Early signs of anger and aggression can be identified in infancy. Our aim was to use person-centered methods to identify which infants were most at risk for clinically significant behavioral problems by age 3 and diagnoses of ODD/CD by 7 years, while considering the role of family risk factors and positive parenting. A representative British community sample of 304 infants was assessed by multiple informants at mean ages of 6, 21, and 36 months of age. Latent Transition Analysis (LTA) identified three ordered subgroups at each age, with one subgroup (18%) displaying high levels of physical force as well as anger. These angry aggressive infants were at elevated risk for behavioral problems in early childhood and diagnoses of conduct disorder (CD) and/or oppositional defiant disorder (ODD) at 7 years of age. After other risk factors were taken into account, parents' beliefs in warm parenting and their observed positive affect while interacting with their infants were protective factors. These findings indicate the significance of very early manifestations of angry aggressiveness and have relevance for developmental theories of aggression and prevention strategies.

We tested the hypothesis that high activity levels in infancy would predict self-regulatory problems and later symptoms of attention deficit and hyperactivity disorder (ADHD) in a longitudinal study of British families (N = 321). Infants’ activity levels were assessed at 6 months, using 3 informants’ reports from the Infant Behavior Questionnaire (IBQ) and ActiGraphs during baseline, attention, and restraint tasks. At a mean of 33 months, the children were assessed on self-regulatory tasks; at a mean of 36 months, 3 informants reported symptoms of ADHD. At a mean of 7.0 years, the children were assessed on executive function tasks; 3 informants reported on the child's symptoms of ADHD; and diagnoses of disorder were obtained using the Preschool Age Psychiatric Assessment. Informants’ reports of high activity levels at 6 months predicted ADHD symptoms in early childhood and diagnoses of ADHD with clinical impairment at age 7. The IBQ activity scale was also associated with the children's later performance on self-regulation tasks in early and middle childhood. Activity level in infancy reflects normal variation and is not a sign of psychopathology; however, these findings suggest that further study of the correlates of high activity level in infancy may help identify those children most at risk for disorder.

The rate of multiple births is substantially elevated in women who have had assisted reproduction treatment (ART; ˜26%) compared to the general population (˜1%), and these offspring are usually included in twin studies. Several studies have attempted to identify possible consequences of undergoing ART on the subsequent offspring. However, most studies have only included singleton births. We first examined whether twins born by ART differed from other twins on measures of childhood psychopathology, putative risk factors and correlates, and secondly tested for differences in the degree of twin similarity for available outcome measures. From a population-based twin sample, 101 families with dizygotic (DZ) twins conceived via ART were identified and compared with 1073 naturally conceived (NC) control DZ twin pairs. Analyses performed were (1) univariate and multivariate comparisons of between-group mean differences; and (2) comparison of twin 1–twin 2 correlations between the groups. The groups differed significantly on demographic factors (parental age, family size and social class) and pregnancy variables (smoking during pregnancy and birthweight) but did not differ on family conflict scores or in the frequency of obstetric complications. Family cohesion was higher in the ART group but this was accounted for by demographic factors. For child psychopathology there was a difference between the groups only for teacher-rated ADHD (Attention Deficit Hyperactivity Disorder). Differences were also found between groups for twin correlations. The differences found between ART and NC twins on group means and twin correlations suggest that researchers should be aware that including ART twins may influence results from twin studies.

Nearly a century of observational studies and more recent longitudinal surveys reveal that, in infancy, girls and boys use force at similar rates. Over the next few years boys become significantly more aggressive. Alternative hypotheses accounting for the widening gender gap are evaluated. These include hypotheses about normative patterns of male escalation and female desistance; boys' preference for active play that promotes aggression; girls' tendency to hide aggression; girls' use of alternative forms of aggression; boys' increased risk for the cognitive and emotional problems that are linked to aggression; boys' sensitivity to situational triggers of aggression; and boys' vulnerability to adverse rearing environments. The evidence bearing on each hypothesis is mixed. In general, the overall difference between the sexes appears to be produced by a minority of boys who deploy aggression at high rates. Three general principles govern the emergence of sex differences in aggression: female precocity, male vulnerability, and the salience of sex as a social category that shapes children's lives.

The aim of the study was to examine long-term sequelae in the children of mothers who were depressed at 3 months postpartum. In a community sample from two general practices in South London, 149 women were given psychiatric interviews at 3 months postpartum and 132 of their children (89%) were tested at 11 years of age. The children of women who were depressed at 3 months postpartum had significantly lower IQ scores. They also had attentional problems and difficulties in mathematical reasoning, and were more likely than other children to have special educational needs. Boys were more severely affected than girls, with the sex difference most pronounced on Performance IQ. The links between postnatal depression and the children's intellectual problems were not mediated by parental IQ and were not accounted for by measures of social disadvantage nor by the mother's later mental health problems. Breastfeeding did not remove the effect of the mother's illness on Full Scale IQ, but exerted its own influence on Verbal IQ and appeared to mediate the link with mathematical ability. The findings show that adverse experiences in infancy predict cognitive ability and academic performance a decade later.

Correlates of parents' ratings of behavioural problems were explored in a sample of 93 British families, in which mothers and fathers rated their children at the time of the fourth birthday on the Achenbach Child Behavior Checklist. As in other samples, there was moderate convergence in mothers' and fathers' total problem scores, but also signs that they were reporting different sorts of problems linked to different influences. The father's rating was primarily associated with the child's cognitive ability. The mother's rating was primarily affected by her own mental state and view of her marriage. The father's but not the mother's rating provided unique information that predicted teachers' reports of the children's problems 7 years later. In general, parents' ratings of preschool children's problems reflect particular informants' perspectives on family life.

We tested a model of prosocial development, which predicted that prosocial action might decline, not increase, throughout childhood, becoming increasingly selective, individual, gender-related, and linked to emotional dysregulation. Sixty-six focal children at 18, 24, or 30 months of age were observed at home with familiar peers and then again 6 months later. Episodes of peer interaction were analysed for instances of sharing. The predicted decline in sharing with age was qualified by cohort differences and many associations with gender. Most children shared less as they grew older, but the oldest girls slightly increased their rate of sharing over time. As peer relationships developed, girls were more likely to share with other girls; boys were more likely to show reciprocity in sharing. Individual differences in sharing were moderately stable over time and linked to another form of prosocial action, sensitivity to the peer's distress. As predicted, children who shared at higher rates were rated more negatively by their mothers. The positive relationship between prosocial action and mothers' ratings of negative personality traits was especially strong for boys.

The diffusivity of implanted As in crystalline Si has been measured using Rutherford backscattering and channeling for specimens annealed at temperatures between 850 and 1000°C under pressures up to 30 kilobars. The diffusivity, at a given temperature, was found to increase with pressure with a maximum increase of a factor of ten. This diffusivity enhancement can be described by an average activation volume of -5.7±.8 cm3/mole. The activation enthalpy ranges from an ambient value of 4.5 eV to 3.6 eV at 30 kilobars