1.3 Autism Spectrum Disorder and Intellectual Disabilities

Autism Spectrum Disorder (ASD): DSM-5 and IDEA Criteria

Autism Spectrum Disorder (ASD) is a neurodevelopmental disorder characterized by persistent deficits in social communication and social interaction, alongside restricted, repetitive patterns of behavior, interests, or activities. Under federal IDEA regulations (34 CFR § 300.8(c)(1)) and DSM-5 (299.00), diagnosis requires meeting criteria across two main clinical domains:

Domain 1: Social Communication and Social Interaction Deficits

Must demonstrate persistent deficits across all three of the following areas:

1. Deficits in Social-Emotional Reciprocity: Abnormal social approach, failure of normal back-and-forth conversation, reduced sharing of interests, emotions, or affect, and failure to initiate or respond to social interactions.
2. Deficits in Nonverbal Communicative Behaviors: Poorly integrated verbal and nonverbal communication, abnormalities in eye contact, body language, deficits in understanding gestures, or total lack of facial expressions and nonverbal communication.
3. Deficits in Developing, Maintaining, and Understanding Relationships: Difficulties adjusting behavior to fit social contexts, difficulty sharing imaginative play, making friends, or apparent absence of interest in peers.

Domain 2: Restricted, Repetitive Patterns of Behavior, Interests, or Activities

Must demonstrate at least two of the following four areas:

1. Stereotyped or Repetitive Motor Movements, Speech, or Use of Objects: Motor stereotypies (hand flapping, body rocking), echolalia (immediate or delayed repetition of words/phrases), lining up toys, or flipping objects.
2. Insistence on Sameness, Inflexible Adherence to Routines, or Ritualized Behavior: Extreme distress at small schedule changes, rigid transition rituals, or repetitive questioning.
3. Highly Restricted, Fixated Interests: Intense preoccupations with unusual objects or hyper-focused topics (e.g., train schedules, vacuum cleaner serial numbers).
4. Sensory Hyper- or Hypo-Reactivity: Adverse reactions to specific sounds or textures, apparent indifference to pain/temperature, excessive smelling/touching of objects, or visual fascination with lights/movement.

DSM-5 Severity Levels for ASD

• Level 1 ("Requiring Support"): Without support, social communication deficits cause noticeable impairments. Inflexible behavior causes interference in functioning.
• Level 2 ("Requiring Substantial Support"): Marked deficits in verbal/nonverbal social communication; limited initiation of social interactions. Inflexible behavior appears frequently across contexts.
• Level 3 ("Requiring Very Substantial Support"): Severe deficits in verbal and nonverbal social communication cause severe impairments in functioning. Very limited initiation of social interaction. Severe distress modifying focus or routine.

Intellectual Disability (ID): IQ and Adaptive Behavior Criteria

Under federal IDEA regulations (34 CFR § 300.8(c)(6)) and the American Association on Intellectual and Developmental Disabilities (AAIDD), Intellectual Disability (ID) is defined as significantly subaverage general intellectual functioning, existing concurrently with deficits in adaptive behavior and manifested during the developmental period, that adversely affects educational performance.

Dual Diagnostic Criteria for Intellectual Disability

To be determined eligible for special education under ID, a student must meet both psychometric and functional criteria:

1. Significantly Subaverage Intellectual Functioning: Standardized Full Scale IQ score of 70 or below (measured on individually administered assessments such as WISC-V or Stanford-Binet 5). An IQ score of 70 represents approximately two standard deviations below the mean (100), taking into account the standard error of measurement (typically ±5 points).
2. Concurrent Deficits in Adaptive Behavior: Significant limitations in daily functioning across standardized adaptive behavior assessments (e.g., Vineland-3, ABAS-3). Limitations must exist in at least one of three core adaptive domains:
   • Conceptual Domain: Competencies in academic skills, spoken/written language, reading, writing, mathematics reasoning, money concepts, memory, and problem-solving.
   • Social Domain: Interpersonal communication skills, empathy, social judgment, friendship capabilities, rule compliance, and avoiding victimization.
   • Practical Domain: Self-care, personal hygiene, dressing, eating, mobility, safety awareness, home management, occupational skills, and recreational leisure.
3. Developmental Origin: Onset during the developmental period (defined as prior to age 22 under current AAIDD guidelines).

AAIDD Levels of Support Needs

Rather than relying strictly on rigid IQ categories (mild, moderate, severe, profound), modern special education practice utilizes the AAIDD Levels of Support Needs framework. This model evaluates the intensity, frequency, and duration of environmental supports required for a student to participate meaningfully across educational and community settings.

The Four Levels of Support

1. Intermittent Support: Support is provided on an "as needed" basis. It is episodic in nature, occurring during life transitions (e.g., starting high school, seeking employment) or acute personal crises, but is not consistently required on a daily basis.
2. Limited Support: Support is consistent over time, but time-limited. It requires fewer staff hours than extensive support (e.g., temporary job-coaching for 6 months, targeted travel training to navigate a public bus route).
3. Extensive Support: Support is characterized by regular, daily involvement in at least some environments (e.g., daily ongoing assistance with meal preparation, hygiene, or financial budgeting at school and home).
4. Pervasive Support: Support is constant, high-intensity, and provided across all environments. It is long-term and potentially life-sustaining, requiring continuous 24/7 personal care, safety monitoring, and physical assistance.

Evidence-Based Interventions for ASD and ID

Effective special education programming for students with ASD and ID incorporates evidence-based behavioral and instructional strategies:

• Applied Behavior Analysis (ABA): Systematic application of learning principles to increase prosocial behaviors and decrease target behaviors. Key techniques include Discrete Trial Training (DTT) (breaking skills into small components taught systematically with prompts and reinforcements) and Naturalistic Developmental Behavioral Interventions (NDBI).
• Visual Support Systems: Using visual schedules, TEACCH structured workstations, first-then boards, and visual timers to increase predictability, facilitate task completion, and reduce transition anxiety.
• Picture Exchange Communication System (PECS): An augmentative communication intervention that explicitly teaches non-verbal students to initiate communication by exchanging picture icons for desired items or activities.
• Functional Communication Training (FCT): Identifying the function of a challenging behavior via Functional Behavior Assessment (FBA) and explicitly teaching a functionally equivalent communication alternative (e.g., pointing to a "break" card instead of engaging in task-avoidant aggression).
• Social Stories (Carol Gray): Short, individualized written stories with visual cues that describe social situations, relevant social cues, and expected behaviors to improve perspective-taking.