MENTAL RETARDATION

 

MENTAL RETARDATION

 

INTRODUCTION

In each country approximately 1% of the population have mental retardation. Mental Retardation is a disability, which starts before adulthood, and has a lasting effect on development producing:

Reduced ability to cope independently (impaired social functioning) due to Reduced ability to understand new information and to learn new skills (impaired intelligence).

 

The essential features of mental retardation are a significantly sub-average general intellectual

function, accompanied by significant deficits in social functioning in areas such as social skills,

communication and in addition difficulties in attaining personal independence and social

responsibility. The onset of mental retardation must be before the age of 18 years.

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CAUSES OF MENTAL RETARDATION

Causes of mental retardation are grouped into two, genetic and environmental categories.

Ø  Problems with brain development intra uterine which may be caused by different factors.

 For example, drug and alcohol intake by a pregnant mother, ante natal infection.

 

Ø  Brain damage during birth. For example, in cephalic pelvic disproportion, mechanical brain damage in the prolonged labour the brain is deprived of oxygen.

 

Ø  Prematurity [Brain not fully developed]

 

Ø  Conditions after birth e.g. meningitis, cerebral malaria, hydrocephalus,

 

Ø  Head injury; caused by falls, penetrating, and blunt object.

 

Ø  Drug use [by the child] example marijuana etc.

 

 

CLASSIFICATIONS OF MENTAL RETARDATION

 

Traditionally, Intellectual functioning has been measured by IQ tests [intellectual Quotient which refers to a person’s ability to learn, reason, make decisions and solve problems]. A significantly sub-average intellectual functioning was defined as an IQ of 70 or below.

 

However IQ tests are now treated with some flexibility that might permit the exclusion from the diagnosis of mental retardation of some people with IQ's lower than 70. This is the case if it is felt that there are no significant deficits in adaptive function (the person's effectiveness in areas such as social skills, communication, daily living skills, etc).

 

Mental retardation can be further broken down into borderline, mild, moderate, severe according to IQ. The IQ level gives an approximate guide to the individual's general level of functioning.

 

·       Borderline / Mild Mental Retardation (IQ 51 to 69 percent)

They represent about 80% of people with mental retardation and their appearance is usually

unremarkable and any sensory or motor deficits are slight. In adult life most of these people are

never diagnosed. Most of these people can live independently in ordinary surroundings, although

they may need help with housing and employment or when under some unusual stress.

 

·       Moderate Mental Retardation(IQ 40 to 50 percent)

People in this group account for about 12% of the learning disabled population. Most of them can

Talk or at least learn to communicate and they take care of themselves with some supervision. As adults they can usually undertake simple or routine work and find their way about.

 

·       Severe Mental Retardation (IQ 20 to 39 percent)

This group accounts for about 7% of the learning disabled population. In pre school years, their

development is usually greatly slowed. Eventually they may acquire some skills to look after

themselves although under close supervision. They may also be able to communicate in a simple way. These people can undertake simple tasks and engage in limited social activities.

 

·       Profound Mental Retardation (0 to 24 percent)

People in this group account for less than 1% of the learning disabled group. Few of them learn to care for themselves although some eventually acquire some simple speech and social behaviour.

 

SIGNS AND SYMPTOMS OF MENTAL RETARDATION

Though some children may not have been detected early, but later in life with minimal signs and symptoms especially in mild mental retardation

Ø  Primary manifestations are delayed intellectual development (low IQ)

Ø  Immature behaviour

Ø  limited self care,

Ø  Motor deficit(flaccid muscles)

Ø  Language delay and impaired ability to communicate

Ø  Anxiety and depression later in life because of discrimination(rejected by other children)

                            

DIAGNOSIS OF MENTAL RETARDATION

Diagnosis is made using intellectual quotient (IQ) and developmental assessment.

 

Ø  Intellectual assessment can be class continuous assessment exams results below average/sub-average may indicate mental retardation.

 

Ø  Developmental assessment includes neuromuscular examination which will reveal retrograde neuromuscular function (Flaccid muscle).

 

MANAGEMENT

 

MULTIDISCIPLINARY THERAPY

Multidisciplinary team is required that includes neurologists, developmental paediatrician, physiotherapist, orthopaedists, occupational therapist, speech therapist and audiologist help with language delay or with a suspected hearing loss.

 

MEDICAL TREATMENT

 

The medications most commonly prescribed for persons with mental retardation and mental illness fall into the following classes:

• Anti-depressants

• Mood-stabilising agents

• Sedatives (hypnotics)

 

Anti-depressants

 

Antidepressants are used primarily for the treatment of depressive mood disorders. The newer antidepressants often referred to as Serotonin Selective Reuptake Inhibitors (SSRIs), have become the agents of first choice in most cases. They have also been used in the treatment of self-injurious behaviour, obsessive-compulsive disorder, panic disorder, and Tourette's syndrome.

 

- Examples:

• Older tricyclic anti-depressants: amitriptyline, dothiepin, nortriptyline, and Imipramine

 

• Newer anti-depressants: sertraline, fluoxetine, fluvoxamine, nefazodone, and clomipramine

(Clomipramine is a tricyclic which differs from the others in this group)

 

• Monoamine oxidase inhibitors (MAOIs): phenelzine, are rarely used in mental retardation

due to side effects

 

Mood-Stabilising Agents

 

Mood stabilising agents are used for people suffering from "mood swings", commonly referred to as bi-polar affective disorders or manic-depressive disorders. The medications prescribed are diverse but have in common a propensity to stabilise central neuronal activity. These same medications are also used to treat non-specific aggression and over-aroused behaviour of people with mental retardation and as adjunctive therapy for unipolar depressive disorders and psychotic disorders.

 

- Examples:

• Benzodiazepines: diazepam, nitrazepam, lorazepam, alprazolam, clonazepam, and flurazepam

 

• Non diphenhydramine, and -Benzodiazepines:

 

Anti-anxiety (anxiolytic)

 

Generalised anxiety is often first treated with medications such as hydroxyzine and buspirone. If these are unsuccessful, benzodiazepines are often used such as; diazepam, lorazepam, or alprazolam.

 

PREVENTION

Ø  Genetic counselling may help couple with high risk e.g. couple with mental retardation predispose the off spring.

Ø  Prenatal testing (e.g. amniocentesis) which enables the couple to terminate pregnancy and subsequent family planning.

Ø  Proper obstetric management e.g. treatment of uterine infection, prevention of birth injuries as in case of cephalous pelvic disproportion by doing caesarean section neonatal care.

Ø  Proper and prompt treatment  of infection e.g. meningitis

Ø  Prevention of head injury