Overlapping And Differentiating Clinical Features of Autism and Borderline Personality Disorder in Women and People Assigned Female at Birth: A Cross-Sectional Study

= 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.Lay AbstractAutism can look similar to borderline personality disorder (BPD), leading to misdiagnosis. For example, both diagnostic groups may experience difficulties in regulating their emotions. To improve diagnosis, we wanted to understand similarities and differences between autism and BPD in adult women and people assigned female at birth (PAFAB). We asked two groups of people to complete online questionnaires: (1) 51 women/PAFAB with an autism diagnosis, who do not meet diagnostic criteria for BPD and (2) 51 women/PAFAB diagnosed with and meeting diagnostic criteria for BPD, who are not autistic. The questionnaires asked participants how they experience their emotions, how they interact and relate with other people, how they experience their identity and self-concept, how they react to sensory input, for example, sounds and smells, and how they use repetitive movements, as well as their preferences for sticking to familiar ways of doing things. We found more differences than we expected between autistic people and people meeting diagnostic criteria for BPD. For example, autistic people described being more sensitive to sensory input, described 'masking' more during social interactions and described more challenges in understanding the social behaviour of non-autistic people, compared to people meeting diagnostic criteria for BPD. People meeting diagnostic criteria for BPD described more difficulties with emotion regulation and with their sense of self ('knowing who I am'), were more likely to behave impulsively and found being on their own more difficult, compared to autistic people. Clinicians, and people with a BPD diagnosis who think they may be autistic, can use these findings to better understand the differences between the two diagnoses. Even though we found lots of differences, it is still likely that autistic people experience more similarities with BPD than non-autistic people do and vice versa.