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Indian Journal of Medical Sciences, Vol. 59, No. 3, March, 2005, pp. 95-103 Original Article Comparison of cognition abilities between groups of children with specific learning disability having average, bright normal and superior nonverbal intelligence Karande Sunil, Sawant S., Kulkarni M., Galvankar P., Sholapurwala R. Learning Disability Clinic, Division of Pediatric Neurology, Department of Pediatrics, Lokmanya Tilak Municipal Medical College and General Hospital, Sion, Mumbai - 400 022 Code Number: ms05014 Abstract BACKGROUND: Specific learning disabilities (SpLD) viz. dyslexia, dysgraphia and dyscalculia are an important cause of academic underachievement. Aims: To assess whether cognition abilities vary in children with SpLD having different grades of nonverbal intelligence.SETTING: Government recognized clinic in a medical college. DESIGN: Cross-sectional study. SUBJECTS AND METHODS: Ninety-five children with SpLD (aged 9-14 years) were assessed. An academic achievement of two years below the actual grade placement on educational assessment with a Curriculum-Based test was considered diagnostic of SpLD. On basis of their nonverbal Intelligence Quotient (IQ) scores obtained on the Wechsler Intelligence Scale for Children test, the study children were divided into three groups: (i) average-nonverbal intelligence group (IQ 90-109), (ii) bright normal-nonverbal intelligence group (IQ 110-119), and (iii) superior-nonverbal intelligence group (IQ 120-129). A battery of 13 Cognition Function tests (CFTs) devised by Jnana Prabodhini's Institute of Psychology, Pune based on Guilford's Structure of Intellect Model was administered individually on each child in the four areas of information viz. figural, symbolic, semantic and behavioral. STATISTICAL ANALYSIS USED: The mean CFTs scores obtained in the four areas of information were calculated for each of the three groups and compared using one-way analysis of variance test. A P value < 0.05 was to be considered statistically significant. RESULTS: There were no statistically significant differences between their mean CFTs scores in any of the four areas of information. CONCLUSIONS: Cognition abilities are similar in children with SpLD having average, bright-normal and superior nonverbal intelligence. KEYWORDS: Cognition, Dyslexia, Intelligence, Remedial teaching, Schools INTRODUCTION Specific learning disabilities (SpLD) viz. dyslexia, dysgraphia and dyscalculia is a generic term that refers to a heterogeneous group of disorders manifested by significant unexpected, specific and persistent difficulties in the acquisition and use of reading (dyslexia), writing (dysgraphia) or mathematical (dyscalculia) abilities despite conventional instruction, normal intelligence, proper motivation and adequate socio-cultural opportunity.[1] The term SpLD does not include children who have learning problems which are primarily the result of visual, hearing, or motor handicaps, of subnormal intelligence, of emotional disturbance, or of socio-cultural disadvantage.[1],[2] SpLD are presumed to be due to central nervous system dysfunction.[3] They constitute an invisible handicap and are important causes of poor school performance in children.[1],[2],[3],[4]Dyslexia (or specific reading disability) is the most common and most carefully studied of the SpLD, affecting 80% of all those identified as learning-disabled.[2] Dyslexia represents a disorder of cognitive (intellectual) functioning.[2],[3] Children with SpLD in spite of having normal cognitive ability (i.e. intellectual ability or intelligence) have significant deficits in their cognitive functioning (i.e. intellectual processes).[5] Recent genetic linkage studies have implicated loci on chromosomes 6 for a range of dyslexia-related deficits in cognitive functioning, viz. deficits of :(1) phonemic awareness (of spoken words); (2) phonological decoding (of printed non-words); (3) rapid automatized naming (of colored squares or object drawings); (4) single-word reading (orally, of printed real words); (5) vocabulary; and (6) spelling (of dictated words).[6] Information on SpLD in Indian children is scanty. Children with SpLD, especially those who have not undergone remedial education, exhibit discrepancy between their level of intelligence, as measured by their Intelligence Quotient (IQ) scores, and their academic achievement.[1],[2],[3],[4] The cornerstone of treatment of SpLD is remedial education, and it is known to alleviate the underlying cognitive problems and help in achieving academic competence.[1],[2],[3],[4] Guilford′s (1967) three-dimensional theoretical model of intelligence, the Structure of Intellect (SOI) Model, has provided a convenient technique for measuring students′ learning capacity.[7] In this SOI model, cognition is the first of five intellectual processes concerned with the learning process. Guilford has defined "cognition" as an intellectual process concerning immediate awareness, recognition, or comprehension of stimuli.