Diagnosis and Treatment of Autism Spectrum Disorder (ASD)

Diagnostic Approach

The American Academy of Child and Adolescent Psychiatry recommends a comprehensive multidisciplinary assessment for diagnosing ASD, including individualized behavioral interventions as first-line treatment, with pharmacotherapy reserved for specific symptoms like irritability 1, 2
Screening for ASD should be performed routinely during developmental assessments of young children, particularly at 18 and 24 months of age, using tools like the Modified Checklist for Autism in Toddlers (M-CHAT) 3, 4
A thorough diagnostic evaluation should be performed by trained professionals using objective criteria, including a standard psychiatric assessment, review of past records, and direct observation of the child 1, 2, 5
Hearing should be formally assessed with an audiogram to rule out hearing loss that could mimic ASD symptoms, and genetic testing, such as chromosomal microarray and fragile X testing, should be considered 6, 5, 7

The American College of Medical Genetics recommends a stepwise genetic evaluation, including high-resolution chromosomal analysis, DNA testing for Fragile X, and examination for dysmorphic features as the first tier 7, 6
The second tier of genetic evaluation should include chromosomal microarray, MECP2 gene testing, and PTEN gene testing, as clinically indicated 7, 8

The American Academy of Child and Adolescent Psychiatry recommends intensive behavioral interventions as first-line therapy for ASD, particularly for children 5 years or younger, focusing on improving language, play, and social communication skills 1, 2
Medications, such as risperidone, are indicated primarily for co-occurring conditions or specific symptoms, like irritability and aggression, rather than core ASD features 2

Genetic counseling should be provided to all families, with recurrence risk information, and regular follow-up is essential to monitor development, treatment response, and address emerging comorbidities 9, 7
Primary care providers should partner with specialists in coordinating care, and common pitfalls to avoid include delaying diagnosis, focusing only on core ASD symptoms, and failing to provide genetic counseling and recurrence risk information to families 3, 9, 7

Between 12 and 24 months, key markers of ASD include reduced levels of social attention and social communication, as well as increased repetitive behavior with objects 10, 11
Specific behaviors to assess include impaired social attention, such as reduced eye contact and limited social smiling, with fewer nonverbal behaviors to initiate shared experiences and differences in frequency of requesting behaviors 10, 12
Atypical object use and repetitive behaviors are also important markers of ASD in this age group 11

The American Academy of Pediatrics recommends formal screening for ASD at 18 and 24 months, but earlier screening is warranted when concerns exist, using validated tools such as the Communication and Symbolic Behavior Scales Developmental Profile (CSBS DP) Infant/Toddler Checklist and the First Year Inventory (FYI) 13
A comprehensive multidisciplinary assessment should include direct observation of the child's behavior using standardized measures such as the Autism Diagnostic Observation Schedule (ADOS), structured parent interviews, cognitive and language assessment 10

The positive predictive value (PPV) of screening tools is lower in younger children, with higher false-positive rates before 24 months, but early evaluation is still justified due to the high PPV for any diagnosable developmental disorder 13
Early identification allows for implementation of specialized interventions tailored to the specific needs of the child, with a focus on improving long-term outcomes 11

Children who are non‑verbal represent a more severe ASD phenotype, and cerebral folate deficiency (CFD) has been linked to more complex ASD presentations, indicating a higher likelihood of underlying folate metabolism abnormalities in this subgroup. 14

Approximately 38 % of children diagnosed with ASD exhibit CFD, and genetic abnormalities (e.g., chromosomal microarray anomalies, fragile‑X) frequently coexist with this metabolic condition. 15

The American Academy of Child and Adolescent Psychiatry (AACAP) recommends intensive behavioral interventions—such as Applied Behavior Analysis (ABA) and sensory integration therapy—as first‑line treatment for ASD; pharmacologic agents like leucovorin are to be used only as adjunctive therapy alongside these behavioral approaches. 16