Study Notes on Intellectual Developmental Disorder

Intellectual Developmental Disorder

General Overview

  • The term 'intellectual developmental disorder' is often used interchangeably with 'intellectual disability'.

  • Label Preference: Preference leans towards 'disability', but 'disorder' is the term utilized in DSM context.

Understanding Intelligence

  • Intelligence is often viewed beyond just IQ, with emotional intelligence being a significant component.

  • Intelligence Quotient (IQ):

    • Defined as a score from standardized tests assessing cognitive abilities in comparison to peers within the same age group.

    • Cognitive abilities include:

    • Working memory

    • Processing speed

    • Geospatial abilities

    • Problem solving

    • Abstract thinking

  • Average IQ is around 100, with a standard deviation of 15:

    • Above average (1 SD): 115

    • Below average (1 SD): 85

  • IQ remains relatively stable across ages, showing consistency from early childhood to late adulthood:

    • Individuals tested at age 5 with an IQ of 100 generally maintain a similar score throughout their lives.

    • Cognitive abilities may evolve, with declines noticed in later adulthood but IQ stability remains.

  • IQ is independent of academic achievement or motivation.

    • Standardized tests can have issues but provide a consistent measure of cognitive abilities.

Intellectual Developmental Disorder

Definition

  • Describes a mismatch between:

    • An individual’s cognitive abilities.

    • Demands of their environment.

  • Individuals with intellectual disabilities may require additional support to meet environmental demands.

Diagnosis

  • Identification requires:

    1. Low Intelligence:

    • Must be defined by standardized tests (e.g., Wechsler Intelligence Scale for Children).

    • For children aged 6 to 16, an IQ below 70 (2 standard deviations below 100) is required (2.5th percentile).

    • Only 2-3 out of 100 children fall within this IQ range.

    1. Limitation in Adaptive Skills: Requires significant limitation in at least one of three domains:

    • Conceptual Skills: Understanding language, mathematics, reading, comprehension, and managing time and money.

    • Social Skills: Ability to form relationships, avoid gullibility, adhere to social rules, and protect against victimization.

    • Practical Skills: Daily self-care, maintaining cleanliness, scheduling, safety skills (cooking, navigation).

    1. Developmental Nature: The disorder is neurodevelopmental, generally evident from birth or early childhood, and is not changeable through interventions.

Severity Levels

  • Focus is on functional abilities rather than solely IQ:

    1. Mild Intellectual Disability: 85% of cases.

    • Some age-appropriate skills but need support for more complex tasks.

    1. Moderate Intellectual Disability: Requires extended teaching and support to gain independence.

    2. Severe Intellectual Disability: Needs support for most activities of daily living.

    3. Profound Intellectual Disability: Relies on others for nearly all activities.

  • Individual functioning is influenced by intellectual abilities, adaptive behaviors, overall health, and available supports.

Supports and Adaptation

  • Emphasis on support systems rather than focusing solely on deficits:

    • Importance of social support from parents, educators, and community resources.

    • Adaptive behaviors can be optimized with appropriate strategies and support programs.

Etiology of Intellectual Developmental Disorder

  • Difficult to ascertain a single cause; significant proportion has unknown causes.

Organic Influences

  • Biological differences accounting for a portion of cases, including:

    • Genetic conditions (e.g., Down syndrome, Williams syndrome).

    • Issues during prenatal development or congenital anomalies.

    • Brain injuries or diseases occurring during the developmental period.

Multigenic Influences (Heritability)

  • While intelligence is highly heritable, intellectual disabilities may not directly be:

    • Shared environmental factors where lower intelligence in parents can influence children’s outcomes.

Psychosocial Influences

  • Often tied to socio-economic status:

    • Neglect or inadequate mental stimulation can hinder intellectual development.

    • Example: Case study of Jeanie exemplifies impact of neglect on functioning and development.

Interaction of Influences

  • Often multiple causes interact to produce an intellectual disability, including genetic, organic, and psychosocial factors.

Prevalence of Intellectual Developmental Disorder

  • Expected prevalence: 1%-3% of population.

  • Disproportionately affects boys compared to girls.

  • Variability in prevalence due to consideration of both IQ and adaptive functioning.