To compare and analyze the clinical characteristics of children with delayed language acquisition due to two different diagnoses, which were specific language impairment (SLI, a primarily delayed language development) and global developmental delay (GDD, a language delay related to cognitive impairment).

Among 1,598 children who had visited the developmental delay clinic from March 2005 to February 2011, 467 children who were diagnosed with GDD and 183 children who were diagnosed with SLI were included in this study. All children were questioned about past, family, and developmental history, and their language competences and cognitive function were assessed. Some children got electroencephalography (EEG), in case of need.

The presence of the perinatal risk factors showed no difference in two groups. In the children with GDD, they had more delayed acquisition of independent walking and more frequent EEG abnormalities compared with the children with SLI (p<0.01). The positive family history of delayed language development was more prevalent in children with SLI (p<0.01). In areas of language ability, the quotient of receptive language and expressive language did not show any meaningful statistical differences between the two groups. Analyzing in each group, the receptive language quotient was higher than expressive language quotient in both group (p<0.01). In the GDD group, the Bayley Scales of Infant Development II (BSID-II) showed a marked low mental and motor quotient while the Wechsler Intelligence Scale showed low verbal and nonverbal IQ. In the SLI group, the BSID-II and Wechsler Intelligence Scale showed low scores in mental area and verbal IQ but sparing motor area and nonverbal IQ.

The linguistic profiles of children with language delay could not differentiate between SLI and GDD. The clinicians needed to be aware of these developmental issues, and history taking and clinical evaluation, including cognitive assessment, could be helpful to diagnose adequately and set the treatment plan for each child.