Difference Between BPD and Bipolar: How to Tell Them Apart

At first sight, borderline personality disorder (BPD) and bipolar disorder might seem pretty similar. They both can cause intense mood fluctuations, influence self-image, and cause excessive impulsivity. Yet, if we dig deeper, we’ll see how different they are. Read the article to discover what people with bipolar disorder and borderline personality disorder experience, compare their symptoms, and find out more about treatment approaches.

What is borderline personality disorder (BPD)?

Borderline personality disorder is a mental health condition which, according to the American Psychiatric Association, is characterized by a pattern of ‘extreme changes in self-image, impulsive actions, and troubled relationships.’ [1] BPD may involve deep emotional wounds that might stem from minor reasons, lack of self-confidence, and trouble managing thoughts that may lead to reckless behavior. 

DSM-5-TR diagnostic criteria for BPD:

1. Intense fear of being abandoned, real or imagined
2. Very unstable relationships that swing between idealizing and devaluing others
3. Unstable sense of self or identity
4. Risky behavior in at least two areas (like spending, sex, drugs, driving, or eating)
5. Repeated suicidal thoughts, threats, or self-harm
6. Strong mood fluctuations that come and go quickly (like sadness, anger, or intense anxiety)
7. Ongoing feelings of emptiness
8. Intense or hard-to-control anger (like frequent outbursts or fights)
9. Brief episodes of paranoia or feeling disconnected under stress [2]

Statistics show that around 1.4% of the adult US population experiences BPD. [3] Yet, the real percentage can be higher as some may confuse this mental illness with other conditions, particularly bipolar disorder.

What is bipolar disorder?

Bipolar disorder is a mental health disorder that can cause intense mood shifts as well. The Mayo Clinic clarifies that it can include emotional highs, also known as mania or hypomania, and lows, also known as depression. [4] Moreover, both mania and depression at the same time are also possible to experience, which is called a mixed episode.

DSM-5 diagnostic criteria of manic episodes:

1. Feeling overly confident or having an exaggerated sense of self-importance (grandiosity)
2. Needing much less sleep than usual without feeling tired
3. Talking nonstop or feeling like you can’t stop talking
4. Thoughts racing or jumping quickly from one idea to another
5. Getting easily distracted
6. Being unusually active or driven, whether socially, at work, school, or sexually, or just feeling restless and unable to sit still, having an elevated mood
7. Getting caught up in risky behaviors, like spending too much money, having impulsive sex, or making bad business choices

The symptoms of depressive episodes include:

1. Feeling low most of the day (or others notice you seem down)
2. Losing interest in things you used to enjoy
3. Gaining or losing weight without trying, or changes in appetite
4. Trouble sleeping or sleeping too much
5. Feeling very restless or moving much slower than usual
6. Feeling tired or low on energy
7. Feeling worthless or overly guilty
8. Having trouble focusing or making decisions
9. Thinking a lot about death or having thoughts of suicide (even without a clear plan) [5]

3 main types of bipolar disorder:

Scientists identify 3 main types of bipolar disorder that share common symptoms in each phase but differ in how intense the mood swings are and how long they last.

1. Bipolar I disorder. You’ve had at least one really high-energy mood (mania), which can be so intense that it might lead to losing touch with reality. You may also have had low moods (depression) or milder highs (hypomania) before or after.

2. Bipolar II disorder. You’ve had at least one big low mood (depression) and one mild high (hypomania) but never a full-blown manic episode.

3. Cyclothymic disorder. You’ve had lots of ups and downs for at least two years (or one year for kids/teens), but the highs and lows aren’t as strong as full mania or major depression. [4]

Key differences between BPD and bipolar disorder

While these two mental health disorders may seem similar at first sight, there are significant differences in symptoms, causes, and treatment plans. Here are the main ways they differ so you can tell them apart more clearly. 

Aspect	Borderline personality disorder (BPD)	Bipolar disorder
Mood patterns	Tend to be rapid and intense mood changes that can shift within minutes or hours	Can change from severe manic episodes to depressive episodes that last for days or weeks
Type of mood instability	Emotional instability (anger, sadness, anxiety)	Highs (mania/hypomania) and lows (depression)
Sense of identity	Unstable self-image	Between episodes, identity might be more or less stable
Impulsivity	May be rather frequent and involve self-harm, risky relationships, and suicidal behaviors	Might happen during manic episodes (spending sprees, reckless driving, making poor financial decisions, etc.
Self-harmful behavior	Common and may be triggered by emotional pain or fear of rejection	Can happen during depressive episodes
Treatment	Dialectical behavior therapy (DBT), cognitive behavioral therapy (CBT), and mentalization-based treatment (MBT)	Medications (mood stabilizers, antidepressants), electroconvulsive therapy (ECT)  and talk therapy)

Symptoms comparison of bipolar disorder and borderline personality disorder

Borderline personality disorder and bipolar disorder are associated with intense mood swings. Moreover, people with these personality disorders can experience extreme impulsivity. Yet, there are some differences.

