Prevalence and clinical characteristics of dyslexia in primary school students.

BACKGROUND: Dyslexia is the most common subtype of learning disabilities with a prevalence ranging from 5-10 per cent. The central difficulty in dyslexia is the phonological awareness deficit. The authors have developed a screening test to assess the reading ability of Thai primary school students. OBJECTIVE: 1. To study the prevalence of dyslexia in first to sixth grade students at Wat Samiannaree School. 2. To study the clinical characteristics such as sex, neurological signs, verbal intelligence and comorbid attention deficit hyperactive disorder (ADHD) of the dyslexia group. METHOD: A total of 486 first to sixth grade students were administered "Raven's progressive matrices test" for estimation of intellectual functioning. Those who scored below the fifth percentile were labeled as mental retardation and excluded from the study. The students' reading ability was evaluated by 3 steps; first by classroom teachers using some items of the screening test, second by the researchers examining some more items individually, and third by the special educator assessing more details in reading and phonology. The students who had a reading ability two-grade levels below their actual grades and impairment in phonology were diagnosed with dyslexia. RESULTS: The prevalence of dyslexia and probable dyslexia were found to be 6.3 per cent and 12.6 per cent, respectively. The male to female ratio of dyslexia was 3.4:1. The dyslexia group had significantly lower Thai language scores than those of the normal group (p < 0.05). All of the dyslexia group had a normal grossly neurological examination but 90 per cent showed positive soft neurological signs. Mean verbal intellectual quotient score in the dyslexia group assessed by using Wechsler Intelligence Scales for Children--Revised was 76 +/- 7. The comorbid ADHD was 8.7 per cent in the dyslexia group. CONCLUSION: Dyslexia was a common problem among primary school students in this study. Further studies in a larger population and different socioeconomic statuses are required to determine the prevalence of dyslexia in the general population. The authors suggest evaluating the reading ability carefully by using a test that can detect phonological awareness deficit in all children who have learning problems.

Effect of oral vitamin E supplementation in children with cholestasis.

OBJECTIVE: Malabsorption and deficiency of vitamin E are common consequences of chronic cholestasis. The objective of this study was to determine vitamin E status by using plasma vitamin E/total lipid ratio (E/L) in children with cholestasis during supplementation with 20 IU/kg/day and 100 IU/kg/day of oral vitamin E capsule, and 50 IU/kg/day of cold water soluble form (CWSIF) of vitamin E. METHOD: Children with cholestasis who were being supplemented with 20 IU/kg/day of oral vitamin E capsule (dl-alpha-tocopherol) were enrolled into this study. After initial evaluation for vitamin E status and liver function, doses of oral vitamin E supplementation were increased to 100 IU/kg/day for 1 month. Then, supplementation was switched to 50 IU/kg/day of CWS/F vitamin E for 1 month. Vitamin E status was assessed by using plasma E/L after each period of supplementation. RESULTS: Eleven children with biliary atresia, aged between 2 and 18 months, were studied. Their median weight standard deviation score (SDS) was -1.35 and median height SDS was -1.26. The medians of serum direct bilirubin and total bilirubin were 6.5 and 12.9 mg/dl, respectively. Only 2 and 3 out of 9 children had plasma E/L above normal cut-off levels during supplementation with 20 and 100 IU/kg/day of vitamin E capsule, respectively. Additionally, 4 of 9 children had plasma E/L above normal cut-off level after one month's supplementation with 50 IU/kg/day of CWS/F vitamin E. All the responders had serum bilirubin levels less than 4 mg/dl while the remainder with serum direct bilirubin level more than 4 mg/dl had their plasma E/L below normal cut-off levels in spite of any vitamin E supplementation. CONCLUSION: Oral vitamin E supplementation with 20 IU/kg/day and 100 IU/kg/day of vitamin E capsule and with 50 IU/kg/day of CWS/F vitamin E were able to normalize vitamin E status in a few cholestatic children who had serum direct bilirubin levels less them 4 mg/dl. In cases of serum direct bilirubin more than 4 mg/dl, neither of vitamin E supplementations was able to correct the vitamin E deficiency status.