Language Delays
James Coplan
I. Description of the problem.
Language is a symbol system for the storage or exchange of information.
Expressive language refers to the ability to generate symbolic output. This output may be either visual (picture exchange cards, signing, writing) or auditory (speech).
Receptive language refers to the ability to decode (i.e., extract meaning from) the language output of others. Receptive language encompasses visual (visual schedules, sign language comprehension, reading) and auditory (listening comprehension) skills.
Speech refers to the mechanical aspects of sound production (articulation, rate, rhythm, volume, pitch, and vocal quality).
Language disorders encompass any defect in the ability to encode or decode information through symbolic means.
Speech disorders encompass any deficit in the production of speech sounds. Children with disordered language (as in autistic spectrum disorder—ASD) may have normal speech. Conversely, children with disordered speech (as in hearing impairment, dysarthria, or stuttering) may have normal language.
A. Epidemiology. Delayed speech or language development are the most common developmental disorders of childhood, occurring in approximately 10% of preschool children (Table 53-1).
B. Development of language.
1. Language acquisition results from a complex interplay of innate biological capabilities and environmental stimulation. Infants acquire language through observation and through listening to speakers in their environment. Vocalizations during the first six months of life (cooing, laughing, monosyllabic and polysyllabic babbling) are biologically programmed; they are universal across all cultures, and occur even in infants who are deaf. By the latter half of the first year of life, a hearing infant’s vocalizations begin to reflect the vocal repertoire of his or her caregivers, with selective refinement of some sounds (the guttural “ch” for Germanic and Semitic speakers, the rolling “r” in Spanish, etc.), and the pruning away of others. This is also the age when vocalizations begin to dwindle in an infant with congenital deafness.
2. By age 12 months, normal infants have grasped the notion that an arbitrary set of sounds symbolically represent a specific object or action; the arbitrary sound “bottle” not only produces a bottle (courtesy of the baby’s caregiver), but the sound “bottle” also means bottle. Likewise, a 12-month-old knows that he or she can signify a desired object by pointing to it rather than reaching for it. This ability to represent objects or actions in symbolic form constitutes the central feature of language. Two-word phrases appear by age 24 months, and complete sentences by age 36 months. The ability to respond to common “wh” questions (who, what, when, where, and why) is fully developed by 48 months. That is also the age by which a child’s speech should be completely understandable (even though the child may make minor articulation errors).
3. Some consider language development to be just one aspect of overall cognitive development, marked by a general ability to infer rules and causal relationships. Alternatively, language acquisition may represent a highly modular skill, emerging simultaneously with, but independently of, general cognitive ability. There are theoretical and clinical examples to support both views: In children with normal development or global delay (intellectual disability), language proficiency correlates closely with overall cognitive ability. On the other hand, there are many examples of children with normal overall cognitive ability but selective impairment of language (Developmental Language Disorder—DLD; see below), as well as children with superficially preserved language skills but broader evidence of general cognitive impairment (Williams Syndrome).
Table 53-1. Causes of delayed speech or language
Disorder
Prevalence (per 1,000 children)
Hearing loss (HL)
• Permanent, profound
1-3
• Permanent, mild to moderate
3-10
• Intermittent, mild to moderate (otitis media with effusion.*)
30-50?
Intellectual disability
30
Developmental language disorders (DLD)†
50
Autistic spectrum disorders (ASD)
10
Dysarthria‡
1-3
* Up to 25% of children have chronic/recurrent otitis media with effusion (OME) during the first 3 years of life. The “attack rate” for speech and language delay due to OME remains unknown.
† Focal impairment of brain systems serving language, with sparing of the rest of the central nervous system (CNS).
‡ Usually encountered within the context of cerebral palsy.
C. Etiology of language delays.
1. Environmental.
In a typical home environment, lack of stimulation is seldom, if ever, the cause of speech or language delay. Suggestions that such parents become “more stimulating” may do more harm than good, either by instilling parental guilt or by delaying a search for an underlying organic disorder as the basis for the child’s delay.
Bilingual upbringing does not cause speech or language delay. The bilingual child may intermix the vocabularies of both languages, but total vocabulary size and length of utterance should be equivalent to those of a child reared in a monolingual environment.
Birth order or having an older sibling who “talks for the child” do not cause speech or language delay.
Social or environmental risk factors for delayed speech or language (e.g., poverty, lack of parental stimulation) are frequently intertwined with organic risk factors such as nutritional status, low-level lead exposure, low-grade iron deficiency, or parental genetic endowment (language disorders have a strongly genetic component). Thus, a child may receive a multifactorial “hit” to speech or language development. (Conversely, some children will be fortunate enough to get a multifactorial “boost” from these same genetic, nutritional, cultural, and environmental factors.)
2. Organic. Speech or language delay may occur in isolation, as in the case of developmental language disorders (DLD), or may occur as one facet of some other disorder, such as hearing loss (HL), intellectual disability, autistic spectrum disorders (ASD), or dysarthria (physical impairment of oral motor movement, typically seen within the context of generalized upper motor neuron impairment, i.e., cerebral palsy). DLDs are clinically heterogeneous, and may involve some combination of phonologic development (speech sound production), semantics (meaning), syntax (sentence structure), and pragmatics (use of language as a tool for social interchange).
3. Developmental.
Laziness, twinning, and tongue-tie do not cause language delay.
So-called twin speech is often indicative of the fact that both twins have an organically based language disorder, rather than a private language.
“Constitutional delay” implies a normal long-term developmental outcome. Although constitutional delay of speech acquisition exists, this is a diagnosis that can be established only in retrospect. If a preschool child’s speech pattern is deficient based on comparison with age norms, then action is called for. Adopting a wait-andsee attitude in the hope that the child will “outgrow” the problem is inappropriate.
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