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E Simonoff

Publications and source records attributed to E Simonoff.

46 records · Page 3Linked to original sources
PubMed1995

Autism as a strongly genetic disorder: evidence from a British twin study.

Two previous epidemiological studies of autistic twins suggested that autism was predominantly genetically determined, although the findings with regard to a broader phenotype of cognitive, and possibly social, abnormalities were contradictory. Obstetric and perinatal hazards were also invoked as environmentally determined aetiological factors. The first British twin sample has been re-examined and a second total population sample of autistic twins recruited. In the combined sample 60% of monozygotic (MZ) pairs were concordant for autism versus no dizygotic (DZ) pairs; 92% of MZ pairs were concordant for a broader spectrum of related cognitive or social abnormalities versus 10% of DZ pairs. The findings indicate that autism is under a high degree of genetic control and suggest the involvement of multiple genetic loci. Obstetric hazards usually appear to be consequences of genetically influenced abnormal development, rather than independent aetiological factors. Few new cases had possible medical aetiologies, refuting claims that recognized disorders are common aetiological influences.

Abnormalities, Multiple↗
PubMed1995

The Child and Adolescent Psychiatric Assessment (CAPA).

Great advances have been made during the last 20 years in the development of structured and semi-structured interviews for use with psychiatric patients. However, in the field of child and adolescent psychiatry there have been weaknesses in the specification and definition of both symptoms and the psychosocial impairments resulting from psychiatric disorder. Furthermore, most of the available interviews for use with children have been tied to a single diagnostic system (DSM-III, DSM-III-R, or ICD-9). This has meant that symptom coverage has been limited and nosological comparisons have been inhibited. The Child and Adolescent Psychiatric Assessment (CAPA) represents an attempt to remedy some of these shortcomings. This paper outlines the principles adopted in the CAPA to improve the standardization, reliability and meaningfulness of symptom and diagnostic ratings. The CAPA is an interviewer-based diagnostic interview with versions for use with children and their parents, focused on symptoms occurring during the preceding 3 month period, adapted for assessments in both clinical and epidemiological research.

Adolescent↗
PubMed1995

The impact of child IQ, parent IQ and sibling IQ on child behavioural deviance scores.

In an epidemiological sample of 411 13-year-old twins of normal intelligence, both parents and teachers reported more behavioural problems among children with lower IQs. This was not attributable to the effects of parental IQ or social class and was not entirely mediated by lower scholastic attainments. Different causal models are discussed: "rater bias" and "IQ is a consequence" explanations seem less plausible than "IQ is a cause" and "IQ is a marker" explanations. Higher parental IQ was associated with more emotional symptoms in the child, both by parental and school report. There was no evidence that being brighter or less bright than a (twin) sibling influenced behavioural deviance, casting doubt on the importance of contrast effects.

Adolescent↗
PubMed1994

Survival models for developmental genetic data: age of onset of puberty and antisocial behavior in twins.

The use of survival analysis for developmental genetic data is discussed. The main requirements for models based on the decomposition of frailty distributions into shared and unshared components are outlined for the simple case of twins. Extending the earlier work of Clayton, Oakes, and Hougaard, among others, three forms of hazard model are presented, all of which can be applied to pedigree data with flexible baseline hazards without the use of numerical integration. The first two models use an additive decomposition of frailty, with either gamma or positive stable law distributed (PSL) components. The third model previously described by Hougaard involves a multiplicative PSL decomposition. The models are applied to data on the onset of puberty in male twins and illustrate the importance of correct specification of the baseline hazard for correct inference about genetic effects. The difficulty of assessing model specification using information only on the margins is also noted. Overall, the new model with additive PSL components appeared to fit these data best. A second application illustrates the use of a time-varying covariate in examining the impact of puberty on the onset of conduct disorder symptomotology.

Adolescent↗
PubMed1994

A simple method for censored age-of-onset data subject to recall bias: mothers' reports of age of puberty in male twins.

