Borderline personality disorder (BPD) is one of the least understood mental health conditions out there. With that, researchers still aren’t 100% sure what causes it.

Still, we’re aware of a few factors that could lead to the condition. Furthermore, it’s believed that BPD is caused by multiple elements rather than a single factor.

What is Borderline Personality Disorder?

Borderline personality disorder (BPD) is a mental health condition that is pronounced by the following: ¹

• Behavior
• Mood swings
• Self-image

More specifically, someone with BPD is likely to experience intense mood swings and face uncertainty in how they view themselves and their place in this world. Due to this, their interests, values, and behavior can show rapid changes.

Those who struggle with the condition are likely to view life through extremes, usually all good or all bad. For example, if you’re good friends with someone who has BPD, they may unexpectedly view you as an enemy the next day.

Such intense emotions often lead to instability in day-to-day tasks and relationships. Not to mention, people with BPD are likely to experience symptoms of other mental illnesses, such as anxiety and depression.

BPD Symptoms

Common symptoms of borderline personality disorder include:

• Abandoment issues (both real and imagined)
• Anger issues (inappropriate, intense anger)
• Difficulties with self-image (distorted or unstable)
• Dissociation from other people and reality
• Engaging in impulsive behaviors (i.e. spending sprees, unsafe sex, substance abuse, etc.)
• Feelings of emptiness
• Lack of trust for other people (irrational fears)
• Sequences of unstable and intense relationships

It’s worth noting that not everyone with BPD will experience all these symptoms. Furthermore, some symptoms may be a product of another mental illness. For example, if you find yourself engaging in risky behavior, but only during periods of elevated mood, you likely struggle with a mood disorder. ²

What Causes Borderline Personality Disorder?

While researchers still aren’t sure exactly what causes BPD, evidence suggests it’s a combination of multiple factors. ³ Still, it’s important to note that there’s only so much research into the causes of BPD. That said, we may only have a small understanding of a much larger issue. As of this time, scientists agree the following can lead to BPD:

Brain Chemistry

Our brains contain neurotransmitters that act as “messenger chemicals” to link signals between brain cells. ⁴ While there’s only so much evidence to suggest it, many scientists believe those who struggle with BPD have something wrong with their neurotransmitters. More specifically, serotonin. ⁵

In one review study, it was found that there is a relationship between impulsive aggression and serotonin dysfunction. Furthermore, the study found that emotional difficulties may also be caused by imbalances in cholinergic, noradrenergic, and GABAminergic neurotransmission (though, to a lesser degree). ⁶

Brain Development

Beyond neurotransmissions, researchers have used MRI scans to observe other areas of the brain that may cause BPD. In one study, it was discovered that people with BPD had irregularities in the following areas of the brain: ⁷

• The amygdala is a key player in emotional regulation, especially “negative” emotions, such as aggression, anxiety, and fear. ⁸

• The hippocampus is important in regulating behaviors and self-control. ⁹

• The orbitofrontal cortex is used when making plans and decisions. ¹⁰

Since these areas of the brain are most affected during your upbringing, certain childhood developments may lead to BPD.

Environmental Factors

Environmental factors can make intense changes in the brain. For people with BPD, these may include: ¹¹

• Exhibiting fear or distress during childhood
• Growing up with a family member who struggles with a mental illness, such as bipolar disorder
• Neglection from one or both parents
• Victimization of emotional, physical, or sexual abuse

However, there are a few other factors in childhood that may lead to BPD. These include: ¹²

• Conducting yourself so other people are adults and you’re not
• Expecting people to bully you (even strangers)
• Idealising other people
• Seeing parents in other people
• Unresolved fear, distress, and anger

Genetics

One of the most significant causes of BPD is genetics. If you have a close family member (parent, sibling, etc.) who’s been diagnosed with BPD, you’re more likely to struggle with it.

