How do you differentiate autism spectrum disorder (ASD) from obsessive-compulsive disorder (OCD)?

Differentiating Autism Spectrum Disorder from OCD

The key distinction is that OCD has a later onset than ASD, features ego-dystonic (unwanted, distressing) repetitive behaviors rather than ego-syntonic (comfortable, routine) ones, and lacks the prominent social and communicative impairments that define ASD. 1

Core Distinguishing Features

Age of Onset and Developmental History

• ASD typically presents early in development, with parents reporting either no period of normal development or unusual behaviors from infancy (e.g., the child seemed too good and undemanding). 1
• OCD has a later onset than ASD, typically emerging in later childhood or adolescence rather than early developmental periods. 1

Nature of Repetitive Behaviors

The most critical distinction lies in how the patient experiences their repetitive thoughts and behaviors:

• In OCD, repetitive behaviors are ego-dystonic: The rumination is experienced as intrusive, unwanted, and causes marked anxiety or distress that the individual actively attempts to suppress or neutralize, with recognition that these thoughts are excessive or unreasonable. 2
• In ASD, repetitive behaviors are ego-syntonic: The rumination feels comfortable, is part of their routine, and the individual does not experience them as unwanted or anxiety-provoking. 2

Social and Communication Functioning

• ASD is characterized by prominent social and communicative impairments including deficits in nonverbal behaviors (eye contact, pointing, use of conventional gestures) to regulate social interaction, and lack of developed social insight. 1
• OCD is not typically associated with social and communicative impairments; while severe OCD may secondarily impair social functioning, it does not cause primary social-communication deficits. 1, 2

Structured Assessment Approach

Key Questions to Ask

Ask these specific questions to differentiate the conditions:

• "Do these thoughts feel like they're intruding against your will, or are they topics you enjoy thinking about?" - Intrusive thoughts suggest OCD; enjoyable rumination suggests ASD. 2
• "Do these thoughts cause you anxiety or distress, or do they feel comforting?" - Anxiety and distress point to OCD; comfort suggests ASD. 2
• Assess for mental acts: Ask about counting, praying, or repeating words silently performed rigidly in response to obsessions or to prevent dreaded outcomes, which indicates OCD. 2

Content of Obsessions/Interests

• OCD obsessions typically involve themes of contamination, harm, symmetry, or forbidden thoughts that are perceived as threatening, with the individual feeling driven to perform mental acts to reduce anxiety. 2
• ASD restricted interests are typically focused on specific topics or activities that provide comfort and are pursued for enjoyment rather than anxiety reduction. 3, 4

Developmental Markers (Particularly Useful in Children)

At specific ages, certain behaviors differentiate ASD from other conditions:

• At 20-42 months: Lack of pointing for interest and absence of conventional gestures suggest ASD. 1
• At 24 months: Deficits in directing attention (showing) and attention to voice indicate ASD. 1
• At 36 months: Use of other's body as a tool, poor attention to voice, lack of pointing, and finger mannerisms classify ASD. 1

Quantifying OCD Severity

• Use the Yale-Brown Obsessive Compulsive Scale (Y-BOCS) to quantify OCD symptom severity. 2
• Scores ≥14 for obsessions alone indicate clinically significant OCD requiring treatment consideration. 2

Common Pitfalls to Avoid

Diagnostic Overshadowing

• Do not assume all repetitive behaviors in ASD are simply autistic traits; individuals with ASD can have comorbid OCD, and failing to diagnose this comorbidity (diagnostic overshadowing) can lead to inadequate treatment. 1
• The prevalence of OCD is higher in ASD populations than in the general population, so maintain vigilance for true OCD symptoms. 5, 6, 3

Distinguishing Stereotypies from Compulsions

• Care must be taken to distinguish stereotyped and repetitive behaviors characteristic of ASD from obsessive compulsive acts in OCD. 5
• Stereotyped behaviors in ASD are repeated without apparent useful function and are not driven by anxiety reduction. 5
• Compulsions in OCD are performed specifically to reduce anxiety or prevent a dreaded outcome. 2

Treatment Implications

If OCD is Diagnosed

• Initiate Cognitive Behavioral Therapy with Exposure and Response Prevention (ERP) as first-line treatment. 2
• Consider sertraline 50 mg daily as first-line SSRI pharmacotherapy for moderate-to-severe OCD symptoms. 2
• Note that CBT may be less effective in those with OCD co-occurring with ASD, and modifications to standard CBT protocols may be necessary to optimize outcomes. 5, 6

If ASD is Diagnosed

• Treatment focuses on social skills training, communication interventions, and behavioral supports for core ASD symptoms rather than anxiety-reduction strategies used in OCD. 1