, it is uncertain whether birth weight is associated with both of the ADHD dimensions, inattentiveness and hyperactivity-impulsivity. Second, it remains uncertain whether the association between birth weight and ADHD symptom severity is confounded by familial factors. Method Parents of all Swedish 9- and 12-year-old twins born between 1992 and 2000 were interviewed for DSM- IV inattentive and hyperactive-impulsive ADHD symptoms by the Autism - Tics, AD/ HD and other Comorbidities (A- TAC) inventory ( N = 21,775 twins). Birth weight was collected prospectively through the Medical Birth Registry. We used a within-twin pair design to control for genetic and shared environmental factors. Results Reduced birth weight was significantly associated with a mean increase in total ADHD (β = −.42; 95% CI: −.53, −.30), inattentive (β = −.26; 95% CI: −.33, −.19), and hyperactive-impulsive (β = −.16; 95% CI: −.22, −.10) symptom severity. These results imply that a change of one kilogram of birth weight corresponded to parents rating their child nearly one unit higher (going from 'no' to 'yes, to some extent' on a given symptom) on the total ADHD scale. These associations remained within pairs of MZ and DZ twins, and were also present when restricting the analyses to full term births. Conclusions There is an independent association between low birth weight and all forms of ADHD symptoms, even after controlling for all environmental and genetic confounds shared within twin pairs. These results indicate that fetal growth restriction (as reflected in birth weight differences within twin pairs) and/or the environmental factors which influence it is in the casual pathway leading to ADHD. [ABSTRACT FROM AUTHOR]

Background and Aims Anabolic androgenic steroid ( AAS) use is associated with aggressive and violent behaviour, but it remains uncertain if this relationship is causal in humans. We examined the link between AAS use and violent crime while controlling for polysubstance abuse and additional suggested risk factors for violence. Design Cross-sectional study of a population-based sample. Setting In 2005, all Swedish-born male twins aged 20-47 years were invited to participate in the Swedish Twin Adults: Genes and Environment ( STAGE) survey of the Swedish Twin Register (response rate = 60%). Participants A total of 10 365 male survey participants with information on AAS use. Measurement Data on self-reported use of AAS, alcohol and other substances, attention deficit hyperactivity disorder ( ADHD) and personality disorder symptoms were linked to nation-wide, longitudinal register information on criminal convictions, IQ, psychological functioning and childhood socio-economic status ( SES) covariates. Findings Any life-time use of AAS was associated strongly with conviction for a violent crime [2.7 versus 0.6% in convicted and non-convicted men, respectively; odds ratio ( OR) = 5.0, 95% confidence interval ( CI) = 2.7-9.3]. However, this link was substantially reduced and no longer significant when controlling for other substance abuse ( OR = 1.6, 95% CI = 0.8-3.3). Controlling for IQ, psychological functioning, ADHD, personality disorder symptoms and childhood SES did not reduce the risk further. Conclusion In the general population, co-occurring polysubstance abuse, but not IQ, other neuropsychological risks or socio-economic status, explains most of the relatively strong association between any anabolic androgenic steroid use and conviction for a violent crime. [ABSTRACT FROM AUTHOR]

Background Although neurodevelopmental disorders are demarcated as discrete entities in the Diagnostic Statistical Manual of mental disorders, empirical evidence indicates that there is a high degree of overlap among them. The first aim of this investigation was to explore if a single general factor could account for the large degree of observed overlap among neurodevelopmental problems, and explore whether this potential factor was primarily genetic or environmental in origin. The second aim was to explore whether there was systematic covariation, either genetic or environmental, over and above that contributed by the potential general factor, unique to each syndrome. Method Parents of all Swedish 9- and 12-year-old twin pairs born between 1992 and 2002 were targeted for interview regarding problems typical of autism spectrum disorders, ADHD and other neurodevelopmental conditions (response rate: 80 percent). Structural equation modeling was conducted on 6,595 pairs to examine the genetic and environmental structure of 53 neurodevelopmental problems. Results One general genetic factor accounted for a large proportion of the phenotypic covariation among the 53 symptoms. Three specific genetic subfactors identified 'impulsivity,' 'learning problems,' and 'tics and autism,' respectively. Three unique environment factors identified 'autism,' 'hyperactivity and impulsivity,' and 'inattention and learning problems,' respectively. Conclusion One general genetic factor was responsible for the wide-spread phenotypic overlap among all neurodevelopmental symptoms, highlighting the importance of addressing broad patient needs rather than specific diagnoses. The unique genetic factors may help guide diagnostic nomenclature, whereas the unique environmental factors may highlight that neurodevelopmental symptoms are responsive to change at the individual level and may provide clues into different mechanisms and treatments. Future research would benefit from assessing the general factor separately from specific factors to better understand observed overlap among neurodevelopmental problems. [ABSTRACT FROM AUTHOR]

