| 1. |
- Tuvblad, Catherine, 1968-, et al.
(författare)
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Human aggression across the lifespan : genetic propensities and environmental moderators
- 2011
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Ingår i: Aggression. - San Diego : Academic Press. - 9780123808585 - 9780123808592 ; , s. 171-214
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Bokkapitel (refereegranskat)abstract
- This chapter reviews the recent evidence of genetic and environmental influences on human aggression. Findings from a large selection of the twin and adoption studies that have investigated the genetic and environmental architecture of aggressive behavior are summarized. These studies together show that about half (50%) of the variance in aggressive behavior is explained by genetic influences in both males and females, with the remaining 50% of the variance being explained by environmental factors not shared by family members. Form of aggression (reactive, proactive, direct/physical, indirect/relational), method of assessment (laboratory observation, self-report, ratings by parents and teachers), and age of the subjects—all seem to be significant moderators of the magnitude of genetic and environmental influences on aggressive behavior. Neither study design (twin vs. sibling adoption design) nor sex (male vs. female) seems to impact the magnitude of the genetic and environmental influences on aggression. There is also some evidence of gene-environment interaction (G × E) from both twin/adoption studies and molecular genetic studies. Various measures of family adversity and social disadvantage have been found to moderate genetic influences on aggressive behavior. Findings from these G × E studies suggest that not all individuals will be affected to the same degree by experiences and exposures, and that genetic predispositions may have different effects depending on the environment.
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| 2. |
- Björkenstam, C., et al.
(författare)
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Suicidal behavior among delinquent former child welfare clients
- 2013
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Ingår i: European Child and Adolescent Psychiatry. - : Springer Science and Business Media LLC. - 1018-8827 .- 1435-165X. ; 22:6, s. 349-355
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Tidskriftsartikel (refereegranskat)abstract
- Child welfare clients represent a high-risk group for delinquency and adult criminality, but also for future suicidal behavior. We examine associations between delinquency and suicidal behavior in a national child welfare population. This register-based cohort study is based on data for all Swedish former child welfare clients born between 1972 and 1981 that experienced interventions before their adolescent years. We followed 27,228 individuals from age 20 years until 31 December 2006. Juvenile delinquency was defined as being convicted of at least one crime between age 15 and 19. The risk of suicidal behavior was calculated as incidence rate ratios (IRRs). Fifteen percent of the women and 40 % of the men had at least one conviction between the age 15 and 19. The adjusted risk of suicidal behavior among women with five or more convictions was 3.5 (95 % CI 2.0-6.2); corresponding IRR for men was 3.9 (95 % CI 3.1-4.9). Child welfare experience-specifically of out-of-home care-in combination with delinquency is a potent risk factor for suicidal behavior among young adults. However, we cannot exclude that some of this association is an epiphenomenon of uncontrolled confounders, such as impulsivity or severity of psychiatric disease. Despite this caveat, results should be disseminated to practitioners in the health and correction services.
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| 3. |
- Dhamija, Devika, et al.
(författare)
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Heritability of startle reactivity and affect modified startle
- 2017
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Ingår i: International Journal of Psychophysiology. - : Elsevier. - 0167-8760 .- 1872-7697. ; 115, s. 57-64
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Tidskriftsartikel (refereegranskat)abstract
- Startle reflex and affect-modified startle reflex are used as indicators of defensive reactivity and emotional processing, respectively. The present study investigated the heritability of both the startle blink reflex and affect modification of this reflex in a community sample of 772 twins ages 14–15 years old. Subjects were shown affective picture slides falling in three valence categories: negative, positive and neutral; crossed with two arousal categories: high arousal and low arousal. Some of these slides were accompanied with a loud startling noise. Results suggestedsex differences in meanlevels of startle reflex as well as in proportions of variance explained by genetic and environmental factors. Females had higher mean startle blink amplitudes for each valence-arousal slide category, indicating greater baseline defensive reactivity compared to males. Startle blink reflex in males was significantly heritable (49%), whereas in females, variance was explained primarily by shared environmental factors (53%) and non-shared environmental factors (41%). Heritability of affect modified startle (AMS) was found to be negligible in both males and females. These results suggest sex differences in the etiology of startle reactivity, while questioning the utility of the startle paradigm for understanding the genetic basis of emotional processing.
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| 4. |
- Baker, Laura, et al.
