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Biomedical subjects

Karen Thorpe

Publications and source records attributed to Karen Thorpe.

9 recordsLinked to original sources
PubMed2006

Twin children's language development.

Scientific studies have consistently reported that, in group analyses, twin children have higher rates of language delay when compared with single-born children. This paper reviews the evidence on twin language by addressing five key questions:The paper concludes that language delay in twins when compared with singletons is mild yet prevalent, particularly in males and is most likely a result of experience of poorer quality of language environment compared to single born children. Occurrence of "private" or "twin" language is rare and not an explanation for the findings of generalised language delay among twins. Given that language delay in twins relates to social-language experience, appropriate intervention and remediation of language delay should focus on providing a more stimulating language environment both within and outside the home. It is recommended that future research examine, longitudinally, the developmental course and consequences of language delay in twin children and trial interventions designed to improve their language experiences.

Child↗
PubMed2006

Twins and their friendships: differences between monozygotic, dizygotic same-sex and dizygotic mixed-sex pairs.

This study examined the influence of twin status (monozygotic [MZ], dizygotic same-sex [DZss] and dizygotic opposite-sex [DZos]) on friendship patterns. It examined the friendships of 60 children from 30 twin pairs, mean age 8 years, 4 months. The study sought to establish how number of friendships and degree to which these are shared vary according to twin status. Additionally, it sought to assess the children's meaning of shared friendship and to examine whether there were group differences according to twin status. Results indicated that, while number of friends did not vary, the degree to which friendships were shared was significantly associated with twin status. MZ children shared approximately 50% of their friends, DZss 25% and DZos 5%. Group patterns emerged from interviews with the children concerning shared friendships. MZ twins were characteristically positive or accepting about shared friends; DZos pairs shared fewer friends and were, therefore, less challenged by the twin situation in negotiating friendships; and DZss pairs were more diverse in their reaction with some expressing ambivalent or negative views about the twin situation and sharing of friendship. The results are presented in the light of their implications for twin children's developmental and scholastic progress.

Analysis of Variance↗
PubMed2006

Being opposite: is there advantage for social competence and friendships in being an opposite-sex twin?

A recent large-scale study of Finnish adolescent twins (Pulkkinen et al., 2003) reported that individuals from opposite-sex twin pairs were more socially adaptive than individuals from same-sex pairs or singletons. This finding raised questions about the social learning effects of being an opposite-sex twin. The current article predicted on the basis of this finding, and evidence from singleton populations, that having an opposite-sex twin would yield social advantage. It sought to examine the social competencies of opposite-sex twins and compare them with same-sex twins and singletons. The study focused on the preschool years (age 3 to 6), a period in which the majority of children encounter their first large group, nonfamilial social experiences. The study obtained reports from parents and teachers of children aged 3 to 6 years: 72 children (36 pairs) who were dizygotic opposite-sex twins (DZOS), 50 children (25 pairs) who were dizygotic same-sex twins (DZSS), and 85 singletons of the same age and sex as the twins, who had at least one sibling. Reports were made using standardized measures of social competencies, behavior problems, language development and friendships. The main effects found were of differences in social competency between twins and singletons. Twins had lower social competency scores. No differences between same-sex and opposite-sex twins were found. The findings did not support the hypothesis of social advantage for opposite-sex twins in early childhood.

Analysis of Variance↗
PubMed2006

Compatibility and conflict: negotiation of relationships by dizygotic same-sex twin girls.

This article conceptualizes the child as having active agency in the constructions of their social worlds, and reports on a study that understands the twin experiences from the perspectives of the twins. It examines how twins account for their relationships with their co-twins. The study drew on accounts of 60 twin children--10 monozygotic (MZ), 10 dizygotic (DZ) same-sex, 10 DZ opposite-sex pairs--aged 5 to 10 years and their parent (n = 30). The children engaged in a sticker activity in which they represented their friendships, including their friendship with their co-twin. Using the task as a resource, the children were asked about their friends, the attributes of friendship and examples of everyday friendships encounters. These were audio-recorded and transcribed. Further, parents completed a questionnaire that provided demographic information and asked parents about the children's social experiences including twin children's time spent together, shared interests and their co-twin relationship. Using data from the pictorial representation from the sticker task and parent questionnaires, differences in relationship between MZ, DZ same-sex and DZ opposite-sex twins were examined and used to select a smaller sample for detailed study. DZ same-sex twins tended to view their co-twin less favorably and there was a nonsignificant trend in which conflict was elevated, compared to the other two groups. Based on these findings, the transcripts selected for analysis focuses on the DZ same-sex girls. The girls reported that they had differences of thought, activity and self-presentation. Conflict, competition and challenge as types of social interaction were described, suggesting that the everyday relationship of the twin with her co-twin is always being negotiated and realigned. Evident here is the complexity of social interactions in which the twins engaged everyday with each other.

Analysis of Variance↗
PubMed2003

Twins as a natural experiment to study the causes of mild language delay: I: Design; twin-singleton differences in language, and obstetric risks.

