Clinical significance of a broad autism phenotype (BAP) seems to be increasingly supported by growing reports of high prevalence of subthreshold autism spectrum disorder (sASD) or autistic traits (AT) in various demographic samples, particularly in individuals with psychiatric conditions. We question this increasing extension of the autism spectrum and its potential negative consequences for clinical services, research, cultural attitudes, and resource allocation, as well as alternative explanations of what is currently attributed to sASD and AT. In modern psychiatry the diagnostic threshold is paramount and associated with a significant impairment of functioning, implying that symptom specificity is more relevant than sensitivity. Within a syndrome, symptoms have to be present together, with the parts related to and interconnected with the whole. Single autism symptomatic dimensions have low syndromic specificity and can be observed in many different mental disorders. For instance, communication problems may present in communication disorders, social-cognitive difficulties can be found in schizophrenia, and rigid and/or repetitive behaviors can be found in obsessive compulsive disorder. One alternative interpretation of AT and/or sASD relates to personality traits. For example, within the Big 5 Model, low openness is associated with a dislike of change and a narrow range of interests, low extraversion with social withdrawal and coldness, and low agreeableness with disinterest in others and disregard for their feelings. These risks of overreliance on non-specific aspects of autism are particularly likely to occur with screening checklists, self-assessment, or assessment by a lay interviewer with only limited expertise in clinical assessment.
