What is the recommended approach for diagnosing and treating Autism Spectrum Disorder (ASD)?

Autism Spectrum Disorder Diagnosis and Management

Screening and Early Detection

Screen all children at 18 and 24 months using the Modified Checklist for Autism in Toddlers (M-CHAT) during routine well-child visits, even without specific parental concerns. 1

• Between 12-24 months, identify these specific red flags: reduced eye contact, limited social smiling, absent or minimal nonverbal gestures to initiate shared experiences (like pointing to show interest), lack of response to name when called, absence of imaginative play, atypical object use (such as spinning or lining up toys), and repetitive motor behaviors 1, 2, 3
• Screen earlier than 18 months when developmental concerns exist, using validated tools like the Communication and Symbolic Behavior Scales Developmental Profile (CSBS DP) or First Year Inventory (FYI) 2
• Note that false-positive rates are higher before 24 months, but early evaluation remains justified because positive screens predict any diagnosable developmental disorder with high accuracy 2

Diagnostic Confirmation Process

Diagnosis must be performed by trained professionals using standardized objective measures in a comprehensive multidisciplinary assessment. 1, 2

• Use the Autism Diagnostic Observation Schedule-Second Edition (ADOS-2), which has 91% sensitivity and 76% specificity, combined with the Autism Diagnostic Interview (80% sensitivity, 72% specificity) 1, 3
• Conduct direct observation focusing specifically on social interaction patterns and restricted/repetitive behaviors, with modifications based on the child's developmental level 4
• Obtain detailed developmental history including timing of symptom onset, regression history if present, response to previous interventions, and family psychiatric history 4, 2
• Interview family members when possible, particularly for adult evaluations where developmental history may be less accessible 5

Common Diagnostic Pitfall to Avoid

• Do not delay diagnosis in adults or atypical presentations due to misconceptions about how ASD manifests across the lifespan 5

Essential Medical Workup

Every child with suspected ASD must have a formal audiogram before proceeding with further evaluation to rule out hearing loss that could mimic ASD symptoms. 1, 2

• Perform physical examination including Wood's lamp examination for tuberous sclerosis signs 4
• Establish a primary care medical home to coordinate all diagnostic testing and ongoing care 1

Tiered Genetic Evaluation Approach

Offer genetic consultation to all individuals and families with ASD, as clinical genetics evaluation identifies an underlying etiology in 30-40% of cases. 1, 2

First Tier (Order These Tests):

• Chromosomal microarray (CMA): 10% diagnostic yield - this is now the standard of care for initial evaluation 4, 1, 2
• Fragile X DNA testing: 1-5% yield 1, 2
• High-resolution karyotype: 3% yield (though largely replaced by CMA) 1, 2
• Clinical geneticist examination for dysmorphic features and detailed family history analysis - this remains high-yield and cost-effective 1, 2

Second Tier (Order When Clinically Indicated):

• MECP2 gene testing in females: 4% yield 1, 2
• PTEN gene testing when head circumference exceeds 2.5 standard deviations above the mean: 5% yield 1, 2

Additional Testing Based on Clinical Features:

• Order EEG, neuroimaging, metabolic testing, or additional genetic studies only when specific clinical features warrant them: history of regression, seizures or staring spells, dysmorphic features, or family history suggesting specific genetic syndromes 4
• Consider Landau-Kleffner syndrome evaluation (EEG) when marked aphasia develops 4

Critical Genetic Testing Pitfall to Avoid:

• Do not order extensive genetic testing panels without clinical geneticist evaluation first - the stepwise approach is more cost-effective and better tolerated by families 1, 2

Psychological and Developmental Assessment

• Conduct cognitive testing and adaptive skills measurement for treatment planning, as these frame social-communication difficulties relative to overall developmental level 4
• Expect considerable scatter in intelligence test results, with possible "splinter skills" or savant abilities in specific domains 4
• Assess for areas of intense, circumscribed interests in higher-functioning individuals 4

Treatment Approach

Intensive behavioral interventions are first-line therapy, particularly for children 5 years or younger, focusing on improving language, play, and social communication skills. 1, 2, 3

• Implement programs like the Early Start Denver Model, which demonstrates small to medium effect sizes for core symptom improvement 1, 3
• Reserve pharmacotherapy exclusively for co-occurring conditions and specific target symptoms, not for core ASD features 1, 2, 3

Pharmacotherapy for Specific Symptoms:

For irritability and aggression: Risperidone or aripiprazole are FDA-approved for irritability associated with autistic disorder in children and adolescents ages 5-17 years, with large effect sizes (standardized mean difference 1.1) 6, 3, 7

• Risperidone dosing: Start 0.25 mg/day (weight <20 kg) or 0.5 mg/day (weight ≥20 kg), titrate to clinical response with mean effective dose around 1.9 mg/day or 0.05-0.06 mg/kg/day 6
• Monitor for adverse effects including weight gain (33% experience >7% weight gain), somnolence (most common, typically early-onset and transient), and metabolic changes 6, 3

For co-occurring ADHD: Psychostimulants demonstrate moderate effect size (standardized mean difference 0.6) 3, 7

For co-occurring anxiety or depression: Consider SSRIs or other antidepressants as clinically appropriate 7

Genetic Counseling and Recurrence Risk

Provide genetic counseling to all families regardless of whether an etiology is identified. 1, 2

Empiric Recurrence Risk Data (When No Specific Etiology Found):

• Full sibling recurrence risk: 3-10% overall 1, 2
• Modified by sex of affected child: 7% if affected child is female, 4% if affected child is male 1, 2
• With two or more affected children: at least 30% recurrence risk 1, 2

Critical Counseling Pitfall to Avoid:

• Do not fail to provide recurrence risk information to families - this is essential for family planning decisions 1, 2

Follow-up and Ongoing Management

• Schedule periodic reevaluations for patients without definitive etiology, as diagnostic technology and understanding continue to evolve 1, 2
• Monitor for common comorbidities: depression (20% vs 7% in general population), anxiety (11% vs 5%), sleep difficulties (13% vs 5%), and epilepsy (21% with co-occurring intellectual disability) 3
• Coordinate care through the established medical home, partnering with specialists as needed 1, 2