Stephen Petrill - US grants

Understanding the mechanisms by which the environment affects the development of reading-related cognitive skills and reading outcome has important implications for education and the prevention of reading problems. Although informative, many environmental studies of reading have not taken into account the potential mediating effects of genes upon reading-related environmental influences. The long-term goal of this study therefore is to systematically examine the effect of genes upon reading-related environmental influences. The long-term goal of this study therefore is to systematically examine the effect of environmental influences upon the acquisition of reading, using a genetically-sensitive research design. The proposed research has four specific aims: (1) To examine genetic and environmental influences on the growth of reading and related cognitive and behavioral skills, (2) To examine the correlation between distal and proximal environmental factors and the growth of reading and related cognitive and behavioral cognitive and behavioral skills, and (4) To examine the links between sibling differences in environments and sibling differences in the growth of reading and related cognitive and behavioral skills. A longitudinal twin study is proposed to achieve these aims. A sample of 350 MZ and same-sex DZ twin pairs will be assessed at 5.5, 6.5, and 7.5 years of age using a comprehensive battery of cognitive, reading-related, and environmental measures. Additionally, parents and teachers of the twins will be asked to provide additional information concerning each twin's cognitive and reading level at each point of assessment, as well aspects of each twin's environment. The proposed study is innovative in its integration of environmental theory, empirical research examining the underpinings and development of reading outcome, and behavioral genetic methodology. Practically, developing a more informative model of how genes and environments work together to yield reading outcome has important implications on how to prevent, detect, and ameliorate reading problems.

DESCRIPTION (provided by applicant): Understanding the genetic and environmental mechanisms that underlie individual differences in general and specific mathematics cognition has important implications for mathematics education and prevention of specific learning disabilities in mathematics. The proposed research will provide the first systematic genetic investigation of individual differences in early mathematics learning and disabilities as well as the links among mathematics, reading, other cognitive abilities, motivation, and the environment. The proposed three-year project will capitalize on two ongoing twin studies - one in the U.S. and one in the U.K. - by testing the twins in their homes on diverse processes of mathematics learning. The U.S. study includes a representative sample of 350 same-sex twin pairs born between 1996 and 1998 who are being assessed longitudinally at three measurement occasions from kindergarten through third grade on a broad battery of measures of reading, cognitive skills, and family environmental factors. Examining these 700 children in their homes at eight years of age on a battery of mathematics measures will determine the role of genetic and environmental influences on individual differences in the normal range of mathematics development and links to reading and cognition. The U.K. study has investigated 7,500 twin pairs on language and cognitive development at two, three, four, and seven years of age, with ongoing testing at nine years of age, which includes teacher assessments of mathematics and reading based on the U.K. National Curriculum criteria at seven and nine years of age. Data from these 15,000 children will be used to select 350 twin pairs in which at least one child is in the lowest 5% of teacher assessments after exclusions. Assessing these 700 children in their homes at ten years of age on a battery of mathematics measures will assess the role of genetic and environmental influences on mathematics disabilities and their links to reading and cognition. DNA has been obtained on these children, which will provide a resource for future molecular genetic analyses. In addition to investigating genetic and environmental influence in mathematics abilities and disabilities, the proposed research will bring a multivariate genetic approach to bear on the vexed issue of general and specific mathematics abilities and disabilities. Developing a more informative model of how genes and environments work together to affect general and specific mathematics development has important implications on how to foster mathematics development as well as to detect, ameliorate and prevent problems.

Understanding the genetic and environmental mechanisms that underlie the development of reading ability and disability has important implications for literacy education and the prevention of learning disabilities in reading. To that end, the goal of the proposed competing continuation of HD38075 is to conduct a systematic developmental genetic examination of reading comprehension. The Western Reserve Reading Project (HD38075 "Environmental Influences on Reading: A Twin Study") includes a representative sample of 350 same-sex twin pairs born between 1996 and 1998 who, by the proposed start date, will have been assessed longitudinally across four measurement occasions from kindergarten through third grade on a broad battery of measures of reading skills, oral language skills, cognitive skills, mathematics, and family environmental factors. The proposed continuation will extend testing via three additional annual home visits spanning middle childhood to early adolescence, with a focus on emerging reading comprehension skills. We propose to examine the univariate genetic and environmental influences upon reading comprehension, the covariance between reading comprehension and oral language skills, decoding skills, and other related skills, as well as the relationship between proximal and distal measures of the home and school environments that are associated with reading comprehension and related skills. In doing so, the proposed research will offer a unique opportunity to examine the genetic and environmental etiology of the longitudinal development of reading comprehension and related skills during the critical transition from when children are "learning to read" to when they are "reading to learn." Extending the unique resources of the Western Reserve Reading Project is an important opportunity for a highly cost-effective and powerful genetically-sensitive investigation of the etiology of reading ability within its various developmental, cognitive, behavioral, and environmental contexts. Developing a more informative model of how genes and environments work together to affect the development of reading comprehension has important implications fostering reading development as well as to detect, ameliorate and prevent reading problems.