Genetic analysis of variation in age of onset of development milestones or psychopathological behaviors has been little researched, owing largely to the computational difficulty of dealing with "censored" observations. Censored observations arise when the only information on individuals is that they have reached a particular age but without onset having occurred. This paper shows how models can be simply fitted to such data using programs that can perform genetic analysis of categorical data by maximum likelihood. The method is illustrated using the program Mx with data on maternal report of the onset of puberty in twin sons from the Virginia Twin Study of Adolescent Behavioral Development. Frequently, data on age of onset is collected by retrospective recall. This can pose a variety of measurement problems. Suggestions are made for models that account for some of these problems or are robust to their presence. Substantial evidence for "telescoping" of onset dates is found for the puberty data. If left unaccounted for, these effects can artifactually inflate estimates of common environment effects.

Adolescent↗
PubMed1992

A comparison of twins and singletons with child psychiatric disorders: an Item Sheet study.

An important assumption underlying the twin method of comparing MZ and DZ twins is that results from twin samples can be generalized to the larger singleton population. This study uses Item Sheet data on child psychiatric patients to compare twins and singletons on demographic, diagnostic and symptomatic variables. Although little difference was found between the two groups, conduct disorders were significantly over-represented in the twin population. The significance of this finding is discussed. This study lends overall support for the use of the twin method in child psychiatric samples.

Adolescent↗
PubMed1991

Reliability of clinical ratings by trainee child psychiatrists: a research note.

Trainee and senior psychiatrists separately rated the symptoms and signs of 14 consecutive referrals to a child psychiatric team. Inter-rater reliabilities ranged from 0.61 to 0.94 on four clinically relevant dimensions of psychopathology. Aggregating all items, trainees' ratings identified whether or not items were definitely present with greater than 95% accuracy, as judged by a senior psychiatrist's ratings and a review of the case notes. This pilot study suggests that trainees' ratings can be of acceptable reliability for research purposes.

Affective Symptoms↗
PubMed1980

Risk factors for genetic typing and detection in retinitis pigmentosa.

An outpatient population with retinitis pigmentosa was evaluated with respect to best corrected visual acuity, cycloplegic refractive error, appearance of the lenses, presence or absence of bone spicule pigmentation, age of onset of night blindness by history, and presence or absence of a history of parental consanguinity. The population included 489 affected patients subdivided into the four following groups: 69 (14.1%) dominant, 67 (13.7%) autosomal recessive, 34 (7.0%) X-chromosome-linked, and 319 (65.2%) isolate. Contingency table and life table analyses showed that significant differences existed for these criteria among the various groups. An analysis based on data from 35 families showed significant differences with respect to best corrected visual acuity and cylindrical refractive error when comparing affected patients with their age-matched normal relatives. These findings support the idea that observations in a routine ocular examination can aid in genetic classification of affected patients and in selection of relatives of affected patients who are at higher risk for having early stages of retinitis pigmentosa.

Adolescent↗
PubMedDate not supplied

Genetic and environmental influences on ratings of manifest anxiety by parents and children.

Parental reports and children's self-reports of manifest anxiety were obtained from a community-based sample of twin pairs on two occasions approximately 19 months apart, using the Revised Child Manifest Anxiety Scale (Reynolds & Richmond, 1978). In prior cross-sectional studies, a low degree of agreement between parent and child assessments of anxiety was found. Furthermore, parental reports were found to reflect a higher heritability than children's self-reports (Eaves et al., 1997; Thapar & McGuffin, 1995). The index of temporal stability was moderate for all informants (circa r = .5 to r = .6). To test whether the components contributing to the temporal stability differed between the informants, structural equation models were fitted to the data using the program, Mx: Statistical Modeling (Neale, 1995). The results showed substantial differences in genetic effects according to both gender and informant. For children's self-reports, temporal stability was largely a function of environmental effects, with genetic effects contributing a modest 20%, whereas for parental reports, temporal stability was largely a function of genetic effects. The heritability was higher for parental reports than for boys' self-reports and the genetic covariance between parents and their sons was near zero, indicating that they were reporting on quite different aspects of anxiety. However, for girls, heritability for maternal reports was lower than for self-reports, and the genetic covariance between mother and daughter was about the same as that between mothers and fathers, meaning that they were assessing the same genetically influenced aspect of anxiety. These results highlight the need to focus on gender differences.

Adult↗