NARRATIVE REVIEW OF AUTISM SPECTRUM DISORDER DIAGNOSTICS: CURRENT PERSPECTIVES AND CHALLENGES
Background Autism spectrum disorder (ASD) is a heterogeneous neurodevelopmental condition characterized by persistent impairments in social communication and social interaction, together with restricted and repetitive patterns of behavior, interests, or activities. Accurate diagnosis remains clinically challenging because ASD presentation varies according to age, language level, cognitive functioning, adaptive skills, sex-related characteristics, compensatory strategies, and psychiatric or neurodevelopmental comorbidities. Aims The aim of this narrative review was to summarize contemporary evidence on diagnostic approaches to ASD, with particular emphasis on the Autism Diagnostic Observation Schedule, Second Edition (ADOS-2). The review also considered complementary diagnostic instruments and the main diagnostic challenges in females, adults, high-functioning individuals, and patients with comorbid conditions. Methods A narrative literature review was conducted using PubMed. The search was performed on 23 March 2026 and focused on ASD diagnosis, ADOS-2, ADI-R, diagnostic accuracy, differential diagnosis, psychiatric comorbidity, intellectual disability, adult ASD assessment, female ASD presentation, masking, and camouflaging. A total of 44 sources were included in the final reference list and synthesized qualitatively. No formal systematic review protocol, formal risk of bias assessment, or quantitative meta-analysis was performed. Results The reviewed literature indicates that ADOS-2 remains an important standardized observational instrument for ASD assessment, but it should not be interpreted as an independent basis for diagnosis. Its diagnostic value depends on appropriate module selection, examiner training, clinical context, and integration with developmental history, informant-based data, language level, cognitive functioning, adaptive functioning, and comorbidity assessment. Diagnostic interpretation is particularly challenging in females, adults, high-functioning individuals, and patients with ADHD, anxiety symptoms, depressive symptoms, obsessive-compulsive symptoms, intellectual disability, language impairment, or camouflaging behaviors. Conclusions ASD diagnosis requires a multimodal and individualized approach based on comprehensive clinical judgement rather than on a single test result. ADOS-2, ADI-R, screening questionnaires, and adaptive functioning measures should be interpreted as complementary components of broader clinical assessment. Further research should improve diagnostic sensitivity across diverse populations and develop assessment models that better capture the heterogeneity of autism spectrum disorder.