Differentiation between Autism Spectrum Disorder and Personality Disorders: a systematic review

The differential diagnosis of Autism Spectrum Disorder (ASD) and Personality Disorders in adults presents a clinical challenge due to characteristics overlap and the absence of standardized guidelines, making accurate diagnoses and appropriate interventions difficult. We synthesize the main clinical criteria used to distinguish Autism Spectrum Disorder from Personality Disorders and analyze their impact on diagnostic accuracy. This systematic review followed PRISMA guidelines and was registered on the PROSPERO platform (ID: CRD42025638588). The search was conducted in January 2025 across the PubMed/Medline, Scopus, LILACS and SciELO databases, including studies published between 2020 and 2024. Original articles addressing the differential diagnosis between Autism Spectrum Disorder and Personality Disorders were selected, while reviews, editorials and incomplete texts were excluded. The total sample analyzed comprised 684 individuals, including 550 clinical participants and 134 health-care professionals. A comparative Diagnostic and Statistical Manual of Mental Disorders (5th edition) based framework was developed to distinguish ASD from Personality Disorders. Characteristics overlap, particularly between Autism Spectrum Disorder and Borderline Personality Disorder, compromise diagnostic accuracy. Individuals with Autism Spectrum Disorder exhibit cognitive rigidity and difficulties in interpreting social norms, whereas those with Personality Disorders demonstrate emotional instability, impulsivity and fear of abandonment. Self-harm in Autism Spectrum Disorder is often linked to sensory overload and difficulties with routine changes, while in Personality Disorders, it occurs as a response to emotional conflicts. The lack of standardized criteria and reliance on subjective assessments increase diagnostic errors and delays. Characteristics overlap underscores the need for structured, evidence-based methods with standardized guidelines that minimize diagnostic errors and promote more accurate and effective interventions, ultimately improving patient prognosis.