Bipolar disorder and borderline personality disorder are two different mental health conditions from different groups of mental health diagnoses, with different diagnostic criteria. However, despite the difference between bipolar and borderline personality disorder, there is a lot of overlap between the two conditions, especially with regards to how they affect mood and behavior.
Some experts say BPD is on a bipolar spectrum. Most agree that the two should be considered entirely separate.
Understanding the similarities, differences, and overlap between the two can help patients with either better understand their potential comorbidity, as well as how treatments and medication work to affect the symptoms of both conditions.
What is Bipolar Disorder?
Bipolar disorder is a mood disorder characterized by distinctive and major shifts in mood, occurring in the form of episodes. These episodes can last days to weeks, and typically occur no more than four times per year. Some bipolar disorder patients experience more frequent mood shifts. This is called rapid cycling bipolar disorder.
A bipolar episode is typically either depressive, manic, hypomanic, or mixed.
Depressive episodes are characterized by low mood, lack of motivation, fatigue, oversleeping, and loss of interest in hobbies and most activities.
Manic episodes are characterized by disordered levels of irritability and high mood, restlessness, delusions of grandeur, outbursts of energy, and feeling fine with very little sleep.
Hypomanic episodes share most of the symptoms of a manic episode, but without losing functioning. A manic episode can be destructive and typically alienates other people. Hypomanic behavior is still unusual for the person but does not actively disrupt their day-to-day.
Mixed episodes are rare, but involve a combination of manic and depressed symptoms, with day-to-day or hour-to-hour shifts in mood.
What is Mania and Hypomania?
Whereas depression is low mood, physical and mental fatigue, brain fog, loss of motivation, anhedonia, and even suicidal ideation, mania is the mirror opposite – an excessive level of energy, irritability and anger, feelings of grandeur, heightened risk-taking behavior and forwardness.
The general difference between mania and hypomania is severity. Hypo, as in under, describes a form of mild mania that may be unusual for the person, but cannot be characterized as disordered or debilitating. Manic symptoms, on the other hand, can be very debilitating for someone. They can lead to dangerous consequences, including unintentional self-harm and property damage.
Types of Bipolar Disorder
Mania and hypomania are at the heart of a bipolar disorder diagnosis. Bipolar disorder can be split into three distinct types, depending on the severity and frequency of symptoms.
Bipolar I requires a diagnosis of at least one or more manic episodes, either lasting more than a week, or severe enough to cause hospitalization.
Bipolar II is characterized by hypomanic and depressive episodes. Patients cannot be diagnosed with bipolar II if they have ever experienced a fully manic episode.
Cyclothymic disorder is a form of mild bipolar disorder, with both mild depressive and mild manic symptoms.
Any bipolar condition that doesn’t fall into the above three categories is defined as not otherwise specified. These include cases where a patient may be rapid cycling between episodes or has symptoms that don’t fit into the other categories.
What is Borderline Personality Disorder?
Borderline personality disorder is one of four cluster B personality disorders, and one of ten recognized personality disorders. Cluster B is known as the erratic cluster, due to a common thread of impulsive actions, risk-taking, dramatic behavior, and rapid shifts in mood.
Among these personality disorders, borderline personality disorder is defined by intense, sudden shifts in mood, polarizing attitudes (all or nothing), and a rapidly shifting, unstable sense of self.
Borderline personality disorder is one of the most researched personality disorders, and even had a well-known form of talk therapy created to treat it (dialectical behavior therapy).
At the core of a borderline personality disorder is a fundamentally shaky self-image. People struggling with borderline personality disorder struggle with impulse control and mood shifts, and can experience symptoms of severe anger, physical outbursts, deep depression, and anxiety, lasting days at a time. Because of these massive shifts – which can even apply to their opinions of people – they have a hard time maintaining relationships with others, including family.
Bipolar Disorder and BPD Similarities
The most significant overlap between bipolar disorder and borderline personality disorder is mood shifts. Both conditions are marked by impulsive actions, irritability, and both depressed and high days. Both conditions struggle with emotional dysregulation. Both conditions are characterized by high-risk behavior. But that is generally where the overlap ends.
The Difference Between Bipolar and Borderline Personality Disorder
Where bipolar episodes appear with some sort of structure or consistency, borderline personality disorder shifts can occur much more rapidly. Bipolar disorder episodes are consistently defined as either manic, depressive, or mixed.
The shifts and episodes of borderline personality disorder patients are much more varied, and based on outbursts of a specific feeling, such as sudden overwhelming anger, sudden overwhelming loneliness, or sudden overwhelming emptiness.
Mood and personality changes in BPD are short-lived and frequent, while most cases of bipolar disorder have episodes that last days or weeks.
Hypomania and mania are core parts of the definition of a bipolar disorder, characterized by elation and feeling high. BPD outbursts rarely feel positive or self-aggrandizing.
Bipolar Disorder and BPD Co-Occurrence
While the two conditions exist separately and have their own established definitions, diagnostic guidelines, and potential causes, there is an overlap in diagnostic frequency between bipolar disorder and borderline personality disorder – about 20 percent of people diagnosed with either will also struggle with the other.
This frequency is part of the reason why there is a debate on the topic to begin with. Serious researchers and expert voices in the field of psychiatry have advocated for the idea of the bipolar spectrum, with borderline personality disorder intersecting with bipolar disorder to such a degree that it would be on said spectrum.
While the most recent science makes a clear distinction between BPD and bipolar disorder cases, it’s important for us to understand the relationship between these two conditions, to be able to better identify and treat them.
What we do know is that the overlap between these two conditions is clinically significant. Patients with a comorbidity between BPD and bipolar disorder are at an elevated risk for suicide and suffer from greater levels of social impairment. They usually also require greater levels of care.
Treating Bipolar and Borderline Personality Disorder
Both conditions are treatable. But when co-occurring, these conditions lead to significantly longer inpatient stays, higher prevalence of drug abuse, and higher inpatient charges. More attention and care must be directed towards patients with both BPD and bipolar disorder, and more research is needed to develop effective clinical strategies to help optimize outcomes for these patients.