<unk>  <unk>  is diagnosed when a child has delayed or disordered language development for no apparent reason. Usually the first indication of<unk>  is that the child is later than usual in starting to speak and subsequently is delayed in putting words together to form sentences. Spoken language may be immature. In many children with<unk> , understanding of language, or receptive language, is also impaired, though this may not be obvious unless the child is given a formal assessment. Although difficulties with use and understanding of complex sentences are a common feature of<unk> , the diagnostic criteria encompass a wide range of problems, and for some children other aspects of language are problematic (see below). In general, the term<unk>  is reserved for children whose language difficulties persist into school age, and so it would not be applied to toddlers who are late to start talking, most of whom catch up with their peer group after a late start. Terminology The terminology for children's language disorders is extremely wide-ranging and confusing, with many labels that have overlapping but not necessarily identical meanings. In part this confusion reflects uncertainty about the boundaries of<unk> , and the existence of different subtypes. Historically, the terms "developmental dysphasia" or "developmental aphasia" were used to describe children with the clinical picture of<unk> . These terms have, however, largely been abandoned, as they suggest parallels with adult acquired aphasia. This is misleading, as<unk>  is not caused by brain damage. Some synonyms currently in use for<unk>  are language impairment, developmental language delay (DLD), language disorder, and language-learning disability. Researcher Bonnie Brinton argues that the term<unk> " is misleading because the disorder does not only affect language, but also affects reading, writing, and social/pragmatics. In medical circles, terms such as<unk>  developmental language disorder are often used, but this has the disadvantage of being wordy, and is also rejected by some people who think<unk>  should not be seen as a "disorder". In the UK educational system, speech, language and communication needs (SLCN) is currently the term of choice, but this is far broader than<unk> , and includes children with speech and language difficulties arising from a wide range of causes. Subtypes (Rapin and Allen 1987) Although most experts agree that children with<unk>  are quite variable, there is little agreement on how best to subtype them. There is no widely accepted classification system. In 1983 Rapin and Allen proposed a classification of developmental language disorders based on the linguistic features of language impairment, which was subsequently updated by Rapin. Note that Rapin is a child neurologist, and she refers to different subtypes as "syndromes"; many of those coming from the perspective of education or speech-language therapy reject this kind of medical label, and argue that there is not a clear dividing line between<unk>  and normal variation. Also, although most experts would agree that children with characteristics of the Rapin subtypes can be identified, there are many cases who are less easy to categorise, and there is also evidence that categorisation can change over time. Rapin's subgroups fall into three broad categories: Receptive/expressive developmental language disorder Receptive/expressive phonologic/syntactic deficit syndrome is the most common form of<unk> , in which the child's most obvious problems are a tendency to speak in short, simplified sentences, with omission of some grammatical features, such as past tense -ed. It is common also to see simplified speech production when the child is young. For instance, clusters of consonants may be reduced, so that "string" is pronounced as "ting". Vocabulary is often limited, with a tendency to use "general all-purpose" terms, rather than more<unk>  words. Verbal auditory agnosia is a very rare form of language impairment, in which the child appears unable to make sense of speech sounds. It typically occurs as a symptom of Landau-Kleffner syndrome, in which case a diagnosis of<unk>  would not be appropriate, as there is a known neurological origin of the language difficulties. Expressive developmental language disorder syndromes Developmental verbal dyspraxia (DVD) – in the child with DVD, comprehension is adequate; the onset of speech is very delayed and extremely limited with impaired production of speech sounds and short utterances. The poor speech production cannot be explained in terms of structural or neurological damage of the articulators. There is much disagreement about diagnostic criteria, but the label most often used for children whose intelligibility declines markedly when they attempt complex utterances, compared to when they are producing individual sounds or syllables. Another key feature is inconsistency of speech sound production from one occasion to another. Although the term "dyspraxia" suggests a pure output disorder, many – perhaps all – of these children have difficulty in doing tasks that involve mentally manipulating speech sounds, such as phonological awareness tasks. Children with DVD also typically have major literacy problems, and receptive language levels may be poor on tests of vocabulary and grammar. Phonologic programming deficit syndrome – the child speaks in long but poorly intelligible utterances, producing what sounds like jargon. Outside Rapin's group, little has been written about this subtype, which is not generally recognised in diagnostic frameworks. Higher order processing disorders Lexical deficit disorder – the child has word finding problems and difficulty putting ideas into words. There is poor comprehension for connected speech. Again, there is little research on this subtype, which is not widely recognised. Pragmatic language impairment – the child speaks in fluent and well-formed utterances with adequate articulation; content of language is unusual; comprehension may be over-literal and language use is odd. The child may chatter incessantly and be poor at turn-taking in conversation and maintaining a topic. There has been a great deal of controversy about this category, which is termed pragmatic language impairment (PLI) in the UK. Debate has centred over the question of whether it is a subtype of<unk> , part of the autistic spectrum, or a separate condition. In DSM-5, the term Social Communication Disorder has been introduced; this is equivalent to PLI. Relationship with other neurodevelopmental disorders Although textbooks draw clear boundaries between different neurodevelopmental disorders, there is much debate about overlaps between them. Many children with<unk>  meet diagnostic criteria for developmental dyslexia, and others have features of autism.
Specific language impairment
Nonverbal learning disorder
Language delay
Mixed receptive-expressive language disorder
Global perceptions of autism
Speech and language impairment
Language disorder
Global developmental delay