Appendix 1

Criteria for the classification of intellectual impairment

Degree of mental retardation Preschool years (0–5 y) School years (6–21 y) Adulthood
Simplified scale
Mild (IQ 50–70) Is rarely distinguishable from a normal child
 Mildly delayed development in the sensorimotor fieldAble to acquire a basic level of education, but doesn’t reach the competence level of the last year of primary school Able, with special education and special training to reach a satisfactory professional and social functioning
Mild language delay 
 Good social skills Often needs guidance and supervision in stressful circumstances
Moderate (35 < IQ < 50) Learns language and communication 
 Motor development reaches a satisfactory level
 Is only able to learn very few pedagogic milestones Able to do non-qualified work, usually in a protected environment
Able to acquire satisfactory autonomy 
 Able to be self-sufficient with moderate controls (Some reading, some writing and calculation, usually during adolescence) Needs supervision and guidance 
 Is unable to work autonomously
Severe (20 < IQ < 35) Poor motor development Able to learn a few words Is able partially to earn his or her income when working in a protected environment and under full supervision
Little or no language Able to communicate
Little or no language Hygiene rules and minimal behavioural habits are acquired
Unable to acquire school education
Profound (IQ < 20) Very low functioning capacity Mild motor development Some motor development is observed
Needs nursing Unable to acquire personal autonomy No development of language
Needs permanent care Needs permanent care