Impairment in written expression
Written language comprises several components. Handwriting or keyboarding skills involve fine motor skills, letter memory and the ability to form letters. Spelling draws on semantics, morphology, orthography and phonology. Usage embraces grammar, punctuation and capitalisation. Vocabulary involves word knowledge, word retrieval and morphology. The DSM-5 (American Psychiatric Association) outlines within the context of specific learning disorder the essential features of 'impairment in written expression'. The subskills involved as set out in the section on diagnostic criteria involve spelling, grammar and punctuation, and written composition. Theories of typical writing development reflect the complexity of the activity. Cognitive/motivational theories emphasise the mental operations and the motivational resources that a writer uses when composing writing. Many areas of the brain appear to be implicated in the complex activity of written expression. A central factor may be executive and working memory deficits, which have been associated with poor sentence coherence and lexical cohesion.