Objective: We examined the association among current self-reported sleep problems, lifetime binge eating (BE), and current obesity in women from the Swedish Twin study of Adults: Genes and Environment. Method: Logistic regression analyses were used to evaluate these associations in 3,790 women aged 20-47 years. Results: BE was reported by 244 (6.4%) women and was positively associated with not getting enough sleep ( p < .015), sleeping poorly ( p < .001), problems falling asleep ( p < .001), feeling sleepy during work or free time ( p < .001), and disturbed sleep ( p < .001). These same sleep variables, as well as napping and being a night person, were also significantly associated with obesity. The associations between BE and sleep remained after accounting for obesity. Discussion: This investigation offers empirical support for an independent association between sleep problems and BE, which is likely due to complex psychological, biological, neuroendocrine, and metabolic factors. © 2012 by Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Objective: We assessed the impact of reducing the binge eating frequency and duration thresholds on the diagnostic criteria for bulimia nervosa (BN) and binge eating disorder (BED). Method: We estimated the lifetime population prevalence of BN and BED in 13,295 female twins from the Swedish Twin study of Adults: Genes and Environment employing a range of frequency and duration thresholds. External validation (risk to cotwin) was used to investigate empirical evidence for an optimal binge eating frequency threshold. Results: The lifetime prevalence estimates of BN and BED increased linearly as the frequency criterion decreased. As the required duration increased, the prevalence of BED decreased slightly. Discontinuity in cotwin risk was observed in BN between at least four times per month and at least five times per month. This model could not be fit for BED. Discussion: The proposed changes to the DSM-5 binge eating frequency and duration criteria would allow for better detection of binge eating pathology without resulting in a markedly higher lifetime prevalence of BN or BED. © 2011 by Wiley Periodicals, Inc. (Int J Eat Disord 2012) [ABSTRACT FROM AUTHOR]

Background: Although the clinical utility of categorically defined attention-deficit hyperactivity disorder (ADHD) is well established, there is also strong evidence supporting the notion of ADHD as an extreme of a continuous trait. Nevertheless, the question of whether the etiology is the same for different levels of DSM-IV ADHD symptoms remains to be investigated. The aim of this study was to assess genetic links between the extreme and the subthreshold range of ADHD symptoms. Method: Parents of all Swedish 9- and 12-year-old twins born between 1992 and 2000 were interviewed for DSM-IV ADHD symptoms and associated conditions. Two validated cutoff values were used for screening and assigning research diagnoses. Response rate was 80%. Twin methods were applied to investigate the extent to which ADHD is etiologically distinct from subthreshold variations in ADHD symptoms. Results: Extremes analyses indicated a strong genetic link between the extreme and the subthreshold variation, with almost identical group heritability estimates around .60 for the diagnostic (prevalence 1.78%) and screening (prevalence 9.75%) criteria of ADHD. Conclusion: A strong genetic link between the extreme and the subthreshold variation of DSM-IV based assessments of ADHD symptoms was found. The data suggest that ADHD is best viewed as the quantitative extreme of genetic and environmental factors operating dimensionally throughout the distribution of ADHD symptoms, indicating that the same etiologic factors are involved in the full range of symptoms of inattention, hyperactivity and impulsivity. [ABSTRACT FROM AUTHOR]

Objectives To examine job control, job demands, social support at work, and job strain (ratio of demands to control) in relation to risk of any dementia, Alzheimer's disease ( AD), and vascular dementia ( VaD). Design Cohort study. Setting The population-based Study of Dementia in Swedish Twins. Participants Two hundred fifty-seven people with dementia (167 AD, 46 VaD) and 9,849 without. Measurements Dementia diagnoses were based on telephone screening for cognitive impairment followed by in-person clinical examination. An established job exposure matrix was matched to main occupation categories to measure work characteristics. Results In generalized estimating equations (adjusted for the inclusion of complete twin pairs), lower job control was associated with greater risk of any dementia (odds ratio ( OR) = 1.17, 95% confidence interval ( CI) = 1.04-1.31) and VaD specifically ( OR = 1.39, 95% CI = 1.07-1.81). Lower social support at work was associated with greater risk of dementia ( OR = 1.15, 95% CI = 1.03-1.28), AD ( OR = 1.14, 95% CI = 1.00-1.31), and VaD ( OR = 1.28, 95% CI = 1.02-1.60). Greater job strain was associated with greater risk of VaD only ( OR = 1.28, 95% CI = 1.02-1.60), especially in combination with low social support ( OR = 1.35, 95% CI = 1.11-1.64). Age, sex, and education were controlled for. Work complexity, manual work, and vascular disease did not explain the results. No differences in work-related stress scores were observed in the 54 twin pairs discordant for dementia, although only two pairs included a twin with VaD. Conclusion Work-related stress, including low job control and low social support at work, may increase the risk of dementia, particularly VaD. Modification to work environment, including attention to social context and provision of meaningful roles for employees, may contribute to efforts to promote cognitive health. [ABSTRACT FROM AUTHOR]