A language disorder is a deficit or problem with any function of language and communication.
Speech and language disorders are extremely common. They can range from slow acquisition of language to sound substitution or stuttering to the inability to understand or produce and language at all. The federal Agency for Healthcare Research and Quality estimated in 2002 that communication disorders cost the United States between $30 and $154 billion annually in lost productivity and money spent on medical care, special education , and remediation.
Language disorders and the brain
Speech and language pathologists and neurologists (doctors who specialize in the brain and nervous system) have known for about 100 years that certain areas in the left hemisphere of the brain—Broca's area in the posterior frontal lobe and Wernicke's area in the temporal lobe—are centrally involved in language functions. Damage to Broca's area results in problems with language fluency: shortened sentences, impaired flow of speech, poor control of rhythm and intonation, and a telegraphic style with missing inflections. Damage to Wernicke's area produces speech that is fluent and often rapid, but with relatively senseless content, many invented words, and word substitutions.
With the invention of new technologies, including computed tomography (CT) scans and magnetic resonance imaging (MRI), several studies have looked at the language development in very young children with lesions in the traditional language areas of the brain. There is surprising agreement among the studies in their results: all find initial delays in language development followed by remarkably similar progress after about age two to three years. Lasting deficits have not been noticed in these children. Surprisingly, there are also no dramatic effects of laterality; lesions to either side of the brain seem to produce virtually the same effects. However, most of the data comes from conversational analysis or relatively unstructured testing, and these children have not been followed until school age. Nevertheless, the findings suggest remarkable plasticity and robustness of language in spite of brain lesions that would devastate an adult's language abilities.
Language disorders and hearing loss
Children with a hearing loss, either from birth or acquired during the first year or two of life, generally have a serious delay in spoken language development. The hearing loss occurs despite very early diagnosis and fitting with appropriate hearing aids. However, in the unusual case that sign language is the medium of communication in the family rather than speech, the child shows no delay in learning to use that language. Hearing development is always one of the first things checked if a pediatrician or parent suspects a language delay . The deaf child exposed only to speech will usually begin to babble ("baba, gaga") at a slightly later point than the hearing child. Recent work suggests that the babbling is neither as varied nor as sustained as in hearing children. However, there is often a long delay until the first words are spoken, sometimes not until age two years or older.
Depending on the severity of the hearing loss, the stages of early language development are also quite delayed. It is not unusual for the profoundly deaf child at age four or five years to only have two-word spoken sentences. It is only on entering specialized training programs for oral language development that the profoundly deaf child begins to acquire more spoken language. Often, such children do not make the usual preschool language gains until they reach grade school. Many deaf children learning English have pronounced difficulties in articulation and speech quality, especially if they are profoundly deaf, since they get no feedback in how they sound. A child who has hearing for the first few years of life has an enormous advantage in speech quality and oral language learning over a child who is deaf from birth or within his or her first year.
Apart from speech difficulties, deaf children learning English often show considerable difficulty with the inflection and syntax of the language, which marks their writing as well as their speech. The ramifications of this delayed language are also significant for learning to read, and reading proficiently. The average deaf high school student often only reads at fourth grade level.
Language disorders and mental retardation
Mental retardation can also affect the age at which children learn to talk. A mentally retarded child is defined as one who falls in the lower end of the range of intelligence , usually with an IQ (intelligence quotient) below 80 on some standardized IQ tests. There are many causes of mental retardation, including identified genetic syndromes such as Down syndrome , Williams syndrome , or fragile X syndrome .
Retardation can also be caused by damage to the fetus during pregnancy due to alcohol, drug abuse or toxicity, and disorders of the developing nervous system such as hydrocephalus . Finally, there are environmental causes following birth such as lead poisoning , anoxia, or meningitis .
Any of these situations is likely to slow down the child's rate of development in general, and thus to have effects on language development. However, most children with very low IQs develop some language, suggesting it is a relatively "buffered" system that can survive a good deal of insult to the developing brain. In cases of hydrocephalus, for example, it has been noted that children who are otherwise quite impaired intellectually can have impressive conversational language skills. Sometimes called the "chatterbox syndrome," this linguistic sophistication belies their poor ability to deal with the world. In an extreme case, a young man with a tested IQ in the retarded range has an apparent gift for acquiring foreign languages, and could learn a new one with very little exposure. For example, he could do fair translations at a rapid pace from written languages as diverse as Danish, Dutch, Hindi, Polish, French, Spanish, and Greek. He is, in fact, a savant in the area of language, and delights in comparing linguistic systems, although he does not have the mental capacity to live independently.
Adults should not consider retarded children to be a uniform class; different patterns can arise with different syndromes. For example, in hydrocephalic children and Williams syndrome, language skills may be preserved to a degree greater than their general intellectual level. In other groups, including Down syndrome, there may be more delay in language than in other mental abilities.
Most retarded children babble during the first year and develop their first words within a normal time span, but are then slow to develop sentences or a varied vocabulary. Vocabulary size is one of the primary components of standardized tests of verbal intelligence, and it grows slowly in retarded children. Nevertheless, the process of vocabulary development seems quite similar: retarded children also learn words from context and by incidental learning, not just by direct instruction.
