There has been much debate about the diagnostic categories of bipolar disorder and borderline personality disorder; they are treated as separate diagnoses, even though there are many overlapping symptoms.1-3 Perhaps partly as a result of this categorical confusion, there are high rates of comorbidity between bipolar disorder and borderline personality disorder.2
References:
1. American Psychiatric Association (APA). Diagnostic and Statistical Manual of Mental Disorders. Fifth edition, text revision. Washington DC: APA; 2022.
2. Fornaro M, Orsolini L, Marini S, et al. The prevalence and predictors of bipolar and borderline personality disorders comorbidity: systematic review and meta-analysis. J Affect Disord 2016; 195: 105–118.
3. Durdurak BB, Altaweel N, Upthegrove R, Marwaha S. Understanding the development of bipolar disorder and borderline personality disorder in young people: a meta-review of systematic reviews. Psychol Med 2022; 52 (16): 3769–3782.