mental retardation

MENTAL RETARDATION

Introduction
Mental retardation is a significantly subaverage general intellectual functioning. It may be caused by different factors. It manifests during the developmental period. Very often, it is assumed that the mentally retarded persons constitute a homogenous group. That is not true. The mentally retarded persons vary in their behavioral, psychological, physical and social characteristic as much as normal general population does. Low IQ scores and limitations in adaptive skills are the hallmarks of mental retardation. Aggression, self-injury, and mood disorders are sometimes associated with the disability. The severity of the symptoms and the age at which they first appear depend on the cause

Definition

Subnormal intellectual development as a result of congenital causes, brain injury, or disease and characterized by any of various cognitive deficiencies, including impaired learning, social, and vocational ability. Also called mental deficiency.

Incidence
 1-2 to percent of the general population is mentally retarded.

Etiology
Children who are mentally retarded reach developmental milestones significantly later than expected, if at all. If retardation is caused by chromosomal or other genetic disorders, it is often apparent from infancy. If retardation is caused by childhood illnesses or injuries, learning and adaptive skills that were once easy may suddenly become difficult or impossible to master.
In about 35% of cases, the cause of mental retardation cannot be found.
Risk factors are related to the causes. Causes of mental retardation can be roughly broken down into several categories:
• unexplained (This category is the largest and a catchall for unexplained occurrences of mental retardation.)
• trauma (before and after birth)
o intracranial hemorrhage before or after birth
o lack of oxygen to the brain before, during, or after birth
o severe head injury
• infections (present at birth or occurring after birth)
o congenital rubella
o meningitis
o congenital CMV
o encephalitis
o congenital toxoplasmosis
o listeriosis
o HIV infection
• chromosomal abnormalities
o errors of chromosome numbers (such as Down's syndrome)
o defects in the chromosome or chromosomal inheritance (for example, fragile X syndrome, Angelman syndrome, Prader-Willi syndrome)
o chromosomal translocations (a gene is located in an unusual spot on a chromosome, or located on a different chromosome than usual)
o chromosome deletions (cri du chat syndrome)
• genetic abnormalities and inherited metabolic disorders
o galactosemia
o Tay-Sachs disease
o phenylketonuria
o Hunter syndrome
o Hurler syndrome
o Sanfilippo syndrome
o metachromatic leukodystrophy
o adrenoleukodystrophy
o Lesch-Nyhan's syndrome
o Rett syndrome
o tuberous sclerosis
• metabolic
o Reye's syndrome
o congenital hypothyroid
o very high bilirubin levels in babies (bilirubin is a byproduct of normal breakdown of red blood cells)
o hypoglycemia (poorly regulated diabetes mellitus)
• toxic
o intrauterine exposure to alcohol, cocaine, amphetamines, and other drugs
o methylmercury posisoning
o lead poisoning
• nutritional
o malnutrition
• environmental
o poverty
o low socioeconomic status
o deprivation syndrom

Classification

Mental retardation varies in severity. The Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) is the diagnostic standard for mental healthcare professionals in the United States. The DSM-IV classifies four different degrees of mental retardation: mild, moderate, severe, and profound. These categories are based on the functioning level of the individual.

1. Mild Mental Retardation.
Approximately 85% of the mentally retarded population is in the mildly retarded category. Their IQ score ranges from 50-75, and they can often acquire academic skills up to the 6th grade level. They can become fairly self-sufficient and in some cases live independently, with community and social support.

2. Moderate Mental Retardation
About 10% of the mentally retarded population is considered moderately retarded. Moderately retarded individuals have IQ scores ranging from 35-55. They can carry out work and self-care tasks with moderate supervision. They typically acquire communication skills in childhood and are able to live and function successfully within the community in a supervised environment such as a group home.

3. Severe Mental Retardation
About 3-4% of the mentally retarded population is severely retarded. Severely retarded individuals have IQ scores of 20-40. They may master very basic self-care skills and some communication skills. Many severely retarded individuals are able to live in a group home.

