Intellectual Disability(Mental Retardation)

(Mental Handicap)by

Dr. Azher ShahAssociate Professor

Department of Paediatric MedicineAzra Naheed Medical College, Lahore

IntroductionIntellectual disability (ID) is a static encephalopathy with multiple etiologies that encompasses a broad spectrum of functioning, disability, and strengths

The term is synonymous with and is now preferred over the older term, mental retardation

The term global developmental delay is usually used to describe children younger than age five with significant cognitive deficits

ID is an important public health issue because of its prevalence and the need for extensive support services

Management requires early diagnosis and intervention

Definitions

A state of functioning that typically begins in childhood and is characterized by limitations in intelligence and adaptive skills

• Published by the Diagnostic and Statistical Manual of Mental Disorders, 4th edition, text revision (DSM–IV)

• Published by the American Association on Intellectual and Developmental Disabilities (AAIDD)

Two definitions are commonly used

DSM-IV DefinitionDiagnostic and Statistical Manual of Mental Disorders, 4th edition (DSM- IV) uses the term mental retardation instead of intellectual disability

• Significant sub-average intellectual function • Significant limitations in adaptive functioning • Onset before 18 years of age

Defines by three co-existing criteria

DSM-IV Definition (Cont…)

Cognitive / Intellectual Impairment

• Severity of cognitive impairment is characterized by the extent of deviation of the IQ below 100

• Lower limit of normal is considered to be two standard deviations below the mean or an IQ of 70

Gradations of severity include IQs in the following ranges

• Mild – between 50 to approximately 70 • Moderate – between 35 to 50 • Severe – between 25 to 35 • Profound – below 25 • Unspecified – not readily testable but presumed low (ie, <70)

DSM-IV Definition (Cont…)

Adaptive Skills

• Skills of daily living that are needed to live, work, interact, and play in the community

Examples are

• Communication, social and interpersonal skills, self-care, home living, use of community resources, self-direction, functional academic skills (reading, writing and basic mathematics), work, leisure, health and safety

Adaptive functioning is considered to be impaired when there is a deficit in at least two of these areas

AAIDD Definitions (Cont…)

American Association on Intellectual and Developmental Disabilities (AAIDD) Definition• AAIDD encourages the use of the term "intellectual disability" in

place of "mental retardation" • Intellectual disability is characterized as "significant limitations

both in intellectual functioning (reasoning, learning, problem solving) and in adaptive behavior, which covers a range of every day social and practical living skills" with onset before 18 years of age

Assumptions to the application of the AAIDD definition

• Limitations in function must be assessed relative to the child's age, culture, experience, and environment

• An important purpose of characterizing limitations is to identify supports that are needed

Syndromic vs Non- syndromic Intellectual Disability

Syndromic ID (S-ID) is applied when a child presents with ID in addition to one or more clinical abnormalities or comorbidities of a known syndrome

Non- syndromic ID (NS-ID) is usually applied when a child presents with ID alone

Global Developmental Delay

Terms intellectual disability (ID) or mental retardation usually are applied to children older than five years of age, when IQ testing is more reliable

Preferred term in younger children with significant deficits in learning skills and adaptation is global developmental delay

Global developmental delay has been defined as performance at least two standard deviations below the mean, using standardized age-appropriate and developmentally appropriate criteria, in at least two of the following developmental subscales - Motor (gross/fine), speech and language, cognition, social, and daily living skills

Terms global developmental delay and ID are not interchangeable

EpidemiologyPrevalence of ID in the general population is estimated to be approximately 1 percent and ID is mild in approximately 85 percent of affected individuals

Prevalence varies with age and gender and is highest in school-age and male populations

Prevalence of mild ID is more variable than severe ID, varying with environmental factors of maternal education, educational access, or opportunities and access to healthcare

ID, and mild ID in particular, is more prevalent in developing countries or areas with lower socioeconomic status

In children less than five years of age, the prevalence of global developmental delay is estimated at 1 to 3 percent

EtiologyIdentifying a cause enables appropriate counseling, focused interventions, treatments

Genetic causes may have implications for future pregnancies, and there may also be reproductive implications for the extended family

Causes usually are classified according to the time of the insult, as prenatal, perinatal, and postnatal or acquired

Some causes, such as environmental toxins or endocrine disorders, may act at multiple times

