It is difficult to argue a priori knowledge when studies incorporate more diagnostic-based diagnoses versus symptom-based dimensional diagnoses. However, researchers Lee and Vaillancourt (2023) found that “approximately half of individuals with an eating disorder present with a comorbid personality disorder, most commonly (22%), borderline personality disorder (BPD)” (Lee & Vaillancourt, 2023). Observing individuals from an earlier developmental stage helps discover which disorder comes first. It makes sense that an individual would develop poor eating habits if they are experiencing severe personality disorder symptoms. On the other hand, not having enough nutrition can cause the body and brain to develop patterns similar to those seen in certain personality disorders. In Lee and Vaillancourt's longitudinal study of adolescents aged 14–18, which found that high levels of disordered eating predicted high BPD features, but the initial presence of BPD features was less predictive of later eating pathology. There is a clear bidirectionality between the two disorders; however, eating disorders tend to promote BPD patterns. 

Which Came First, The Eating Disorder or Borderline Personality Disorder?

Newton, J. R. (2019). Borderline personality disorder and eating disorders: a trans-diagnostic approach to unravelling diagnostic complexity. Australasian Psychiatry : Bulletin of the Royal Australian and New Zealand College of Psychiatrists, 27(6), 556–558. https://doi.org/10.1177/1039856219852297

Borderline personality disorder and eating disorders: a trans-diagnostic approach to unravelling diagnostic complexity.

According to the DSM-5 criteria (American Psychiatric Association, 2013), the overlapping symtons consist of:

- Impulsivity
- Affective instability
- Mood regulation
- Disturbed self-image

Other sources notice various symptoms that the DSM-5 does not include. Newton (2019) found in his research that the two disorders also overlap in the following:

- Self-harm (cutting)
- Suicidal ideation
- Difficulty differentiating between hunger or anger
- Negative Coping behavior to prevent further distress-*

Saint Olaf College

There is significant overlap between Borderline Personality Disorder (BPD) and Eating Disorders (specifically bulimia and binge eating) symptoms, suggesting that they may stem from similar environments, events, or chemistry. Additionally, learning more about the similarities and effects of each disorder on the other can lead to the development of new, effective treatment protocols. The intersection of BPD and EDs brings up deep psychological questions: Is disordered eating a form of affect regulation in those who can’t tolerate intense emotions? Does controlling food become a substitute for controlling unstable identity, a core issue in BPD? This makes the comorbidity a rich area for exploring self-concept, autonomy, and emotional survival strategies.

Comorbidity of BPD and ED

American Psychiatric Association. (2013). Diagnostic and statistical manual of mental disorders (5th ed.). https://doi.org/10.1176/appi.books.9780890425596

DSM-5

Costa, J., Marôco, J., Pinto-Gouveia, J., Ferreira, C., & Castilho, P. (2016). Validation of the Psychometric Properties of the Self-Compassion Scale. Testing the Factorial Validity and Factorial Invariance of the Measure among Borderline Personality Disorder, Anxiety Disorder, Eating Disorder and General Populations. Clinical Psychology and Psychotherapy, 23(5), 460–468. https://doi.org/10.1002/cpp.1974

Bozzatello, P., Garbarini, C., Rocca, P., & Bellino, S. (2021). Borderline Personality Disorder: Risk Factors and Early Detection. Diagnostics (Basel, Switzerland), 11(11), 2142. https://doi.org/10.3390/diagnostics11112142
Khosravi, M. Eating disorders among patients with borderline personality disorder: understanding the prevalence and psychopathology. J Eat Disord 8, 38 (2020). https://doi.org/10.1186/s40337-020-00314-3

Dyson Tori, Thomas Susan J., Townsend Michelle L., Finch Adam, South Alexandra, Barkus Emma, Walter Emma, Mendonca Carley, Grenyer Brin F. S., Pickard Judy A. (2023). Salivary testosterone and cortisol levels in borderline personality disorder before and after a 12-week group dialectical behavior therapy intervention. Frontiers in Psychology, 14(14). https://www.frontiersin.org/journals/psychology/articles/10.3389/fpsyg.2023.1195187

Federici, A. (2009). Dialectical Behaviour Therapy for the Treatment of Eating Disorders. NEDIC, NEDIC Eating Disorders Bulletin.

Lee, K. S., & Vaillancourt, T. (2024). Trajectories, comorbidity, and risk factors for adolescent disordered eating and borderline personality disorder features. Development and Psychopathology, 36(4), 1546–1557. doi:10.1017/S0954579423000792

Lee, S. S. M., Keng, S.-L., & Hong, R. Y. (2024). Validating the biosocial model of borderline personality disorder: Findings from a longitudinal study. Development and Psychopathology, 36(4), 1752–1762. doi:10.1017/S0954579423001116

Lester, R. J. (2009). Brokering Authenticity: Borderline Personality Disorder and the Ethics of Care in an American Eating Disorder Clinic. Current Anthropology, 50(3), 281–302. https://doi.org/10.1086/598782

