Purpose: The goal of this study was to investigate the etiologic basis for the association between deficits in phonological memory (PM) and vocabulary in school-age children. Method: Children with deficits in PM or vocabulary were identified within the International Longitudinal Twin Study (ILTS; Samuelsson et al., 2005). The ILTS includes 1,045…

Objective: The Strengths and Weaknesses of ADHD Symptoms and Normal Behavior (SWAN) Rating Scale differs from previous parent reports of ADHD in that it was designed to also measure variability at the positive end of the symptom spectrum. Method: The psychometric properties of the SWAN were tested and compared with an established measure of ADHD,…

Background: Reading disability (RD) and attention deficit/hyperactivity disorder (ADHD) are comorbid and genetically correlated, especially the inattentive dimension of ADHD (ADHD-I). However, previous research indicates that RD and ADHD enter into opposite gene by environment (G x E) interactions. Methods: This study used behavioral genetic…

Identical and fraternal twins (N = 540, age 8 to 18 years) were tested on three different measures of writing (Woodcock-Johnson III Tests of Achievement--Writing Samples and Writing Fluency; Handwriting Copy from the Group Diagnostic Reading and Aptitude Achievement Tests), three different language skills (phonological awareness, rapid naming, and…

Although previous research has identified contemporaneous associations between cognitive deficits and symptom phenotypes in Attention Deficit/Hyperactivity Disorder, no studies have as yet attempted to identify direction of effect. The present study used cross-lagged path modeling to examine competing hypotheses about longitudinal associations…

This article examines Gene x Environment (G x E) interactions in two comorbid developmental disorders--reading disability (RD) and attention-deficit/hyperactivity disorder (ADHD)--as a window on broader issues on G x E interactions in developmental psychology. The authors first briefly review types of G x E interactions, methods for detecting…

Genetic and environmental relations between vocabulary and reading skills were explored longitudinally from preschool through Grades 2 and 4. At preschool there were strong shared-environment and weak genetic influences on both vocabulary and print knowledge but substantial differences in their source. Separation of etiology for vocabulary and…

This commentary explains how the field of developmental cognitive neuroscience (DCN) holds the promise of a much wider interdisciplinary integration across sciences concerned with development: psychology, molecular genetics, neurobiology, and evolutionary developmental biology. First we present a brief history of DCN, including the key theoretical…

Numerous studies have examined the etiology of the association between reading difficulties and attention-deficit hyperactivity disorder (ADHD) in school-age children, but little is known about the relation between prereading skills and ADHD behaviors prior to the beginning of formal reading instruction. A population-based sample of 809 pairs of…

A discussion of basic genetic principles is followed by a review of selected genetic syndromes involving learning disabilites (such as Noonan Syndrome, Neurofibromatosis, Pheuylketonuria, and cleft lip and palate). Guidelines for securing a genetic evaluation are given. (CL)

Genetic research has shown that dyslexia is familial, substantially heritable, and heterogeneous in its genetic mechanisms. Evidence also supports the view that the primary symptom in dyslexia is a deficit in the phonological coding of written language, a symptom that appears to be heritable. (Author/JDD)

Background: It has been proposed that some of the variability in reporting of associations between attention deficit hyperactivity disorder (ADHD) and candidate genes may result from mixing of genetically heterogeneous forms of ADHD using DSM-IV criteria. The goal of the current study is to test whether population-based ADHD subtypes defined by…

Research in the genetics of behavioral traits, undertaken by family studies, twin studies, and adoption studies, has revealed information on normal variation in cognitive abilities as well as specific learning disabilities (primarily dyslexia). Genetic evaluation of learning disabled students have implications for counseling and recurrence risk…

Results obtained from 44 children (ages 7 through 16) with sex chromosome abnormalities and from 17 chromosomally normal siblings demonstrated that children in the former group have an increased risk of encountering learning problems. (MP)

Comparison of twins (40 identical and 23 fraternal) for mathematics deficits (MD), in which at least one member had a mathematics disability, found evidence for a significant genetic etiology. However, tests for the differential etiology of MD as a function of reading performance level were nonsignificant. (Author/DB)