How is Autism Diagnosed? Understanding Criteria and Tools

Receiving an autism diagnosis for your child can be a pivotal moment in your family’s journey. Understanding how autism is diagnosed provides clarity during what can be an overwhelming process. This comprehensive guide walks you through the diagnostic journey, from recognizing early signs to navigating the evaluation process with healthcare professionals.

Understanding Autism Spectrum Disorder

Autism spectrum disorder (ASD), previously grouped under the broader category of pervasive developmental disorder, is a neurodevelopmental condition characterized by challenges in social communication and interaction, alongside restricted or repetitive patterns of behavior, interests, or activities. The term “spectrum” reflects the wide variation in challenges and strengths possessed by each person with autism.

According to the Centers for Disease Control and Prevention (CDC), approximately 1 in 36 children in the United States is diagnosed with autism spectrum disorder. While autism can be diagnosed at any age, signs typically appear in early childhood. Because autism affects each person differently, the diagnostic process is comprehensive and multi-faceted.

The Early Signs of Autism

Recognizing the early signs of autism is crucial for timely diagnosis and intervention. While every child develops at their own pace, certain developmental delays or differences may indicate autism spectrum disorder.

Some key signs to watch for include:

• Social communication differences: Limited or no eye contact, not responding to their name by 12 months, reduced social smiling, or not sharing enjoyment or interests with others
• Language development: Delayed speech, loss of previously acquired words, unusual tone or rhythm when speaking
• Social interaction challenges: Difficulty with back-and-forth conversation, reduced interest in peers, challenges in understanding social cues
• Repetitive behaviors: Hand-flapping, rocking, spinning objects, lining up toys
• Rigid thinking patterns: Strong attachment to routines, distress at small changes, highly restricted interests

It’s important to note that autism often presents differently in girls compared to boys. Girls may demonstrate more subtle social differences and might develop coping strategies that mask their challenges, sometimes leading to delayed diagnosis.

The Diagnostic Process: A Step-by-Step Guide

Diagnosing autism spectrum disorder is a comprehensive process that typically involves multiple healthcare professionals. There’s no single medical test to diagnose autism. Instead, clinicians rely on observing the child’s behavior and development, alongside standardized screening tools and assessments.

Step 1: Developmental Screening

The journey typically begins with developmental screening during well-child visits with your primary care provider. The American Academy of Pediatrics recommends that all children be screened for developmental delays during regular check-ups at 9, 18, and 24 or 30 months, with autism-specific screening at 18 and 24 months.

During these screenings, your child’s pediatrician will observe how your child plays, learns, speaks, and behaves. They’ll also ask you questions about your child’s development and may have you fill out a questionnaire like the Modified Checklist for Autism in Toddlers, Revised (M-CHAT-R).

Step 2: Comprehensive Diagnostic Evaluation

If a screening indicates potential developmental concerns, your primary care provider will refer you for a comprehensive diagnostic evaluation. This thorough assessment is typically conducted by a multidisciplinary team, which may include developmental-behavioral pediatricians, child neurologists, child psychologists or psychiatrists, speech-language pathologists, and occupational therapists. The evaluation includes gathering a detailed developmental history, observing your child’s behavior in various settings, and administering standardized assessments to examine social, communication, and behavioral patterns. Clinicians also work to rule out other conditions, such as intellectual developmental disorders, to ensure an accurate diagnosis.

Step 3: Formal Diagnosis Based on DSM-5 Criteria

Healthcare professionals diagnose autism using the diagnostic criteria outlined in the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5), published by the American Psychiatric Association. According to the DSM-5, a person must meet all of the following criteria to receive an autism diagnosis:

A. Persistent deficits in social communication and social interaction across multiple contexts, as manifested by:

1. Deficits in social-emotional reciprocity (difficulty with back-and-forth conversation, reduced sharing of interests or emotions, failure to initiate or respond to social interactions)
2. Deficits in nonverbal communicative behaviors used for social interaction (poorly integrated verbal and nonverbal communication, abnormalities in eye contact and body language, difficulties understanding and using gestures, lack of facial expressions)
3. Deficits in developing, maintaining, and understanding relationships (difficulties adjusting behavior to suit different social contexts, difficulties in sharing imaginative play or making friends, absence of interest in peers)

B. Restricted, repetitive patterns of behavior, interests, or activities, as manifested by at least two of:

1. Stereotyped or repetitive motor movements, use of objects, or speech (simple motor stereotypies, lining up toys, echolalia, idiosyncratic phrases)
2. Insistence on sameness, inflexible adherence to routines, or ritualized patterns of verbal or nonverbal behavior (extreme distress at small changes, difficulties with transitions, rigid thinking patterns)
3. Highly restricted, fixated interests that are abnormal in intensity or focus
4. Hyper- or hypo-reactivity to sensory aspects of the environment (apparent indifference to pain/temperature, adverse response to specific sounds or textures, excessive smelling or touching of objects, visual fascination with lights or movement)

C. Symptoms must be present in the early developmental period

D. Symptoms cause clinically significant impairment in functioning

E. These disturbances are not better explained by intellectual disability or global developmental delay

The DSM-5 also specifies severity levels based on the amount of support needed:

• Level 1: Requiring support
• Level 2: Requiring substantial support
• Level 3: Requiring very substantial support

Diagnostic Tools and Methods

Several standardized tools help clinicians diagnose autism spectrum disorder. These assessments are often administered by professionals trained in developmental and behavioral pediatrics, psychology, and related specialties. These include:

Autism Diagnostic Observation Schedule, Second Edition (ADOS-2)

The ADOS-2 is considered the gold standard observational assessment for diagnosing autism. It involves structured and semi-structured activities that allow clinicians to observe social interaction, communication, play, and restricted and repetitive behaviors. The assessment is age-appropriate and language-level-appropriate.