Grammatical development, though slow, comes in the same way, and in the same order, as it does for normal IQ children. The child's conversation, however, may contain more repetition. The Down syndrome adolescent with an IQ of around 50 points does not seem to progress beyond the grammatical level of the normally intelligent child at three years, with short sentences that are restricted in variety and complexity. Children with Down syndrome are also particularly delayed in speech development. This is due in part to the facial abnormalities that characterize this syndrome, including a relatively large tongue. It is also linked to the higher risk they appear to suffer from ear infections and hearing loss.
Specific language impairment
Specific language impairment describes a condition of markedly delayed language development in the absence of any apparent handicapping conditions such as deafness, autism , or mental retardation. Specific language impairment (SLI) is also sometimes called childhood dysphasia, or developmental language disorder.
Children with SLI usually begin to talk at approximately the same age as normal children, but are markedly slower in their progress. 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 grade school and beyond, where these children encounter difficulties in reading and writing. The child with SLI often has difficulties learning language "incidentally," (picking up the meaning of a new word from context or generalizing a new syntactic form). This is in contrast to the normal child's development, 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 the autistic child.
Very little is known about the cause or origin of specific language impairment, although evidence is growing that the underlying condition may be a form of brain abnormality. However, any such brain abnormality is not readily apparent with existing diagnostic technologies. When compared to other children, SLI children do not
About one in six people, or 42 million individuals in the United States, have some type of communication disorder. About 28 million have speech, voice, or language problems associated with hearing loss, and about 14 million have similar problems not associated with impaired hearing. More than one million children in special education classes are categorized as having a speech or language disability.
Causes and symptoms
Language disorders can arise at many points in the language production process such as:
- from damage to the part of the brain that produces language
- from damage to the part of the brain that understands language
- from hearing loss
- from damage to the muscles and tissues of the mouth and throat needed for speech (e.g. cleft palate )
- from neurological disorders that interrupt the transmission of information necessary to receive and produce language
- from unknown (idiopathic) causes
Symptoms of language disorders vary widely, but include:
- slow acquisition of speech and language
- inability to make the physical sounds associated with language production (mutism)
- failure to make sense of spoken or written words
- inability to speak under certain social circumstances (selective mutism)
- transformations of words or sounds when speaking
- inability to recall known words
When to call the doctor
Parents should talk to their pediatrician immediately if their child appears to have hearing impairment . They should also consult with their doctor if the child does not babble or begin to use single words within the normal time frame. Parents of older children may need a referral to a speech and language specialist if their child stutters, lisps, has difficulty forming words or producing coherent speech, or exhibits certain learning disabilities.
Speech and language disorders are usually diagnosed by a speech and language pathologist, often with the help of a pediatrician, audiologist (hearing specialist), and neurologist. Many assessment tests are designed specifically for use in children, including the Clinical Evaluation of Language Fundamentals (also available in Spanish); the Preschool Language Scale (also available in Spanish); the Test of Language Development, Primary; and the Test of Language, Intermediate. There are assessments designed to evaluate speech production, such as the Goldman-Fristoe test of Articulation.
Treatment varies, depending on the type and cause of the language disorder. However, in all language disorders and delays, early intervention is key to improvement. Many educators of the deaf now urge early compensatory programs in signed languages, because the deaf child shows no handicap in learning a visually based language. Deaf children born to signing parents begin to "babble" in sign at the same point in infancy that hearing infants babble speech, and proceed from there to learn a fully expressive language. However, only 10 percent of deaf children are born to deaf parents, so hearing parents must show a commitment and willingness to learn sign language. Furthermore, command of at least written English is still a necessity for such children to be able to function in the larger community.
Speech therapy can be a considerable aid to many children with language disorders For example, it can help to make a Down syndrome child's speech more intelligible. Despite the delay, children with Down syndrome are often quite sociable and interested in language for conversation.
Surgery, followed by speech therapy, can correct physical deformities, such as cleft palate, that interfere with speech production.
Psychotherapy can help older children whose language disorders are psychologically based.
Prognosis varies on an individual basis, depending on the cause, type, and severity of the language disorder. Those children who receive early intervention therapies are more likely to have a better outcome than those for whom services are delayed.
Many language disorders are not preventable. However, those that arise from damage to the fetus due to the mother's use of drugs or alcohol during pregnancy can be prevented by avoiding these substances.
Language is such a critical part of our society that parents are justly concerned when their child has a language disorder. The parents' approach to the disorder can greatly influence the child's self-image, self-esteem , and ultimately his or her success in reaching the fullest language potential.
Speech pathologist —An individual certified by the American Speech-Language-Hearing Association (ASHA) to treat speech disorders.
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American Speech-Language-Hearing Association. 10801 Rockville Pike, Rockville, MD 20852. (800) 638-8255. Web site: http://www.asha.org.
Tish Davidson, A.M. Jill De Villiers, Ph.D.