The prevalence of expressive language disorder is estimated to be as high as 6 percent in children between the ages of 5 and 11 years of age. Surveys have indicated rates of expressive language disorder as high as 15 percent in children younger than age 3 years. In school-age children older than the age of 11 years, the estimates are lower, ranging from 3 percent to 5 percent. The disorder is two to three times more common in boys than in girls and is most prevalent among children whose relatives have a family history of phonological disorder or other communication disorders.

Children with developmental language disorders, such as expressive language disorder, have above-average rates of comorbid psychiatric disorders. In one large study of children with speech and language disorders by Lorian Baker and Dennis Cantwell, the most common comorbid disorders were attention-deficit/hyperactivity disorder (ADHD) (19 percent), anxiety disorders (10 percent), and oppositional defiant disorder and conduct disorder (7 percent combined). Children with expressive language disorder are also at higher risk for a speech disorder, receptive difficulties, and other learning disorders.

Many disorders—such as reading disorder, developmental coordination disorder, and other communication disorders—are associated with expressive language disorder. Children with expressive language disorder often have some receptive impairment, although not always sufficiently significant for the diagnosis of mixed receptive-expressive language disorder. Delayed motor milestones and a history of enuresis are common in children with expressive language disorder. Phonological disorder is commonly found in young children with the disorder, and neurological abnormalities have been reported in a number of children, including soft neurological signs, depressed vestibular responses, and electroencephalogram (EEG) abnormalities. On the other hand, a recent study found that boys with serious behavior problems also had high levels of unidentified expressive language disorders; thus, it may be important to screen for language dysfunction in children who are extremely behaviorally disordered.

The specific cause of developmental expressive language disorder is likely to be multifactorial. Subtle cerebral damage and maturational lags in cerebral development have been postulated as underlying causes. Some children with language disorders have difficulty processing information in a time-limited manner. Scant data are available on the specific brain structure of children with language disorder, but limited magnetic resonance imaging (MRI) studies suggest that language disorders are associated with a loss of the normal left-right brain asymmetry in
the perisylvian and planum temporale regions. Results of one small MRI study suggested possible inversion of brain asymmetry (right > left). Left-handedness or ambilaterality appears to be associated with expressive language problems. Evidence shows that language disorders occur with higher frequency in certain families. Genetic factors have been suspected to play a role, and several studies of twins show significant concordance for monozygotic twins for developmental language disorders. Some studies have found that some individuals with Williams-Beuren syndrome are at an increased risk of expressive language disorder. Environmental and educational factors are also postulated to contribute to developmental language disorders. Data suggest that prenatal exposure to substances such as alcohol and cocaine, for example, are likely to be associated with both delays in language acquisition and expressive language ability.

Expressive language disorder is present when a child has a selective deficit in language skills and is functioning well in nonverbal areas and in receptive skills. Markedly below-age-level verbal or sign language, accompanied by a low score on standardized expressive verbal tests, is diagnostic of expressive language disorder (Table 37-1). The disorder is not caused by a pervasive developmental disorder, and a child with an expressive language disorder usually develops some nonverbal strategies to aid in socialization. A child with an expressive language disorder exhibits the following features: limited vocabulary, simple grammar, and variable articulation. “Inner language” or the appropriate use of toys and household objects is present. To confirm the diagnosis, a child is given standardized expressive language and nonverbal intelligence tests. Observations of children’s verbal and sign language patterns in various settings (e.g., schoolyard, classroom, home, and playroom) and during interactions with other children help ascertain the severity and specific areas of a child’s impairment and aid in early detection of behavioral and emotional complications. Family history should include the presence or absence of expressive language disorder among relatives.

The essential feature of expressive language disorder is marked impairment in the development of age-appropriate expressive language, which results in the use of verbal or sign language markedly below the expected level in view of a child’s nonverbal intellectual capacity. Language understanding (decoding) skills remain relatively intact. When severe, the disorder becomes recognizable by about the age of 18 months, when a child fails to utter spontaneously or even echo single words or sounds. Even simple words, such as “Mama” and “Dada,” are absent from the child’s active vocabulary, and the child points or uses gestures to indicate desires. The child seems to want to communicate, maintains eye contact, relates well to the mother, and enjoys games such as pat-a-cake and peek-a-boo. The child’s vocabulary is severely limited. At 18 months, the child may be limited to pointing to common objects when they are named.

When a child with expressive language disorder begins to speak, the language impairment gradually becomes apparent. Articulation is often immature; numerous articulation errors occur but are inconsistent, particularly with such sounds as th, r, s, z, y, and l, which are either omitted or are substituted for other sounds.

By the age of 4 years, most children with expressive language disorder can speak in short phrases but may have difficulty retaining new words. After beginning to speak, they acquire language more slowly than do most children. Their use of various grammatical structures is also markedly below the age-expected level, and their developmental milestones may be slightly delayed. Emotional problems involving poor self-image, frustration, and depression may develop in school-age children.