1. Mood swings

• Borderline personality disorder involves quick and short-lived mood changes that typically come from stressful events, interpersonal conflicts, or fear of abandonment.

• People with bipolar disorder tend to experience more long-term mood swings that can last for weeks. Typically, these changes aren’t tied to specific events and triggers but rather to inner reasons.

2. Impulsivity

• Those with borderline personality disorder may exhibit impulsive behavior because of excessive emotional pain and inner worries. Impulsive actions can be quite reactive and unpredictable.

• Bipolar disorder can also cause extreme mood swings and troubles with emotional control. People tend to behave impulsively during manic phases. Moreover, their actions can be driven by elevated energy or unrealistic confidence rather than emotional distress.

3. Interpersonal relationships

• Those living with borderline personality disorder may experience intense relationships with others, which might be rather unstable. As a core symptom of BPD is the fear of abandonment, such people may live with insecure attachment styles, idealize others, and be involved in unstable relationships.

• Relationships of people with bipolar disorder may be highly affected by the episode they’re experiencing. During manic phases, they may engage in chaotic relationships, while during depression, people may withdraw or find it difficult to maintain emotional closeness.

4. Managing emotions

• Reactivity and problems with emotional regulation are quite common for BPD, according to the study published in Harvard Review of Psychiatry. [6] A person may experience intense anger outbursts, sudden mood shifts, or overwhelming sadness.

• While intense emotions may be typical, those with bipolar disorder don’t tend to show up as emotionally reactive in everyday situations. Over manic phases, there can be heightened irritability or exaggerated emotional responses — but they are usually tied to the episode, not everyday interactions.

Causes and risk factors of bipolar disorder and borderline personality disorder

While studies are still being conducted, these separate conditions seem to have some similar causes. However, they differ in how these factors interact and show up in symptoms. Let’s review where bipolar disorder and borderline personality disorder might stem from.

Borderline personality disorder

There are several factors that can influence the development of BPD. These particularly include childhood trauma, genetics, brain structure and function, and hyperbolic temperament.

1. Childhood experiences and trauma

Studies prove that in 30% to 90% of cases, BPD is associated with emotional neglect and childhood abuse (emotional, physical, or sexual abuse). [7] When caregivers don’t accept the child’s emotions, the child may struggle to understand and manage their feelings and start swinging between emotional outbursts and shutdowns.

Over time, these early wounds can shape how the child sees themselves and others and lead to unstable self-image and fear of abandonment. The child may also develop coping strategies, such as impulsive behavior or emotional withdrawal, which are also symptoms of borderline personality disorder.

2. Genetic factors

The National Alliance of Mental Illnesses states that there’s no specific gene or gene profile that directly causes BPD. Yet, people who have a close family member with borderline personality disorder may be at a higher risk of developing this mental illness. [8]

Even more, genetic factors account for 40-60% of BPD variation. [9] So, inherited traits can significantly contribute to the development of BPD, especially when combined with other factors.

3. Brain differences

People with borderline personality disorder often show changes in how their brain handles emotions. Their amygdala — the part of the brain linked to fear and emotional reactions — can be overly active, while another part of the brain called the anterior cingulate cortex (ACC), which helps control emotions, may be functioning differently.

This brain pattern is similar to what’s seen in animals under long-term stress or depression. Scientists believe these brain changes might explain some of the intense emotions and difficulty with control seen in BPD. [10]

4. Hyperbolic temperament

Zanarini and Frankenburg suggested that BPD may develop when a person has a very intense, sensitive temperament. When something stressful happens in their environment, it can “set off” or trigger strong symptoms. [11] 

This temperament may be marked by deep emotional sensitivity, frequent feelings of being misunderstood, and a strong need for validation. When this intense emotional nature isn’t supported or understood, it can lead to long-term difficulties managing feelings. Over time, this emotional sensitivity, combined with negative life experiences, might contribute to the development of BPD symptoms.

Bipolar disorder

Genetics and brain differences are also among the causes of bipolar disorder. There are also researchers who suggest that childhood trauma may be the cause of bipolar disorder. [12] Yet, further studies are necessary, so we won’t include it in the list.

1. Genetic factors

According to the study published in Dialogues in Clinical Neuroscience, bipolar disorder, especially type I, has a strong genetic component. [13] Another study reveals that genetics accounts for around 60-80% of the risk of developing bipolar disorder. Even more, 36 genes are involved in the onset and development of bipolar disorder. [14]

2. Brain function

Bipolar disorder can also stem from brain differences. As such, studies have proved that neurons in specific brain regions, like the prefrontal cortex and hippocampus, might play significant roles in bipolar disorder’s development. [14]

Diagnosis: how to tell the difference

As these two mental disorders require pretty different treatment approaches, it’s essential for mental health professionals to accurately diagnose each condition. Understanding the differences in symptoms, duration, and triggers is key to making the correct diagnosis.

Diagnosing BPD involves observing a person’s behavior over a period of time to understand how they function in the long run. [2] Diagnostic criteria include persistent patterns of instability in relationships, self-image, and emotions. 