4. Profound mental retardation

Only 1-2% of the mentally retarded population is classified as profoundly retarded. Profoundly retarded individuals have IQ scores under 20-25. They may be able to develop basic self-care and communication skills with appropriate support and training. Their retardation is often caused by an accompanying neurological disorder. The profoundly retarded need a high level of structure and supervision.

Symptoms
• failure to meet intellectual developmental markers .
• persistence of infantile behavior .
• lack of curiosity.
• inability to meet educational demands of school.
• Failure to achieve devoplopmental milestones.
• Reduced ability to learn or to meet acadamic demands
• Psychomotor skill deficits
• Neurologic impairments
• Negativity and low self esteem
• Depression or labile moods
• Lack of curiosity.


Diagnosis
The diagnosis is made by the following steps.
1. History
2. General physical examination
3. Detailed neurological examination
4. Mental status examination, for assessment of associated psychiatric disorders and clinical assessment of level of intelligence.
5. Investigations.
 Routine investigations
 Urine test, e.g. for Phenylketonuria,
 EEG, especially in presence of seizures
 Blood levels for inborn errors of metabolism
 Chromosomal studies, e.g. in Down's syndrome. Prenatal and post natal
 CT scan or MRI brain, e.g. in tuberous sclerosis, anomalies of skull configuration.
 Thyroid function test, particularly when cretinism is suspected
 Liver function tests, e.g. in mucopolysaccharidosis.

6. psychological tests
The commonly used test for measurement of intelligence are
• Seguin form board test
• Stanford-Binet, Binet-simon or Binet Kamath tests.
• Wechsleer Intelligence Scale for Children (WISC) for 6 1/2 to 16 years of age.
• Wechsler's Preschool and primary Scale of Intelligence (WPPSI) for 4 to 6 1/2
• Bhatia's battery of performance tests.
• Raven's progressive matrices.

Diagnostic criteria
Mental retardation is diagnosed when the patient meets the criteria in the Diagnostic and Statistic Manual of Mental Disorders, Fourth Edition, text revision.
Intellectual Functioning
The persons intellectual functioning must be significantly below average, as shown by an IQ of approximately 70 or below on an individually administered IQ test. In infant, a clinical judgement of significantly below average intellectual functioning is made.
Adaptive Functioning
The person must also have deficits or impairments in adaptive functioning in at least two of the following areas.
• Communication
• Self care
• Home living
• Social and interpersonal skills
• Use of community resources
• Self direction
• Functional academic skills
• Work
• Leisure
• Health
• Safety

Onset
The onset must be before age 18.
Management

The primary goal of treatment is to develop the person's potential to the fullest. Special education and training may begin as early as infancy. This includes social skills to help the person function as normally as possible
The management of mental retardation can be discussed under prevention at primary, secondary, ant tertiary levels.
1. primary prevention
This consist of
 Improvement in socio-economic condition of society at large, aiming at elimination of undernutrition, malnutrition, prematurity and perinatal factors.
 Education of lay public, aiming at removal of misconceptions about mentally retarded individuals
 Medical measures for good perinatal medical care to prevent infections, trauma, excessive use of medications, malnutrition, obstetric complications and diseases of pregnancy
 Facilitating research activities to study the cause of mental retardation and their treatment
 Genetic counseling in at risk parents e.g. on Phenylketonuria, down's syndrome.

2. Secondary prevention
 Early detection and treatment of preventable disorders, e.g. Phenylketonuria (low phenylalanine diet), Maple syrup urine disease
 Early detection of handicaps in sensory, motor or behavioral areas with early remedial measures and treatment
 Early treatment of correctable disorders e.g. infections, skull configuration anomalies
 Early recognition of presence of mental retardation. a delay in diagnosis may cause unfortunate delay in rehabilitation
Tertiary Prevention
 Treatment of psychological and behavioral problems
 Behaviour modification
 Rehabilitation in vocational, physical, and social areas commensurate with the level of handicap
 Parental counseling
 institutionalization for individuals with profound mental retardation

Nursing Management






Complications
Complications vary. They may include:
• social isolation
• inability to care for self
• inability to interact with others appropriately.

Bibliography.

1.Schilling A Judith, "psychiatric nursing made incredibly easy", First Edition, Lippincott
Williams and Wilkins Publishers, Page No.93-96