Bipolar Disorder vs. Borderline Personality Disorder: Key Differences Explained

What is the difference between bipolar disorder and BPD?

Bipolar disorder is a biologically based mood disorder defined by sustained mood episodes lasting weeks or months, separated by periods of stability. BPD is a personality disorder characterized by chronic, rapid mood shifts often triggered by interpersonal stress.¹ ²

Talkiatry psychiatrists who specialize in mood disorders frequently see patients who have been told they might have one condition or the other. The confusion makes sense: both involve mood instability and impulsivity, which is why they're often mistaken for each other.

The distinction comes down to what kind of condition each one is and how symptoms show up over time. BD involves distinct episodes that represent a clear departure from how someone usually feels. BPD, on the other hand, involves a persistent pattern of emotional reactivity, unstable relationships, and an unsteady sense of self that doesn't come and go in episodes.

What is bipolar disorder?

BD is a mood disorder characterized by extreme shifts in mood, energy, and activity levels that occur in distinct episodes.³ Manic or hypomanic episodes are characterized by elevated moods or irritability. Depressive episodes are marked by low moods. Between episodes, many people return to a stable baseline.

Bipolar I disorder

Bipolar I is defined by the presence of at least one full manic episode lasting at least seven days, or severe enough to require hospitalization.³ Most people with bipolar I also experience major depressive episodes, though one isn't required for diagnosis.

Bipolar II disorder

Bipolar II involves a pattern of hypomanic episodes and major depressive episodes.³ Hypomania is less severe than full mania and doesn't lead to hospitalization, but the depressive episodes can be long-lasting. Bipolar II isn't a "milder" form of bipolar I; it's a distinct diagnosis. Understanding the difference between bipolar II and borderline personality disorder is particularly important, since both can involve significant depressive symptoms.

Cyclothymia

Cyclothymia is a milder, more chronic form of bipolar disorder involving numerous periods of hypomanic symptoms and depressive symptoms lasting at least two years.³ The symptoms don't meet the full criteria for a hypomanic or major depressive episode.

What is borderline personality disorder?

Borderline personality disorder is marked by a persistent pattern of instability in emotions, self-image, and interpersonal relationships, along with a fear of abandonment.² Despite including the term "borderline," the condition is better understood today as involving enduring patterns of thinking and behavior that are pervasive and persistent, rather than episodic.

Core features of BPD include:

• Emotional instability: Rapid, reactive mood shifts, often lasting only a few hours, typically in response to interpersonal events
• ‍Unstable relationships: A pattern of relationships marked by alternating between idealization and devaluation
• ‍Identity disturbance: A persistently unstable sense of self or self-image
• ‍Fear of abandonment: Frantic efforts to avoid real or imagined abandonment or rejection ‍
• Impulsivity: Engaging in impulsive behaviors in at least two areas that are potentially self-damaging, such as spending money, substance use, or risky sexual behavior

Bipolar disorder symptoms vs. BPD symptoms

While both conditions involve mood changes and impulsivity, the pattern and context of symptoms are what help clinicians tell them apart. If you're wondering, "How do I know if I'm bipolar or borderline?" understanding how symptoms present in each is a good starting point.

Bipolar disorder symptoms

Symptoms occur in distinct episodes that represent a noticeable change from a person's usual state.³

Manic symptoms may include:

• Elevated or irritable mood
• Decreased need for sleep without feeling tired
• Racing thoughts or talking faster than usual
• Grandiosity or inflated self-esteem
• A marked increase in goal-directed activity or energy

Depressive symptoms may include:

• Persistent sadness or hopelessness
• Low energy and fatigue
• Changes in sleep or appetite
• Difficulty concentrating
• Loss of interest in activities once enjoyed

BPD symptoms

Symptoms are part of a persistent, long-term pattern rather than  discrete episodes.²

• Chronic feelings of emptiness
• Intense and highly unstable relationships
• Unstable self-image or sense of identity
• Impulsivity in areas like spending, sex, or substance use
• Recurrent suicidal behavior, gestures, or threats, or self-harming behavior
• Stress-related paranoia or dissociative symptoms
• Inappropriate anger or difficulty controlling anger

How mood disorders differ from personality disorders

Mood disorders involve episodic changes in a person's emotional state. Personality disorders involve enduring, pervasive patterns of thinking, feeling, and behaving that are relatively stable over time.¹ ²

• Mood disorders (like bipolar): Characterized by distinct episodes of illness, like mania or depression, that represent a clear change from baseline functioning. Between episodes, mood may return to normal, which clinicians call euthymia.
• ‍Personality disorders (like BPD): Characterized by long-standing, inflexible patterns of inner experience and behavior. The patterns are part of how a person consistently experiences themselves and the world, rather than episodic.

