Specific language impairment (SLI) is a serious and long-lasting developmental disorder that affects the acquisition and development of spoken language. It can affect either comprehension, expression, or both.
It is classified as a “heterogeneous” disorder because no two SLI are alike. Symptoms vary greatly from one child to another and do not always manifest in the same form and with the same intensity.
Specific language impairment may involve one or more components of language: phonetics and phonology, semantics, morphosyntax, and/or pragmatics.
Specific difficulties by area
Phonetics / Phonology
In the phonetic / phonological area, children might have unintelligible speech, make phonological simplification errors, have dyslalia, and auditory discrimination problems.
In the semantic area, children might have a reduced vocabulary and difficulties in lexical access and recalling words; for this reason, they usually use general purpose words and circumlocutions. Children with SLI present difficulties in expression and with understanding abstract words, that is, language that is not in context. They experience difficulties in learning new words as well.
The area of morphosyntax is the most seriously impaired. Children usually use simple sentences with few elements, generally poorly structured with agreement errors, badly conjugated verbs, omissions of prepositions, pronouns, etc.
If the area of morphosyntax is not impaired, we cannot speak of SLI.
The area of pragmatics is always impaired in individuals with SLI. They have difficulties with establishing social relationships through play, understanding and respecting rules, etc. In addition, children experience difficulties in understanding emotional states and solving interpersonal problems. Children with SLI have difficulty making inferences, that is, understanding what is not literal and/or contextualized like ironies, double entendres, metaphors, jokes, etc. All of this significantly influences the way in which they relate to others.
All these difficulties cannot be attributed to or associated with any other disorder or condition, hence hearing loss, brain damage, low intelligence quotient, motor deficit, socio-environmental factors or developmental alterations are ruled out as the cause (Leonard, 1998).
Developmental areas affected by SLI
The term ‘specific language impairment’ (SLI) has been in use only since the 1980s; however, it has already undergone several terminology changes (“dysphasia” being the best known term). Currently, the term has been removed from the new DSM-5 classification, which has taken the word ‘specific’ out and adopted the label “language disorder,” which is included in the diagnostic category “communication disorders.”
SLI is further subdivided in two types:
There is still no clear consensus among the committee of experts on the most appropriate term for SLI. However, many seem to agree that “specific” is a somewhat incongruous term since it does not only affect language (most common impairment in children with SLI) but also affects many other areas of development such as:
- Working memory
- Mentalizing skills
- Executive functions
- Motor control
- Social development
- Academic performance
Causes of specific language impairment
While the causes of the disorder are still unknown, recent studies suggest a strong genetic influence. In fact, 50 to 70% of children with SLI have at least one other family member with the same disorder. In addition, mutations have been identified in the FOXP2 gene, known as the ‘language gene.’
Symptoms of specific language impairment
SLI has a prevalence of 2-7% among the child population with a male to female ratio of 2:1 (among females it is 3:1). It is a severe and persistent disorder that affects the acquisition of language from the beginning and the impact persists into adulthood. For this reason, early detection and intervention are of vital importance.
Certain red flags must be heeded as soon as we notice them. Some myths and legends should be avoided and we should stop saying things like “he will eventually speak,” “she is still very young,”, “everyone learns at their own pace.” SLI always manifests itself as a delay in language acquisition. This does not mean that all late talkers will develop specific language impairment, yet all kids with SLI were late talkers.
Children with SLI often start talking later and their vocabulary repertoire is very limited. Strong indicators of SLI are:
- A restricted lexicon at the age of 2, that is, if children don’t have at least 50 words in their lexical storage and, out of those words, 20% are verbs. Another good indicator at this age is the inability to produce 2-word phrases.
- At age 3, they may talk but their speech is unintelligible, sentences—mostly 3-word sentences—are filled with phonetic and phonological errors. They also have difficulties in the comprehension of Wh-questions (what, how, who, etc.).
- At age 4, they use only 3-word sentences or less, do not use adjectives or pronouns, have limited vocabulary, and do not construct narratives.
- At age 5, they produce grammatically incorrect sentences and have trouble recalling words when telling stories, etc.
Watch out! These are warning signs that may indicate possible language difficulties. However, if a child shows one of them, that does not necessarily imply a SLI diagnosis.
Diagnosis and intervention in children with SLI
Evaluation, diagnosis and early intervention are essential in the progress of children with SLI.
The diagnosis is very complex and poses many problems, especially at an early age.
- Before age 3, it is difficult to determine whether spoken language problems are due to a language delay or a language disorder.
- By the age of 4, one can already speak of a possible SLI.
- At the age of 5, the diagnosis is usually confirmed.
We should not wait to confirm a diagnosis but pay attention to the signs from the moment they are first detected; we need to keep in mind the great impact this disorder has on their academic, personal and emotional life, not only at a young age.
When these children go on to primary education, they compensate for these difficulties; we could say that the symptomatology becomes less evident or visible, especially in the 2nd and 3rd years of primary school, since they are able to communicate with a more formal and elaborated language, which can be mistaken for having overcome their linguistic difficulties. But this is not the case: they will continue to experience difficulties with the lexicon, impairments in expressive language and will have difficulty in constructing narratives and maintaining a coherent discourse by using appropriate cohesive devices. In addition, their stories tend to be shorter and include fewer main and secondary story ideas, and often told in the wrong sequence, etc.
Moreover, children with SLI tend to have learning difficulties, especially in reading and writing development as well as in mathematics due to problems of comprehension and acquisition of more abstract content. Their academic performance is impaired at all stages, including secondary education.
Comorbidity of specific language impairment
SLI is comorbid with other disorders such as dyslexia, dyscalculia, dysgraphia, attention deficit hyperactivity disorder, and alterations in social interaction among others.
Language disorder is considered to be a special educational need. If there is a large curriculum gap (1.5-2 years), children may have significant curricular adaptations.
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