(författare)
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The Southern California twin register at the University of Southern California : III
- 2013
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Ingår i: Twin Research and Human Genetics. - : Cambridge University Press (CUP). - 1832-4274 .- 1839-2628. ; 16:1, s. 336-343
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Tidskriftsartikel (refereegranskat)abstract
- The Southern California Twin Register at the University of Southern California (USC) was initiated in 1984 and continues to provide an important resource for studies investigating genetic and environmental influences on human behavior. This article provides an update on the current register and its potential for future twin studies using recruitment through school district databases and voter records. An overview is also provided for an ongoing longitudinal twin study investigating the development of externalizing psychopathology from childhood to young adulthood, the USC Study of Risk Factors for Antisocial Behavior. Characteristics of the twins and their families are presented, including recruitment and participation rates, as well as attrition analyses and a summary of key findings to date.
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| 5. |
- Younan, Diana, et al.
(författare)
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Environmental Determinants of Aggression in Adolescents : Role of Urban Neighborhood Greenspace
- 2016
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Ingår i: Journal of the American Academy of Child and Adolescent Psychiatry. - Amsterdam, Netherlands : Elsevier. - 0890-8567 .- 1527-5418. ; 55:7, s. 591-601
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Tidskriftsartikel (refereegranskat)abstract
- Objective: Neighborhood greenspace improves mental health of urban-dwelling populations, but its putative neurobehavioral benefits in adolescents remain unclear. We conducted a prospective study on urban-dwelling adolescents to examine the association between greenspace in residential neighborhood and aggressive behaviors.Method: Participants (n = 1,287) of the Risk Factors for Antisocial Behavior Study, a multi-ethnic cohort of twins and triplets born in 1990 to 1995 and living in Southern California, were examined in 2000 to 2012 (aged 9-18 years) with repeated assessments of their aggressive behaviors by the parent-reported Child Behavior Checklist. Normalized Difference Vegetation Index (NDVI) derived from satellite imagery was used as a proxy for residential neighborhood greenspace aggregated over various spatiotemporal scales before each assessment. Multilevel mixed-effects models were used to estimate the effects of greenspace on aggressive behaviors, adjusting for within-family/within-individual correlations and other potential confounders.Results: Both short-term (1- to 6-month) and long-term (1- to 3-year) exposures to greenspace within 1,000 meters surrounding residences were associated with reduced aggressive behaviors. The benefit of increasing vegetation over the range (∼0.12 in NDVI) commonly seen in urban environments was equivalent to approximately 2 to 2.5 years of behavioral maturation. Sociodemographic factors (e.g., age, gender, race/ethnicity, and socioeconomic status) and neighborhood quality did not confound or modify these associations, and the benefits remained after accounting for temperature.Conclusion: Our novel findings support the benefits of neighborhood greenspace in reducing aggressive behaviors of urban-dwelling adolescents. Community-based interventions are needed to determine the efficacy of greenspace as a preemptive strategy to reduce aggressive behaviors in urban environments.
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| 6. |
- Young-Wolff, Kelly C., et al.
(författare)
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Drinking experience uncovers genetic influences on alcohol expectancies across adolescence
- 2015
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Ingår i: Addiction. - : Wiley. - 0965-2140 .- 1360-0443. ; 110:4, s. 610-618
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Tidskriftsartikel (refereegranskat)abstract
- Aims: To test whether drinking onset moderates genetic and environmental contributions to individual differences in theetiology of alcohol expectancies across adolescence.Design: Longitudinal twin design.Setting: Community samplefrom Los Angeles, CA, USA.Participants: A total of 1292 male and female twins, aged 11–18 years, were assessed at 1(n =440), 2 (n =587) or 3 (n = 265) occasions as part of the risk factors for the Antisocial Behavior Twin Study.Measurements: Social behavioral (SB) alcohol expectancies were measured using an abbreviated version of the Social Behavioral subscale from the Alcohol Expectancy Questionnaire for adolescents (AEQ-A). Drinking onset was defined as>1 full drink of alcohol.Findings: Alcohol expectancies increased over age and the increase became more rapid following onset of drinking. The importance of genetic and environmental influences on SB scores varied with age and drinking status, such that variation prior to drinking onset was attributed solely to environmental influences, whereas all post-onset variation was attributed to genetic influences. Results did not differ significantly by sex.Conclusion: Only environmental factors explain beliefs about the social and behavioral consequences of alcohol use prior to drinking onset, whereas genetic factors explain an increasing proportion of the variance in these beliefs after drinking onset.
