How Autism Is Diagnosed: Evaluation Guide

Important Note: Buzz ABA Therapy does not provide autism diagnosis services. We specialize in ABA therapy after diagnosis. This guide is provided as an educational resource to help families understand the diagnosis process and know what to expect.

Understanding Autism Diagnosis

Getting an autism diagnosis for your child can feel overwhelming, but understanding the process helps families prepare and advocate effectively. According to the Centers for Disease Control and Prevention (CDC), autism can be reliably diagnosed as early as age 2, though many children aren't diagnosed until much later.

Early diagnosis is crucial because it opens the door to early intervention services, which research consistently shows improve long-term outcomes. The sooner families can access appropriate support, the better.

A Personal Perspective on the Diagnosis Journey

"When our son was diagnosed with autism at age 8, the journey to getting that diagnosis felt long and uncertain. Like many families, we noticed differences early on but weren't sure what to make of them. Once we received the diagnosis, everything changed – we finally had a path forward and could access the right support. That experience is what led us to found Buzz ABA, so we could help other families navigate this journey with confidence."

– The Monico Family, Founders of Buzz ABA in Concord, NH

Early Signs That May Prompt Evaluation

Parents and caregivers are often the first to notice developmental differences. While some signs are obvious, others can be subtle. Learn more about identifying mild symptoms of autism. According to the Autism Speaks organization, early signs may include:

Limited or no eye contact
Not responding to name by 12 months
Limited pointing or waving by 12 months
No single words by 16 months or two-word phrases by 24 months
Loss of previously acquired language or social skills
Limited interest in other children
Unusual play patterns (lining up toys, repetitive actions)
Strong reactions to sensory input (sounds, textures, lights)
Repetitive movements or behaviors

For a more comprehensive overview, see our guide on autism symptoms and signs.

The Diagnosis Process: Step by Step

Step 1: Developmental Screening

The American Academy of Pediatrics (AAP) recommends that all children be screened for autism at their 18-month and 24-month well-child visits. Developmental screening involves:

Brief questionnaires completed by parents about their child's development
Observation of the child during the visit
Discussion of any concerns

Common screening tools include the M-CHAT-R/F (for toddlers) and the CAST (for older children). A positive screen doesn't mean a child has autism—it indicates the need for further evaluation.

Step 2: Comprehensive Diagnostic Evaluation

If screening suggests the possibility of autism, a comprehensive evaluation is recommended. According to the National Institute of Mental Health (NIMH), this evaluation typically includes:

Developmental History

A detailed interview covering pregnancy, birth, developmental milestones, medical history, family history, and current behaviors. Parents may be asked to bring baby books, videos, and early photos.

Behavioral Observation

Direct observation of the child during structured and unstructured activities. The gold-standard tool is the ADOS-2 (Autism Diagnostic Observation Schedule), which uses standardized activities to assess communication, social interaction, and play.

Cognitive and Developmental Testing

Assessment of intellectual abilities, adaptive functioning, language skills, and motor development. This helps understand the child's overall profile and identify areas of strength and need.

Parent/Caregiver Interview

Structured interviews like the ADI-R (Autism Diagnostic Interview-Revised) gather detailed information about the child's behavior and development from those who know them best.

Medical Evaluation

Rule out medical conditions that might explain symptoms and identify any co-occurring conditions. May include hearing tests, genetic testing, or other medical assessments.

Who Can Diagnose Autism?

Several types of professionals are qualified to diagnose autism:

Developmental Pediatricians: Pediatricians with specialized training in child development and behavioral issues
Child Psychologists/Neuropsychologists: Specialists in child behavior, development, and psychological testing
Child Psychiatrists: Medical doctors specializing in mental health conditions in children
Pediatric Neurologists: Specialists in brain and nervous system disorders in children
Multidisciplinary Teams: Groups of specialists working together for comprehensive evaluation

The American Psychological Association notes that multidisciplinary team evaluations are often considered the gold standard, as they bring multiple perspectives to the assessment.

