Diagnostic Process for ASD
Diagnosing autism spectrum disorder (ASD) can be challenging due to the young age at which symptoms appear, the variety and severity of possible symptoms, and the lack of a specific medical test. Consequently, ASD diagnosis is typically a multi-step process.
ASD Diagnosis – Screening and Early Detection
Screening for ASD should ideally occur during well-child visit, especially at the 18-month and 24-months checkups. Before the age of 2, diagnosis is usually not reliable. Despite, these recommended early screenings, ASD is often not diagnosed until much later, sometimes even during adolescents or early adulthood. During a developmental screening for ASD, the pediatrician looks closely for ASD symptoms, beyond the regular developmental monitoring that occurs at well-child visits. Developmental monitoring involves observing how a child grows and whether they meet typical developmental milestones such as walking and talking and social interaction skills.
ASD Diagnosis – a Multi-Step Process
Healthcare providers generally follow the DSM-5 manual for diagnosing ASD, using a combination of standardized diagnostic instruments, physician’s observations, and parent/caregiver reports.
During a semi-structured interview, the provider may:
- Ask about the individual’s behavior, development, movement, language skills, thinking skills, emotions, and age-appropriate daily functioning and independence (e.g., eating, dressing, toileting).
- Inquire about the family’s health and mental health history.
- Make clinical observations of behavior, cognitive abilities, and language abilities.
Common standardized diagnostic tools include:
- Autism Diagnostic Observation Schedule (ADOS) for ages 12 months to adults
- Computer-generated Developmental, Dimensional, and Diagnostic Interview (3di)
- Screening Tool for Autism in Toddlers and Young Children (STAT)
- Autism Diagnostic Interview-Revised (ADI-R)
- Diagnostic Instrument for Social Communication Disorders (DISCO), primarily used in the UK
- Childhood Autism Rating Scale (CARS)
- Social Responsiveness Scale (SRS)
- Social Communication Questionnaire (SCQ)
The provider will also conduct:
- a thorough medical examination (including blood tests and hearing tests)
- a neurological examination
These examinations are important to rule other possible conditions. Depending on the screening and evaluation results, the provider may refer the individual to specialists such as neurologists, psychologists or psychiatrists, developmental pediatricians, speech-language pathologists, educational specialists, and occupational therapists.
DSM-5 Criteria
DSM-5 Criteria (Diagnostic and Statistical Manual of Mental Disorders, 5th Edition) is a manual used by healthcare providers to assess and diagnose mental health and brain-related conditions, including ASD.
According to the DSM-5, an ASD diagnosis requires persistent deficits in social communication and interaction across multiple contexts. Individuals must also have past or present difficulties in the following 3 social communication subdomains:
- Deficits in social-emotional reciprocity, e.g., difficulty with normal back-and-forth conversations or reduce sharing of emotions.
- Deficits in nonverbal communicative behaviors used for social interaction.
- Deficits in developing, maintaining, and understanding relationships.
For an ASD diagnosis, individuals must also exhibit at least 2 behaviors associated with restricted/repetitive behavior or unusual sensory-motor behaviors:
- Stereotyped or repetitive motor movements, use of objects, or speech.
- Insistence on sameness, inflexible adherence to routines, or ritualized patterns of verbal or nonverbal behavior.
- Highly restricted, fixated interests that are abnormal in intensity or focus.
- Hyper- or hyperactivity to sensory input or unusual interest in sensory aspects of the environment.
Symptoms must be present in the early developmental period, cause clinically significant impairment in social, occupational, or other important areas of current functioning, and not be better explained by other health conditions, learning disabilities, or mental health disorders.
For more information, visit the DSM-5 website.