Study Notes on Intellectual Disability

Chapter 5: Intellectual Disability (Intellectual Developmental Disorder)

Agenda

  • Intelligence and Intellectual Disability

  • Features of Intellectual Disabilities

  • Developmental Course and Adult Outcomes

  • Causes

  • Prevention, Education, and Treatment

Intelligence and Intellectual Disability

Introduction

  • Intellectual disability (ID) is characterized by:

    • Significant limitations in mental abilities (reasoning, planning, judgment).

    • Impairments in adaptive functioning (conceptual, social, practical skills) required for daily life.

  • Three essential elements defining this condition:

    1. Intellectual limitations

    2. Deficits in adaptive skills

    3. Early onset

  • Modern definitions of ID take into account the intellectual functioning relative to an individual's peers and cultural context.

Defining and Measuring Children’s Intelligence and Adaptive Behavior

  • General intellectual functioning is defined using an intelligence quotient (IQ).

  • IQ is derived from standardized, individually administered intelligence tests assessing:

    • Various verbal and visual-spatial skills (knowledge, reasoning, similarities/differences).

    • Mathematical concepts.

  • ID is no longer solely based on IQ scores; adaptive functioning is also a crucial metric.

  • Adaptive functioning:

    • Refers to how effectively individuals cope with life demands and their capacity for independent living.

    • Individuals may learn to adapt, even with lower IQ scores, and might not be classified as having an ID.

  • Instruments for measuring adaptive functioning are standardized.

Specific Examples of Adaptive Behavior Skills

  • Conceptual Skills:

    • Receptive and expressive language, reading and writing.

    • Money concepts and responsibilities.

  • Social Skills:

    • Interpersonal relationships, self-esteem, gullibility.

  • Practical Skills:

    • Activities of daily living (e.g., eating, dressing, mobility).

    • Instrumental activities (preparing meals, medication management, etc.).

    • Following rules and maintaining a safe environment.

The Controversial IQ

  • IQ is generally stable over time, but:

    • No correlation with IQ scores measured in infants under one year.

    • High correlation by age 4 with scores at age 12 (r = 0.77).

  • Mental ability is influenced by experience, with early stimulation facilitating development in children with delays.

  • Cognitive trajectories can change by 10-20 points from childhood to adolescence depending on environmental stimuli.

Case Studies

  • Matthew (6):

    • Diagnosed with mild intellectual disability; speech delays but effective verbal skills.

    • Encountered challenges in establishing friendships due to misunderstandings in games.

  • Vanessa (8):

    • Moderate intellectual disability; capable of self-care but requires daily assistance.

    • Attended school but had limits due to economic and educational circumstances.

Features of Intellectual Disabilities

General Features

  • Wide variability in abilities and qualities among affected individuals:

    • Some excel in school and community settings while others need daily supervision.

  • DSM-5 Diagnostic Criteria:

    • Deficits in intellectual functioning.

    • Concurrent deficits in adaptive functioning.

    • Must show these characteristics before age 18.

Diagnostic Criteria for Intellectual Disability

  • ID requires three criteria to be diagnosed:
    A. Deficits in intellectual functions (e.g., reasoning, problem-solving).
    B. Deficits in adaptive functioning, with significant limitations affecting daily life across contexts.
    C. Onset during developmental periods.

  • Clarification of terminology:

    • The term intellectual disability is preferred and replaces the term mental retardation (as per Rosa's Law).

  • Severity Levels:

    • 317 (F70) Mild

    • 318.0 (F71) Moderate

    • 318.1 (F72) Severe

    • 318.2 (F73) Profound

Importance of Criterion B

  • Excludes individuals who perform well in their settings but may struggle on IQ tests due to various reasons (e.g., ADHD, ASD).

  • Adaptive skills are influenced by experience and opportunity.

Importance of Criterion C

  • Establishes the age of onset to differentiate ID from degenerative conditions (like Alzheimer’s).

Intellectual Measurement

  • Individuals with ID often score 2+ standard deviations below the mean IQ (typically under 70).

    • Average IQ = 100; standard deviation = 15.

Severity Level Descriptions
Mild ID (approx. 85% of cases)

  • Typically identified in elementary years.

  • Minority overrepresentation may arise from social disparities.

  • Can reach about a sixth-grade academic level with support.

Moderate ID (approx. 10% of cases)

  • Identified during preschool due to delays.

  • Academic performance stays at an elementary level; may require vocational training.

Severe ID (approx. 3-4% of cases)

  • Often linked with organic causes; significant delays observed early.

  • Basic self-care skills typically learned by age 9; continuous assistance needed.

Profound ID (approx. 1-2% of cases)

  • Marked disability and poor communication; life-altering assistance needed.

Prevalence

  • Approximately 1-3% of the population have ID.

  • Disparities in prevalence related to race, socioeconomic status (SES), and definitions used.

Developmental Course and Adult Outcomes

  • Developmental Position: Hypothesizes similar developmental milestones for all children, varying in rate.

  • Difference Position: States cognitive development may qualitatively differ for children with ID compared to others.

The Two-Group Approach

  • Organic Group: ID linked to biological causes; typically severe.

  • Cultural-Familial Group: No clear organic basis; often associated with mild ID.

Familial vs. Organic ID

  • Familial ID shows normal developmental stages with slight deficits; often correlated with motivation.

  • Organic ID displays distinct deficits and developmental differences.

Motivation and Changes in Abilities

  • Children with mild ID often struggle with motivation, reflecting learned helplessness.

  • IQ scores can fluctuate based on opportunities and training received.

Language and Social Behavior

  • Children with ID exhibit predictable developmental patterns, with social challenges due to delays in expressive language.

Emotional and Behavioral Problems

  • Higher rates of anxiety, impulse control disorders, mood disorders, and violence, linked to communication barriers and stressors.

Health Considerations

  • Higher prevalence of chronic health conditions among individuals with ID; life expectancy impacts depending on severity and associated conditions.

Causes

Genetic and Environmental Factors

  • Numerous genetic conditions (over 1,000) linked to ID; only a fraction of mild ID cases are understood.

  • Prenatal, perinatal, and postnatal risk factors, including:

    • Prenatal: Chromosomal disorders, maternal illness, poor prenatal care.

    • Perinatal: Birth injuries, prematurity.

    • Postnatal: Traumatic brain injuries, malnutrition.

Inheritance and Environment

  • Environmental variations significantly influence IQ; disadvantages impact cognitive performance.

  • Adoption studies reveal improvements in children transitioned from disadvantaged homes to more privileged environments.

Genetic and Constitutional Factors

  • Specific syndromes such as Down syndrome (trisomy 21) and Fragile-X syndrome, presenting unique physical and cognitive profiles impacting ID severity.

Prevention, Education, and Treatment

Prenatal Education and Screening

  • Involves educating prospective parents on risks associated with substance exposure during pregnancy.

  • Genetic screening to determine risk factors and identify disorders prior to birth.

Psychosocial Treatments

  • Early interventions provide necessary educational experiences to children before they enter school.

Behavioral Approaches

  • Emphasis on positive behavior reinforcement is essential in enhancing social skills and integrating children into regular education systems.

Family-Oriented Strategies

  • Essential to assist families in coping and adjustment with ID; integration into typical educational and social settings to promote inclusion.

Conclusion

  • Awareness of the complexities associated with ID improves understanding, supportive measures, and individualized approaches for enhancing quality of life for patients and families involved. END OF CHAPTER 5