In the DSM-5 the term 'mental retardation' was officially replaced by 'intellectual disability (intellectual developmental disorder)'. The term 'intellectual disability' is the equivalent of 'intellectual development disorders', which was adopted in the draft ICD-11. To emphasize an increasing convergence between the two classificatory systems this second term has been reported in brackets in the title of the chapter of the DSM.
The new terms of the DSM-5 refer to a disorder with its onset in childhood which includes intellectual and adaptive deficits in the areas of conceptualization, socialization, and practical skills.
From now on, in order to make a diagnosis according to DSM, the following 3 criteria must be satisfied:
A. Deficit of intellectual functions, such as reasoning, problem solving, planning, abstract thinking, judgment, academic learning or learning from experience, and confirmed by both individual clinical assessment and standardized intelligence testing.
B. Deficits in adaptive functioning that failure to meet developmental and socio-cultural standards for personal independence and social responsibility.
Without ongoing support, the adaptive deficits limit functioning in one or more activities of daily life, such as communication, social participation, and independent living, across multiple environments, such as home, school, work and community.
C. Onset of intellectual and adaptive deficits during the developmental period.
The severity levels are defined on the basis of adaptive functioning and not on Intelligence Quotient (IQ) scores because it was judged that both the adaptive functioning in the areas of conceptualization, socialization, and practical skills determine the level of support necessary to maintain an acceptable condition of life. In addition, when low (under 60), measures of IQ are no longer valid.
Therefore, we continue to distinguish four levels of severity (mild, moderate, severe, and very serious), but with different criteria from the DSM-IV and IV-TR.
The disorder has been placed in a meta-syndromic, or meta-structural grouping, named 'neurodevelopmental disorders'. The group includes conditions with onset in childhood, typically early, often prior to entry to school and characterized by developmental deficits that produce impairments of the personal, social, academic, or occupational functioning. The range of deficits extends from very specific limitations of learning and control of executive functions to a global impairment of social skills or intelligence.
The neurodevelopmental disorders often occur together, for example individuals with autism often have intellectual disabilities (intellectual developmental disorder), and many children with attention deficit disorder and hyperactivity often have a specific learning disorder.