Developmental Disorders

The various psychiatric disorders seen in childhood(‘disorders of psychological development’ and ‘behavioural and emotional disorders with onset usually occurring in childhood and adolescence’)are

  1. Mental retardation
  2. Specific developmental disorders
  3. Pervasive developmental disorders
  4. Hyperkinetic disorders
  5. Conduct disorders
  6. Tic disorders
  7. Enuresis and encopresis
  8. Speech disorders
  9. Habit disorders
  10. Other disorders.

Common Clinical Features Are:

  • An onset that is invariably during infancy or childhood
  • An impairment or delay in the development of functions that are strongly related to biological maturation of the central nervous system
  • A steady course that does not involve the remissions and relapses that tend to be characteristic of many mental disorders.

In most cases, the functions affected include language, visuo-spatial skills and/or motor coordination. It is characteristic for the impairments to lessen progressively as children grow older (although milder deficits often remain in adult life). Usually, the history is of a delay or impairment that has been present from as early as it could be reliably detected, with no prior period of normal development. Most of these conditions are several times more common in boys than in girls. It is characteristic of developmental disorders that a family history of similar or related disorders is common, and there is presumptive evidence that genetic factors play an important role in the etiology of many (but not all) cases.

Environmental factors often influence the developmental functions affected but in most cases they are not of paramount influence. However, although there is generally good agreement on the overall conceptualization of disorders in this section, the etiology in most cases is unknown and there is continuing uncertainty regarding both the boundaries and the precise subdivisions of developmental disorders. Moreover, two types of condition are included in this block that does not entirely meet the broad conceptual definition outlined above.
• First, there are disorders in which there has been an undoubted phase of prior normal development, such as the childhood disintegrative disorder, the Landau-Kleffner syndrome, and some cases of autism. These conditions are included because, although their onset is different, their characteristics and course have many similarities with the group of developmental disorders; moreover it is not known whether or not they are etiologically distinct.
• Second, there are disorders that are defined primarily in terms of deviance rather than delay in developmental functions; this applies especially to autism. Autistic disorders are included in this block because, although defined in terms of deviance, developmental delay of some degree is almost invariable.

Furthermore, there is overlap with the other developmental disorders in terms of both the features of individual cases and familiar clustering.