Miller, A. E., Hotte-Meunier, A., Bain, T., Macdonald, E. P., Steiger, H., & Racine, S. E. (2025). A Qualitative Study of the Lived Treatment Experiences of Women With an Eating Disorder and Comorbid Borderline Personality Disorder. The International journal of eating disorders, 58(5), 860–867. https://doi.org/10.1002/eat.24390

Navarro-Haro, M. V., Botella, C., Guillen, V., Moliner, R., Marco, H., Jorquera, M., Baños, R., & Garcia-Palacios, A. (2018). Dialectical Behavior Therapy in the Treatment of Borderline Personality Disorder and Eating Disorders Comorbidity: A Pilot Study in a Naturalistic Setting. Cognitive Therapy and Research, 42(5), 636–649. https://doi.org/10.1007/s10608-018-9906-9

Newton, J. R. (2019). Borderline personality disorder and eating disorders: a trans-diagnostic approach to unravelling diagnostic complexity. Australasian Psychiatry : Bulletin of the Royal Australian and New Zealand College of Psychiatrists, 27(6), 556–558. https://doi.org/10.1177/1039856219852297

Ni, X., Chan, D., Chan, K., McMain, S., & Kennedy, J. L. (2009). Serotonin genes and gene–gene interactions in borderline personality disorder in a matched case-control study. Progress in Neuro-Psychopharmacology & Biological Psychiatry, 33(1), 128–133. https://doi.org/10.1016/j.pnpbp.2008.10.022.

Ntshingila, N., Poggenpoel, M., Myburgh, C. P. H., & Temane, A. (2016). Experiences of women living with borderline personality disorder. Health SA = SA Gesondheid, 21(1), 110–119. https://doi.org/10.1016/j.hsag.2016.01.001

Sansone, R. A., & Sansone, L. A. (2007). Childhood Trauma, Borderline Personality, and Eating Disorders: A Developmental Cascade. Eating Disorders, 15(4), 333–346. https://doi.org/10.1080/10640260701454345

Sansone, R. A., & Sansone, L. A. (2010). Personality Disorders as Risk Factors for Eating Disorders: Clinical Implications. Nutrition in Clinical Practice, 25(2), 116–121. https://doi.org/10.1177/0884533609357563.

Steiger, H. (2004). Eating disorders and the serotonin connection: state, trait, and developmental effects. Journal of psychiatry & neuroscience: JPN, 29(1), 20–29.

Power, R. A., & Pluess, M. (2015). Heritability estimates of the Big Five personality traits based on common genetic variants. Translational psychiatry, 5(7), e604. https://doi.org/10.1038/tp.2015.96

Reference List: Comorbidity of Borderline Personality Disorder and Eating Disorders

Overlapping Criteria in DSM-5 of BPD and EDs (specifically Bulimia Nervosa)

The comorbidity is a result of the shared cognitive distress that both disorders build off of. This includes:

- Interpersonal/Environmental Effects
- Biological Effects
- Emotion Dysregulation
- Early Childhood Trauma

Additionally, eating disorders, specifically anorexia nervosa as well as bulimia nervosa tend to act as a form of coping and self-harm (symptomology) for BPD.

Causes to the Comorbidity Between Eating Disorders and Borderline Personality Disorder

Miller et al. (2025) published a fascinating article on their research, which included qualitative data from 14 of the participants who were diagnosed with both borderline personality disorder (BPD) and an eating disorder (ED). Before discussing their findings, they elaborate on the fact that hospitalization, self-harm, and suicide attempts occur more often in patients with both disorders rather than one or the other. As a result, it is beneficial for clinicians to gain insight into their experiences, thereby expanding treatment options in an eating disorder rehabilitation center. 

They found five central themes throughout their qualitative data collection:

- The central role of emotions in the relationship between EDs and BPD.
- Perception of BPD in ED maintenance and treatment. 
- Relational dynamics faced by patients during treatment. 
- A feeling that treatment was “never enough.” 
- The importance of addressing ED and BPD symptoms simultaneously.

Lived Treatment experiences: The Complexity and Clinical Impact of having both an Eating Disorder and Borderline Personality Disorder.

Clinicians are attempting to both diagnose and treat clients accurately while working within the American Healthcare system to ensure that their clients receive continued care. One researcher, Lester (2009), found that they worked in an eating disorder clinic and observed the difficulties that their clinicians faced. 

Some challenges include:

- The resident needs to be sick enough but also appear genuine in their recovery for insurance companies to provide continued support. 
- Having enough resources to continue care even when at a healthy weight.
- Documenting behaviors so that they appear less borderline.

Ethical Concerns of Care and the Impact of Clinical Diagnostics for BPD Patients with Eating Disorders

The two approaches in treating comorbid BPD and ED:

- Cognitive Behavioral Therapy
- Dialectical Behavioral Therapy

Cognitive Behavioral Therapy (CBT) and Dialectical Behavior Therapy (DBT) are both widely used to treat comorbid Borderline Personality Disorder (BPD) and Eating Disorders (EDs), but they approach symptom management differently.

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