Defining the Optimal Threshold Scores for Adult Autism Subthreshold Spectrum (AdAS Spectrum) in Clinical and General Population

Liliana Dell’Osso1, Claudia Carmassi1, Ivan Mirko Cremone1, Dario Muti1, Antonio Salerni1, Filippo Maria Barberi1, Enrico Massimetti1, Camilla Gesi1, Pierluigi Politi2, Eugenio Aguglia3, Mario Maj4, Barbara Carpita1, *
1 Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy
2 Department of Brain and Behavioral Sciences, University of Pavia, Pavia, Italy
3 Department of Clinical and Experimental Medicine, Psychiatry Unit, University of Catania, Catania, Italy
4 Department of Psychiatry, University of Nalpes SUN, Naples, Italy

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© 2020 Dell'Osso et al.

open-access license: This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International Public License (CC-BY 4.0), a copy of which is available at: This license permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

* Address correspondence to this author at Department of Clinical and Experimental Medicine University of Pisa, Pisa, Italy; Tel: +393911105675; E-mail:



The Adult Autism Subthreshold Spectrum (AdAS Spectrum) is a recently developed instrument tailored to assess the broad range of full-threshold as well as sub-threshold manifestations related to the autism spectrum. Although it has proved to be a valuable instrument for quantitative assessment of autistic symptoms, the AdAS Spectrum still lacks validated diagnostic thresholds.


The aim of this study was to define the best cut-off scores of the AdAS Spectrum for determining the presence of subthreshold autistic traits as well as a clinically significant autism spectrum disorder (ASD).


Our sample was composed of 39 patients with full-blown ASD, 73 subjects with autistic traits, and 150 healthy controls. Subjects were evaluated by trained psychiatrists, who performed a clinical diagnosis according to DSM-5 and then assessed with the AdAS Spectrum and the Autism Spectrum Quotient.


Our results showed that the most discriminant cut-off scores were 70 for identifying subjects with full-blown ASD, and 43 for determining the presence of significant autistic traits.


The threshold values proposed here showed satisfying levels of specificity and sensibility, as well as a good agreement with the diagnosis according to DSM-5 criteria, confirming the validity of the AdAS Spectrum as a psychometric tool for measuring ASD-related conditions in the clinical and general population.

Keywords: Autistic traits, Autism Spectrum Disorder, Psychometric instrument, AdAS Spectrum, Diagnostic threshold, RAADS.