Preschool children with neurotypical development (ND) trained on sentential complements (“X thinks/says that”) improve their Theory of Mind (ToM) performance. Can complementation training also enhance ToM in children with Autism Spectrum Disorder (ASD)? Thirty-three children with ASD (Mage = 8;11) and 20 younger ND peers (Mage = 4;3) were trained on sentential complements (4–6 weeks, 2–3 times per week, via the DIRE i-Pad App). Pre-training and post-training comparisons show that (1) training boosted both complementation and ToM performance across groups; (2) improvements remained 4–6 weeks after training ended; (3) participants with milder ASD symptoms made most gains. Training on sentential complements thus seems beneficial for addressing ToM difficulties in children with ASD, especially those with milder symptoms.

Objectives: Autism spectrum disorders and personality disorders are spectrum conditions with shared clinical features. Despite similarities, previous attempts to synthesise literature on co-existing prevalence and shared traits have employed a unidirectional focus, assessing personality characteristics of individuals with an autism spectrum disorder diagnosis. Here, we assess the prevalence of autism spectrum disorder diagnosis and/or traits among persons diagnosed with a personality disorder. Methods: We systematically reviewed the English-language literature following Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, according to a pre-registered protocol (PROSPERO: CRD 42021264106). Peer-reviewed quantitative studies reporting the prevalence of autism spectrum disorder diagnosis or traits in persons with an established personality disorder diagnosis were included. Studies were critically appraised using the Appraisal tool for Cross-Sectional Studies. Results: Fifteen studies were identified, including 72,902 participants (median: 48, interquartile range: 30–77). Diagnoses included borderline, schizotypal and obsessive-compulsive personality disorders, and cohorts with unspecified personality disorder diagnoses. There was significant heterogeneity in diagnostic methodology and assessment tools used. We identified preliminary evidence of an increased prevalence of co-existing autism spectrum disorder diagnosis and traits among those diagnosed with a personality disorder, although significant limitations of the literature were identified. Conclusion: Our research suggests clinicians should consider conducting a careful developmental assessment when assessing service-users with possible or confirmed personality disorder. Future research directions may include larger studies featuring clinical control groups, an exploration of shared and differentiating behavioural-cognitive features of the two conditions, and investigation into potentially shared aetiological factors. Research investigating demographic factors that may contribute to potential diagnostic overshadowing would also be welcomed.