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11.
In order to assess the etiology of reading disability as a function of mathematics performance, data from 168 monozygotic (MZ) and 127 same-sex dizygotic (DZ) twin pairs in which at least one member of each pair was reading-disabled were subjected to quantitative genetic analyses. MZ and DZ concordance rates for reading disability were computed for different levels of mathematics performance, and reading performance data were fitted to an extension of the basic multiple regression model for the analysis of selected twin data. Results of these analyses suggest that genetic factors may be especially salient as a cause of reading disability in children with borderline deficits in mathematics performance: thus, mathematics performance may be a valid dimension for diagnosing subtypes of reading disability. 相似文献
12.
Genetic Change and Continuity from Fourteen to Twenty Months: The MacArthur Longitudinal Twin Study 总被引:3,自引:0,他引:3
Robert Plomin Jerome Kagan Robert N. Emde J. Steven Reznick Julia M. Braungart JoAnn Robinson Joseph Campos Carolyn Zahn-Waxler Robin Corley David W. Fulker J. C. DeFries 《Child development》1993,64(5):1354-1376
Genetic change as well as continuity was investigated within the domains of temperament, emotion, and cognition/language for 200 pairs of twins assessed at 14 and 20 months of age in the laboratory and home. The second year of life is marked by change rather than continuity: correlations from 14 to 20 months averaged about .30 for observational measures of temperament and emotion, about .40 for language measures, and about .50 for mental development. 2 types of genetic change were examined: changes in the magnitude of genetic influence (heritability) and genetic contributions to change from 14 to 20 months. In general, heritability estimates were similar at 14 and 20 months. Evidence for genetic influence on change from 14 to 20 months emerged for several measures, implying that heritability cannot be equated with stability. Analyses of continuity indicated that genetic factors are largely responsible for continuity from 14 to 20 months. 相似文献
13.
Brian Byrne Stefan Samuelsson Sally Wadsworth Jacqueline Hulslander Robin Corley John C. DeFries Peter Quain Erik G. Willcutt Richard K. Olson 《Reading and writing》2007,20(1-2):77-102
Grade 1 literacy skills of twin children in Australia (New South Wales) and the United States (Colorado) were explored in
a genetically sensitive design (N = 319 pairs). Analyses indicated strong genetic influence on word and nonword identification, reading comprehension, and
spelling. Rapid naming showed more modest, though reliable, genetic influence. Phonological awareness was subject to high
nonshared environment and no reliable genetic effects, and individual measures of memory and learning were also less affected
by genes than nonshared environment. Multivariate analyses showed that the same genes affected word identification, reading
comprehension, and spelling. Country comparisons indicated that the patterns of genetic influence on reading and spelling
in Grade 1 were similar, though for the U.S. but not the Australian children new genes came on stream in the move from kindergarten
to Grade 1. We suggest that this is because the more intensive kindergarten literacy curriculum in New South Wales compared
with Colorado, consistent with the mean differences between the two countries, means that more of the genes are “online” sooner
in Australia because of accelerated overall reading development. 相似文献
14.
J. C. DeFries 《Annals of dyslexia》1988,38(1):120-130
Extensive psychometric test data were obtained from two independent samples of reading-disabled and control children: 70 probands
and 75 controls tested on two occasions over an average interval of 4.2 years, and 35 probands and 22 controls tested on three
occasions over an average interval of 8.6 years. When composite measures of reading performance and symbol-processing speed
were subjected to mixed-model multivariate analyses of variance, significant effects due to group (reading-disabled versus
control) and time (i.e., test session) were obtained in both samples, and a significant group-by-time interaction was obtained
for the sample tested on three occasions. In general, rates of change in reading performance are highly similar for reading-disabled
and control children. However, with regard to symbol-processing speed, differences between the two groups increase as a function
of age. Although no evidence was obtained for differential longitudinal stability of either composite measure in reading-disabled
and control children, results of a multiple regression analysis suggest that reading deficits during middle childhood are
highly predictive of later reading problems, even into early adulthood.
