A diagnosis is made if an individual has limitations in two fields: intellectual function and adaptive behavior. Intellectual function refers to a person’s ability to learn, reason, make decisions and solve problems. One’s intellectual functioning level is defined by standardized tests for intelligence quotient or IQ. An IQ below 70 is considered a marker for mental retardation. Adaptive skills are the skills needed for daily life. These skills include the ability to produce and understand language, home-living skills, use of community resources, health, safety, leisure, self-care, social skills, self-direction, functional academic skills, and work skills.
If symptoms arise, a comprehensive physical examination should be completed. Physicians should first assess possible organic causes of symptoms. Conditions such as hyperthyroidism and PKU can cause symptoms of mental retardation. If discovered early, the progression of retardation can be stopped, and in some cases, partially reversed. If a neurological syndrome or injury is suspected, you may be referred to a neurologist for further assessment.
The evaluation process to diagnosis mental retardation is holistic. A complete medical, family, social and educational history should be compiled. An interview with parents and/or caregivers is a vital mode of information gathering since they can provide the best insight into the child’s daily living. Thorough intelligence testing is done to measure learning abilities and intellectual functioning. Tests include the Stanford-Binet Intelligence Scale, the Wechsler Intelligence Scale, the Wechsler Preschool and Primary Scale of Intelligence, and the Kaufmann Assessment Battery for Children. For infants with symptoms of mental retardation, the Bayley Scales of Infant Development may be used for evaluation.
Associated aggression, self-injury, or mood disorders are not uncommon for those with mental retardation. Symptom severity may depend on symptom onset or underlying cause. Children with mental retardation have significant developmental delays. Chromosomal or genetic causes of mental retardation are often evident from infancy. Mental retardation caused by illness or injury may come on suddenly.