BACKGROUND: Twins tend to lag behind singletons in their language development, but the causes were unknown. The possibilities suggested include obstetric complications, twin-specific features, and postnatal differences in family interaction. The present study was designed to pit these alternatives against one another as possible causal influences. METHOD: The Avon Longitudinal Study of Parents and Children (ALSPAC) was used to identify the 116 twin pairs (of whom 96 participated) and 114 pairs of singletons (of whom 98 participated) whose ages were no more than 30 months apart. The McArthur Communicative Development Inventory was completed at 20 months, and the Pre-School Language Scales (PLS-3), and the McCarthy Scales of Children's Abilities at 36 months. Obstetric and perinatal complications were assessed on the basis of detailed systematic parental reports, together with a systematic coded abstraction of all medical records dealing with pregnancy and the neonatal period. Family background details were assessed from parental reports, and the primary carer's verbal functioning was assessed by the Mill Hill Vocabulary Scale. Congenital anomalies were assessed using the method of Waldrop and Halverson. RESULTS: The language of twins was 1.7 months below that of singletons at 20 months and 3.1 months at 3 years. The verbal cognitive score of twins was about half a standard deviation lower than that of singletons. The twin-singleton differences in language level were found tobe unassociated with obstetric/perinatal features as assessed from both parental reports and medical records, to birthweight or gestation, to birthweight discrepancy within the twin pair, or to congenital anomalies. CONCLUSION: It is concluded that obstetric/perinatal features do not account for the slower language development in twins as compared with singletons, within a sample born after at least 33 weeks gestation.

Case-Control Studies↗
PubMed2003

Twins as a natural experiment to study the causes of mild language delay: II: Family interaction risk factors.

BACKGROUND: Twins tend to lag behind singletons in their language development, but the causes were unknown. METHOD: Ninety-six twin pairs from the Avon Longitudinal Study of Parents and Children (ALSPAC), for whom birth was after at least 33 weeks of gestation, were compared with 98 pairs of singletons, no more than 30 months apart in age. Parental qualities and family interaction were assessed through standardised questionnaires and interviews and both structured and unstructured observations in the home at 20 months and 36 months. The possible causal role of postnatal family influences was assessed through five criteria: i) the feature had to differ between twins and singletons; ii) individual differences in that feature had to relate to individual differences in language level within the sample of singletons and of twins; iii) the feature as measured at 20 months had to predict language as assessed at 36 months; iv) that had to apply after controlling for language level at 20 months; and v) introduction of the predictive feature into an overall model had to obliterate the twin-singleton difference in language level. RESULTS: Patterns of parent-child interaction and communication met these five criteria. The maternal factors all concerned aspects of interaction that were broadly concerned with communication: encouraging the child to speak, providing elaborating comments, engaging in reading to the child and talking about the story and its illustrations. The HOME inventory findings provided similar findings with respect to responsiveness, involvement and level of experiences involved. Family features that might have been influential, but which were not, included parental depression, breast-feeding, family size, and style of sibling interaction. CONCLUSION: Patterns of parent-child interaction and communication within the normal range have environmentally mediated effects on language and account for twin-singleton differences in language developmently. The results indicate the value of a natural experiment in testing competing causal hypotheses, and show the role of environmental factors as influences on language variations within the normal range, for both twins and singletons.

Breast Feeding↗
PubMed2003

Twins and friendship.

A growing body of literature asserts the importance of friendships for a child's emotional wellbeing, behavioural adjustment and developmental attainment. However, few studies have examined friendships in the twin situation. This paper examines the literature on friendships among children who are twins and asks two questions: (1) What are the implications of the twin situation for friendship formation? (2) How can the twin situation inform theoretical knowledge concerning friendship formation in the general population? The discussion examines the implications of the twin situation for the size and nature of twin children's friendship pool and questions whether children who are twins are more likely to be adaptive or maladaptive in their social behaviour. The paper argues for the need to study the process and mechanisms in friendship formation among twin children because the findings might inform not only studies of friendship but also behavioural genetic research.

Friends↗
PubMed2003

Dynamics of estrogen biomarker responses in rainbow trout exposed to 17beta-estradiol and 17alpha-ethinylestradiol.

We have investigated the response dynamics of the estrogen-dependent genes vitellogenin (VTG) and the vitelline envelope proteins (VEPs) as well as circulating VTG in immature female rainbow trout (Oncorhynchus mykiss) exposed to 17beta-estradiol (E2) and 17alpha-ethinylestradiol (EE2) for periods of 7 and 14 d. Gene responses were quantified by measurement of messenger RNA (mRNA) in liver extracts using a chemiluminescent hybridization protection assay. Circulating VTG was measured by a homologous enzyme-linked immunosorbent assay. Exposure to both E2 and EE2 induced concentration-dependent increases in all biomarkers. The data presented indicate that VEP genes may be more sensitive to estrogens than the VTG gene. The biomarker lowest-observed-effect concentrations (biomarkerLOEC) in the 14-d study with E2 were 14 ng/L (VTG protein, VTG mRNA, VEPbeta, and VEPgamma) or 4.8 ng/L (VEPalpha). The EE2 was 5- to 66-fold more potent depending on the biomarker studied. In the 7-d study, all biomarkers were elevated after 48-h exposure to E2, with biomarkerLOECs of 30 ng/L (VTG protein, VTG mRNA, and VEPgamma) or 9.7 ng/L (VEPalpha and VEPbeta). Vitellogenin mRNA was induced up to 1,000-fold above baseline, and this translated into an increase of approximately 50,000-fold in circulating VTG. In conclusion, all biomarkers responded to estrogen exposure at environmentally relevant concentrations.

Animals↗