Someone with bipolar disorder might say, "I wasn't myself during that episode." With BPD, the patterns are more woven into how someone experiences life on an ongoing basis.

What causes bipolar disorder and BPD

Both conditions have complex causes that involve a combination of genetic, biological, and environmental factors. However, the specific contributing factors often differ.

Bipolar disorder causes

The causes of BD are primarily linked to biological factors.³ A strong genetic predisposition exists, as the disorder often runs in families. Differences in brain structure and neurotransmitter function are also believed to play a role. Environmental factors like stress or trauma can potentially trigger episodes in people who are already vulnerable.

BPD causes

BPD is thought to be caused by a mix of genetics and environment.² Many people with BPD have a history of childhood trauma, abuse, or neglect, though not everyone with such experiences develops the condition. Research points to differences in brain areas that control emotion regulation and impulsivity.

How psychiatrists diagnose bipolar disorder vs. borderline personality disorder

Diagnosis for either condition involves a comprehensive psychiatric evaluation, a detailed clinical interview, and a careful assessment of symptom patterns over time. There is no blood test or brain scan that can diagnose BD or BPD; diagnosis relies on a clinician's expertise in differentiating between the two.

A psychiatrist will typically consider:

• Timeline of symptoms: Are mood changes episodic and lasting for days or weeks (suggesting BD), or are they chronic, moment-to-moment, and reactive (suggesting BPD)?
• ‍Triggers: Do mood shifts occur spontaneously, or are they primarily a reaction to interpersonal events? The latter is more characteristic of BPD.
• ‍Sleep patterns: A decreased need for sleep without feeling tired during a period of elevated mood is a hallmark symptom of mania in bipolar disorder.
• ‍Self-image: A chronic and pervasive pattern of an unstable sense of self points more toward BPD.
• ‍Relationship patterns: A history of unstable relationships characterized by a fear of abandonment is a core feature of BPD.

Misdiagnosis is common, and a thorough evaluation by a qualified mental health professional is essential for an accurate diagnosis.

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Treatment for bipolar disorder vs. BPD

Treatment approaches for bipolar disorder and BPD differ significantly, which is one of the main reasons getting an accurate diagnosis matters. Bipolar disorder treatment is centered on medication to stabilize mood, while BPD treatment is centered on specialized, skills-based psychotherapy.

Bipolar disorder treatment

Medication is the cornerstone of treatment for bipolar disorder.⁴ Mood stabilizers (like lithium or valproate) and atypical antipsychotics are typically used to manage manic and depressive episodes. Antidepressants may be used in some cases, but they're typically prescribed cautiously alongside a mood stabilizer to avoid triggering mania.

Psychotherapy, such as cognitive behavioral therapy (CBT), can be a helpful addition to medication for managing symptoms and improving coping skills. However, ongoing medication management is typically necessary for long-term stability.

BPD treatment

Psychotherapy is the cornerstone of treatment for BPD.² Dialectical behavior therapy (DBT) is the most well-researched treatment, focusing on teaching skills in mindfulness, distress tolerance, emotion regulation, and interpersonal effectiveness. Other therapies like mentalization-based therapy (MBT) can also be effective.

While there are no FDA-approved medications specifically for BPD, a psychiatrist may prescribe medications to target specific symptoms like mood instability, impulsivity, or co-occurring depression. Medications are used as an adjunct to therapy, not as the primary treatment.

Can you have both bipolar disorder and BPD?

Yes, it is possible to have both bipolar disorder and BPD at the same time; this is known as comorbidity.⁵ When the conditions co-occur, the overlapping symptoms of mood instability and impulsivity can make diagnosis particularly challenging.

