Mental retardation is characterised by varying degrees of mental retardation and social adjustment difficulties, with patients significantly below the level of healthy children of the same age in cognition, language, memory, comprehension, imagination and movement.
In mild cases, intellectual development, speech and walking are slower than those of children of the same age in the preschool years.
Most of them can only add or subtract single-digit numbers, and some cannot even learn simple calculations.
Most of them can only add or subtract single-digit numbers and some cannot even learn simple calculations. In severe cases, the child’s pronunciation is so slurred that he or she cannot even speak, can barely count, cannot attend primary school and cannot take care of himself or herself, requiring assistance with eating, dressing and toileting.
Very severe children are born with physical and neurological deformities, generally do not walk, have no speech at all, can only make simple sounds, can only understand simple commands and gestures, and are completely unable to care for themselves.