[7] We undertook this preliminary study to assess whether cognition abilities (as defined by Guilford′s SOI model) vary in children with newly diagnosed SpLD having different grades of intelligence. To our knowledge, such a study has not been reported in India. SUBJECTS AND METHODS This cross-sectional study was conducted in a Government recognized clinic situated in a medical college over a period of 15 months, from January 2001 to March 2002. Children, nine years and above, who had been referred to our clinic for complaints of poor school performance, and in whom SpLD were newly diagnosed, i.e. they had not yet undergone remedial education, were consecutively enrolled. Currently, SpLD cannot be conclusively diagnosed until the child is about nine year′s old.[2]There is no reliable data which mentions the prevalence of SpLD in Indian children. Therefore the subject sample was by necessity a convenience sample and all children who met the study criteria during the study period were included in the study. All children were attending English medium schools in our city and nearby districts. First, audiometric and ophthalmic examinations were done to rule out hearing and visual deficits. Children in whom non-correctable hearing or visual deficits were detected did not qualify for a diagnosis of SpLD. Each child was assessed in detail by a multidisciplinary team comprising of Pediatrician, Counselor, Clinical Psychologist and Special Educator. The Pediatrician took a detailed clinical history and did a thorough neurological examination. The Counselor ruled out that any emotional problem, due to stress at home or school, was primarily responsible for the child′s poor school performance. If severe emotional disturbances, or depression, or attention deficit hyperactivity disorder (ADHD) were suspected the child was also assessed by a Child Psychiatrist. Children in whom severe emotional disturbances or depression was diagnosed were not enrolled in the study, as these children need to be first treated for these conditions for a few months before assessment for SpLD can be done.[1] The Clinical Psychologist conducted the standard intelligence test viz. Wechsler Intelligence Scale for Children (WISC) test [Indian adaptation by MC Bhatt] to determine the child′s level of intelligence (i.e. intellectual or cognitive ability) viz. the verbal, nonverbal (performance) and global (full scale) IQ scores.[1],[8] Employing a locally developed Curriculum-Based test, the Special Educator conducted the educational assessment in specific areas of learning viz. basic learning skills, reading comprehension, oral expression, listening comprehension, written expression, mathematical calculation and reasoning. An academic achievement of two years below the actual grade placement was considered diagnostic of SpLD.[1],[2] In our clinic, since both the WISC test and the Curriculum-Based test are conducted in English, children in whom "language barrier" was suspected to be the cause of poor school performance, viz. they were not conversant in English as they came from non-English speaking families, could not be assessed for SpLD. Children diagnosed with SpLD and having co-morbid conditions which are known to impair cognitive functioning viz. ADHD, or epilepsy being treated with antiepileptic drugs were excluded from the study.[1],[9] In the present study we have graded the intelligence of children with SpLD on basis of their nonverbal (performance) subtests scores on the WISC test, as these scores reflect their true level of intelligence.[10],[11] It is known that children with SpLD generally perform poorly on verbal subtests on the WISC test as compared to the nonverbal subtests.[10],[11] This occurs because verbal subtests measure skills in areas such as arithmetic, information, and digit span wherein these children tend to have deficits.[10],[11] Thus their verbal IQ scores and consequently their full scale (global) IQ scores, tend to be spuriously low.[10],[11] The study children were thus divided into three groups: (i) the average-nonverbal intelligence group (nonverbal IQ 90-109), (ii) the bright normal-nonverbal intelligence group (nonverbal IQ 110-119), and (iii) the superior-nonverbal intelligence group (nonverbal IQ 120-129).[8] This study was approved by the Scientific and Ethics Committees of our institution and all patients had an informed consent form signed by their parents. After taking informed written consent from the parent(s) and verbal consent from the child, one of the authors (SS) would administer a battery of 13 cognition function tests (CFTs) on each child individually. These psychometric tests have been devised by Jnana Prabodhini′s Institute of Psychology, Pune, with support of the National Council of Educational Research and Training, New Delhi. They are based on the Guilford′s Structure of Intellect (SOI) Model and have been standardized for use after administering them to over 300 Indian school children.[5],[12] These CFTs assessed cognition in four areas of information [Table - 1]: figural (test code numbers 112, 113, 114), symbolic (test code numbers 121, 122, 125), semantic (test code numbers 131, 133, 134, 135, 136), and behavioral (test code numbers 141, 146).