The overall goals of this study were to test single vs. multiple cognitive deficit models of dyslexia (reading disability) at the level of individual cases and to determine the clinical utility of these models for prediction and diagnosis of dyslexia. To accomplish these goals, we tested five cognitive models of dyslexia: two single-deficit models, two multiple-deficit models, and one hybrid model in two large population-based samples, one cross-sectional (Colorado Learning Disability Research Center—CLDRC) and one longitudinal (International longitudinal Twin Study—ILTS). The cognitive deficits included in these cognitive models were in phonological awareness, language skill, and processing speed and/ or naming speed. To determine whether an individual case fit one of these models, we used two methods: 1) the presence or absence of the predicted cognitive deficits, and 2) whether the individual’s level of reading skill best fit the regression equation with the relevant cognitive predictors (i.e. whether their reading skill was proportional to those cognitive predictors.) We found that roughly equal proportions of cases met both tests of model fit for the multiple deficit models (30–36%) and single deficit models (24–28%); hence, the hybrid model provided the best overall fit to the data. The remaining roughly 40% of cases in each sample lacked the deficit or deficits that corresponded with their best fitting regression model. We discuss the clinical implications of these results for both diagnosis of school age children and preschool prediction of children at risk for dyslexia.

Environmental moderation of the level of genetic influence on children's reading disabilities (RD) was explored in a sample of 545 identical and fraternal twins (mean age = 11.5 years). Parents' years of education, which are correlated with a broad range of environmental factors related to reading development, were significantly related to the level of genetic influence on reading disability (t = 3.23, Prep = .99). Genetic influence was higher and environmental influence was lower among children with higher compared to children with lower parent education. We discuss the implications of these results for behavior- and molecular-genetic research, for the diagnosis and remediation of RD, and for policy in public education.

Objectives Attempts to understand the effects of maltreatment subtypes on childhood functioning are complicated by the fact that children often experience multiple subtypes. This study assessed the effects of maltreatment subtypes on the cognitive, academic, and mental health functioning of preadolescent youth in out-of-home care using both “variable-centered” and “person-centered” statistical analytic approaches to modeling multiple subtypes of maltreatment. Methods Participants included 334 preadolescent youth (ages 9 to 11) placed in out-of-home care due to maltreatment. The occurrence and severity of maltreatment subtypes (physical abuse, sexual abuse, physical neglect, and supervisory neglect) were coded from child welfare records. The relationships between maltreatment subtypes and children’s cognitive, academic, and mental health functioning were evaluated with the following approaches: “Variable-centered” analytic methods: Regression approach: Multiple regression was used to estimate the effects of each maltreatment subtype (separate analyses for occurrence and severity), controlling for the other subtypes. Hierarchical approach: Contrast coding was used in regression analyses to estimate the effects of discrete maltreatment categories that were assigned based on a subtype occurrence hierarchy (sexual abuse > physical abuse > physical neglect > supervisory neglect). “Person-centered” analytic method: Latent class analysis was used to group children with similar maltreatment severity profiles into discrete classes. The classes were then compared to determine if they differed in terms of their ability to predict functioning. Results The approaches identified similar relationships between maltreatment subtypes and children’s functioning. The most consistent findings indicated that maltreated children who experienced physical or sexual abuse were at highest risk for caregiver-reported externalizing behavior problems, and those who experienced physical abuse and/or physical neglect were more likely to have higher levels of caregiver-reported internalizing problems. Children experiencing predominantly low severity supervisory neglect had relatively better functioning than other maltreated youth. Conclusions Many of the maltreatment subtype differences identified within the maltreated sample in the current study are consistent with those from previous research comparing maltreated youth to non-maltreated comparison groups. Results do not support combining supervisory and physical neglect. The “variable-centered” and “person-centered” analytic approaches produced complementary results. Advantages and disadvantages of each approach are discussed.

This article examines Gene × Environment (G × E) interactions in two comorbid developmental disorders-reading disability (RD) and attention-deficit/hyperactivity disorder (ADHD)-as a window on broader issues on G × E interactions in developmental psychology. The authors first briefly review types of G × E interactions, methods for detecting them, and challenges researchers confront in interpreting such interactions. They then review previous evidence for G × E interactions in RD and ADHD, the directions of which are opposite to each other: bioecological for RD and diathesis stress for ADHD. Given these results, the authors formulate and test predictions about G × E interactions that would be expected at the favorable end of each symptom dimension (e.g., aboveaverage reading or attention). Consistent with their prediction, the authors found initial evidence for a resilience interaction for above-average reading: higher heritability in the presence of lower parental education. However, they did not find a G × E interaction at the favorable end of the ADHD symptom dimension. The authors conclude with implications for future research.Correspondence concerning this article should be addressed to Bruce F. Pennington, Department of Psychology, University of Denver, 2155 South Race Street, Denver, CO 80208-0001. bpenning@du.edu. NIH Public Access Author ManuscriptDev Psychol. Author manuscript; available in PMC 2010 January 1. In this article, we review current models of Gene × Environment (G × E) interaction and apply them to two comorbid developmental disorders-reading disability (RD) and attention-deficit/ hyperactivity disorder (ADHD)-and to the favorable ends of their symptom dimensions. These two disorders are good models in which to explore G × E interactions because they are common developmental disorders, with estimates of 5%-10% prevalence in both cases (American Psychiatric Association, 2000; Shaywitz, Shaywitz, Fletcher, & Escobar, 1990), and they both have genetic and environmental components to their etiology. Current behavior genetic analyses estimate the heritability of RD to be about 58% (Pennington & Olson, 2005) and the heritability of ADHD to be about 76% (Faraone et al., 2005). As these estimates show, the influence of genetics in these disorders is quite strong, but the fact that the heritability estimates are not 100% in either disorder leaves room for environmental influences. On the basis of this pattern, it is not too surprising that both disorders show preliminary evidence of G × E interactions.What is intriguing is that this evidence indicates opposite directions for these interactions: RD is more heritable in a favorable environment (a bioecological G × E interaction, which is explained in more detail below), and ADHD is more heritable in a risk environment (the familiar diathesis-stress interaction found in other psychopathologies). This opposite pattern of interactions is important to understand, and we discuss what it may mean. We also test whether this opposite pattern occurs in ...