9.1 ASD Core Knowledge: Diagnosis, Red Flags, Comorbidity & Differential

ASD Core Knowledge: Diagnosis, Red Flags, Comorbidity & Differential

Domain A of the QABA QBA exam tests whether you can read an autism diagnosis like a clinician—not to diagnose (that is outside QBA scope), but to interpret criteria, red flags, comorbidities, and differentials so treatment goals match the person’s actual profile.

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DSM-5-TR Criteria: Two Domains, Not a Vague “Spectrum Feeling”

Under the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, Text Revision (DSM-5-TR), Autism Spectrum Disorder (ASD) requires both:

1. Criterion A — Social communication and social interaction deficits that are persistent and present across multiple contexts (currently or by history). DSM-5-TR organizes these into three facets that must all be present: social-emotional reciprocity; nonverbal communicative behavior used for social interaction; and developing, maintaining, and understanding relationships.
2. Criterion B — Restricted, repetitive patterns of behavior, interests, or activities (RRBs). At least two of four RRB examples must be met: stereotyped/repetitive motor movements, use of objects, or speech; insistence on sameness / inflexible routines / ritualized patterns; highly restricted, fixated interests abnormal in intensity or focus; and hyper- or hypo-reactivity to sensory input or unusual sensory interests.

Symptoms must have been present in the early developmental period (though they may not become fully obvious until social demands exceed capacity, or they may be masked by learned strategies). Symptoms must cause clinically significant impairment, and the presentation must not be better explained solely by intellectual developmental disorder or global developmental delay—though ASD and intellectual disability frequently co-occur and both may be diagnosed when social communication is below what would be expected for the developmental level.

Severity levels (1–3) are assigned for social communication and for RRBs based on how much support is required, not on whether the person “looks autistic”:

For QBAs, severity language is a support-intensity signal. A Level 3 social-communication profile usually implies denser teaching trials, more environmental engineering, and caregiver coaching; a Level 1 profile may emphasize nuanced pragmatic skills, flexible routines, and workplace or campus accommodations.

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Historical Triad vs. Current Two-Domain Model; DSM-IV Labels

Older literature described a triad of impairments: (1) social interaction, (2) communication, and (3) restricted/repetitive behavior. DSM-5 merged social and communication into one social-communication domain, yielding the current two-domain model (social communication + RRBs). Sensory features moved explicitly into Criterion B.

Under DSM-IV, clinicians used discrete labels such as Autistic Disorder, Asperger’s disorder, and Pervasive Developmental Disorder Not Otherwise Specified (PDD-NOS). DSM-5/DSM-5-TR collapsed these into a single ASD diagnosis with specifiers (e.g., with/without intellectual impairment, with/without language impairment, severity). Exam items often trap candidates who treat “Asperger’s” as a current DSM-5-TR code rather than a historical (or community/self-identity) term. Conversely, someone previously labeled PDD-NOS may still meet ASD criteria—or may fit another diagnosis after re-evaluation.

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Early Diagnostic Red Flags

Red flags are screening signals, not diagnoses. Patterns that should prompt referral for comprehensive evaluation include:

• Limited joint attention (rarely following a point or gaze, seldom showing/sharing objects for social interest)
• Reduced social smiling, limited response to name, or little interest in reciprocal play
• Few communicative gestures (pointing, waving, showing) by expected ages
• Delayed, sparse, or atypical language use, including echolalia that does not serve flexible social functions
• Regression of previously acquired words or social engagement
• Intense insistence on routines, unusual object play (lining up, spinning parts), or marked sensory distress/seeking

QBAs working with early childhood teams should document observable examples, share data with the diagnostician/physician, and avoid labeling a child “autistic” based on red flags alone.

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Risk Factors and Prevalence (Verify Current CDC Figures)

ASD is associated with multifactorial risk: genetic contributions (including elevated recurrence in siblings), advanced parental age in some studies, certain prenatal/perinatal complications, and rare identifiable genetic syndromes. There is no evidence-based link between vaccines and ASD—an item still used to test scientific literacy.

Prevalence: CDC Autism and Developmental Disabilities Monitoring (ADDM) Network estimates have risen over successive surveillance years (recent reports have placed prevalence on the order of roughly 1 in the low-to-mid 30s among 8-year-olds in monitored U.S. communities). Treat any single ratio as approximate and time-bound. For exam and clinical communication, state the most recent official CDC figure you verified, note the surveillance year, and do not memorize a stale “1 in X” as permanent fact.

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Common Comorbidities

Comorbidity is the rule, not the exception. High-frequency co-occurring conditions include:

• ADHD — competing attention, impulsivity, and task persistence issues that interact with skill acquisition and escape-maintained behavior
• Anxiety — including social anxiety and intolerance of uncertainty that can inflate escape/avoidance functions
• Intellectual disability (ID) — requires goals scaled to developmental level while still targeting social communication relative to that level
• Epilepsy / seizure disorders — safety protocols, medical collaboration, and careful interpretation of “blanking” or sudden behavior change
• Gastrointestinal (GI) problems — pain and discomfort as setting events/MOs for irritability or aggression
• Sleep disturbance — chronic sleep loss as a powerful establishing operation for problem behavior and poor learning

A QBA does not treat epilepsy or prescribe for anxiety, but must coordinate, track setting events, and adjust programming when medical factors change the context of behavior.

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Differential Diagnosis Essentials

Differential skill for QBAs is practical: if RRBs are absent and the primary issue is pragmatic language, programming should emphasize conversational context, audience awareness, and perspective-taking supports—not assume stereotypy or sameness targets that were never clinically present.

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Terminology QBAs Must Use Precisely

• Pragmatic language — social use of language (topic maintenance, turn-taking, adjusting register).
• Receptive language — understanding spoken/signed/written input.
• Expressive language — producing communicative output (speech, sign, AAC).
• Joint attention — coordinating attention with another person toward an object/event for social sharing, not only for requesting.
• Sensory-motor — integration of sensation with movement/posture (relevant to play, self-care, and some stereotypy).
• Executive functioning — skills such as planning, inhibition, flexible shifting, and working memory that affect task completion and coping with change (described behaviorally as observable performance under specific demands—not as a mentalistic “willpower” explanation).

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How Diagnostic Results Inform ABA Goal Development

Diagnostic reports (ADOS-2 summaries, ADI-R themes, speech-language evaluations, cognitive testing, medical notes) should be translated into behavioral programming, not filed and ignored:

1. Map Criterion A deficits to skill targets — mand diversity, listener responding, joint attention/social referencing, play/social initiation, conversational pragmatics, AAC if speech is limited.
2. Map Criterion B features to context supports — visual schedules for insistence on sameness; graded exposure/flexibility programs when clinically indicated; sensory accommodations as antecedents; intervene on RRBs only when harmful or highly restrictive.
3. Use severity and adaptive scores to set intensity and scope — denser supervision, more caregiver training, and safety plans when support needs are high.
4. Integrate comorbidity — sleep/GI/seizure plans as setting-event management; ADHD/anxiety collaboration so escape and attention functions are not misread as “noncompliance.”
5. Stay in scope — QBAs implement and refine ABA goals; they do not overturn or independently assign DSM diagnoses.

When a report says “marked deficits in nonverbal communication and limited peer interest, Level 2,” your goals should visibly address gesture use, shared attention, and peer engagement with substantial environmental support—not a generic compliance curriculum labeled “autism program.”