Mental Retardation


mentalMental retardation is a generalized, triarchic disorder, characterized by subaverage cognitive functioning and deficits in two or more adaptive behaviors with onset before the age of 18. Once focused almost entirely on cognition, the definition now includes both a component relating to mental functioning and one relating to the individual’s functional skills in their environment.

Mental Retardation is a part of a broad category of developmental disability; it is defined by the American Association of Mental Deficiency as significantly subaverage general intellectual functioning existing concurrently with deficits in adaptive behavior and manifested during the developmental period (18 years of age). Adaptive behaviors include communication, self-care, work, leisure, health, and safety.


A diagnosis of mental retardation cannot be made on the basis of intellectual ability alone; there must be both intellectual and adaptive (personal independence and social responsibility) impairment.

Causes of mental retardation are genetic, biochemical, viral, and developmental.

  • Prenatal Infection and intoxication
  • Trauma or physical agent (e.g. lack of oxygen)
  • Metabolic Disturbance
  • Inadequate Prenatal Nutrition
  • Gross postnatal brain disease (e.g. Neurofibromatosis or tuberous sclerosis)
  • Chromosomal abnormalities
  • Prematurity
  • Low birth weight
  • Autism
  • Environmental deprivation

Associated Factors Include:

  • Maternal Lifestyle (e.g. Poor nutrition, smoking, and substance abuse)
  • Chromosomal disorders (most related to Down Syndrome)
  • Specific Disorders such as fetal alcohol syndrome
  • Cerebral Palsy, microencephaly or infantile spasms


The Pathophysiology of Mental Retardation depends on the cause; early diagnosis and prompt treatment may particularly important in cases involving an identifiable and possibly correctable cause such as phenylketonuria (PKU), malnutrition, or child abuse.

Diagnosis usually is made after a period of suspicion. Diagnosis may be made at birth from recognition of specific syndromes such as Down Syndrome. Diagnosis and classification are based on standard IQ test scores.

Clinical Manifestations:

Findings may vary depending on the classification or degree of retardation.






Mild (50-70 IQ)

The child often is not noted as retarded, but is slow to walk, talk and feed self.

The child can acquire practical skills, and learn to read and do arithmetic to sixth grade level with special education classes. The child achieves a mental age of 8 to 12 years

The adult can usually achieve social and vocational skills. Occasional guidance may be needed. The adult may handle marriage, but not child rearing.

Moderate (35-55 IQ)

Noticeable delays, especially in speech are evident.

The child can learn simple communication, health, and safety habits, and simple manual skills. A mental age of 3 to 7 years is achieved.

The adult can perform simple tasks under sheltered conditions and can travel alone to familiar places. Help with self-maintenance is usually needed.

Severe (20-40 IQ)

The child exhibits marked motor delay and has little to no communication skills. The child may respond to training in elementary self-help, such as feeding.

The child usually walks with disability. Some understanding of speech and response is evident. The child can respond to habit training and has the mental age of a toddler.

The adult can conform to daily routines and repetitive activities, but needs constant direction and supervision in a protective environment.

Profound (below 20 IQ)

Gross retardation is evident. There is a capacity for function in sensorimotor areas, but the child needs total care.

There are obvious delays in all areas. The child shows basic emotional response and may respond to skillful training in the use of legs, hands and jaws. The child needs close supervision and has the mental age of a young infant.

The adult may walk but needs complete custodial care. The adult will have primitive speech. Regular physical activity is beneficial.


  • By most definitions mental retardation is more accurately considered a disability rather than a disease.
  • Mental Retardation can be distinguished in many ways from mental illness, such as schizophrenia or depression.
  • Currently, there is no “cure” for an established disability, though with appropriate support and teaching, most individuals can learn to do many things.
  • Although there is no specific medication for mental retardation, many people with developmental disabilities have further medical complications and may take several medications.
  • Beyond that there are specific programs that people with developmental disabilities can take part in wherein they learn basic life skills.
  • These “goals” may take a much longer amount of time for them to accomplish, but the ultimate goal is independence.
  • This may be anything from independence in tooth brushing to an independent residence.
  • People with developmental disabilities learn throughout their lives and can obtain many new skills even late in life with the help of their families, caregivers, clinicians and the people who coordinate the efforts of all of these people.

Nursing Management:

1. Assess all children for signs of developmental delays.

2. Administer prescribed medications for associated problems such as anticonvulsants for seizure disorders, and methylphenidate (Ritalin) for attention deficit hyperactivity disorder.

3. Support the family at the time of initial diagnosis by actively listening to their feelings and concerns and assessing their composite strengths.

4. Facilitate the child’s self-care abilities by encouraging the parents to enroll the child in an early stimulation program, establishing a self-feeding program, initiating independent toileting, and establishing an independent grooming program (all developmentally appropriate).

5. Promote optimal development by encouraging self-care goals and emphasize the universal needs of children, such as play, social interaction and parental limit setting.

6. Promote anticipatory guidance and problem solving by encouraging discussions regarding physical maturation and sexual behaviors.

7. Assist the family in planning for the child’s future needs (e.g. Alternative to home care, especially as the parents near old age); refer them to community agencies.

8. Provide child and family teaching

  • Identify normal developmental milestones and appropriate stimulating activities including play and socialization.
  • Discuss the need for patience with the child’s slow attainment of developmental milestones.
  • Inform parents about stimulation, safety and motivation.
  • Supply information regarding normal speech development and how to accentual nonverbal cues, such as facial expression and body language, to help cue speech development.
  • Explain the need for discipline that is simple, consistent and appropriate to the child’s .
  • Review an adolescent’s need for simple, practical sexual information that includes anatomy, physical development and conception.
  • Demonstrate ways to foster learning other than verbal explanation because the child is better able to deal with concrete objects than abstract concepts.
  • Point out the importance of positive self-esteem, built by accomplishing small successes in motivating the child to accomplish other tasks.

9. Encourage the prevention of mental retardation

  • Encourage early and regular prenatal care.
  • Provide support for high risk infants.
  • Administer immunizations, especially rubella immunization.
  • Encourage genetic counselling when needed.
  • Teach injury prevention – both intentional and unintentional.


Lippincott Review Series

What Do You Think?