Mental retardation can be considered a spectrum disorder, with a wide range of severity. Some mental retardation cases are mild and some others are quite severe.
Mentally retarded individuals are typically classified into four different categories based on their level of functioning or severity as measured by IQ and adaptive functioning scores.
About 85 percent of mentally retarded people fall into the 'mild' category of mental retardation. This group can be educated and may function quite well in society. Some are able to live independently, or in a group home or with family with little supervision. Mild mental retardation mostly affects intellect and is generally not associated with substantial behavioral problems.
Ten percent of mental retardation cases have 'moderate' mental retardation. This group is considered trainable. They learn best through repetition and cause and effect teaching methods. Few, if any, moderately mentally retarded individuals are able to function independently as adults. Nearly all require lifelong assistance in navigating through everyday situations.
Three to four percent of mental retardation cases are classified as 'severe', and an additional one to two percent of cases are classified as 'profoundly retarded'. People with more severe mental retardation tend to display more behavioral problems and to be far less socially developed than higher functioning mentally retarded individuals do.