Having both conditions may require an integrated treatment plan that addresses the episodic nature of bipolar disorder with medication while also using psychotherapy to manage the pervasive patterns of BPD. Working with a psychiatrist experienced in complex presentations can help ensure both conditions are being addressed appropriately.

Which is worse: BPD or bipolar disorder?

Neither condition is inherently "worse" than the other. Both bipolar disorder and BPD are serious mental health conditions that can significantly impact a person's quality of life, relationships, and overall functioning if left untreated. Both are also treatable.

The severity of each condition varies greatly from person to person. Comparing them is less helpful than focusing on obtaining an accurate diagnosis and an effective, personalized treatment plan.

The bottom line

The key difference between the two conditions is the bipolar disorder is an episodic mood disorder defined by sustained periods of mania and depression, while BPD is a personality disorder characterized by a pervasive pattern of emotional reactivity and instability in relationships. Because symptoms can overlap while treatments are very different, an accurate diagnosis is critical.

If you're unsure which condition might apply to you, or if you've been given conflicting information in the past, a comprehensive evaluation from a psychiatrist can help clarify what's going on and what kind of treatment is most likely to help.

Getting started with Talkiatry

Talkiatry is a national psychiatry practice that makes it easier to get care from doctors who listen. Start by answering a few questions online, then get matched with a psychiatrist based on your needs. From there, you can schedule a visit, often within days, and meet with your provider from home.

First visits are 60 minutes, so there's time to talk through what's going on and build a treatment plan together. Talkiatry is in-network with most major insurers, and you can check your coverage during the assessment.

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FAQs about bipolar disorder and borderline personality disorder

Can bipolar disorder be misdiagnosed as borderline personality disorder?

Yes, misdiagnosis can occur in both directions because both conditions involve significant mood instability and impulsivity. A comprehensive psychiatric evaluation that carefully examines the timeline and triggers of symptoms is important for distinguishing between them.

How long do mood episodes last in bipolar disorder compared to BPD?

Bipolar mood episodes are sustained, typically lasting for days, weeks, or even months. In contrast, the mood shifts in BPD are much more rapid, often occurring within hours, and are usually a direct reaction to interpersonal events.

Can bipolar disorder or BPD be diagnosed through telehealth?

Yes, a psychiatrist can conduct a comprehensive evaluation, assess symptoms, and make an accurate diagnosis for either condition through telehealth. The process involves a detailed clinical interview and assessment of symptom history, just as would be done in person.

Are medications used differently for bipolar disorder and BPD?

Yes, medication is a primary treatment for bipolar disorder, utilizing mood stabilizers and antipsychotics to manage episodes. For BPD, psychotherapy is the main treatment, and medications are only used as an adjunct to target specific symptoms rather than the disorder itself.

Is there a genetic link for bipolar disorder and borderline personality disorder?

Yes, both conditions have genetic components, meaning they can run in families. However, environmental factors, such as stress and trauma, also play a significant role in the development of both disorders.

Medical disclaimer and sources

The information in this article is for informational and educational purposes only and should never be substituted for medical advice, diagnoses, or treatment. If you or someone you know may be in danger, call 911 or the National Suicide and Crisis Lifeline at 988 right away.

Sources

1. National Institute of Mental Health. Bipolar Disorder. https://www.nimh.nih.gov/health/topics/bipolar-disorder
2. National Institute of Mental Health. Borderline Personality Disorder. https://www.nimh.nih.gov/health/topics/borderline-personality-disorder
3. American Psychiatric Association. What Is Bipolar Disorder? https://www.psychiatry.org/patients-families/bipolar-disorders/what-are-bipolar-disorders
4. American Psychiatric Association. Practice Guideline for the Treatment of Patients With Bipolar Disorder. https://psychiatryonline.org/doi/book/10.1176/appi.books.9780890425787
5. Zimmerman M, Morgan TA. The relationship between borderline personality disorder and bipolar disorder. Dialogues Clin Neurosci. 2013;15(2):155-169. https://pubmed.ncbi.nlm.nih.gov/24174890/

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