[12] In our clinic, we have also employed these CFTs to assess cognition in 125 non-disabled children, whose age ranged from 9-14 years; with mean age 11.83 years (S.D., 1.73) and male: female ratio 1.1:1. The non-disabled children were selected from a nearby English medium school and the classroom teacher was consulted to ensure that the children did not have history of academic underachievement or any current schooling problems. The mean CFTs scores (± S.D.) obtained in the four areas of information in these children (control group) were 25.14 ± 3.36 for figural information, 28.30 ± 4.29 for symbolic information, 27.36 ± 4.17 for semantic information, and 7.54 ± 1.46 for behavioral information ("unpublished data") and are further referred to as "the standard scores". Each of these 13 CFTs comprised of sub-tests, which tested the same specific cognition ability. This ensured that the test scores obtained by the child were valid and not due to chance.[12] Each test had two sample questions. As recommended, each child was explained (by SS) these two examples before undertaking the test.[12] The sequence for the CFTs was: first, tests of figural information, then symbolic, semantic and finally, behavioral. The child was allowed to alter this sequence if so desired, as this in no way influences the scores.[12] However, while performing the CFTs the child was not allowed to: (i) answer another test without having completed the one being administered, or (ii) change answers of any previously administered test. There were no time constraints for completing the CFTs, and a child had the freedom to leave a test without answering all its sub-tests if it was found to be difficult.[12] It took about 60 to 90 minutes for a child to complete the CFTs. The data obtained was analyzed using the Statistical Package for the Social Sciences, version 7.5 for Windows (SPSS, Chicago, Illinois, USA). Each child′s CFTs scores were calculated in the four areas of information. Then the mean scores ± SD obtained in the four areas of information were calculated for each of the three study groups and compared between themselves using one-way analysis of variance (ANOVA) test to find out whether there were any significant differences. Also, mean scores ± S.D. obtained in the four areas of information for each of the three study groups were compared with the standard scores using Independent Samples t-test to find out whether there were any significant differences. A P value < 0.05 was considered statistically significant. RESULTS During the study period 216 children, aged nine years and above, were referred for poor school performance. Of these: 42 were diagnosed as "slow learners" i.e. having dull-normal or borderline intelligence (nonverbal IQ 70-89), 14 had mental retardation (nonverbal IQ <69), four had non-correctable hearing or visual deficits, seven had severe emotional disturbances or depression, 14 had language barrier and 135 children were diagnosed as having SpLD. Of these 135 children with SpLD: 19 had associated ADHD, and 2 had associated epilepsy being treated with antiepileptic drugs and were excluded from the study. Of the remaining 114 children with SpLD, parents of 19 children refused to participate in the study. Thus 95 children were enrolled in the study and all completed the CFTs.The age of these 95 study children ranged from 9-14 years [Table - 2]; with mean age 12.3 years (SD, 1.48). There was a male preponderance, with a male: female ratio of 3.8: 1. A diagnosis of dyslexia was made in 94/95 (98.9%), of dysgraphia in 92/95 (96.8%), and of dyscalculia in 89/95 (93.7%). However, most of the children viz. 86/95 (90.5%) had all three types of SpLD present concomitantly. Of the 95 study children: 45 had average-nonverbal intelligence, 35 had bright normal-nonverbal intelligence, and 15 had superior-nonverbal intelligence. The differences in the mean CFTs scores obtained by the three study groups in the four areas of information were not statistically significant when compared between themselves [Table - 3]. The mean CFTs scores obtained by the three study groups were significantly lower than the standard scores in all four areas of information. For children with SpLD having: (i) average nonverbal intelligence- the mean difference was 8.72 for figural information (P <0.0001, df =168, 95% CI 7.45- 9.99), 9.97 for symbolic information (P <0.0001, df = 168, 95% CI 8.47- 11.47), 8.69 for semantic information (P <0.0001, df = 168, 95% CI 7.20- 10.19), and 2.32 for behavioral information (P <0.0001, df = 168, 95% CI 1.76- 2.89); (ii) bright nonverbal intelligence- the mean difference was 7.34 for figural information (P <0.0001, df =158, 95% CI 5.83- 8.85), 8.70 for symbolic information (P <0.0001, df = 158, 95% CI 7.02- 10.38), 7.77 for semantic information (P <0.0001, df = 158, 95% CI 6.08- 9.46), and 1.45 for behavioral information (P <0.0001, df = 158, 95% CI 0.82- 2.08); and (iii) superior nonverbal intelligence- the mean difference was 7.41 for figural information (P <0.0001, df =138, 95% CI 5.40- 9.42), 10.50 for symbolic information (P <0.0001, df = 138, 95% CI 8.12- 12.88), 10.13 for semantic information (P <0.0001, df = 138, 95% CI 7.84- 12.42), and 1.41 for behavioral information (P =0.0005, df = 138, 95% CI 0.62- 2.20). DISCUSSION The present study results indicate that children with SpLD having average, bright normal and superior nonverbal intelligence have similar range of cognition abilities, which are significantly lower than those of normal children. Their significantly lower cognition abilities viz. abilities for immediate awareness, recognition, or comprehension of stimuli explain why these children have significant and persistent difficulties in the acquisition and use of reading, writing or mathematical abilities. We believe that the present study′s finding are important and will help educators be empathetic towards the difficulties faced by these children at school.SpLD is not just a school disability; it is a life-time disability. The same dysfunctions that interfere with normal learning processes may also have adverse impact on self-image, peer and family relationships, and social interactions.