City Research Online

Abstract

Previous research has suggested potential phenotypic similarities between autism and borderline personality disorder (BPD). We aimed to identify overlapping and differentiating characteristics of the two diagnostic groups in women and people assigned female at birth (PAFAB). Women and PAFAB with an autism diagnosis (n = 51) or a BPD diagnosis (n = 51), who had few or subclinical traits of the comparator diagnosis, completed a range of self-report questionnaires. Emotional reactivity, emotional dysregulation, identity disruption, difficulties being alone and rejection sensitivity were significantly more characteristic of BPD-diagnosed participants, with identity disruption representing the biggest difference from autistic participants (d = −1.36, 95% confidence interval [CI] = [−1.79, −0.92]). Autistic participants scored significantly more highly on measures of sensory processing, social cognition and behaviour, preference for sameness and repetitive motor behaviour, with sensory processing representing the biggest difference from BPD-diagnosed participants (d = 1.19, 95% CI = [0.76, 1.60]). Group differences in social cognition, social camouflaging, identity disruption, impulsivity and coping with being alone, together correctly classified 95.1% of participants (area under the curve [AUC] = 0.98). However, comparison with measure scores in previous research suggests more complex phenotypic similarities, whereby autistic individuals may show more BPD-aligned characteristics than the general population and vice versa.

Publication Type:	Article
Additional Information:	© The Author(s) 2026. This article is distributed under the terms of the Creative Commons Attribution-NonCommercial 4.0 License (https://creativecommons.org/licenses/by-nc/4.0/) which permits non-commercial use, reproduction and distribution of the work without further permission provided the original work is attributed as specified on the SAGE and Open Access pages (https://us.sagepub.com/en-us/nam/open-access-at-sage).
Publisher Keywords:	autism, co-occurring conditions, diagnosis, health services, mental illness, sensory profiles, social cognition, social interaction, statistical modelling
Subjects:	R Medicine > RC Internal medicine > RC0321 Neuroscience. Biological psychiatry. Neuropsychiatry
Departments:	School of Health & Medical Sciences School of Health & Medical Sciences > Department of Population Health & Policy
SWORD Depositor:	Symplectic Administrator

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