Language disorders are associated with many other psychiatric disorders, and, thus, the language disorder itself may be difficult to separate from other difficulties. In mental retardation, patients have an overall impairment in intellectual functioning, as shown by below-normal intelligence test scores in all areas, but the nonverbal intellectual capacity and functioning of children with expressive language disorder are within normal limits. In mixed receptive-expressive language disorder, language comprehension (decoding) is markedly below the expected age-appropriate level, whereas in expressive language disorder, language comprehension remains within normal limits.

In pervasive developmental disorders, in addition to the cardinal cognitive characteristics, affected children have no inner language, symbolic or imagery play, appropriate use of gesture, or capacity to form warm and meaningful social relationships. Moreover, children show little or no frustration with the inability to communicate verbally. In contrast, all these characteristics are present in children with expressive language disorder.

Children with acquired aphasia or dysphasia have a history of early normal language development; the disordered language had its onset after a head trauma or other neurological disorder (e.g., a seizure disorder). Children with selective mutism have a history of normal language development. Often these children will speak only in front of family members (e.g., mother, father, and siblings). Children affected by selective mutism are socially anxious and withdrawn outside of the family.

Children with speech and language disorders should have an audiogram to rule out hearing loss.

The prognosis for expressive language disorder is related to the severity of the disorder. Studies of “late talkers” concur that 50 to 80 percent of these children master language skills that are within the expected level during the preschool years. Most children who begin to talk later than average but catch up during preschool years are not at high risk to develop further language or learning disorders. Outcome of expressive language disorder is influenced by other comorbid disorders. If children do not develop mood disorders or disruptive behavior problems, the prognosis is better. The rapidity and extent of recovery depend on the severity of the disorder, the child’s motivation to participate in therapy, and the timely institution of speech and other therapeutic interventions. The presence or absence of other factors—such as moderate to severe hearing loss, mild mental retardation, and severe emotional problems—also affects the prognosis for recovery. As many as 50 percent of children with mild expressive language disorder recover spontaneously without any sign of language impairment, but children with severe expressive language disorder may later display features of mild to moderate language impairment.

Controversy exists among experts whether intervention for young children with expressive language difficulties should be initiated as soon as it is noted or whether waiting until age 4 or 5 years is the optimal time to begin treatment. Treatment for expressive language disorder is generally not initiated unless it persists after the preschool years. Various techniques have been used to help a child improve use of such parts of speech as pronouns, correct tenses, and question forms. Direct interventions use a speech and language pathologist who works directly with the child. Mediated interventions, in which a speech and language professional teaches a child’s teacher or parent how to promote therapeutic language techniques, have also been efficacious. Language therapy is often aimed at using words to improve communication strategies and social interactions as well. Such therapy consists in behaviorally reinforced exercises and practice with phonemes (sound units), vocabulary, and sentence construction. The goal is to increase the number of phrases by using block-building methods and conventional speech therapies.

Psychotherapy may be useful for children whose language impairment has affected their self-esteem, insofar as it can be used as a positive model for more effective communication and broadening social skills. Supportive parental counseling may be indicated in some cases. Parents may need help to reduce intrafamilial tensions arising from difficulties in rearing language-disordered children and to increase their awareness and understanding of the disorder.

More research is needed to establish whether early intervention for preschoolers with language deficits has long-term benefits and to develop comprehensive treatment programs that may address the direct language interventions along with interventions for common comorbid communication and learning disorders.

Mixed receptive-expressive language disorder is believed to occur in about 5 percent of preschoolers and to persist in approximately 3 percent of school-age children. It is less common than expressive language disorder alone. Mixed receptive-expressive language disorder is believed to be at least twice as prevalent in boys as in girls.

Children with mixed receptive-expressive disorder are at high risk for additional speech and language disorders, learning disorders, and additional psychiatric disorders. About half of children with this disorder also have pronunciation difficulties leading to phonological disorder, and about half also have reading disorder. These rates are significantly higher than the comorbidity found in children with expressive language disorder alone. ADHD is present in at least one third of children with mixed receptive-expressive language disorder.

Language disorders most likely have multiple determinants, including genetic factors, developmental brain abnormalities, environmental influences, neurodevelopmental immaturity, and auditory processing features in the brain. As with expressive language disorder alone, evidence is found of familial aggregation of mixed receptive-expressive language disorder. Genetic contribution to this disorder is implicated by twin studies, but no mode of genetic transmission has been proved. Some studies of children with various speech and language disorders have also shown cognitive deficits, particularly slower processing of tasks involving naming objects, as well as fine motor tasks. Slower myelinization of neural pathways has been hypothesized to account for the slow processing found in children with developmental language disorders. Several studies suggest an underlying impairment of auditory discrimination because most children with the disorder are more responsive to environmental sounds than to speech sounds.

Children with mixed receptive-expressive language disorder develop language more slowly than their peers and have trouble understanding conversations that peers can follow. In mixed receptive-expressive language disorder, receptive dysfunction coexists with expressive dysfunction. Therefore, standardized tests for both receptive and expressive language abilities must be given to anyone suspected of having mixed receptive-expressive language disorder.

A markedly below-expected level of comprehension of verbal or sign language with intact age-appropriate nonverbal intellectual capacity, confirmation of language difficulties by standardized receptive language tests, and the absence of pervasive developmental disorders confirm the diagnosis of mixed receptive-expressive language disorder (Table 37-2).