Overlap of autism spectrum disorder and borderline personality disorder: A systematic review and meta-analysis.

Autism spectrum disorder (ASD) and borderline personality Disorder (BPD) share features, including social and emotion regulation difficulties. The evidence for the overlap in prevalence and clinical characteristics was systematically reviewed. Ovid Medline, PsycInfo, and PubMed were searched until November 30, 2020 using keywords relating to BPD and ASD. Studies that reported on the overlap of ASD and BPD diagnoses or traits and used a case, cohort, or case-controlled design were included. Of 1633 screened studies, 19 were included, of which 12 reported data suitable for meta-analysis. Most samples were of small, clinically ascertained groups, with 11 having high risk of bias. The pooled prevalence of BPD in ASD was 4% [95% CI 0%-9%] and of ASD in BPD, 3% [95% CI 1%-8%]. There were inconsistent findings across clinical areas. The prevalence of a dual diagnosis of BPD in ASD cohorts and of ASD in BPD cohorts was within population prevalence estimates of each disorder. Based on this data we were not able to assess whether there is misdiagnosis of one in favor of the other. Neurocognitive differences may underlie similar behavioral symptoms, but further research using larger, well-validated samples is needed. LAY SUMMARY: Autism spectrum disorder (ASD) and borderline personality disorder (BPD) have overlaps in their symptoms. The overlap in how frequently they co-occur and their presentation was systematically reviewed. We searched the key databases and including all studies that reported on the overlap of ASD and BPD diagnoses or traits and used a case, cohort or case-controlled design. Of 1633 studies, 19 were included, of which 12 reported data suitable for pooling. Most samples were of small, clinical groups, with 11 having high risk of bias. The pooled prevalence of BPD in ASD was 4% [95% CI 0%-9%] and of ASD in BPD, 3% [95% CI 1%-8%]. There were inconsistent findings across studies comparing ASD and BPD related symptoms and problems. The prevalence of a dual diagnosis of BPD in ASD cohorts and of ASD in BPD cohorts was similar to the population prevalence of each disorder. Further research using larger, well-validated samples is needed.