Dr Ira Shah
Consultant Pediatrician, Nanavati Hospital and B.J.Wadia Hospital for Children, Mumbai
Editor - Pediatric Oncall

What is mental subnormality?
There is no perfect definition of mental retardation. However it is broadly considered as a condition where intelligence is low. Children are usually mentally slow.

What are the causes of mental subnormality?
The common causes of mental subnormality are genetic causes such as chromosomal syndromes such as Down’s syndrome, Fragile X syndrome, Prader Willi syndrome etc; metabolic disorders such as phenylketonuria, maple syrup urine disease, lesch-nyhan syndrome etc; hypothyroidism; infections at birth such as congenital rubella, congenital Toxoplasma, congenital syphilis; prematurity, birth asphyxia, meningitis in newborn and brain malformations. Sometimes intelligence may be borderline if there is lack of stimulating environment.

What is intelligence measured?
Intelligence is measured by intelligent quotient (IQ). With borderline mental subnormality, IQ ranges from 70-90, with mild subnormality it is between 70-51, with moderate subnormality it is between 50-36, with severe subnormality, it is between 35-21 and with profound subnormality it is between 0-20. In children with profound and severe mental subnormality, there may be associated blindness, deafness, seizures or gross physical abnormalities. These children are fully dependent for care. Children with moderate subnormality can be trained at self help skills but are also dependent for their care partially. Children with mild subnormality are normal in walking, talking, toilet training and in daily routines but compromised in highly intellectual skills. They can be trained to live an independent life. Children with borderline mental subnormality are slow achievers.

What is the management of children with low IQ?
Management of children with low IQ is individualized. Special education facilities, stimulation to achieve maximum genetic potential are done. This however should be done within limits of the child’s capabilities.

Last Updated On 26/11/2010