Borderline Personality Disorder vs. Bipolar Disorder: Causes, Treatment, and the Role of Nurse Practitioners

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A nurse consults with a mental health patient.

Long-term efforts to address mental health issues and combat their stigmatization have brought about important changes. Today, 87% of Americans believe mental health issues are no cause for shame, according to the American Psychological Association. Despite this increased openness, misconceptions and confusion about mental health disorders still persist.

Because some symptoms of the two mental conditions are similar, and because symptoms are often misunderstood, correctly assessing a patient can be difficult. Diagnosing and addressing the needs of individuals with these mental health conditions requires the right expertise. An advanced degree, such as an online Master of Science in Nursing, can train nurse practitioners to recognize the differences between borderline personality disorder vs. bipolar disorder, helping to ensure patients receive the help they need.

Borderline Personality Disorder vs. Bipolar Disorder: What’s the Difference?

Approximately 2.8% of American adults will experience bipolar disorder and 1.4% will experience borderline personality disorder in a given year, according to the National Institutes of Health. Health professionals, such as nurse practitioners, can better serve patients when they have a clear understanding of these mental health conditions.

Borderline personality disorder, an often misunderstood condition, is characterized by struggles to regulate emotions. Individuals with this condition experience extremely intense emotions that they struggle to control, making it difficult to maintain stable emotional states. Small stressors can trigger intense emotions that can often lead to impulsive behavior, self-harm, and chaotic relationships.
Those with borderline disorder often experience intense fears of abandonment, extreme views of people as either wholly good or bad, poor self-image, self-harming behaviors, and difficulty managing unpleasant feelings.

Bipolar disorder can also act as a disruptive force in people’s lives. As the name suggests, the disorder involves severe swings between two emotional states: depression and mania.
Sadness, hopelessness, and a loss of interest in most of life’s activities characterize depressive states. Euphoria, irritability, and high energy levels characterize manic states. Extreme and unexpected mood shifts can lead to impulsive behavior, altered judgment, and difficulty thinking clearly.

Bipolar disorder involves altered emotional states that can last days or even months. Unlike borderline personality disorder, interpersonal conflicts do not cause mood swings in people with bipolar disorder.

Both borderline personality disorder and bipolar disorder affect people’s moods, which has led to confusion between the two. However, each mental health condition is distinctive and requires unique treatment approaches.

What Causes Borderline Personality Disorder?

Mental health experts do not attribute borderline personality disorder to any single cause. However, to understand what causes borderline personality disorder, it’s useful to consider several factors.


Studies indicate that heredity can put individuals at a genetic predisposition to develop borderline personality disorder.

Environmental Factors

Studies show that childhood trauma can contribute to development of the disorder. For example, 70% of those with borderline personality disorder have experienced physical and sexual abuse, abandonment, neglect, or parental substance abuse, along with other types of mistreatment.

Brain Abnormalities

Brain imaging of patients with borderline personality disorder have shown irregularities in the amygdala, hippocampus, and medial temporal lobes. Researchers believe these differences in the brain make it more likely for a person to inaccurately interpret neutral facial expressions as either angry or disgusted.


Other brain studies indicate that people with borderline personality disorder have impaired serotonin function. Serotonin is a chemical that helps regulate mood and anxiety.

Traumatic Experiences

As noted, traumatic experiences in childhood can factor into the development of borderline personality disorder. According to a meta-analysis of numerous studies that examined people with the disorder, this holds true especially when the trauma involves emotional abuse and neglect.
Mental health experts explain that during childhood, the brain is in a process of development and learning to manage negative emotions. Under chronic and overwhelming stress, healthy responses to stress may not develop appropriately, resulting in greater sensitivity to stress, a common symptom of borderline personality disorder.

How Borderline Personality Disorder Interferes with People’s Lives

Borderline personality disorder can interfere with a person’s ability to live a healthy and fulfilling life. Since those with the disorder often struggle to manage negative emotions, they may turn to dangerous or risky behaviors that are often related to sex and drugs.

The disorder also makes stable relationships challenging, because afflicted individuals tend to overreact to small stressors that can cause ongoing turmoil and conflict in their personal lives. This difficulty sustaining stable relationships can also carry over into the workplace, making career success difficult as well.

Borderline personality disorder can negatively affect an individual’s self-image, resulting in depression, eating disorders, and substance abuse. Additionally, because of the dramatic ups and downs they experience, individuals with the disorder may struggle to complete their education or achieve other goals that require sustained focus and stability.

Borderline Personality Disorder Treatment Strategies

A variety of therapeutic approaches have been shown to help those with borderline personality disorder. Proper treatment strategies can help individuals overcome their symptoms, develop healthier responses to stress, and learn to build more stable relationships.

