PURPOSE: It is well known that expressive language impairment is commonly less severe than receptive language impairment in children with autism spectrum disorder (ASD). However, this result is based on experiments in Western countries with Western language scales. This study tries to find whether the result above is applicable for toddlers in a non-Western country; more specifically, in Korea with non-Western language scales. MATERIALS AND METHODS: The participants were 166 toddlers aged between 20 months and 50 months who visited the clinic from December 2010 to January 2013. The number of toddlers diagnosed as ASD and developmental language delay (DLD) was 103 and 63, respectively. Language development level was assessed using Sequenced Language Scale for Infants (SELSI), a Korean language scale. Using SELSI, each group was divided into 3 sub-groups. Moreover, the group difference by age was observed by dividing them into three age groups. Chi-square test and linear-by-linear association was used for analysis. RESULTS: Receptive language ability of the DLD group was superior to that of the ASD group in all age groups. However, expressive language ability in both groups showed no difference in all age groups. A greater proportion of expressive dominant type was found in ASD. The 20-29 months group in ASD showed the largest proportion of expressive language dominant type in the three age groups, suggesting that the younger the ASD toddler is, the more severe the receptive language impairment is. CONCLUSION: These findings suggest that receptive-expressive language characteristics in ASD at earlier age could be useful in the early detection of ASD.
Child Development Disorders, Pervasive/*complications ; Child, Preschool ; Developmental Disabilities/*complications ; Early Diagnosis ; Female ; Humans ; Infant ; *Language ; *Language Development ; Language Development Disorders/complications/*diagnosis ; Language Tests ; Male ; Republic of Korea

Autism spectrum disorder (ASD) is a complex neurodevelopmental disorder, with multiple genetic and environmental risk factors. The interplay between genetic and environmental factors has become the subject of intensified research in the last several years. Vitamin D deficiency has recently been proposed as a possible environmental risk factor for ASD. Vitamin D has a unique role in brain homeostasis, embryogenesis and neurodevelopment, immunological modulation (including the brain's immune system), antioxidation, antiapoptosis, neural differentiation and gene regulation. Children with ASD had significantly lower serum levels of 25-hydroxy vitamin D than healthy children.Therefore vitamin D deficiency during pregnancy and early childhood may be an environmental trigger for ASD.
Child Development Disorders, Pervasive ; etiology ; genetics ; Embryonic Development ; Homeostasis ; Humans ; Vitamin D ; physiology ; Vitamin D Deficiency ; complications