In many cases, no etiology can be identified despite extensive evaluation

Etiology

Prenatal Causes (Genetic)

• Chromosomal abnormalities (Down syndrome or Trisomy 21)• X-linked disorders (Fragile X syndrome)• Autosomal recessive disorders (Metabolic disorders)• Autosomal dominant disorders

Chromosomal microarray testing is currently the most valuable tool to identify genetic causes of ID

Genetic abnormality may have different phenotypes or clinical expressions and may present as ID alone (non-syndromic ID), or as ID associated with a clinical syndrome (syndromic ID)

Known genetic disorders or conditions include

Etiology

Prenatal Causes (Non Genetic)

• Central nervous system (CNS) malformations• Congenital infection• Environmental toxins or teratogens (eg, alcohol,

lead, mercury, hydantoin, valproate)• Radiation exposure (especially between 9 and

15 weeks of gestation)• Congenital hypothyroidism• Inborn errors of metabolism (phenylketonuria)

Etiology

Perinatal Causes

• Preterm birth• Hypoxia• Infection• Trauma• Intracranial haemorrhage

Etiology

Postnatal Causes

• Accidental or non accidental trauma• CNS haemorrhage• Hypoxia (eg, near-drowning)• Environmental toxins• Psychosocial deprivation• Malnutrition• Intracranial infection• CNS malignancy• Acquired hypothyroidism

Risk FactorsMale gender

Low-birth-weight infants

Higher and lower maternal age

Low maternal education

Multiple births

Children of consanguineous parents

Clinical Presentation

Language delay

Immature behaviour

Immature self-help skills

Difficulty in learning

Delayed development

Clinical Presentation

Associated Conditions

• Autism and other behavioral disorders• Seizure disorders• Motor handicaps affecting gross, fine, and speech motor functions• Problems with vision, hearing• Abnormal thyroid function• Short stature• Growth hormone deficiency

Clinical Presentation

Mental disorders

• Affect approximately 30 to 70 percent of children with ID

• Affect functioning, quality of life, and adaptation

Diagnosis

Diagnosis of ID is based on measures of intellectual and adaptive function through a battery of standardized tests

Selection of the appropriate testing instruments depends on the child's age, culture, language, socioeconomic status, and personal handicaps, including motor, sensory, and communication disorders

For tests of intellectual function, the lower limit of normal is considered to be two standard deviations below the mean, or an intelligence quotient (IQ) of 70

Tests of adaptive function are used to assess for deficits in conceptual skills (eg, receptive and expressive language, reading and writing, and money concepts), social skills (eg, interpersonal skills, responsibility, gullibility, and obedience of laws), and practical daily living skills (eg, eating, dressing, toileting, preparing meals, and using transportation)

Management of Intellectual Disability

Goals of Management

Strengthen areas of reduced function

Prevent or minimize further cognitive-adaptive deterioration relative to peers

Promote optimal functioning in society

Provide ongoing family support

General Measures of ManagementRequire ongoing health surveillance similar to normal children

Developmental, academic, and psychosocial progress should be monitored

Evaluation of nutritional status to ensure a well-balanced diet

Vigilant surveillance should be maintained to detect and prevent abuse and neglect

Family Psychosocial Screen may be helpful to screen families for concerns of abuse and maternal depression

General Measures of Management

Require a broad range of interventions that should be applied early to improve short-term and long-term outcomes

• Speech and language therapy • Occupational therapy • Physical therapy and rehabilitation, including mobility and postural support • Family counseling and support • Behavioral intervention • Educational assistance • Parent support, information, and advocacy (Support groups)

Specific Interventions

If an underlying cause is identified, it should be promptly treated

Phenylketonuria

Hypothyroidism

Hydrocephalus

Specific Interventions

•Cataracts•Vision and hearing impairments•Congenital heart disease•Seizures•Constipation

Associated conditions should be treated in order to

maximize functioning

Specific Interventions

Patients with ID due to specific conditions may have characteristic sleep disorders

• Smith Magenis syndrome is associated with insomnia• Prader-Willi or Down syndrome are at risk for obstructive sleep apnea• These children require sleep-related behaviour interventions or counseling

Specific Interventions

Lead screening should be obtained

for possible exposure and re-exposure

Behavioural InterventionsNeeded to improve socialization skills and behavioral functioning in children with ID