Autism Diagnostic Interview-Revised (ADI-R)

This structured interview conducted with parents or caregivers collects detailed information about a person’s developmental history and current behavior. It focuses on three functional domains: language/communication, reciprocal social interactions, and restricted, repetitive, and stereotyped behaviors and interests.

Childhood Autism Rating Scale, Second Edition (CARS-2)

This 15-item rating scale helps identify children with autism and determine symptom severity. It covers relating to people, imitation, emotional response, body use, object use, adaptation to change, visual response, listening response, sensory response, fear or nervousness, verbal communication, nonverbal communication, activity level, level of intellectual response, and general impressions.

Social Communication Questionnaire (SCQ)

This parent-completed questionnaire helps evaluate communication skills and social functioning in children who may have autism. It serves as a useful screening tool to determine whether a more comprehensive autism evaluation is warranted.

The Parent’s Role in Diagnosis

Parents play a crucial role in the diagnostic process. As the expert on your child, your observations and concerns provide valuable information. Here’s how you can participate effectively:

• Document developmental concerns: Keep a journal of specific behaviors that concern you, noting when they occur and in what circumstances
• Gather developmental history: Compile information about your child’s developmental milestones, health history, and family history
• Prepare for appointments: Write down questions and concerns before appointments
• Share videos: If possible, record videos of your child that show the behaviors you’re concerned about
• Be persistent: If you have concerns about your child’s development, continue to seek answers even if initial screenings are inconclusive

Remember that you know your child best. If you notice developmental differences, trust your instincts and discuss them with your child’s healthcare provider.

Age-Specific Diagnostic Considerations

• Early Childhood (Under 3 Years): Autism can often be diagnosed by age 2, with early signs including reduced eye contact, delayed babbling, and limited social smiling.
• Preschool Years (3–5 Years): Social communication challenges and repetitive behaviors become more noticeable as peer interactions increase.
• School-Age Children: Diagnosis may occur later as social and behavioral expectations rise, especially for children with stronger language or cognitive skills.
• Adolescents and Adults: Later diagnoses are becoming more common as earlier challenges may have been masked or only emerge with increasing social demands.

After the Diagnosis: Next Steps

Receiving an autism diagnosis can evoke a range of emotions. Remember that your child is the same person they were before the diagnosis – now you have more information to support them effectively. After diagnosis, consider these steps:

1. Learn about autism: Understand how autism affects your child specifically
2. Access early intervention services: Research shows that early intervention can significantly improve outcomes
3. Develop a support team: This may include therapists, educators, medical professionals, and other parents
4. Create a treatment plan: Work with professionals to develop goals based on your child’s needs
5. Take care of yourself: Connect with support groups and resources for parents

Conclusion

The path to an autism diagnosis can feel overwhelming, but gaining clarity about the process empowers families to take the right steps. Early identification is key—unlocking access to crucial interventions that can positively shape a child’s development. With knowledge, advocacy, and support, families can navigate this journey with greater confidence and hope.

At Apple ABA, we proudly provide in-home ABA therapy throughout New Jersey, offering personalized support where your child feels most comfortable. Our experienced team delivers evidence-based tailored to your child’s unique strengths and needs. If you’re ready to take the next step or simply need guidance, contact us because every child deserves the opportunity to thrive, and we’re here to help make that possible.

FAQs

How to diagnose autism?

Autism is diagnosed through a comprehensive evaluation by healthcare professionals that includes developmental screenings, behavioral observations, and standardized assessments. The process typically involves input from multiple specialists including developmental pediatricians, psychologists, and speech therapists who evaluate social communication, behavior patterns, and developmental history.

How do I know if I’m autistic?

Signs of autism include persistent difficulties with social communication, restricted interests, repetitive behaviors, and sensory sensitivities that significantly impact daily functioning. If you suspect you might be autistic, consider seeking an evaluation from healthcare professionals experienced in adult autism diagnosis, as self-assessment tools can provide initial insights but aren’t diagnostic.

Is autism treatable?

While autism isn’t “cured,” many evidence-based interventions like Applied Behavior Analysis (ABA), speech therapy, occupational therapy, and social skills training can significantly improve quality of life and help develop essential skills. Early intervention typically leads to better outcomes, but support at any age can help autistic individuals thrive and navigate challenges.

What are the 5 common signs of autism?

Five common signs of autism include: 1) difficulties with social interactions and understanding social cues, 2) challenges with verbal and nonverbal communication, 3) repetitive behaviors or restricted interests, 4) sensory sensitivities or unusual responses to sensory input, and 5) resistance to changes in routines or environments.