the condition is permanent, though improvement is possible as the level of development reached by a person is influenced by the cause of the impairment together with environmental influences, education, therapy and acceptance.
We will use the classification of Mental retardation as stated in the ICD-10 published by the World Health Organization in 1993. However, this classification shall be used with caution for educational purposes, because it has been developed for medical not educational field. The ICD-10 recognizes the following types of mental retardation:
F 70 Mild mental retardation
IQ approximately between 50 andl 69 (in adulthood matches mental age of 9 – 12). This condition leads to difficulties in education at school. However, many adults are able to work and successfully carry on social relations and fully participate in social life.
F 71 Moderate mental retardation
IQ reaches 35 to 49 (in adulthood matches mental age of 6 – 9). It results in distinct developmental retardation in childhood, however many of the persons are able to develop limited independence and self sufficiency; they achieve adequate communication and school skills. Adults will need different level of support at work and for many social activities.
F 72 Severe mental retardation
IQ between 20 and 34 (in adulthood matches mental age of 3 – 6). These conditions require continual support in all areas of everyday life.
F 73 Profound mental retardation
IQ reaches at most 20 (in adulthood matches mental age of below 3 years). This condition require constant support in all areas of life, including movement, communication and self care.