One study found that an identical twin with BPD gave their other identical twin a 2-in-3 chance of having the condition. ¹³

However, genetics cannot be a determining factor for BPD. With that, scientists view it as a cautionary sign that someone may develop the condition. Especially if they’re vulnerable to other causes of BPD.

Final Word

If you believe you’ve been affected by the causes of BPD, you may want to seek out a mental health professional. Unfortunately, BPD is such a complex condition and these causes alone won’t determine a diagnosis.

BPD is a difficult disorder, but it can be managed with talk therapy and medication. You may also find that incorporating certain vitamins and supplements into your diet can help to ease symptoms.

References

¹ Chapman J, Jamil RT, Fleisher C, Torrico TJ. Borderline Personality Disorder. 2024 Apr 20. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan–. PMID: 28613633.

² Cheniaux E, Filgueiras A, Silva Rde A, Silveira LA, Nunes AL, Landeira-Fernandez J. Increased energy/activity, not mood changes, is the core feature of mania. J Affect Disord. 2014 Jan;152-154:256-61. doi: 10.1016/j.jad.2013.09.021. Epub 2013 Oct 3. PMID: 24140225.

³ Holder S. Mental Disorders: Personality Disorders. FP Essent. 2020 Aug;495:11-16. PMID: 32757561.

⁴ Sheffler ZM, Reddy V, Pillarisetty LS. Physiology, Neurotransmitters. [Updated 2023 May 1]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK539894/

⁵ Hansenne M, Pitchot W, Ansseau M. Serotonin, personality and borderline personality disorder. Acta Neuropsychiatr. 2002 Apr;14(2):66-70. doi: 10.1034/j.1601-5215.2002.140203.x. PMID: 26983967.

⁶ Friedel RO. Dopamine dysfunction in borderline personality disorder: a hypothesis. Neuropsychopharmacology. 2004 Jun;29(6):1029-39. doi: 10.1038/sj.npp.1300424. PMID: 15039763.

⁷ Lis E, Greenfield B, Henry M, Guilé JM, Dougherty G. Neuroimaging and genetics of borderline personality disorder: a review. J Psychiatry Neurosci. 2007 May;32(3):162-73. PMID: 17476363; PMCID: PMC1863557.

⁸ Rasia-Filho AA, Londero RG, Achaval M. Functional activities of the amygdala: an overview. J Psychiatry Neurosci. 2000 Jan;25(1):14-23. PMID: 10721680; PMCID: PMC1407702.

⁹ Fogwe LA, Reddy V, Mesfin FB. Neuroanatomy, Hippocampus. 2023 Jul 20. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan–. PMID: 29489273.

¹⁰ Rolls ET. The functions of the orbitofrontal cortex. Brain Cogn. 2004 Jun;55(1):11-29. doi: 10.1016/S0278-2626(03)00277-X. PMID: 15134840.

¹¹ Reichborn-Kjennerud T, Ystrom E, Neale MC, Aggen SH, Mazzeo SE, Knudsen GP, Tambs K, Czajkowski NO, Kendler KS. Structure of genetic and environmental risk factors for symptoms of DSM-IV borderline personality disorder. JAMA Psychiatry. 2013 Nov;70(11):1206-14. doi: 10.1001/jamapsychiatry.2013.1944. PMID: 24048243; PMCID: PMC3927987.

¹² Hecht KF, Cicchetti D, Rogosch FA, Crick NR. Borderline personality features in childhood: the role of subtype, developmental timing, and chronicity of child maltreatment. Dev Psychopathol. 2014 Aug;26(3):805-15. doi: 10.1017/S0954579414000406. PMID: 25047300; PMCID: PMC4141853.

¹³ Skoglund, C., Tiger, A., Rück, C. et al. Familial risk and heritability of diagnosed borderline personality disorder: a register study of the Swedish population. Mol Psychiatry 26, 999–1008 (2021). https://doi.org/10.1038/s41380-019-0442-0