Mild intellectual disability: Diagnostic and outcome aspects

Abstract

The aim of the thesis was to describe mild intellectual disability (ID) from various neurodevelopmental and neuropsychiatric perspectives in children and young adults. Paper I The objective of the first paper was to analyse coexisting neurodevelopmental disorders/problems and diagnostic concerns in a population-based group of 33 school age children with mild ID. The instrument used was the Five-To-Fifteen questionnaire. The prevalence of mild ID in the study area was found to be 0.85%. High rates of problems were reported regarding motor skills, executive function/attention, social and emotional/ behavioural functioning. It was concluded that school age children with mild ID are in need of a comprehensive work-up covering not only general cognitive abilities, but also many other areas. Paper II In the second paper adaptive functioning was compared between the group of 33 school age children with mild ID (Paper I) and a referral group of 27 school age children with ADHD. The instrument, administered to teachers, was the Adaptive Behavior Assessment System, Second Edition (ABAS-II). At total group levels, the group with ADHD had even lower adaptive functioning compared to the group with mild ID. The difference between the groups was significant in children 12 years or older. The finding has implications for diagnostic concerns and indicates that the level of adaptive functioning cannot be used to differentiate between mild ID and ADHD. Paper III and IV In the third and fourth papers a population based group of 42 children – now young adults – born to mothers with ID was explored with regard to life experiences. Three of the 42 individuals (0.68%) had died before the age of 8 years, one had moved abroad and seven declined participation. Ten individuals were personally interviewed and 21 were searched for in different registers. When the interview and register groups were collapsed, it was found that 11 of the 31 individuals (35%) had mild ID and 9 (29%) had ADHD. Sixteen children (52%) had not been primarily raised by their biological mother. Children born to mothers with ID are exposed to several risks. These include an increased risk of neglect and abuse in the family and also an increased risk for the child to have mild ID and other neurodevelopmental disorders, including ADHD. Individuals with ID who become parents need tailored support from social services and their children need early assessment so as to develop physically, mentally and socially in an optimal way.