What feature would best support the diagnosis of Autism Spectrum Disorder (ASD) in a patient with strong, focused interests, according to the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, Text Revision (DSM-5-TR) diagnostic criteria?

Difficulty Establishing Intimate Peer Relationships Best Supports ASD Diagnosis

Having difficulty establishing intimate peer relationships is the feature that best supports the diagnosis of autism spectrum disorder in this patient according to DSM-5-TR criteria. 1, 2

Core Diagnostic Framework for ASD

The DSM-5-TR requires deficits in two core domains for ASD diagnosis: (1) social communication and social interaction, and (2) restricted, repetitive patterns of behaviors and interests. 1, 3 The patient already demonstrates the second domain through their intense, focused preoccupation with taking apart clock gears—a classic example of encompassing preoccupations with restricted topics. 1, 2

To meet diagnostic criteria, you must identify deficits in the first domain (social communication/interaction). This is where impaired peer relationships becomes critical.

Why Peer Relationship Impairment is the Correct Answer

Social Communication Deficits are Required

• Marked impairment in peer relationships is explicitly listed as one of the core social relatedness disturbances required for ASD diagnosis. 1, 4
• The American Academy of Child and Adolescent Psychiatry emphasizes that lack of interest in other people and failures in peer relationships are hallmark features that distinguish ASD from normal development. 2, 4
• Impaired peer relationships represents a persistent deficit in social-emotional reciprocity, which is a fundamental criterion in DSM-5-TR. 1, 4

This Completes the Diagnostic Dyad

The patient already has restricted interests (Domain 2), so demonstrating impaired peer relationships (Domain 1) would satisfy both required diagnostic domains. 1, 3

Why the Other Options are Incorrect

Having Interests Typical for Same Age

This would argue against ASD diagnosis, not support it. 1 ASD requires atypical restricted interests—the patient's obsessive focus on clock gears is already atypical and supports diagnosis, but having typical interests would not.

IQ Testing Results (Either Direction)

• Intelligence level is NOT a diagnostic criterion for ASD in DSM-5-TR. 1, 5
• Approximately 20% of individuals with ASD have normal-range IQs, 35% have mild-moderate intellectual disability, and 50% have severe-profound intellectual disability. 5
• DSM-5-TR includes intellectual impairment only as a specifier, not a diagnostic requirement. 1
• High IQ (>2 SD above average) does not exclude ASD and is seen in some high-functioning individuals. 5
• Low IQ (<2 SD below average) requires separate formal testing to establish intellectual disability as a comorbid diagnosis, but is not required for ASD diagnosis. 5

Non-Fluent Language

• Language impairment is also a specifier, not a diagnostic requirement in DSM-5-TR. 1
• Many individuals with ASD, particularly those previously diagnosed with Asperger's disorder, have fluent speech but still meet criteria through social communication deficits in pragmatic language use. 5
• The DSM-5 removed the strict language delay requirement that existed in DSM-IV-TR. 1

Clinical Pitfall to Avoid

Do not dismiss ASD concerns because other developmental domains appear intact. 4 Children with ASD may have normal or even advanced language, motor skills, and cognitive abilities while demonstrating profound social impairments. 4, 5 The presence of normal IQ or fluent speech does not rule out ASD—the diagnosis hinges on the two core symptom domains, not on intellectual or language functioning. 1, 3