Characteristics of children referred for autism assessment in an Irish community cohort: co-occurring emotional and behavioural difficulties, gender differences and the impact of age

This thesis comprises two related studies examining the assessment and characteristics of children referred for autism spectrum disorder (ASD) evaluation, with a focus on diagnostic tools and the presentation of co-occurring emotional and behavioural difficulties in an Irish community cohort. Study One presents a systematic review of 49 studies evaluating the sensitivity and specificity of ASD screening and diagnostic tools across the lifespan using DSM-5 and ICD-11 criteria. The findings highlight significant variability in diagnostic accuracy across tools and age groups. For preschool-aged children, the M-CHAT-R/F, RITA-T, and ADEC demonstrated the highest combined sensitivity and specificity. For school-aged children, tools such as the AMSE and 3Di-sv showed strong diagnostic utility, while in adults, the ADOS-2 Module 4 and 3Di-Adult were the strongest evidence-based tools. The review supports the clinical utility of combining screening tools and repeated assessments, especially in low-risk populations, and underscores the need for high-quality, standardised assessments that align with current diagnostic criteria. Study Two investigates the emotional and behavioural profiles of children referred for autism assessment in an Irish community health setting. Using the Developmental, Dimensional and Diagnostic Interview (3Di) and the Child Behaviour Checklist (CBCL), archival data from 100 children were analysed. The study found high rates of co-occurring emotional and behavioural difficulties, particularly inattention and internalising symptoms, with gender differences suggesting that girls presented with higher levels of emotional symptoms and externalising behaviours. Age was significantly associated with symptom severity, indicating that co-occurring difficulties increase in the context of undiagnosed autism. These findings underscore the importance of comprehensive assessments that consider broader psychological profiles, particularly when evaluating girls and older children who may present atypically. Together, these studies inform best practices for ASD assessment by identifying the most effective tools and highlighting the complexity of clinical presentations, with implications for early identification, differential diagnosis, and tailored interventions in community-based settings.