Importantly, only a licensed mental health professional can diagnose borderline personality disorder. Additional assessments might include an interview with your doctor, completing a series of questions, and a discussion of your symptoms. 

On the other hand, bipolar disorder is typically diagnosed by a psychiatrist or another mental health provider. They may need to access your energy and activity levels, family history, and mood patterns. The evaluation might also include lab tests to rule out medical causes, a mental health assessment with a psychiatrist to discuss thoughts and behaviors, and mood charting to track daily patterns like mood and sleep changes. 

Can you have both BPD and bipolar disorder?

In short, yes, co-occurring disorders are possible. Statistics from the research of Mark Zimmerman and Theresa A Morgan state that approximately 10% of patients with BPD had bipolar I disorder, and another 10% had bipolar II disorder. Even more, about 20% of bipolar II patients and 10% of bipolar I patients were diagnosed with BPD. [15]

This overlap can make diagnosis and treatment more challenging, as symptoms like mood swings, impulsivity, and emotional instability can appear in both conditions. As such, a lot of patients get diagnosed in early adulthood, as before such an age, it may be difficult to identify the diagnosis and proper treatment.

Bipolar and borderline personality disorders & co-occurring disorders

Both these disorders — together or separately — can also co-occur with other conditions, which makes treatment even more complicated. Among the most common ones that overlap with BPD are:

• post-traumatic stress disorder (PTSD)
• eating disorders
• attention-deficit/hyperactivity disorder (ADHD) [16]

For bipolar disorder, the most common overlapping disorders are:

• substance abuse [17] 
• anxiety disorders [18]

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Treatment approaches for borderline and BPD personality disorders: how they differ

Once a mental health professional knows the proper diagnosis, they can choose how to manage symptoms in the most effective way. Let’s briefly introduce the most common approaches. 

How to treat borderline personality disorder

• Dialectical behavior therapy (DBT). Dialectical behavior therapy is the type of cognitive behavioral therapy specifically adapted for people who experience intense mood shifts. Cleveland Clinic states that DBT helps people understand and accept their lives and actions, while also showing them how to change behaviors that aren’t helpful. [19] 

• Cognitive behavioral therapy (CBT). This approach is used to treat a lot of personality disorders, particularly. It’s considered highly effective because CBT uses different techniques to help people change their thinking, teach new skills, provide education, gradually face fears, and overcome them. [20]

• Mentalization-based treatment (MBT). MBT is a type of therapy that helps people better understand what’s going on in their own minds and in the minds of others. Patients with BPD show reduced capacities to mentalize, which leads to difficulties in managing impulsivity. [21] So, MBT teaches people to slow down, reflect, and respond more thoughtfully. 

How to treat bipolar disorder

• Mood stabilizers. It’s common to use medications for bipolar disorder treatment. Mood stabilizers help control the extreme highs (mania) and lows (depression) that come with the condition. Lithium is one of the most well-known stabilizers and has been used for decades to manage symptoms. [22] Yet, it’s essential to remember that any medication should only be prescribed by a mental health professional.

• Electroconvulsive therapy. A 2017 study has proven that ECT is an effective and safe treatment for all the phases of severe and drug-resistant bipolar disorder. [23] During ECT, small electric currents are passed through the brain while you’re asleep under anesthesia. This helps reset brain activity and can improve symptoms of the disorder.

Why accurate diagnosis matters

Conclusion

Now, you’re more prepared not to confuse BPD and bipolar disorder, and know how to treat both of them. If you face symptoms like increased impulsivity, mood swings, and difficulties managing emotions, it might be helpful to analyze what triggers them. 

Try Breeze’s mood tracker that allows you to spot hidden patterns and understand why you might feel angry, anxious, or overwhelmed. Additionally, the Breeze app can help you set up a nurturing routine and build new habits to cultivate resilience no matter what happens around you.

Sources

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2. Jennifer Chapman; Radia T. Jamil; Carl Fleisher; Tyler J. Torrico. “Borderline Personality Disorder.” 2024 
3. National Alliance of Mental Illness. “Borderline Personality Disorder.” 2023
4. Mayo Clinic. “Bipolar disorder.” 2024
5. Ankit Jain; Paroma Mitra. “Bipolar Disorder.” 2023
6. Daros, Alexander & Williams, Gregory. “A Meta-analysis and Systematic Review of Emotion Regulation Strategies in Borderline Personality Disorder.” Harvard Review of Psychiatry. 2019
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14. Nature. “Genomics yields biological and phenotypic insights into bipolar disorder.” 2025
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16. The British Journal of Psychiatry. “Pharmacological interventions for co-occurring psychopathology in people with borderline personality disorder: secondary analysis of the Cochrane systematic review with meta-analyses.” 2024
17. Strakowski SM, DelBello MP. “The co-occurrence of bipolar and substance use disorders.” 2000
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19. Cleveland Clinic. “Dialectical Behavior Therapy (DBT).” 2022
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