Beyond Categories : A Dimensional Approach to Autism and Sensorimotor Differences

Autism spectrum conditions (ASC) encompass a range of sensory, motor, and social-communicative differences, reflecting the considerable heterogeneity within the autism spectrum. This diversity underscores the limitations of categorical diagnostic approaches, which often fail to capture the individualized manifestations of autism. Advances in genetics and neuroscience have driven a shift towards dimensional frameworks that emphasize the spectrum nature of autism and the broad autism phenotype (BAP). BAP encapsulates subclinical traits that mirror those of autism in the general population, challenging the conventional boundaries between clinical and non-clinical populations. Furthermore, sensorimotor differences, which are particularly prevalent in individuals with ASC, follow a spectrum-like pattern similar to the BAP and are predictive of developmental outcomes related to social participation, communication, and overall quality of life in people with and without ASC. However, specific descriptions of these relationships are lacking. This dissertation investigated the complex relationships between sensorimotor differences and autistic traits (ATs). Through a series of five interconnected studies, we examined broad sensory processing patterns and specific sensory modalities, namely auditory processing and motor/proprioception, to explore their roles in autistic phenotypes. Study 1 of the dissertation validated a Swedish translation of the Broad Autism Phenotype Questionnaire (BAPQ). By examining parents' BAP traits, the study highlighted significant associations between higher ATs and having a child with ASC. Furthermore, it confirmed the presence of all three AT domains—social interaction (ATSOC), communication (ATCOM), and cognitive rigidity (ATRIG), reinforcing the genetic and phenotypic continuity between clinical and subclinical ATs. Study 2 and Study 3 served as broader investigations into all seven sensory modalities and their associations with ATs. Study 2 exp