Splitting and Dialectical Behavioral Therapy

One common symptom of the disorder is “splitting.” Splitting involves viewing people or things as completely good or bad without being able to see gray areas, or that good and bad can coexist. For example, one moment a person might view their therapist as the best in the world. Then that therapist does something to trigger the patient, and suddenly the therapist is the worst the patient has ever known.

What can cause splitting? As children, people may experience abuse from someone who at times acts with love and concern and at other times behaves in dangerous and abusive ways. Learning to integrate those opposite versions of the same person into one can pose great challenges to children who live with abuse.

As a result, these children may view things in terms of ‘either-or’ and think of the abuser as two different people. As these children mature, they may generalize this perception that good and bad exist in completely separate realms, and apply it to all aspects of their life.

Although this defense mechanism may have served a useful purpose at one time, in adulthood it can act as a disruptive force, exhausting those who use it as well as others around them.

Dialectical behavioral therapy (DBT) can help address splitting and the unregulated emotional shifts those with borderline personality disorder tend to experience. DBT involves a two-pronged approach: individual therapy paired with group-based skills training led by two trained practitioners.

Skills training focuses on the following.

  • Mindfulness: Observing one’s environment without judgment and existing in the moment
  • Regulation of emotions: Effectively moderating feelings and moods
  • Tolerating distress: Understanding and finding ways to manage difficulties without acting out destructively
  • Building healthy interpersonal skills: Limiting conflicts and using empathy to better understand the perspectives of others

Group leaders introduce these skills, patients practice them, and then they discuss them individually with a therapist. Therapists can help patients integrate their extreme versions of the world into more balanced perceptions in which people, events, and experiences can have both negative and positive aspects. This empowers patients to respond to the world in a more stable way, as well as build healthier relationships.

Cognitive Behavioral Therapy

Cognitive behavioral therapy (CBT) can also serve as an effective borderline personality disorder treatment. CBT focuses on changing thought patterns and interpretations of situations to alter behaviors and minimize symptoms.

CBT focuses on present events. Patients consider how their current thinking and behavior patterns affect their symptoms. Then, the therapist introduces tools to help patients shift harmful ways of thinking and behaving. Therapists also give patients assignments to work on between sessions that will help them practice new ways of thinking and behaving.

Medication as a Treatment Strategy

No single medication exists to cure borderline personality. However, several medications such as mood stabilizers and antidepressants can play an effective role in borderline personality disorder treatment. Both can address mood swings and the feeling of profound unease that is often associated with the disorder. Additionally, to help deal with the disorganized thinking linked to the disorder, practitioners may prescribe low doses of antipsychotic medications.

Diagnosing Borderline Personality Disorder

To diagnose borderline personality disorder, mental health professionals conduct comprehensive clinical interviews with their patients. They may also consult with other clinicians and review prior medical evaluations.

Clinical interviews likely use structured diagnostic screening tools, such as the Zanarini Rating Scale for Borderline Personality Disorder. This rating scale examines the pervasiveness of the following:

  • Unstable relationships
  • Impulsive behaviors
  • Feelings of emptiness

The rating scale also measures the following symptoms:

  • Anger levels
  • Temper control
  • Fear levels of abandonment
  • Self-image

Additionally, the tool looks for relationship histories characterized by splitting. It’s important to note that splitting — along with the rapid shift in moods from sad, to angry, to euphoric within short time spans — are symptoms that distinguish borderline personality disorder from bipolar disorder.

Is Bipolar Disorder Genetic?

Though other factors can come into play, it’s fair to say that bipolar disorder is genetic to some degree. The exact patterns of inheritance, however, remain unknown. Scientists believe several genes may cause the disorder and are actively researching the genetics behind bipolar disorder to improve treatment.

Statistical Data about the Heredity of Bipolar Disorder

Although uncertainty still clouds a complete understanding of the role of genetics, research clearly shows that individuals with close relatives who have bipolar disorder are more at risk of developing the condition. Consider the following facts from WebMD.

  • Individuals who have a parent with bipolar disorder have a 10%-25% chance of developing the condition.
  • Individuals who have two parents with bipolar disorder have a 10%-50% chance of developing the condition.
  • Individuals who have an identical twin with bipolar disorder have a 40%-70% chance of developing the condition.

The fact that identical twins, who share the same genes, do not always both develop bipolar disorder shows the condition is not strictly hereditary.

Bipolar disorder manifests itself in equal numbers between men and women. However, women more often experience “rapid cycling” (four or more separate episodes of depression or mania within a single year). Women also tend to experience more depressive episodes and mixed states of depression and mania.

Environmental Factors That Aggravate Bipolar Disorder

Environmental factors can possibly trigger the development of bipolar disorder in people with a genetic predisposition to it. Diagnosis of bipolar disorder often follows traumatic or stressful events. Life-changing occurrences such as job loss or a death in the family can also be linked to the onset of the condition.

Environmental factors exacerbate bipolar conditions. Stress and lifestyle habits can act together to increase the likelihood of developing bipolar disorder and worsen its symptoms. Consider the impact of the following environmental factors on bipolar disorder.

