Borderline personality traits in early adolescence: the role of attachment and reflective functioning.

Autism spectrum disorder (ASD) is a complex and heterogeneous neurodevelopmental condition characterized by challenges with communication, social interaction, and behavior (; ). According to the World Health Organization, approximately 1 in 100 children are diagnosed with ASD (). Approximately 30–50% of individuals with ASD exhibit co-occurring intellectual disability, which contributes to marked heterogeneity in cognitive and language profiles (). The rising prevalence of ASD in recent years exerts a substantial impact on families and society, profoundly affecting the mental health and developmental trajectories of diagnosed individuals (; ). A core challenge in understanding ASD lies in its pronounced heterogeneity, particularly in the dissociation between intellectual ability and social-communicative function. This variability is closely tied to challenges with executive function and verbal fluency — key capacities for social adaptation. Verbal fluency itself integrates processes like vocabulary access and reasoning, which are essential for effective communication (). Neuroimaging studies further indicate altered brain function in ASD, including lower prefrontal-parietal connectivity and atypical prefrontal activation during cognitive tasks (; ). However, how these neural mechanisms differentially support verbal fluency in children with varying levels of overall cognitive ability (often indexed by Full-Scale Intelligence Quotient, FSIQ) remains poorly understood. This gap hinders the development of tailored interventions (; ). Functional near-infrared spectroscopy (fNIRS) is a non-invasive neuroimaging method that measures brain activity by detecting changes in hemoglobin concentration (). It offers higher temporal resolution than fMRI and better tolerance to motion artifacts compared with other neuroimaging techniques. fNIRS is increasingly used to study brain function in psychiatric disorders, including in tasks involving executive function (; ; ). The Verbal Fluency Test (VFT) is a paradigmatic task that probes the interface between language and executive function. It requires not only the retrieval of words from semantic memory (a language-related process) but also the continuous engagement of cognitive control, including mental set-shifting between subcategories, inhibition of previously uttered or irrelevant words, and online monitoring of output against the given rule. Thus, VFT performance reflects the efficiency of verbal-executive integration. Functional near-infrared spectroscopy (fNIRS) is particularly suitable for studying such dynamic processes in children. Crucially, successful performance on complex tasks like VFT is supported by broad cognitive resources, which are commonly indexed by the Full-Scale Intelligence Quotient (FSIQ). FSIQ reflects integrated cognitive resources including attention control, working memory, reasoning, and processing efficiency, which collectively provide the foundational capacity for performing complex cognitive-linguistic tasks such as the VFT (; ). The VFT is described here as a verbal-executive task because it simultaneously draws on both verbal abilities (lexical retrieval and word production) and executive functions (cognitive control, set shifting, inhibition, and online performance monitoring).