Background Difficult temperament in infancy is a risk factor for forms of later internalizing and externalizing psychopathology, including depression and anxiety. A better understanding of the roots of difficult temperament ...

BACKGROUND: This study investigated the potential environmental effects of peer victimization and the quality of relationships with parents and friends on diurnal cortisol secretion in mid-adolescence. METHOD: ...

Background: Developmental dyslexia (DD) and attention deficit/hyperactivity disorder (ADHD) are among the most common neurodevelopmental disorders, whose etiology involves multiple risk factors. DD and ADHD co-occur in the ...

This study investigated the stable and transient genetic and environmental contributions to individual differences in number knowledge in the transition from preschool (age 5) to Grade 1 (age 7) and to the predictive ...

Background: Using a longitudinal twin design and a latent growth curve/autoregressive approach, this study examined the genetic-environmental architecture of substance use across adolescence. Methods: Self-reports of ...

Introduction By and large, studies have reported moderate contributions of genetic factors to cortisol secreted in the early morning and even smaller estimates later in the day. In contrast, the cortisol awakening ...

This investigation examines the spread of problem behaviors (substance use and delinquency) between twin siblings. A sample of 628 twins (151 male twin pairs and 163 female twin pairs) drawn from the Quebec Newborn Twin ...

There is little research to date on the academic implications of teaching twins in the same or different classroom. Consequently, it is not clear whether twin classroom separation is associated with positive or negative ...

This study examined whether social contagion of anxiety symptoms is present between siblings during early adolescence and whether this process is moderated by sex, relationship quality, and zygosity. Based on 634 monozygotic ...

Using a sample of 767 children (403 girls, 364 boys), this study aimed to 1) identify groups with distinct trajectories of peer victimization over a six-year period from primary school through the transition to secondary ...