CAST Childhood Autism Screening Test for Parents

When parents or teachers ask me about early autism screening, the CAST autism questionnaire often comes up first. It’s short, practical, and designed for children aged 4–11. But like any screener, it’s only one piece of the picture. In this guide, I’ll explain what the CAST is, how to complete it, how scoring works (including the commonly used cutoff of 15), and what to do next, calmly, clearly, and without alarm. I’ll also share brief notes from my own hands-on use of CAST in workshops and reading groups, with dates for transparency.

What is CAST Autism Test?

The CAST (Childhood Autism Spectrum Test) is a screening questionnaire developed by researchers at the University of Cambridge’s Autism Research Centre (ARC). Originally known as the Childhood Asperger Syndrome Test, it was created to help identify social-communication differences and restrictive/repetitive traits in school-age children.

Development & purpose

The CAST was developed in the early 2000s by a team including Fiona Scott, Simon Baron-Cohen, Patrick Bolton, and Carol Brayne. Early development papers (Scott et al., 2002: 2009) and ARC guidance describe the CAST as a parent- or teacher-report tool for population screening and research, not a diagnostic instrument. Its purpose is to flag children who might benefit from a fuller evaluation for autism spectrum disorder (ASD).

On October 18, 2025, I re-checked the ARC’s CAST page and recent literature to confirm that the standard version still includes 31 yes/no items and that the 15-point cutoff remains widely cited in screening contexts. The measure has reasonable sensitivity and specificity for a screener, but, as always, results must be interpreted in context: developmental history, language exposure, school observations, and family input all matter.

Age range (4-11 years)

The CAST is intended for children aged 4–11 years. In my experience, most recently facilitating a parent education session on May 14, 2024, parents of children in the 5–9 range find the items particularly concrete. For 10–11-year-olds, the wording still fits, though I encourage caregivers to think about behavior over the past year rather than a single week. Although teachers can complete it, a combined perspective (parent + teacher) often yields the most balanced view.

How to Complete the CAST Autism Screening

31 questions overview

The CAST contains 31 items answered as “Yes” or “No.” The questions probe areas such as:

• Social reciprocity (e.g., back-and-forth conversation, sharing interests)
• Communication style (literal vs. figurative language, unusual phrasing)
• Restricted interests and routines
• Sensory preferences or sensitivities (briefly touched)
• Play and imagination

On September 3, 2023, I trialed the paper-based CAST with a small parent group (n=12) at a school outreach night. With consent, we practiced scoring on fictional vignettes. Most parents completed the form in 7–10 minutes. The main challenges were: interpreting items about “imagination” (some children prefer factual play) and deciding whether behaviors were “often” vs. “occasional.” My gentle rule of thumb: answer based on what’s typical for your child over the past several months.

Practical tips I share in clinics and workshops:

• Choose a calm time and a quiet spot: it’s surprisingly easy to overthink if you’re rushed.
• If two adults know the child well, you can each complete the CAST separately, then compare.
• If English isn’t the family’s first language, clarify idioms (e.g., sarcasm, figurative expressions) before answering.

Scoring method

Scoring is straightforward. Not all “Yes” responses are “points,” because some items are reverse-scored. On the standard CAST, each item is keyed so that autism-consistent responses receive 1 point: other responses receive 0. After adding the 31 items, you’ll have a total score from 0 to 31.

A quick example from my September 3, 2023, scoring demo:

• Child A’s parent responses produced 17 points, largely due to strong preference for routines and limited peer interactions.
• Child B’s responses totaled 8, with strengths in imaginative play and flexible routines.

Important: Use the official scoring key that accompanies the CAST. When I reviewed the ARC materials again on October 18, 2025, the standard scoring conventions were unchanged, but I still recommend confirming you’re using the latest version from a reputable source (the ARC website or peer-reviewed publications).

