Autism Spectrum Disorder – Diagnosis and Evaluation Guidelines

Core Diagnostic Indicators

Children presenting with delayed speech, poor eye contact, and repetitive behaviors with echolalia are highly likely to have Autism Spectrum Disorder (ASD)【1】【2】【3】.
At 24 months, the absence of a response when the child’s name is called is a classic sign of ASD【4】.
Very limited or absent use of communicative gestures (e.g., pointing to share interest) strongly suggests ASD【1】【5】.
Lack of imaginative play is another core indicator of ASD【1】.

A multidisciplinary, structured diagnostic assessment—including caregiver interview and direct behavioral observation with standardized instruments—is recommended for ASD diagnosis【2】【3】.
The Autism Diagnostic Interview‑Revised (ADI‑R) has a sensitivity of 52 % and specificity of 84 % for ASD detection【2】.

All children diagnosed with ASD should receive a comprehensive physical examination to identify dysmorphic features or congenital anomalies【2】.
Formal hearing screening is essential to rule out auditory impairments that can mimic ASD symptoms【1】【2】.
Wood’s lamp examination is advised to detect signs of tuberous sclerosis in children with ASD【2】【3】.
Chromosomal microarray analysis is recommended as a first‑tier genetic test, yielding a diagnostic result in approximately 24 % of cases【2】【3】.
Fragile X testing identifies pathogenic variants in about 0.57 % of ASD cases【2】.
G‑banded karyotype analysis provides a diagnostic yield of roughly 2.5 %【2】.
Lower IQ does not reliably predict a positive chromosomal or genetic finding in ASD evaluations【2】.

Specific language disorder can be distinguished from ASD by the presence of pointing to share interest and use of conventional gestures【1】.
Mild‑to‑moderate developmental delay should be evaluated at 24 months for behaviors such as using another person’s body, responding to sounds, pointing, and finger posturing【1】.
Hearing impairment must be excluded through formal audiologic screening when ASD is suspected【1】【2】.
Reactive attachment disorder typically shows substantial improvement with adequate caregiving, differentiating it from ASD【1】.
Anxiety disorders are characterized by developing social insight, which is not observed in ASD【1】.

Approximately 90 % of individuals with ASD have at least one co‑occurring medical or mental‑health condition【6】.
Attention‑deficit/hyperactivity disorder (ADHD) affects more than 50 % of children with ASD【6】.
Anxiety disorders and specific phobias are common comorbidities in ASD【6】.
Sleep disturbances are reported in over half of the ASD population【6】.
Gastrointestinal problems are present in roughly 50 % of individuals with ASD【6】.
Epilepsy occurs in 20 %–33 % of people with ASD, especially when intellectual disability is also present【6】.
Clinicians should avoid “diagnostic overshadowing” by ensuring that co‑existing conditions are not mistakenly attributed solely to ASD【1】.

About 30 % of individuals with ASD have a comorbid intellectual disability, which can complicate presentation and management【6】.
Developmental regression (loss of previously acquired skills) may occur in ASD and should trigger evaluation for alternative diagnoses such as Rett syndrome or other neurodegenerative conditions【1】.

The American Academy of Child and Adolescent Psychiatry recommends a comprehensive diagnostic evaluation for Autism Spectrum Disorder (ASD), including a thorough medical examination, psychological assessment, and communication evaluation, to identify core characteristics of ASD 7
The Autism Diagnostic Observation Schedule (ADOS-2) is the gold standard for identifying central characteristics of ASD, focusing on deficits in joint attention, absence of conventional gestures, and qualitatively altered eye contact 8
A detailed developmental history is essential to document the presence of unusual behaviors since early childhood, differentiating this from regression or late onset that might suggest other diagnoses 9

The distinction between ASD and Social Anxiety Disorder is crucial, as treatment differs: in ASD, social deficits are pervasive and constant across all contexts, present since early childhood, with fundamental difficulty understanding "invisible" social rules 10
In Social Anxiety Disorder, fear and anxiety are disproportionate to the real danger of the social situation, but the person understands social signals when not anxious 10

The American Academy of Child and Adolescent Psychiatry recommends a multidisciplinary approach to treatment, including medication and behavioral interventions, with a focus on improving social communication and reducing repetitive behaviors 7
Cognitive-behavioral therapy (CBT) modified with visualization is the treatment of choice for individuals with ASD and comorbid anxiety, aiming to help the patient understand the "invisible" social, cognitive, and emotional context of themselves and others 10
Structured educational and behavioral interventions, such as Applied Behavior Analysis (ABA), have been shown to be effective for many individuals with ASD and are associated with better prognosis 11

The American Academy of Child and Adolescent Psychiatry warns against the phenomenon of "diagnostic overshadowing," where all symptoms are attributed to ASD, and other conditions, such as ADHD, anxiety disorders, and depression, are not diagnosed or treated 12
Patients with preserved verbal abilities, such as those who have completed higher education, generally have a better prognosis than those with classic autism 13