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The aim of this study was to investigate the degree to which genetic and environmental influences affect variation in adolescent exercise behavior. Data on regular leisure time exercise activities were analyzed in 8,355 adolescent twins, from three-age cohorts (13-14, 15-16, and 17-19 years). Exercise behavior was assessed with survey items about type of(More)
OBJECTIVE To explain the differential course of anxiety and depression in individuals from childhood to adulthood by examining age-related changes in the genetic and environmental etiology of anxious and depressive symptoms. METHOD A sample of 1470, 1839, and 2023 Dutch twins aged 12, 14, and 16 years reported on symptoms of anxious depression (AD) and(More)
Adolescents' evaluations of family functioning may have a significant impact on their subjective well-being and adjustment. The aim of the study was to investigate the degree to which genetic and environmental influences affect variation in evaluations of general family functioning, family conflict, and quality of life and the overlap between them. We(More)
AIMS To determine the effect of age, sex and cohort on the prevalence and genetic architecture of adolescent alcohol use (AAU). DESIGN Survey study in participants registered with the Netherlands Twin Register. SETTING Twins from the general population. PARTICIPANTS Two cohorts (data collected in 1993 and 2005-08) of twins aged 13-15, 16-17 and 18-21(More)
OBJECTIVE To investigate the degree to which genetic and environmental influences affect individual differences in sedentary behavior throughout adolescence. DESIGN Cross-sectional twin-family design. SETTING Data on self-reported sedentary behavior from Dutch twins and their nontwin siblings. PARTICIPANTS The total sample consisted of 5074 adolescent(More)
This study tests in a genetically informative design whether exercise behavior causally influences subjective wellbeing (SWB) and internalizing problems (INT). If exercise causally influences SWB and INT, genetic and environmental factors influencing exercise behavior will also influence SWB and INT. Furthermore, within genetically identical (MZ) twin(More)
Aims and method This study aimed to identify predictors of symptom severity for post-traumatic stress disorder (PTSD) and depression in asylum seekers and refugees referred to a specialised mental health centre. Trauma exposure (number and domain of event), refugee status and severity of PTSD and depression were assessed in 688 refugees. Results Symptom(More)
This study assessed to what extent genetic and environmental factors contributed to individual differences in adolescent sleep duration, and whether genetic and environmental contributions to sleep duration changed throughout adolescence. A twin-family design was used to gain insight into the genetic and environmental contributions to variation in sleep(More)
PURPOSE The purpose of this study was to examine the relative influence of genetic and environmental factors on variation in truancy during high school. We examined the significance of genetic and shared and nonshared environmental influences. In addition, we tested for the presence of environmental factors specifically shared by twins, but not by their(More)
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