This work was supported in part by a program project grant from the NICHD (HD-11681). The invaluable contributions of staff
members of the many Colorado school districts and of the families who participated in the study are gratefully acknowledged. 相似文献
15.
Stefan Samuelsson Richard Olson Sally Wadsworth Robin Corley John C. DeFries Erik Willcutt Jacqueline Hulslander Brian Byrne 《Reading and writing》2007,20(1-2):51-75
Genetic and environmental influences on prereading skills in preschool and on early reading and spelling development at the
end of kindergarten were compared among samples of identical and fraternal twins from the U.S. (Colorado), Australia, and
Scandinavia. Mean comparisons revealed significantly lower preschool print knowledge in Scandinavia, consistent with the relatively
lower amount of shared book reading and letter-based activities with parents, and lack of emphasis on print knowledge in Scandinavian
preschools. The patterns of correlations between all preschool environment measures and prereading skills within the samples
were remarkably similar, as were the patterns of genetic, shared environment, and non-shared environment estimates: in all
samples, genetic influence was substantial and shared environment influence was relatively weak for phonological awareness,
rapid naming, and verbal memory; genetic influence was weak, and shared environment influence was relatively strong for vocabulary
and print knowledge. In contrast, for reading and spelling assessed at the end of kindergarten in the Australian and U.S.
samples, there was some preliminary evidence for country differences in the magnitude of genetic and environmental influences.
We argue that the apparently higher genetic and lower shared environment influence in the Australian sample was related to
a greater emphasis on formal reading instruction, resulting in more advanced reading and spelling skills at the end of kindergarten,
and thus there was greater opportunity to observe genetic influences on response to systematic reading instruction among the
Australian twins. 相似文献
16.
Gender differences were assessed in three research-identified samples of children who were members of twin pairs: (1) 120
male and 124 female probands from same-sex identical and fraternal twin pairs in which at least one member of each pair is
reading disabled; (2) a comparison sample of 148 males and 161 females from same-sex twin pairs with no history of reading
problems; and (3) 34 pairs of opposite-sex fraternal twin pairs in which at least one member of each pair is reading disabled.
Results of multivariate analyses of variance of psychometric test data from the two samples of same-sex twin pairs, in which
the male and female subjects were reared in different homes, suggest that profiles of gender differences are similar in reading-disabled
and control children. Moreover, this pattern of gender differences also tended to occur in opposite-sex twin pairs, who shared
prenatal, as well as early postnatal, environmental influences. In general, reading-disabled males obtained higher average
scores than affected females on Wechsler (1974, 1981) Verbal and Performance IQ, but lower scores on Reading Recognition and
Spelling subtests of the Peabody Individual Achievement Test (Dunn and Markwardt 1970). With regard to the Wechsler subtests,
reading-disabled males achieved higher average scores on Information, Picture Completion, Block Design, and Object Assembly,
but lower scores on Coding. Although significant and relatively consistent gender differences in cognitive measures were found
in three samples included in this study, these differences account for only a small portion of the observed variance.
This work was supported in part by a program project grant from NICHD (HD-11681), and the report was prepared while J.J. Gillis
was supported by NICHD training grant HD-07289. 相似文献
17.
Rebecca S. Betjemann Erik G. Willcutt Richard K. Olson Janice M. Keenan John C. DeFries Sally J. Wadsworth 《Reading and writing》2008,21(5):539-558
Longitudinal twin data were analyzed to investigate the etiology of the stability of genetic and environmental influences
on word reading and reading comprehension, as well as the stability of those influences on their relationship. Participating
twin pairs were initially tested at a mean age of 10.3 years, and retested approximately five years later. Both word reading
and comprehension were found to be highly stable, and genetic influences were primarily responsible for that stability. In
contrast to studies with younger participants, no unique genetic influences were observed at follow-up testing in this older
sample. High genetic correlations were obtained between word reading and reading comprehension at both ages, indicating common
genetic influences. However, significant genetic influence on comprehension was also observed, independent of that on word
reading. Although the phenotypic relation between the two measures appeared to decline across time, the genetic etiology of
this relation was highly stable. 相似文献
18.