  • Lack of sleep: Not getting enough rest can provoke manic episodes
  • Inappropriate medication treatments: Antidepressants when taken alone can trigger manic states
  • Excessive alcohol use or drug use: Using these substances often triggers bipolar symptoms
  • Traumatic head injury: Brain injuries such as concussions can trigger the onset of bipolar disorder
  • High stress levels: Rape, abuse, and other traumatic life events can induce bipolar symptoms

What Is the Pathophysiology of Bipolar Disorder?

To diagnose and treat bipolar disorder, psychiatric mental health nurse practitioners must build their understanding of the pathophysiology of bipolar disorder. These are the physical and biological abnormalities within the body that result in the condition.

Bipolar Disorder Theories

Several theories try to explain what causes bipolar disorder in addition to those already mentioned.

Brain Structure

The neurotransmitter system — the system in the brain responsible for the chemical messengers that carry and regulate the signals between cells — has a huge impact on how our brains function. Research has linked neurotransmitters such as serotonin, dopamine, and norepinephrine to behavioral and mood disorders. An imbalance between these chemicals is potentially the problem. Another theory posits that the sensitivity of nerve receptors in the brain may contribute to mood disorders.


The stress hormone cortisol can alter how the brain communicates and functions. High levels of cortisol can trigger the cycle of bipolar disorder. People with the condition may have higher levels of cortisol in their systems even in the absence of stress.

The Diathesis Stress Model

This theory considers that individuals are born with particular physical vulnerabilities to health issues. However, stress factors will ultimately determine if those health problems present themselves. This suggests that those with bipolar disorder have an inherent physical vulnerability to the condition, and that events in their lives trigger its onset.

Sleep and Bipolar Disorder

Another important factor worthy of consideration regarding the pathophysiology of bipolar disorder involves the sleep-wake cycle. According to a recent study in the journal Frontiers in Psychiatry, sleep abnormalities often serve as effective indicators that a mood swing is on its way. Additionally, the study reports that 23% to 78% of people with bipolar disorder extend their sleep hours into the day, past nighttime, with episodes of excessive sleepiness during the day.

This sleep issue, along with insomnia that is prevalent in those with bipolar disorder, can affect circadian rhythms in the body. Some postulate that disturbances to circadian rhythms can play a role in bipolar symptoms.

Explore the Role of Nurse Practitioners in Treating Mental Health

Those in advanced nursing roles can play an important role in addressing mental health issues. Often, advanced practice nurses help care for those with conditions such as borderline personality disorder and bipolar disorder.

Psychiatric mental health nurse practitioners, for instance, use their analytical skills and knowledge in advanced concepts, such as contemporary psychotherapies and advanced psychopharmacology, to build effective care delivery strategies.

Regis College offers an advanced Master of Science in Nursing degree with an option to specialize in psychiatric mental health. The program cultivates expertise in assessing and monitoring mental health conditions.

With this knowledge, psychiatric mental health nurse practitioners are better prepared to effectively distinguish the difference between borderline personality disorder vs. bipolar disorder. They are also trained to ensure the proper diagnosis of other mental health conditions so patients receive appropriate treatment. Coursework also deepens nurses’ skills to develop and administer effective mental health treatment plans, as well as help patients develop healthy coping mechanisms.

Explore how the Regis College online Master of Science in Nursing specializing in psychiatric mental health prepares nurses to deliver vital care that can change lives.

Recommended Readings
How to Become a Mental Health Nurse
Psychiatric Nurse Practitioner Salary, Career Outlook & More
What Is a Psychiatric Mental Health Nurse Practitioner?

Acta Psychiatrica Scandinavica, “Childhood Adversity and Borderline Personality Disorder: A Meta‐Analysis”
American Psychological Association, “Survey: Americans Becoming More Open About Mental Health”
EYMT, “How to Practice Interpersonal Effectiveness Every Day”
Frontiers in Psychiatry, “Sleep Disturbance in Bipolar Disorder: Neuroglia and Circadian Rhythms”
Mayo Clinic, Bipolar Disorder
Mayo Clinic, Borderline Personality Disorder
Medical News Today, “How Genes Influence Bipolar Disorder
Medical News Today, “What Is serotonin and What Does It Do?”, Prevalence of Bipolar Disorder
National Alliance on Mental Illness, Borderline Personality Disorder
NCBI, Borderline Personality Disorder
Priory, “Understanding Splitting in Borderline Personality Disorder”
U.S. National Library of Medicine, Bipolar Disorder
VeryWellMind, “Treating BPD With Cognitive Behavioral Therapy”
VeryWellMind, “Understanding the Causes of Bipolar Disorder”
WebMD, Bipolar Disorder: Who’s at Risk?
WebMD, Borderline Personality Disorder vs. Bipolar Disorder
WebMD, Causes of Bipolar Disorder