Dr. Johnston of Johns Hopkins University School of Medicine and Chief Medical Officer at Kennedy Krieger Institute has no relevant financial relationships to disclose.)
This article includes discussion of developmental language disorder, developmental speech disorder, specific language disorder, and specific language impairment. The foregoing terms may include synonyms, similar disorders, variations in usage, and abbreviations.
Developmental language delays and language disorders are a relatively common developmental finding in preschool children. The author reviews current literature; studies indicate a persistence of language delays in a percentage of children.
• Developmental language disorders are not uncommon, and they have some long-term impacts on the lives of the individuals.
• Clinicians need to rule out disorders such as hearing impairment, mental retardation, autism, and other neurologic disorders that can also lead to language delays.
• No clear etiology has been found for developmental language disorders, but there is much interest in finding a gene or genes that affect language development.
Historical note and terminology
Developmental language disorders have been examined in the literature for some time, but no consistent definition or classification system has been used across studies. Developmental language disorders are distinguished from other conditions by a language deficit that results in problems with comprehension, production, or usage of language. Developmental language disorders are those that do not fit into other categories such as autism, elective mutism, degenerative disorders, or mental retardation.
One classification of communication disorders was based on clinical, functional, or anatomical features and associated findings. One of the categories in this classification, developmental speech disorder syndrome, included a wide variety of disorders ranging from mild delays in articulation and language development to severe comprehension difficulties and lack of speech development. No further differentiation was made, and this was a diagnosis of exclusion (Ingram 1972).
The fourth edition of the Diagnostic and Statistical Manual of Mental Disorders classified developmental language disorders as communication disorders and follows a classification that focuses on the phenotypic expression of the disorder: expressive language disorder, mixed receptive-expressive language disorder, phonological disorder (formerly developmental articulation disorder), and communication disorder not otherwise specified (American Psychiatric Association 1994). Each of these disorders must interfere with academic or occupational achievement or with social communication. Expressive language disorder and mixed receptive-expressive language disorder are defined by a discrepancy between nonverbal intelligence and language abilities. They are distinct from pervasive developmental disorder (now called autism spectrum disorder) and each other: expressive language disorder spares receptive abilities, whereas mixed receptive-expressive language disorder affects both receptive and expressive abilities. Communication disorders may coexist with mental retardation, speech-motor or sensory deficit, or environmental deprivation, but the difficulties are in excess of those usually associated with these problems.
An attempt to specifically subcategorize developmental language disorders or dysphasias focused on 3 large subcategories: (1) expressive language disorder, (2) mixed disturbance (both receptive and expressive language is impaired), and (3) a higher order processing disorder based on clinical observations (Klein and Rapin 1990).
Although attempts to classify preschool language disorders have focused on the global nature of the disordered language (receptive, expressive, mixed), other attempts to classify developmental language disorders have focused on the nature of the spoken language deficit (Rapin and Allen 1988; Rapin 1996). Further subgroupings include phonologic-syntactic disorders that display both phonologic disturbances (omissions, substitutions, and distortions of consonants and consonant clusters) and syntactic impairment evidenced by lack of small words and absence of endings. Oromotor dysfunction may be seen in these disorders. Comprehension, semantics, pragmatics, and prosody are relatively spared. Verbal auditory agnosia is characterized by an absence of auditory comprehension and little or no expressive speech. Patients with semantic-pragmatic disorders are fluent but are impaired in comprehension and show deficits in using the rules that govern the use of language in context. They often evidence dysprosody. The lexical-syntactic syndrome is marked by poor syntactic skills and difficulty finding words. Paraphasia is seen, but pragmatics, phonology, and comprehension are relatively spared.
The new DSM-V (Diagnostic and Statistical Manual of Mental Disorders, 5th edition) has moved back to a broader categorization of communication disorders (American Psychiatric Association 2013). The subcategory of language disorders now includes significant delays or functional difficulties in either expressive or receptive language for various forms of communication, including but not limited to, written and spoken communication. Social (pragmatic) communication disorder addresses difficulty using language appropriately in a social context. There is also a general category of unspecified communication disorder, and speech difficulties are covered under speech sound disorder and childhood-onset fluency disorder.
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