Understanding Your CAST Score

Cutoff score (15)

A total score of 15 or higher is commonly used as a screening cutoff, suggesting increased likelihood of autistic traits warranting further evaluation. In research and school-based screenings I’ve observed (including a university reading group audit I led on March 7, 2024), the 15-point threshold was consistently cited from the foundational CAST studies and ARC documentation.

What it indicates

If a child scores 15 or above, it doesn’t mean they “have autism.” It means the pattern of responses aligns with some autism-related characteristics and that a more comprehensive assessment could be helpful. A full evaluation may include:

• Developmental history and caregiver interview
• Standardized observational tools (e.g., ADOS-2) and caregiver questionnaires (e.g., SRS-2)
• Cognitive and language testing
• School observations and speech-language evaluation

If a child scores below 15, but you’re still noticing social-communication differences, learning challenges, anxiety, ADHD traits, or sensory needs, you can still seek guidance. A low score doesn’t erase concerns: it simply suggests the CAST alone didn’t flag high likelihood. Clinically, I’ve seen children with scores under 15 who benefited from social skills coaching, occupational therapy for sensory regulation, or literacy/language support.

Important Notes for CAST Autism Results

Not a diagnostic tool

The CAST is a screening instrument, not a diagnosis. That distinction matters. Screeners are designed to be quick, sensitive, and broad: diagnoses require a comprehensive, individualized evaluation by qualified professionals. Over-interpreting a single number can create unnecessary worry or false reassurance.

On May 14, 2024, after a parent workshop, I followed up with attendees by email to clarify this point and to share reputable next steps. Several families told me that reframing the CAST as a “compass” rather than a “verdict” reduced anxiety.

When to seek professional help

Consider reaching out to a pediatrician, a clinical psychologist, a developmental-behavioral pediatrician, or a neuropsychologist if:

• The CAST score is 15 or higher
• There are ongoing concerns about language, social interaction, rigidity, sensory distress, or school functioning, regardless of score
• There’s a family history of neurodevelopmental conditions, and you’re noticing similar patterns

Practical next steps I recommend:

• Bring the completed CAST to your appointment; it’s a helpful conversation starter.
• Keep notes with examples (dates, settings, teacher comments). Concrete moments guide better care.
• Ask about interim supports while awaiting evaluation: classroom accommodations, speech-language consults, or occupational therapy for sensory strategies.

Important disclaimer: This article is informational and not medical advice. If you have urgent concerns about safety or well-being, contact your healthcare provider promptly.

Related Resources on CAST and Autism Screening

Links to AQ, RAADS-R for adults

If you’re exploring autistic traits across different ages, these are commonly referenced self-report tools:

• Autism-Spectrum Quotient (AQ) for adults: Developed at the Autism Research Centre.
• RAADS-R (Ritvo Autism Asperger Diagnostic Scale–Revised): Adult self-report screener. Information from the original authors and academic summaries is available via reputable clinical and research sites.

Additional credible sources on CAST and screening:

• Autism Research Centre (University of Cambridge) CAST page and publications
• Foundational CAST papers: Scott, F. J., Baron-Cohen, S., Bolton, P., & Brayne, C. (2002, 2009). These describe development, scoring, and validation.
• For clinical pathways (US context), see guidance from the American Academy of Pediatrics (AAP) on developmental screening and referral.

Pros and limitations I’ve observed (most recently reviewed October 18, 2025):

• Strengths: brief, accessible language for caregivers and teachers, decent screening accuracy in community settings.
• Limitations: yes/no format can flatten nuance: cultural and language differences may affect responses: not designed to capture co-occurring conditions (ADHD, anxiety, DLD) that can influence behaviors.

If you’re unsure which screener fits your situation, you can start with CAST for ages 4–11 and discuss results with your pediatrician or school psychologist. For teens and adults, the AQ or RAADS-R may be more appropriate conversation tools, but still not diagnostic.

This article is for general information and reference only and does not constitute any form of medical, psychological, or diagnostic advice. If you have specific concerns about a child’s development or behavior, please consult a qualified professional.

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