[1],[2] However, if SpLD is diagnosed early, during the primary school years, the child can have a reasonably successful future. For achieving this timely referral to a Special Educator for remedial education, the only recommended therapy for SPLD, is crucial.[1],[2],[13],[14] Using specific teaching strategies and teaching materials, the Special Educator formulates an Individual Education Program to reduce, eliminate or preclude the child′s deficiencies in specific learning areas such as reading, writing and mathematics. The child has to undergo remedial education sessions twice or thrice weekly for a few years to overcome SpLD. What is the utility of our study? Our finding that children with SpLD have similar cognition abilities irrespective of their intelligence levels highlights that: even children with SpLD who have high i.e. bright normal or superior intelligence equally need remedial education to improve their cognition abilities. It is well known that although children with SpLD who have bright normal or superior intelligence may not experience school failure, they too perform below their potential in their school examinations.[1],[2] Their disability may remain undetected or get detected very late, after the time for effective remedial education has elapsed. Early detection of SpLD and initiation of remedial education in children with bright normal or superior intelligence would not only help them score marks in their school examinations commensurate with their intellectual potential, but also help them throughout life by improving their self-image, peer relationships, family relationships, and social interactions. We cannot compare the present study with previous work because there isn′t any. A detailed Medline search did not find any study, in India or elsewhere, which has analyzed cognition abilities in children with SpLD using tests based on the Guilford′s SOI Model. However, Das et al (University of Alberta, Canada) have earlier reported that children with dyslexia are poor in specific cognitive processes that require successive processing and rapid articulation, irrespective of their average or high nonverbal intelligence levels.[15] They had employed a locally developed Cognitive Assessment System, but it was not based on the Guilford′s SOI Model.[15] Three potential limitations of the present study need to be mentioned. First, there was a male preponderance in the subjects assessed [Table - 2]. It is well known that more boys than girls are referred for detection of SpLD, and we could not overcome this limitation.[16] Second, children with very superior (IQ 130) nonverbal intelligence did not get enrolled during the study period and we cannot comment about their cognition abilities. Third, our study was restricted to study of "cognition", which is only the first of five intellectual processes concerned with the learning process as described by Guilford in his SOI model.[5] The other four intellectual processes, viz.: "memory" (i.e. retaining and recalling the contents of thought), "convergent production" (i.e. producing a single best solution to a problem), "divergent production" (i.e. producing a variety of ideas or solutions to a problem), and "evaluation" (i.e. deciding whether the intellectual contents are positive or negative, good or bad) have not been evaluated by us. However, we have no reason to believe that this adversely affects the utility of our results, as Guilford has clearly stated that each of the five intellectual processes function independently.[5] We suggest that future researchers should analyze the abilities of children with SpLD with different grades of intelligence on the other four intellectual processes. To conclude, cognition abilities are similar in children with SpLD having average, bright-normal or superior nonverbal intelligence and they are significantly lower than those of normal children. These findings indicate that remedial education is necessary for all children with SpLD to improve their academic performance. Additional studies are required in various parts of our country to determine the generalization of these results. ACKNOWLEDGEMENTS We thank our Dean, Dr. M.E. Yeolekar for granting us permission to publish this study. We also thank the Principal, Jnana Prabodhini′s Institute of Psychology, Pune for granting us permission to use their Cognition Function Tests for our study; and Dr. D.P. Singh, Reader, Department of Research Methodology, Tata Institute of Social Sciences, Mumbai for his help in the statistical analysis of the data. Lastly, we thank the children who participated in this research project.References
Copyright 2005 - Indian Journal of Medical Sciences The following images related to this document are available:Photo images[ms05014t2.jpg] [ms05014t3.jpg] [ms05014t1.jpg] |
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