Borderline Personality Disorder vs. Bipolar Disorder

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Borderline personality disorder (BPD) and bipolar disorder (BD) are both mental illnesses associated with dramatic mood swings. While many of their symptoms overlap, these two conditions have different causes, symptoms, and treatments. One major difference between the two is that BD is a mood disorder, characterized by persistently abnormal moods, while BPD is a personality disorder, characterized by instability in relationships, self-image, and moods.

Like BD, formerly known as manic depression or manic-depressive illness, BPD is characterized by emotional turbulence and impulsive behavior, but it is also associated with unstable personal relationships, which is not a core feature of BD. It is, however, possible to have both BD and BPD simultaneously.

Borderline Personality Disorder vs. Bipolar Disorder

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BPD and BD share some of the same traits, but they have different symptom patterns, duration, and triggers.


The main symptoms of BPD include:

  • Dramatic emotional changes, lasting from a few hours to a few days
  • Impulsive, risky, and unsafe behavior
  • Inappropriate anger
  • Feelings of emptiness and low self-worth 
  • Self-injury or thoughts of self-harm
  • Chronic depression
  • Distorted self-image
  • Fear of abandonment
  • Unstable and intense relationships

People with BPD may also show signs of uncontrolled aggression. The impulsive nature of BPD can make a person more likely to engage in addictive behavior, like drug use and gambling. Moreover, the symptoms are usually triggered by a conflict with another person or institution. A traumatic or stressful event can also cause an increase in BPD symptoms.

Another feature of BPD is called splitting. This term, which refers to two things being split in half, is when someone is unable to hold emotionally opposing viewpoints in relation to themselves and others. It is usually a coping or defense mechanism to manage the intense fear of abandonment, and it can result in impulsive behaviors and relationship difficulties.

Bipolar Disorder

The main symptoms of BD include dramatic changes between mood states. The highs, or elevated, expansive, or irritable periods, are considered manic episodes. The lows, or sad, empty, or hopeless periods, are depressive episodes. Experiencing both manic episodes and depressive episodes differentiates BD from major depressive disorder (MDD), which is dominated by only depressive episodes.

During manic episodes, symptoms of BD include:

  • Decreased need for sleep
  • Inflated self-esteem or grandiosity
  • Elevated mood, euphoria, and irritability
  • Excessively talkative
  • Racing thoughts
  • Impaired judgment
  • Easy distraction
  • Threatening and assaultive behavior

During depressive episodes, symptoms of BD include: 

  • Depressed mood
  • Flat or limited expression
  • Feelings of guilt and failure
  • Impairment in cognition and memory
  • Soft, slow speech
  • Lack of energy and motivation
  • Overemphasis of negative feelings and beliefs
  • Weight changes
  • Insomnia
  • Recurrent thoughts of death or suicide

It’s also important to understand that manic episodes in BD aren’t necessarily beneficial, even though they’re the alternative to depressive episodes. People experiencing mania can be reckless. They often lack self-awareness and are unable to understand how their impulses affect themselves and others.

People with bipolar I disorder often have cycles that switch from a depressive state to a manic state. Manic symptoms sometimes include symptoms of depression within the manic episode, which is called mixed features.

Between cycles, people with BD often have periods of true symptom-free wellness lasting weeks, months, or years.

On the other hand, people diagnosed with BPD typically have more persistent day-to-day emotional symptoms that can impact everyday life.


There are a number of complex factors that can cause BPD or BD. Many of the experiences with emotional dysregulation in BPD are in response to relationship interactions, while BD symptoms can be triggered by a wide variety of factors, including chemical imbalances in the brain and stressful life events.

Borderline Personality Disorder

The exact cause of BPD is not entirely known, but research suggests that it can be influenced by environmental factors, especially those in early childhood.

A history of emotional, physical, or sexual abuse or parental neglect is prevalent in people with BPD. Parental substance abuse is another potential cause. Research has shown that experiencing stress and trauma as a child, and an inability to cope can contribute to BPD later in life.

