Specific Language Impairment
Specific language impairment (SLI) describes a condition of markedly delayed language development in the absence of any apparent handicapping conditions.
Many different terms have been used to describe the childhood disorder that is characterized by markedly delayed language development in the absence of any conditions such as deafness, autism, or mental retardation that would explain the delay. SLI is also sometimes called childhood dysphasia or developmental language disorder.
Estimates of true SLI vary according to the age of identification. Some experts argue that as many as 10 percent of two-year-olds may have a specific language impairment, but by age three or four, that percentage drops considerably, presumably because some difficulties resolve themselves. The incidence in the general population is estimated at about 1 percent. SLI is more common in boys than girls.
Causes and symptoms
Children with SLI usually begin to talk at roughly the same age as normal children but are markedly slower in the progress they make. They seem to have particular problems with inflection and word forms, such as leaving off endings when forming verb tenses (for example, the ed ending when forming the past tense). This problem can persist much longer than early childhood, often into the grade school years and beyond, where these children encounter difficulties in reading and writing. The child with SLI also often has difficulties learning language incidentally, that is, in picking up the meaning of a new word from context or generalizing a new syntactic form. This is in decided contrast to the normal child's case, where incidental learning and generalization are the hallmarks of language acquisition. Children with SLI are not cognitively impaired and are not withdrawn or socially aloof like an autistic child.
Very little is known about the cause or origin of specific language impairment, although evidence in the early 2000s is growing that the underlying condition may be a form of brain abnormality. Any such brain abnormality, however, is not readily apparent with existing diagnostic technologies. SLI children do not have clear brain lesions or marked anatomical differences from other children in either brain hemisphere. However, there is some indication that SLI can be passed down from parents to children. Research as of 2004 suggested a possible genetic link, although there are many problems in identifying such a gene. Sometimes the siblings of an affected child show milder forms of the difficulty, complicating the picture. One of the major stumbling blocks is the definition of the disorder, because children with SLI show many different kinds of symptoms which makes it hard to determine what the genetic cause of the disorder might be.
Some investigators have attributed the difficulties that children with SLI have to problems with speech sound perception, suggesting that inflection and word forms such as endings are hard for the child to perceive because those items are fleeting and unstressed in speech. It is not that the child is deaf in general but that he or she has a specific difficulty discriminating some speech sounds.
Other researchers have argued that this difficulty is not specific to speech but reflects a general perceptual difficulty with the processing of rapidly timed events, of which speech is the most taxing example. The left hemisphere of the brain seems to be specialized for processing rapid acoustic events, so perhaps the child with SLI has a unique difficulty in that part of the brain. Some researchers investigate children with SLI who speak different languages to see if any patterns emerge in the kinds of difficulties the children experience.
When to call the doctor
If a parent notices that a child is having problems with speech or is not achieving language milestones around the usual time, a doctor should be consulted.
Early identification is very important for the success of interventions for SLI. The disorder is usually diagnosed by comparing a child's linguistic abilities to those that are expected for children of the same age. If the child is significantly behind his or her age peers in terms of language development, SLI is likely. One procedure for diagnosing children aged 24 to 36 months asks parents to complete a standardized questionnaire in which they check off the vocabulary the child knows and write down examples of the child's two-word sentences. If the child's vocabulary contains fewer than 50 words and the child does not use any two-word sentences, that is an indication of SLI or another language disorder.
SLI is generally treated by intervention that focuses on helping the child with whatever specific language problems he or she is having. The child with SLI may become increasingly aware of his or her difficulties with language and may lose spontaneity and avoid speaking as he or she gets older. Intensive language intervention can allow these children to make considerable gains, with modeling of appropriate linguistic forms that the child is having difficulty with being especially effective.
The prognosis for children with SLI depends very heavily on the type and severity of the language problem experienced. Many language problems can be largely overcome, although some difficulties usually persist.
There is no known way to prevent SLI.
Children with SLI are often at risk for reduced performance in other areas of their lives because of their difficulty in mastering language. SLI can lead to decreased social interaction and decreased school performance.
Inflection—Variations in the pitch or tone of a voice.
Leonard, Laurence B. Children with Specific Language Impairment. Cambridge, MA: MIT Press, 2000.
Weiss, Amy L. Preschool Language Disorders Resource Guide: Specific Language Impairment. San Diego, CA: Singular Thomson Learning, 2001.
Conti-Ramsden, Gina. "Processing and Linguistic Markers in Young Children with Specific Language Impairment." Journal of Speech, Language, and Hearing Research 46 (October 2003): 1029–38.
Fujiki, Martin, et al. "The Relationship of Language and Emotion Regulation Skills to Reticence in Children with Specific Language Impairment." Journal of Speech, Language, and Hearing Research 47 (June 2004): 637–47.
Nation, Kate, et al. "Hidden Language Impairments in Children: Parallels Between Poor Reading Comprehension and Specific Language Impairment?" Journal of Speech, Language, and Hearing Research 47 (February 2004): 199–212.
Tish Davidson, A.M. Jill De Villers, Ph.D.