DESCRIPTION (provided by applicant): As noted in RFA HD-07-005, the extent to which mathematics difficulties are attributable to deficits in domain-general cognitive mechanisms and/or impairments in math-specific processes involving numerical processing is a matter of considerable debate as is the definition of math disability. The goal of the proposed study is to bring a quantitative genetic perspective to both issues, building on an ongoing systematic behavioral genetic examination of psychometric math skills (HD046167, funded via RFA HD-02-031), the only effort of its kind in the literature. These efforts have been based on two complementary samples of twins, one in the U.S. and the other in the U.K. The U.S. sample includes 500 same-sex pairs of unselected twins who were previously recruited as part of an NICHD-funded study of reading and related cognitive skills (HD38075). As part of HD-02-031, these children were assessed in their homes at 8.5 years on psychometric mathematics skills, spatial skills, and reading skills. The U.K. sample includes 7500 pairs of unselected twins participating in an MRC-funded study of learning disabilities and behavior problems (G0500079). As part of HD-02-031, 2665 pairs of twins have been assessed at age 10 using web- and teacher-based measures of mathematics and reading. Using both samples, the PIs propose to conduct the first quantitative genetic examination of domain-general and math-specific cognitive skills underpinning psychometric math ability and disability. Given their preliminary data, the PIs predict that domain general measures will account for genetic and shared environmental influences on mathematics that overlap with reading outcomes. They also predict that measures of numerical processing will reflect independent genetic and environmental influences on math outcomes above and beyond that explained by general cognitive ability, reading ability, and domain-general skills such as working memory. The proposed study will also provide a unique opportunity to examine the core cognitive mechanisms of math across multiple definitions of disability within the context of a genetically sensitive design. Furthermore, because this proposal is embedded in an ongoing program of research, data emanating from this proposal can be put into the context of previously (and separately) funded longitudinal genetic studies of reading and psychometric math ability and disability. The proposed research is innovative in that it will move beyond estimating genetic and environmental influences on psychometric measures of mathematic ability to understanding how genes and environments influence the fundamental cognitive skills underpinning mathematic ability and disability in the context of reading skills during middle childhood and adolescence. Developing a model of how genes and environments work together to affect the development of math ability and disability has important implications on how to foster math development as well as to detect, ameliorate and prevent math difficulties.

DESCRIPTION (provided by applicant): Reading disability (RD), math disability (MD), and attention-deficit/hyperactivity disorder (ADHD) are common disorders of childhood that frequently co-occur, but the developmental etiology of this comorbidity is largely unknown. The proposed project is an extension of the Western Reserve Reading and Math Project and the International Longitudinal Twin Study of Early Reading Development, two longitudinal twin studies that have followed population-based samples of twins since preschool. The twins will complete an extensive battery of measures of reading, math, ADHD, and neuropsychological functioning at the end of ninth grade. These measures will provide important new information regarding the developmental etiology of word reading and more complex reading fluency and comprehension, the developmental stability of DSM-IV symptom dimensions and subtypes of ADHD, and the longitudinal and cross-sectional etiology of covariance between individual differences and extreme scores on measures of reading, math, and ADHD symptoms. The extensive battery of neuropsychological measures will be used to test which neuropsychological functions are uniquely associated with RD, ADHD, or MD and which are shared risk factors across two or more of these domains, and multivariate twin analyses will be conducted to test the etiology of these associations.

DESCRIPTION (provided by applicant): The LDR-HUB application Neurobiological Underpinnings of Math and Reading Comorbidity: A Twin Study proposes a framework to systematically integrate findings from the behavioral genetic, brain imaging, and reading/math disability literatures to examine some of the plausible mechanisms that affect variation and covariation in brain structure, brain function, math outcomes, and reading outcomes. The Research Project (Years 1 to 4) integrates structural and functional brain imaging within two ongoing longitudinal twin studies to address two Specifc Aims. For Specific Aim 1, we will select N = 300 pairs of 14 - 16 year old MZ and same-sex DZ twins from the Western Reserve Reading and Math Project (WRRMP: Based at Ohio State Univ. and Case Western Reserve Univ./Cleveland Clinic Foundation). For Specific Aim 2, we will select N = 100 pairs of 14 -16 year old same-sex DZ twins from the Colorado Learning Disabilities Research Center Twin Study (CLDRC: Based at the Univ. of Colorado), where one member of the CLDRC twin pair has been selected for Math Disability, Reading Disability, Math Disability + Reading Disability, or Neither Math nor Reading Disability. Across both aims, we will examine Domain-General and Domain-Specific relationships between brain structure, brain function, etiology, math outcomes, and reading outcomes with and without selection for disability. The Administrative Core (Years 1 to 4) will provide oversight of research activities, administer a mechanism for data sharing and dissemination, and supervise training and mentoring activities. The Developmental Core (Years 3 and 4) will solicit and administer seed grants extending the results of the Research Project, targeting both basic and applied research. In summary, the proposed work is a necessary starting point to address the larger questions of how math and reading disabilities develop and how they can be prevented and treated in light of substantial genetic, neurobiological, and environmental variation. PUBLIC HEALTH RELEVANCE: The proposed work fulfills components stipulated in RFA-HD-12-203 by collecting behavioral, functional and structural neuroimaging measures of cognitive processes in a genetically informative design to identify behavioral, biological, and environmental contributions to the overlap and independence of math and reading disabilities. This work also provides mechanisms for mentorship and additional research in these areas.