Mental retardation is a developmental disorder, which becomes noticeable before the adulthood. Severely impaired cognitive functioning and lack in two or more adaptive behaviors characterize mental retardation. Adaptive behavior is defined as a type of behavior, which is used to adjust to another type of behavior or situation. These are typically personal and social behaviors, normally adapted to something else. However, criteria for mental retardation have been different throughout the history. For many years, mental retardation was considered equal to the Intelligence Quotient (IQ) score fewer than 70. More recently, the criteria have extended to include both mental and individual’s functional skills in the environment. In practice, this means that a person with a very low IQ still does not have to be considered mentally retarded, if he or she continues to function normally in the social surrounding.
Mental retardation characteristics
Mental retardation can be symptomatic or non-symptomatic. In symptomatic mental retardation, various medical and behavioral signs and symptoms are present with the condition. On the other hand, people with non-symptomatic mental retardation will have only intellectual deficits without other abnormalities. Typically, signs and symptoms of mental retardation are behavioral. Most of the mentally retarded people will look like any other person but the first symptoms of their condition typically arise when, as children, they learn to talk much later. Problems in oral language development are very common for the mentally retarded people, and they typically affect both children and adults. These persons will have noticeable deficits in memory skills, problems with learning social rules and very rudimentary problem solving skills. As a result, their self-caring skills, as a type of adaptive behavior, such as independent dressing or eating, may not develop for years. Very often, they will need constant care from their parents or supporters. People with severe mental retardation will typically need the support of others for their entire life.
Causes of mental retardation
For most of the cases of mental retardation among children, the causes are completely unknown. As much as 50 percent of mental retardation among children happens for no apparent reason. Sometimes, abnormal genes or errors in gene combination cause disability. Problems during pregnancy and problems at birth may also result in child’s mental retardation. For example, if a woman has drug problems or problems with alcohol, her child is at a very high risk of suffering permanent central nervous system damage, especially to the brain.
Mental retardation can also develop later in life as a result to exposure to certain diseases and toxins: whooping cough, measles, meningitis, lead or mercury. It is also associated with iodine deficiency and malnutrition.