Diagnostic Criteria: DSM-5

Autism diagnosis is based on criteria from the Diagnostic and Statistical Manual of Mental Disorders, 5th Edition (DSM-5). To receive an autism diagnosis, an individual must show:

Persistent deficits in social communication and interaction across multiple contexts:
- Deficits in social-emotional reciprocity
- Deficits in nonverbal communication
- Deficits in developing, maintaining, and understanding relationships
Restricted, repetitive patterns of behavior, interests, or activities (at least 2 of 4):
- Stereotyped or repetitive movements, use of objects, or speech
- Insistence on sameness, inflexible adherence to routines
- Highly restricted, fixated interests that are abnormal in intensity or focus
- Hyper- or hypo-reactivity to sensory input or unusual interest in sensory aspects of environment

Symptoms must be present in early childhood and cause clinically significant impairment. The DSM-5 also specifies support level requirements (Levels 1-3).

Common Screening and Assessment Tools

M-CHAT-R/F

Modified Checklist for Autism in Toddlers—parent questionnaire for children 16-30 months. Try our free M-CHAT screener

ADOS-2

Autism Diagnostic Observation Schedule—gold-standard observational assessment administered by trained clinicians

ADI-R

Autism Diagnostic Interview-Revised—comprehensive parent/caregiver interview covering development and behavior

CAST

Childhood Autism Spectrum Test—screening tool for children ages 4-11. Try our free CAST screener

SRS-2

Social Responsiveness Scale—questionnaire measuring social behavior severity across ages 2.5-adult

Vineland-3

Vineland Adaptive Behavior Scales—assesses daily living skills, socialization, and communication

Finding Evaluation Services in New Hampshire

For families in New Hampshire seeking autism evaluation, options include:

Children's Hospital at Dartmouth-Hitchcock: Offers comprehensive developmental evaluations
NH Early Supports & Services (Birth-3): Free evaluations for children under 3
School District Evaluations: Free through your local school district (ages 3+)
Private Developmental Pediatricians and Psychologists: Often shorter wait times
University-Based Clinics: UNH and other institutions may offer services

See our comprehensive guide to New Hampshire autism resources for more information on local services.

What to Expect: Timeline and Costs

Timeline

Wait times: 3-12+ months for many providers (varies significantly by area)
Evaluation itself: 2-4+ hours, often spread across multiple appointments
Results: Typically provided 1-4 weeks after evaluation completion

Costs

With insurance: Often covered as diagnostic testing; check your specific plan
Without insurance: $1,500-$5,000+ for comprehensive evaluation
Free options: Early Intervention (0-3), school districts (3+)

Many insurance plans cover autism diagnostic evaluations. See our guide on insurance coverage for autism services for more information.

After Diagnosis: Next Steps

Receiving an autism diagnosis opens doors to services and support. Recommended next steps include:

Take time to process: It's normal to experience a range of emotions
Learn about autism: Understanding helps you advocate and support your child
Connect with support: Parent support groups, autism organizations, other families
Access early intervention: ABA therapy and other evidence-based services
Explore school services: IEPs, special education, accommodations
Address co-occurring conditions: Many autistic individuals have additional diagnoses
Build your team: Therapists, educators, medical providers who understand autism

Download our free Early Intervention Checklist: First 100 Days After Diagnosis for a week-by-week action plan.

Frequently Asked Questions

How is autism diagnosed?

Autism is diagnosed through a comprehensive evaluation that includes developmental screening, behavioral observations, standardized assessments (like ADOS-2), parent interviews, and review of developmental history. There is no medical test—diagnosis is based on behavioral criteria outlined in the DSM-5.

At what age can autism be diagnosed?

According to the CDC, autism can be reliably diagnosed by age 2, though many children aren't diagnosed until later. Early signs may be apparent by 12-18 months. The AAP recommends autism screening at 18 and 24 months for all children.

Who can diagnose autism?

Autism can be diagnosed by developmental pediatricians, child psychologists or neuropsychologists, child psychiatrists, pediatric neurologists, and in some states, licensed clinical social workers or nurse practitioners with specialized training.

How long does an autism evaluation take?

A comprehensive evaluation typically takes 2-4 hours of direct assessment, often spread across multiple appointments. From initial referral to diagnosis, the entire process may take several weeks to months depending on wait times.

What screening tools are used for autism?

Common tools include the M-CHAT-R/F for toddlers, the CAST for older children, and the ADOS-2 as the gold-standard diagnostic assessment. Other tools include the ADI-R (parent interview) and SRS-2 (Social Responsiveness Scale).

Start Your Child's Journey Today

Buzz ABA provides comprehensive, evidence-based ABA therapy in Concord, Manchester, Nashua, and surrounding NH communities. Our neurodiversity-affirming approach helps children thrive.

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How Is Autism Diagnosed? A Complete Guide to the Evaluation Process