How do we know how prevalent BPD is?

First, we should note that in the early 1990s BPD was not recognized as a common disorder. Now it is.

A number of studies have been performed in the USA to determine prevalence. One found that 1.8% of Americans meet the criteria, while others suggested a range of 2-4% or even almost 6%. Even the lowest estimate finds that BPD is about as common as Bi-Polar I and more common than Schizophrenia, both of which are far more well known.

Up-to-Date Research:

Summing up the conservative end, Zanarini stated in 2016: 1.8% of Americans meet criteria. BPD is about as common as Bi-Polar I, and more common than Schizophrenia (Zanarini McLean Webinar–BPD Patient and Family Education Initiative, “The Long-Term Course of Borderline Personality Disorder,” Originally aired Wednesday, February 3, 2016, accessed at, although she also stated in 2003 that clinical experience suggests that BPD is often underdiagnosed in many treatment settings. (Zanarini et al. “A SCREENING MEASURE FOR BPD: THE MCLEAN SCREENING INSTRUMENT FOR BORDERLINE PERSONALITY DISORDER (MSI-BPD)” Journal of Personality Disorders, 17(6), 568-573, 2003.)

Gunderson, championing the middle road, states that BPD is the most common of the personality disorders, with a prevalence rate of approximately 2–4% in the general population, accounting for 20% of people receiving inpatient mental health care and 15% of those receiving outpatient care. (Gunderson, J. (2011). A BPD brief: An introduction to borderline personality disorder: Diagnosis, origins, course, and treatment. Retrieved from

Grant provides the highest figures:

“The results of a large, well-conducted study funded by the National Institute of Mental Health [Grant et al, 2008]* suggests that the lifetime prevalence rate of borderline disorder is about 6% of the general population, and  appears to occur equally in men and women.” (Robert O. Friedel M.D. , accessed at , January 17, 2019.)

*Prevalence of lifetime BPD was 5.9% (99% CI: 5.4–6.4) [Grant et al. “Prevalence, Correlates, Disability, and Comorbidity of DSM-IV Borderline Personality Disorder: Results from the Wave 2 National Epidemiologic Survey on Alcohol and Related Conditions” J Clin Psychiatry. 2008 Apr; 69(4): 533–545.]