Erik G. Willcutt Rebecca S. Betjemann Bruce F. Pennington Richard K. Olson John C. DeFries Sally J. Wadsworth 《Mind, Brain, and Education》2007,1(4):181-192
ABSTRACT— The majority of children who receive special education services meet criteria for reading disability (RD) or attention-deficit/hyperactivity disorder (ADHD), but additional research is needed to understand the long-term academic outcome of children in these groups. Individuals with RD only ( N = 71), ADHD only ( N = 66), both RD and ADHD ( N = 51), or neither disorder ( N = 118) were identified through the ongoing Colorado Learning Disabilities Research Center twin study and retested 5 years later. Results of the follow-up testing indicated that, in addition to ongoing reading difficulties, individuals with RD exhibited higher rates of academic difficulties, depression, and adolescent-onset conduct disorder. Initial ADHD status was associated with academic and social difficulties and elevated rates of nearly all comorbid disorders 5 years later. The group with comorbid RD and ADHD had more stable reading deficits than the group with RD without ADHD and exhibited greater impairment than groups with either disorder alone on outcome measures of academic functioning and social difficulties. These results suggest that individuals with both RD and ADHD are at increased risk for negative outcomes as adolescents and young adults and that when RD and ADHD co-occur, interventions should be provided for both disorders. 相似文献
19.
Boada Richard Willcutt Erik G. Tunick Rachel A. Chhabildas Nomita A. Olson Richard K. DeFries John C. Pennington Bruce F. 《Reading and writing》2002,15(7-8):683-707
The present study examined the etiology of highreading ability in an overall sample of 350twin pairs in which at least one member of 100pairs (54 MZ, 46 DZ) had a reading compositescore one standard deviation above the sample mean. These highreaders also had significantly higher scoresthan the rest of the sample on Full Scale,Verbal and Performance IQ scores, as well as onmeasures of phoneme awareness, orthographiccoding, phonological decoding, and verbalshort-term memory. The MZ proband-wiseconcordance rate for high group membership wassignificantly higher than the DZ proband-wiseconcordance rate and further behavioralgenetic analyses corroborated that high readingability is partly due to genetic influence(h2
g = 0.55 ± 0.22). Bivariatemultiple regression analyses demonstrated thathigh phonological awareness, orthographiccoding, phonological decoding, and short-termverbal memory skills all share significantcommon genetic influence with high readingability. These results suggest that readingability and its cognitive correlates are on acontinuous distribution, with both extremes ofthe distribution being similarly heritable. They also support the hypothesis that the samecognitive processes that are associated withdyslexia are important for the development ofhigh reading ability. 相似文献
20.
B F Pennington J W Gilger R K Olson J C DeFries 《Journal of learning disabilities》1992,25(9):562-573
Recent research has raised the question of whether age- and IQ-discrepancy forms of reading disability (RD) are distinguishable in terms of either their underlying linguistic deficit or their response to treatment, thus threatening the external validity of the traditional distinction between specific reading retardation and reading backwardness. The present study pursued the external validity of this distinction in three domains: (a) genetic etiology, (b) sex ratio and clinical correlates, and (c) neuropsychological profiles. Each of these domains was explored in the RD (n = 640) and control (n = 436) twins participating in the Colorado Reading Project (514 males, 562 females, with an overall mean age of 12.42 years). Little evidence for external validity was found in terms of the clinical correlates of attention deficit-hyperactivity disorder (ADHD), immune disorders, or handedness. Most importantly, there was no evidence of differential genetic etiology of the two phenotypes in this sample, in that deficits in both phenotypes were similarly heritable (h2g = .40 and .46 for age and IQ phenotypes, respectively) and the genetic correlation between them was high (rG = .88 to .96). However, the genetic and neuropsychological profile analyses did suggest that age- and IQ-discrepancy definitions of RD may relate differentially to component reading processes, such as phonological awareness and orthographic coding. 相似文献