The incidence of eeg abnormalities in a dyslexic and a control group

Abstract

PROBLEMThe relationship between reading disability and electroencephalographic (EEG) abnormalities has been examined by many investigators. Earlier studies reported that 75% of dyslexic children('), 67% of hyperkinetic children two years retarded in reading('), 63% of children referred to a reading clinic(s), 59% of children with severe speech and reading disabilities("), and over 50% of children who failed to acquire reading and writing abilities ( 4 ) had EEG abnormalities. A review(2) reported a greater range of observations on the incidence of EEG abnormalities-from 28 to 88% in dyslexic children. The study by Cohn(*) included a control group in which 10% of the children had abnormal EEG's.Although these studies report a higher incidence than the 20Oj, base rate given by Gibbs and Gibbs(6), the relationship between abnormal EEG's and dyslexia is still not clear, as most studies are based on samples referred for reasons other than reading disability. This makes interpretation of the results difficult, as groups of children with behavior problems or hyperkinetic behavior also have a higher than expected incidence of EEG abnormalities. (6, 8 , l o ) METHODSubjects. The present study was designed to clarify some of the discrepancies in these findings by the use of a more carefully controlled sample of a learningdisability population and a random sample from the same general population. By restricting the sample to third grade students from a large metropolitan school system, the sample groups were made homogeneous for age and school experience. Homogeneity on these variables removed from the sample developmental factors that have made previous studies difficult to interpret. GROUP 1, CLINICAL GROUP. The 129 Ss in this group were referred for comprehensive diagnosis of their special learning disabilities. All had reading difficulties as indicated by test results, teachers' classification of functional reading level, or both. H eractivity and short attention span were frequently cited by the referring schools. The mean9A was 104.1 months, range 95 to 122. The mean WISC full-scale I& was 99.6, range 77 to 132. GROUP 2, REMEDIAL READING GROUP. The second group of 31 Ss was randomly selected from a list of children awaiting placement in remedial reading classes. The lists were compiled by a screening procedure routinely applied throughout the school system. The basic criteria for entry into the remedial reading classes were that the child have an I& above 90, be two years retarded in reading, and be recommended by the teacher. The mean CA was 106.9, range 100 to 134. The mean full-scale WISC was 100.8, range 82 to 120. GROUP 3, CONTROL GROUP. The control group was obtained by identifying 53 children through a stratified random sampling procedure. The arents of 47 agreed to participate in the study. Participation included bringing the child to a Jagnostic center for a neurological examination, permitting the child to be evaluated by a psychologist, filling out several forms and taking personalit t&s, and keeping the ch...

EEG correlates of developmental dyslexia: a systematic review

“…Bilateral fronto-central 2. Right fronto-central Ayers and Torres ( 1967 ) Higher than expected incidence of abnormal electroencephalograms / Babiloni et al ( 2012 ) Lower amplitude in low- and high-frequency alpha rhythms Parietal, occipital, and temporal cortical sources Bosch-Bayard et al ( 2020 ) 1. More active hub: the calcarine sulcus is sending information to the right postcentral gyrus, the left paracentral gyrus, the right angular gyrus, and the right supplementary motor area in almost all frequency bands, including delta and theta band 2.…”

“…Results obtained from other methodologies are less homogeneous, and a summary is not possible; Table 3 reports the results of these studies (Arns et al, 2007 ; Ayers & Torres, 1967 ; Babiloni et al, 2012 ; Bosch-Bayard et al, 2020 ; Bruni et al, 2009 ; Duffy et al 1980a ; Eroğlu et al, 2022 ; Farrag & El-Behary, 1990 ; Fraga González et al, 2016 ; Gerald Leisman, 2002 ; Reda et al, 2021 ; Shiota et al, 2000 ; Xue et al, 2020 ).…”

Recent Studies of Mentally Handicapped Young People's Behaviour

“…Adverse obstetric factors may contribute to the poor development of communicative skills as has been shown by Hagberg, Hagberg, Lewerth and Lindberg (1981a, b), in that a very high proportion of the handicapped children in their study had additional neurological handicap. Ayres and Torres (1967) and Capute, Neidermeyer and Richardson (1968) took the evidence of raised EEG abnormalities in children with behavioural and learning disorders as indicative of brain dysfunction. The existence of a continuum of reproductive casualty has been given some support by retrospective and prospective studies (Werry, 1972;Driilien, Thomson & Burgoyne, 1980).…”

Dyslexia and Neurodevelopmental Pathology

“…Significant EEG abnormalities have been found to occur more frequently in children with severe reading problems (Ayers & Torres, 1967;Pirozzolo & Hansch, 1982) in comparison to children without reading difficulties.…”