These are individualized and applied consistently to encourage appropriate thinking, expression, adaptive function, conduct, and environmental manipulation

Interventions should be appropriate to the child's level of functioning (particularly language functioning) rather than chronological age

Desirable behaviors should be positively reinforced

Behavioural InterventionsActive intervention to reduce antecedents (triggers) of problem behaviors

Reinforcement of acceptable behavior by providing positive attention ("time in" attention) or desired reinforcer (appropriate treat or preferred activity)

Purposeful "ignoring" of behaviors to encourage their non-use (as long as the behavior is not dangerous)

Redirecting attention to extinguish problem behaviors

Behavioural InterventionsReinforcing behaviors incompatible with problem behaviors

Prompt removal of the child from an activity when a targeted problem behavior occurs ("time out")

Promotion of good self-esteem and independence

Child should also be taught how to resist peer pressure and avoid exploitation

For adolescents, individualized teaching should include issues of sexuality, transition to adult life, and preparation for independent community living

Group psychotherapy

Early Intervention Programme Models

Case management • Speech and language therapy • Occupational and physical therapy • Psychological services • Health services, including hearing and vision • Nutrition counseling • Assistive technology (which may include tape-recorded texts, reading

scanners, or voice-activated computer programs) • Medical diagnostic services • Transportation and other assistive technology

Interventions for the family include

• Counseling • Training • Home visitation • Social services

Outcome

Variable and depends upon the etiology, associated conditions, environmental and social factors

Environmental factors such as education and rehabilitation

Social factors such as caregiver support, expectations, attitudes, socioeconomic characteristics and social opportunities

Outcome( According to the DSM definitions)

•Have a developmental velocity of one-half to two-thirds the average rate, accomplishing third to sixth grade level reading skills by late adolescence•Some mildly affected individuals can work at regular occupations, and many live independently•Many marry and become parents, although raising children is challenging

Mild ID

Outcome( According to the DSM definitions)

•Develop at one-third to one-half the expected rate of normal children•School based academic and social development gains are slow•Reading at a first to third grade level can be accomplished with educational services•Teaching is needed for daily living skills. •Majority need sheltered or supportive employment positions, although some can perform unskilled work•Few are able to marry and raise children

Moderate ID

Outcome( According to the DSM definitions)

•Developmental progress for children with severe ID is approximately one-quarter to one-third of the expected rate•Speech development may be delayed until four to five years of age, or may never occur•Majority require training in social and self-help daily living skills•Majority need assistance with daily living and adult social skills•In general, severely affected individuals do not marry or raise children

Severe ID

Outcome( According to the DSM definitions)

•Develop at less than one-quarter of the typical rate•They need comprehensive assistance that is tailored to their physical needs•Need assistance in all aspects of daily living•Profoundly affected individuals cannot acquire reading skills•Life expectancy of children with profound ID varies and is up to 20 years

Profound ID

Prevention(Most causes of ID cannot be prevented)

Primary preventionAimed at preventing conditions that may cause ID

Avoidance of prenatal exposure to alcohol or other toxins

Use of prenatal

Multivitamins,

especially Folic acid

Appropriate prenatal

care

Newborn screening programs

for metabolic disease

Routine childhood immunizat

ions

Use of car seats and restraints

Prevention of motor vehicle

accidents, violence, and other trauma

Prevention(Most causes of ID cannot be prevented)

Genetic forms of ID could be addressed by the following measures

Provision of clinical genetics services to facilitate

accurate genetic diagnosis and counseling

Genetic counseling may enable estimation of

recurrence risks and about reproductive options in the

future

Pre-implantation genetic diagnosis (PGD) and prenatal diagnosis

Prevention(Most causes of ID cannot be prevented)

Secondary preventionDirected at treating an underlying condition

Lead surveillance in a child at risk for

lead exposure

Dietary restriction in metabolic

diseases such as phenylketonuria or

galactosemia

Thyroid hormone replacement in a hypothyroid child

Treatment of associated conditions

including vision and hearing

impairment, seizures, and other co-morbid medical

disorders

Prevention(Most causes of ID cannot be prevented)

Tertiary preventionAimed at maximizing function and quality of life

Early identification of affected individuals

Access to and provision of appropriate

comprehensive services and resources

Treatment of comorbid

conditions

Prevention and treatment of psychosocial

disorders

Thank you