Delayed speech in children.

Usually normal variation but may be a "specific speech and language disorder" There is immense variation among normal children in the rate they acquire language. Some 3 year olds can hold a sophisticated conversation, whereas others may produce sentences of only two or three unclear words.' Delay in learning to speak is usually a reflection of this normal variation, but it may be a sign of several serious disorders, such as hearing loss, mental handicap, autism, and severe environmental deprivation.2 When these diagnoses have been excluded there remain a few children who fail to develop spoken language for reasons that are obscure. The problem may affect only the production of speech or the child may also have difficulty in compre-hending3 or receiving spoken language. This group of conditions has been given the collective name of "specific speech and language disorders." The normal infant masters native language without any help from specialised teachers, grammar books, or language laboratories. Yet until Chomsky published his works in the 1960s the study ofhow an infant learns to talk was not thought to be a worthwhile subject for scientific inquiry.4 The acquisition ofnormal language and the conditions that disrupt it are now being researched by linguists, psychologists, and anthropologists as well as by investigators from medical and educational disciplines. Recognising that workers in these disparate subjects rarely have the opportunity to exchange ideas, the Association for All Speech Impaired Children (AFASIC) organised in 1987 the first international symposium on the subject. The proceedings (available from AFASIC, 347 Central Markets, London ECIA 9NH) indicate both the extent of the research effort and the difficulties in classifying and treating specific speech and language disorders.3 In children with these disorders conventional neurological examination shows no abnormal signs and the standard investigations are unhelpful. That mental retardation is not the cause of the problem can be shown by using intelligence tests that do not require speech.5 The reasons why these children do not talk are complex. Genetic factors are thought to contribute as pedigrees often show an excess of other family members with language and learning difficulties. Disorders of chromosomes, particularly sex chromosomes, are associated with an increased incidence of specific speech and language disorders.6 Perinatal abnormalities such as anoxia seem rarely, if ever, to be responsible. Only in certain rare well defined entities-notably, the epilepsy-aphasia syndrome and congenital pseudobulbar palsy-is there clear evidence of localised neurological abnormality.' Some …