Mental retardation, which is now renamed as intellectual disability, is a type of neuro-developmental disorder, wherein the affected individuals have poor adaptive functioning along with impaired intellectual development. Individuals with an IQ score below 70 and a significant deficit observed in adaptive behaviors that interferes with general living are considered to be mentally retarded.
Delay in development of language skills, adaptive skills and cognitive skills mark the onset of intellectual disability. In mild cases, signs and symptoms may not be noticeable until the child reaches preschool age. The following are some of the important markers noticed in affected children:
Based on the guidelines provide by the Diagnostic and Statistical Manual of Mental Disorders, the child should meet the following three criteria to be diagnosed with intellectual disability.
The first 2 factors can be diagnosed by measuring the IQ score. The third factor is important to determine, in order to rule out other disorders like Alzheimer disease which share similar signs and symptoms, but have a late onset.
An IQ score of below 70 indicate mental retardation and is done at the preliminary level. This is followed by other methods such as adaptive behavior rating scale and Denver developmental screening test .
Brain imaging tests are also indicated in children with intellectual disability. A MRI scan of brain is preferred, because it enables better assessment of abnormalities of central nervous system .
Treatment is geared towards maximum development of the child’s potential. Therapists and specialized educators help in fulfilling such goals. They help in developing the social skills of the child so that they learn to communicate effectively and put forth their problems and thoughts to the outside world. Behavior counseling forms an important part of the treatment regime to help the child to deal with their mood swings and sometimes aggressive nature.
Pharmacologic treatment is of little help in improving the cognitive functioning. However, the drug donezepil has been found to be effective in improving the cognitive function in children with Down syndrome. Parents might also think of enrolling their children in various support groups for proper grooming .
Prognosis of the condition would largely depend on the underlying etiology, severity of the disease and type of treatment methods administered. In many cases it has been seen that, affected individuals lead a productive life and learn to carry out many tasks on their own. With proper learning and education, children can function properly and can be successful in life .
Amongst the various etiologies, Down syndrome, fetal alcohol syndrome and velocariofacial syndrome are the major causative factors . In about one third to the half of all cases, the exact cause behind development of mental retardation is not known .
The following causes are known to trigger the onset of mental retardation:
Mental retardation affects about 1 – 3% of the total population. The prevalence rate of severe form of intellectual disability has been estimated to occur in 6 per 1,000 population .
It has been assessed that, about 75 – 90% of individuals suffer from mild form intellectual disability. Of these, non-syndromic intellectual disability occurs in about 30 – 50% of cases. Boys are found to be more affected than girls, for both mild and severe form of the disease. Mortality rates at an early age have been found to be higher in children suffering from Down syndrome .
Mental retardation primarily occurs as the outcome of several disorders of the central nervous system. In majority of the cases, no significant structural abnormalities have been noticed in individuals with mild intellectual disability. However, in severe cases, malformations of the central nervous system include hydranencephaly, neural tube defects and microcephaly. Certain studies have indicated a link between poor cognitive functioning and poverty; however the etiologic contribution still remains unclear .
Some of the risk factors such as alcohol consumption during pregnancy, avoiding toxin exposure and iodine deficiency can go a long way in preventing the onset of mental retardation. Getting vaccinated against infectious diseases such as rubella can also help prevent mental retardation from setting in. Proper genetic counseling during pregnancy can help parents take informed decisions.
The condition is diagnosed before one reaches 18 years. Individuals suffering from mental retardation lack in appropriate mental development and do not have the ability to adapt and learn new things. Intellectual disability is further classified into 2 categories: non-syndromic intellectual disability and syndromic intellectual disability .