The Key Differences Between Bipolar Disorder and Borderline Personality Disorder

Key Takeaways

Mental Health awareness has expanded significantly over the years, leading to a broader understanding and acceptance of various conditions. While there are strides made in erasing the stigma around it, nuances and complexities in conditions often create confusion. A recurring point of discussion, for instance, is the distinction between Borderline Personality Disorder (BPD) and Bipolar Disorder.

Let’s dive into this, exploring the similarities and differences of each.

Bipolar Disorder vs. BPD: What’s the Difference?

Both conditions involve difficulty in self-managing emotional regulation and mood fluctuations. Yet, their root causes, manifestations, and treatments can be vastly different. Understanding these distinctions is crucial for accurate diagnosis and effective treatment. As highlighted by this study, the expansion of the Bipolar Disorder spectrum may highlight some similarities between both conditions, but there remains a lack of consensus as to whether these two disorders fall on the same spectrum.

Here are some common characteristics of BPD vs. Bipolar Disorder:


Borderline Personality Disorder vs. Bipolar Disorder Symptoms

The world of Mental Health can be burdensome to navigate, especially when it comes to distinguishing symptoms. We’ll explain the distinct symptoms and behaviors associated with both Borderline Personality Disorder (BPD) and Bipolar Disorder, so you have the foundational knowledge to differentiate between the two.

Borderline Personality Disorder Diagnostic Criteria:

Jami Shanes, LPC based out of LifeStance’s Beachwood Ohio office explains in our
Understanding Borderline Personality Disorder – Convos from the Couch Podcast, “There are ten different personality disorders and they are grouped into clusters, A, B and C. Borderline personality disorder, the one we are focusing on today is in cluster B along with three others, antisocial personality disorder, narcissistic and histrionic. The main thing we are going to see is issues with self-image, and instability with interpersonal relationships. There are nine criteria, and in order for someone to be diagnosed, they must meet five.”

  • Fear of abandonment
  • Intense and unstable relationships
  • Identity disturbance, unstable self-image
  • Impulsive behaviors
  • Self-harming tendencies
  • Mood swings lasting a few hours to a few days
  • Persistent feelings of emptiness
  • Explosive angerParanoid thoughtssubstance use disorder, binge eating disorder, oftentimes this diagnosis is not just occurring by itself.”

    Learn more about the signs and symptoms of Borderline Personality Disorder.

Bipolar Disorder Diagnostic Criteria:

  • Distinct episodes of Depression lasting two weeks or more
  • Manic episodes lasting a week or more
  • Feelings of worthlessness during depressive phases
  • Euphoria or agitation during manic phases
  • Reduced need for sleep in states of mania
  • Racing thoughts

Explore the types of Bipolar Disorder and understand Myths and Facts about Bipolar Disorder.


What Causes Bipolar Disorder and BPD?

Genetic Predisposition

Both disorders have roots in genetics, brain structure, and function, but their triggers and progression pathways vary. The likelihood of developing both Borderline Personality Disorder and Bipolar Disorder is significantly influenced by one’s genetic makeup. Studies have shown that individuals with a close family member diagnosed have a heightened risk of manifesting the disorder. Although no specific genes have been directly linked to each condition, heredity plays a crucial role in susceptibility.

Childhood Trauma

Family history and childhood experiences play a pivotal role in shaping our Mental Health. Individuals with BPD often report histories of physical, emotional, or sexual abuse during their formative years. Such traumatic experiences can lead to unstable self-image, intense emotional responses, and difficulties in building and maintaining relationships—all hallmark symptoms of BPD. Learn more about living with Borderline Personality Disorder here. BPD is a highly stigmatized and misunderstood disorder; here’s what people with BPD wish you knew.

Stressful Life Events

Similarly, stressful life events, such as the loss of a loved one, divorce, or other major life changes, can have a detrimental impact on Mental Health. These stresses can act as triggers for the onset or relapse of Bipolar Disorder. Coping with these situations can be especially challenging for those predisposed to the disorder, leading to the emergence or intensification of symptoms.

Brain Structure

Mental Health starts in the brain, and recent neuroimaging studies suggest that people with BPD might have structural and functional differences in certain areas of the brain responsible for emotion regulation and impulse control. These anomalies may lead to heightened emotional responses and impulsivity seen in BPD patients. BPD is a complex disorder that requires deep understanding from loved ones.

Brain structure and functionality can differ in individuals with Bipolar Disorder as well. While these differences don’t directly cause the disorder, they can contribute to symptom severity and manifestation. Anomalies in certain brain regions may disrupt mood regulation, leading to the manic and depressive episodes typical of the disorder. A lot of false information exists surrounding Bipolar Disorder. Uncover some of the common myths here.

Neurotransmitters and Hormones

Neurotransmitters are the brain chemicals responsible for communication between nerve cells and are crucial in mood regulation. Imbalances in neurotransmitters like serotonin, dopamine, and norepinephrine can lead to mood disturbances. In Bipolar Disorder, these imbalances can result in extreme mood swings, from euphoric highs to devastating lows.

Hormonal changes can influence the onset or exacerbation of Bipolar Disorder. For example, abnormalities in thyroid function can amplify mood disturbances.


Both Bipolar Disorder and Borderline Personality Disorder, though sharing some similarities, are distinct disorders that require specific treatments. Through understanding these nuances and knowing whether it is BPD or Bipolar Disorder, those affected gain access to the specialist support they need for a positive prognosis. LifeStance is here to support, inform, and guide you every step of the healing process.

Authored By 

LifeStance Health
LifeStance Health

LifeStance is a mental healthcare company focused on providing evidence-based, medically driven treatment services for children, adolescents, and adults.