Genetics, chemical imbalances, and brain structure may also play a role in BPD. People with a family history of BPD are at higher risk of having the condition. Many people with BPD have altered brain neurotransmitter function, particularly of serotonin. Studies have shown that people with BPD can have structural and functional changes in the brain, especially in the areas that control impulses and emotional regulation like the amygdala, hippocampus, and orbitofrontal cortex.

Bipolar Disorder

The causes of BD are complex. Most agree that there is no one single cause, and a combination of factors often contributes to BD. People who have a direct relative with BD are more likely to develop it. Some research also suggests that people with certain genes are more likely to develop BD. 

Researchers believe that chemical imbalances play a role in BD. There is evidence that an imbalance in one or more neurotransmitters may result in bipolar symptoms.


According to the Diagnostic and Statistical Manual 5th Edition (DSM-5), which psychologists, psychiatrists, and other mental health professionals use for diagnosing mental health conditions, BD is diagnosed when a person experiences a manic episode that may have been preceded or followed by a depressive episode.

Bipolar 2 disorder is diagnosed when hypomania (less severe mania) and depressive episodes have been present.

Some subtle diagnostic distinctions between BPD and BD:

  • Duration: A manic or depressive episode of BD can last weeks, months, or longer. In contrast, people with BPD have shorter episodes of mood instability that are reactive to stress.
  • Family history: Genetic factors can also help differentiate the two. Mood disorders, like BD, are more likely to be passed down through family members than BPD.
  • Sleep: Sleep changes are often an early indicator of BD. During a bipolar episode, a person might be awake for days without experiencing fatigue. Meanwhile, sleep patterns are less commonly affected in BPD.
  • Relationships: People with BPD have more distinct challenges interacting with others, so they often have a history of turbulent personal relationships or may lack close and trusted friends.
  • Self-harm: Self-harm behaviors such as cutting are more common in BPD.

It isn’t uncommon for BPD and BD to occur simultaneously. Current research shows that 10% to 20% of people with BD also have BPD.


The most effective treatment for these conditions is a personalized treatment plan that suits the symptoms, personal needs, and lifestyle.


Psychotherapy is the first-line treatment for people with BPD.

There are several types of empirically supported psychotherapies used in BPD, including:

  • Dialectical behavioral therapy (DBT), which supports emotional management
  • Mentalization-based therapy (MBT), which promotes better understanding of what happens in your mind

The benefits of medications for BPD are less clear. In some cases, a psychiatrist may recommend medications to treat specific symptoms, such as mood swings, depression, and other co-occurring mental disorders.

Lifestyle adjustments that promote a balanced mood, and practicing self-care habits, like getting regular sleep and exercise, and participating in psychoeducation can help keep the condition under control.  

Bipolar Disorder 

Having BD increases a person’s risk of mortality and shortens their life expectancy. Doctors can treat BD with medications and psychotherapy. Typically, psychiatrists prescribe mood stabilizers and second-generation antipsychotics for the treatment of BD They may also prescribe antidepressant medication to treat depressive episodes in BD.

Psychotherapies that can be used for the treatment of BD include cognitive-behavioral therapy and psychoeducation. Other therapies designed specifically for the treatment of BD include interpersonal and social rhythm therapy and family-focused therapy.

Sometimes BD is treated with electroconvulsive therapy, a brain stimulation procedure used to treat severe or refractory manic and depressive episodes, or transcranial magnetic stimulation, which stimulates the brain with magnetic waves to help treat subtypes of depression.

Since both BPD and BD can be lifelong conditions, ongoing treatment is essential.

A Word From Verywell

BD and BPD are not the same. Having BD or BPD can have a significant impact on your life. However, proper maintenance of symptoms can reduce the risk of potential consequences, including substance abuse, suicidal thoughts, and self-harm. If you or a loved one may be struggling with a mental health challenge like BD or BPD, talk to your doctor about options for evaluation and treatment.

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