Language Disorder 43
Associated Features Supporting Diagnosis
A positive family history of language disorders is often present. Individuals, even chil-
dren, can be adept at accommodating to their limited language. They may appear to be shy
or reticent to talk. Affected individuals may prefer to communicate only with family mem-
bers or other familiar individuals. Although these social indicators are not diagnostic of a
language disorder, if they are notable and pers istent, they warrant referral for a full lan-
guage assessment. Language d isorder, particularly expressiv e deficits, may co-occur with
speech sound disorder.
Development and Course
Language acquisition is marked by changes from  onset in toddlerhood to the adult level of
competency that appears during adolescence.  Changes appear across the dimensions of
language (sounds, words, grammar, narrati ves/expository texts, and conversational
skills) in age-graded increments and synchron ies. Language disorder emerges during the
early developmental period; however, there is considerable variation in early vocabulary
acquisition and early word combinations, an d individual differenc es are not, as single
indicators, highly predictive of later outcomes. By age 4 years, individual differences in
language ability are more stable, with bette r measurement accuracy, and are highly pre-
dictive of later outcomes. Language disorder diagnosed from 4 years of age is likely to be
stable over time and typically persists into adulthood, although the particular profile of
language strengths and deficits is likely to change over the course of development.
Risk and Prognostic Factors
Children with receptive language impairment s have a poorer prognosis than those with
predominantly expressive impairments. They are more resistant to treatment, and diffi-
culties with reading comprehe nsion are frequently seen.
Genetic and physiological. Language disorders are highly heritable, and family mem-