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| 7. |
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| 8. |
- Bezdjian, Serena, et al.
(författare)
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Motor Impulsivity During Childhood and Adolescence : A Longitudinal Biometric Analysis of the Go/No-Go Task in 9- to 18-Year-Old Twins
- 2014
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Ingår i: Developmental Psychology. - : American Psychological Association (APA). - 0012-1649 .- 1939-0599. ; 50:11, s. 2549-2557
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Tidskriftsartikel (refereegranskat)abstract
- In the present study, we investigated genetic and environmental effects on motor impulsivity fromchildhood to late adolescence using a longitudinal sample of twins from ages 9 to 18 years. Motorimpulsivity was assessed using errors of commission (no-go errors) in a visual go/no-go task at 4 timepoints: ages 9–10, 11–13, 14–15, and 16–18 years. Significant genetic and nonshared environmentaleffects on motor impulsivity were found at each of the 4 waves of assessment with genetic factorsexplaining 22%–41% of the variance within each of the 4 waves. Phenotypically, children’s averageperformance improved across age (i.e., fewer no-go errors during later assessments). Multivariatebiometric analyses revealed that common genetic factors influenced 12%–40% of the variance in motorimpulsivity across development, whereas nonshared environmental factors common to all time pointscontributed to 2%–52% of the variance. Nonshared environmental influences specific to each time pointalso significantly influenced motor impulsivity. Overall, results demonstrated that although geneticfactors were critical to motor impulsivity across development, both common and specific nonsharedenvironmental factors played a strong role in the development of motor impulsivity across age.
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| 9. |
- Gao, Yu, et al.
(författare)
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Skin conductance fear conditioning impairments and aggression : a longitudinal study
- 2014
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Ingår i: Psychophysiology. - : Wiley. - 0048-5772 .- 1469-8986. ; 52:2, s. 288-295
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Tidskriftsartikel (refereegranskat)abstract
- Autonomic fear conditioning deficits have been linked to child aggression and adult criminal behavior. However, it is unknown if fear conditioning deficits are specific to certain subtypes of aggression, and longitudinal research is rare. In the current study, reactive and proactive aggression were assessed in a sample of males and females when aged 10, 12, 15, and 18 years old. Skin conductance fear conditioning data were collected when they were 18 years old. Individuals who were persistently high on proactive aggression measures had significantly poorer conditioned responses at 18 years old when compared to others. This association was not found for reactive aggression. Consistent with prior literature, findings suggest that persistent antisocial individuals have unique neurobiological characteristics and that poor autonomic fear conditioning is associated with the presence of increased instrumental aggressive behavior.
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| 10. |
- Jackson, Nicholas J., et al.
(författare)
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Impact of adolescent marijuana use on intelligence : Results from two longitudinal twin studies
- 2016
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 113:5, s. E500-E508
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Tidskriftsartikel (refereegranskat)abstract
- Marijuana is one of the most commonly used drugs in the United States, and use during adolescence-when the brain is still developing-has been proposed as a cause of poorer neurocognitive outcome. Nonetheless, research on this topic is scarce and often shows conflicting results, with some studies showing detrimental effects of marijuana use on cognitive functioning and others showing no significant long-term effects. The purpose of the present study was to examine the associations of marijuana use with changes in intellectual performance in two longitudinal studies of adolescent twins (n = 789 and n = 2,277). We used a quasiexperimental approach to adjust for participants' family background characteristics and genetic propensities, helping us to assess the causal nature of any potential associations. Standardized measures of intelligence were administered at ages 9-12 y, before marijuana involvement, and again at ages 17-20 y. Marijuana use was self-reported at the time of each cognitive assessment as well as during the intervening period. Marijuana users had lower test scores relative to nonusers and showed a significant decline in crystallized intelligence between preadolescence and late adolescence. However, there was no evidence of a dose-response relationship between frequency of use and intelligence quotient (IQ) change. Furthermore, marijuana-using twins failed to show significantly greater IQ decline relative to their abstinent siblings. Evidence from these two samples suggests that observed declines in measured IQ may not be a direct result of marijuana exposure but rather attributable to familial factors that underlie both marijuana initiation and low intellectual attainment.
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