Testing the double-deficit hypothesis in an adult sample

The double-deficit hypothesis of dyslexia posits that reading deficits are more severe in individuals with weaknesses in phonological awareness and rapid naming than in individuals with deficits in only one of these reading composite skills. In this study, the hypothesis was tested in an adult sample as a model of reading achievement. Participants were parents of children referred for evaluation of reading difficulties. Approximately half of all participants reported difficulty learning to read in childhood and a small subset demonstrated ongoing weaknesses in reading. Structural equation modeling results suggest that the double-deficit hypothesis is an accurate model for understanding adult reading achievement. Better reading achievement was associated with better phonological awareness and faster rapid automatized naming in adults. Posthoc analyses indicated that individuals with double deficits had significantly lower reading achievement than individuals with single deficits or no deficits.     

Neurological aspects of dyslexia: comment on the balance model.

The Balance Model rests on a long history of research that suggests that different subtypes of dyslexia exist. Based on the notion that there are two subtypes of dyslexia, Bakker has articulated a developmental neuropsychological model whereby a procedure known as hemisphere-specific stimulation may be beneficial in treatment. This article reviews Bakker's model and provides a critical examination as to why validating research has not been conducted. While Bakker's Balance Model may hold promise for scientific inquiry, validation of treatment effects are needed prior to employing these procedures in clinical practice. Further, important conceptual issues remain to be addressed.     

Developmental dyslexia,neurolinguistic theory and deviations in brain morphology

Although some form of central nervous system involvement is presumed, evidence establishing a relationship between dyslexia and neurological dysfunction has been correlational. Recently, neuroimaging and postmortem studies have begun to provide direct evidence implicating neuropathological structures in dyslexia. This article reviews computed tomography (CT) and magnetic resonance imaging (MRI) studies examining deviations in brain morphology which appear to be associated with neurolinguistic functioning. Methodological and technical issues are discussed. Based on their own and others research, the authors conclude that dyslexics show variations in specific brain regions, namely, reversed or symmetrical plana temporale (LR), smaller insular length bilaterally, and symmetrical frontal regions. Moreover, recent studies by the senior author and colleagues suggest that specific reading tasks are associated with specific variations in brain morphology. Symmetrical frontal widths was related to poorer passage comprehension, and reversed frontal area symmetry was related to poor word attack skills. Though many conceptual and technical issues remain unresolved, neuroimaging procedures appear to provide direct evidence supporting the importance of deviations in normal patterns of brain morphology in dyslexia.     

Children With Dyslexia: Not Necessarily at Risk for Elevated Internalizing Symptoms

The risk for internalizing disorders in children with learning disabilities is frequently debated in the research community and empirical responses are equivocal. For educators and clinicians, the frequent assumption is that children with dyslexia also have at least subtle emotional problems. In this study, school-age children with reading problems and their siblings (N=79) were referred for neuropsychological evaluation. As part of the assessment process, parents, teachers, and the child were asked to rate the child’s level of internalizing symptoms on several behavior rating scales. Results from analyses of the data, using both discrepancy and reading cut scores for diagnosis of dyslexia, suggest that children with dyslexia are not at elevated risk for behaviors related to anxiety, depression, and somatization. Additionally, children at the lowest end of the reading distribution were no more likely to have significant internalizing symptoms than children with less impaired reading.     

Clinical appraisal of spelling ability and its relationship to phonemic awareness (blending,segmenting, elision,and reversal), phonological memory,and reading in reading disabled,ADHD, and normal children

Seventy-eight 8-to-12-year-old children (34 ReadingDisabled; 31 Attention-Deficit-Hyperactivity-Disordered; and 13diagnosed normal controls) were given a battery oftests including cognitive, linguistic, academic,phonemic awareness, and memory tests. As part of theacademic battery an 8-point spelling rating scale wasdeveloped (Rating Scale) that resulted in threedifferent scores which reliably discriminated amongthe three groups. Relationships between phonemicawareness, phonological memory, reading and spellingwere explored. Zero-order and second-ordercorrelations were completed with indications thatphonemic awareness tasks (elision, blending, reversal,and segmenting) and phonological memory (WISC-IIIDigit Span) are significantly correlated with readingdecoding and spelling measures with slightly highercorrelations with the Rating Scale. Regressionanalyses resulted in a large proportion of thevariance on reading and spelling tasks accounted forby phonemic awareness (particularly elision andreversal) and phonological memory. The ReadingDisabled group was found to produce more errors thatwere phonetically inaccurate than the other twogroups. The demand of spelling ten ``error' wordsbeyond the RD students' achievement level appeared toelicit greater weaknesses in their phonologicalrecoding abilities than in those of the ADHD ornormally achieving students.     

College Academic Assistance Programs and Practices

Most public institutions offer some form of academic assistance to help their students adjust to the demands of college level learning tasks. Because these academic assistance efforts vary considerably, ranging from an emphasis on functional reading to an emphasis on strategic learning, it is important to describe these programs and their instructional methodologies and to review the pertinent research supporting them. After examining four critical issues confronting all academic assistance programs, the authors examined the goals, assessment procedures, salient features, and program evaluation methods of four prevalent program models: learning to learn courses, supplemental instruction, required programs for underprepared students, and integrated reading/writing courses. They concluded by outlining suggestions for future research and by listing specific questions that college students need to ask about the programs at their institutions.