Borderline personality disorder and bipolar spectrum disorders: How are they different?

by Michael D. Anestis, M.S.

Borderline personality disorder (BPD) and bipolar spectrum disorders (e.g., bipolar I, bipolar II, cyclothymia) have both been fairly common topics on PBB.  Both disorders are characterized by fluctuating emotions and problematic behaviors and both exhibit highly elevated suicide rates.  That being said, ever since BPD was added to the DSM, there have been a number of individuals who have questioned whether it simply represents another form of bipolar disorder.  Although many researchers have demonstrated that there are profound differences in important variables such as family histories, treatment responses, and longitudinal course between BPD and bipolar spectrum disorders and subsequently concluded that they are distinct from one another (e.g., Paris, 2004), others have pointed to individual similarities, such as the fact that both show relatively positive responses to mood stabilizing medications as justification for assuming that they are the same underlying phenomenon (e.g., Smith, Muir, & Blackwood, 2004).  Today, I would like to give a clear definition of each of these disorders and provide a solid - although by no means comprehensive - summary of the evidence for these positions.

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The following descriptions detail the diagnostic criteria for each of the disorders in question:

Borderline Personality Disorder

In order to meet diagnostic criteria for BPD, a client must exhibit five of the following nine symptoms and this pattern must represent a pervasive pattern in that individual's life (APA, 2000).  Note that, while personality disorders can fluctuate with respect to how severe they are from time to time, they are theorized to be much more stable and consistent than are symptoms of Axis I disorder (e.g., depression).

1. Frantic efforts to avoid real or imagined abandonment
2. Unstable interpersonal relationships characterized by fluctuations between adoring and devaluing significant others
3. Identity disturbance (e.g., who the person is depends upon who they are around)
4. Impulsivity in at least two areas (e.g., binge eating, spending money, risky sexual behavior, aggression, substance use) *do not include self-injury in this symptom*
5. Recurrent suicidal behavior or non-suicidal self-injury (NSSI)
6. Affective instability or extreme emotional reactivity - usually lasting only a few hours for any given mood and rarely more than a day
7. Chronic feelings of emptiness
8. Inappropriate, intense anger and/or difficulty controlling anger
9. Temporary stress-induced paranoia or dissociation

Bipolar I

1. Presence or history of a full manic episode

Note that a depressive episode is not required for this diagnosis.  Once an individual has had a full manic episode, they meet criteria for bipolar I.  Depressive episodes are common, but not required for the diagnosis.

Bipolar II

1. Presence or history of at least one major depressive episode
2. Presence or history of at least one hypomanic episode

Note that there are other requirements regarding the timing of the onset of various phases that are not included in this description but are available through the DSM-IV-TR, which can be found at Psychiatry Online.  Also note that, while it is possible to go from having a bipolar II diagnosis to a bipolar I diagnosis, the opposite pattern is not possible.

Cyclothymia

1. Prominent and persistent disturbance in mood characterized by either a depressed mood or an elevated, expansive, irritable mood.  In other words, fluctuations between sub-threshold depression and hypomania.

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So, looking over all of these criteria, BPD and bipolar spectrum disorders clearly share an element of mood difficulties and behavioral problems.  This, quite obviously, makes for a bit of a confusing picture.  That being said, the confusion is easily clarified through a better understanding of the words "mania" and "hypomania." 

A full manic episode, as defined by the DSM, involves a "distinct period of abnormally and persistently elevated, expansive, or irritable mood lasting at least 1 week." 

A hypomanic episode is defined as "a distinct period of persistently elevated, expansive, or irritable mood, lasting throughout at least four days, that is clearly different from the usual non-depressed mood."

In other words, whereas BPD is characterized by moods that shift from moment to moment, with a particular mood rarely lasting more than a few hours, bipolar spectrum disorders are characterized by mood phases, each of which tends to last at least a week (or four days in the case of hypomania).  So, while an individual with BPD might experience emotions that are unpredictable from one moment to the next, an individual with a bipolar spectrum disorder is unlikely to repeatedly jump from elated to depressed in such a short period of time.  Both situations involve an emotional roller coaster, but for BPD, the ups and downs are more frequent.

Another important distinction to make is the difference between happiness and mania or hypomania. Individuals who are manic often report a decreased need for sleep.  They believe they are capable of accomplishing incredible things without any training (e.g., suddenly writing the Great American Novel or uncovering previously unknown principles of physics) and take on projects at odd hours that, once the episode ends, seem bizarre even to the person him or herself (e.g., painting the outside of a house in the middle of the night).  While the individual is manic, he or she typically enjoys the experience; however, once the episode ends and the consequences are more apparent, the entire experience seems much more aversive.  For individuals with BPD, there is no real parallel.  They certainly engage in problematic, impulsive behaviors, but these are most often utilized in response to negative emotions and represent an effort to regulate emotions (see our previous articles on non-suicidal self-injury for an example).

Although I hope these descriptions have been helpful, I do not believe that on their own they represent sufficient evidence to support the idea that BPD and bipolar spectrum disorders are distinct from one another.  Empirical evidence is much more compelling.  That being said, what does the research tell us?

In 2006, Franco Benazzi examined the similarities between BPD symptoms and Bipolar II symptoms in an outpatient psychiatric private practice.  Diagnoses were assessed through structured clinical interviews, thereby ensuring maximum validity and reliability in diagnostics.  Benazzi (2006) found that, while the emotional symptoms of BPD mirrored those of bipolar II, the impulsive behaviors in BPD showed no relationship to bipolar II.  

Also in 2006, John Gunderson and colleagues found that, while a greater number of individuals with BPD also had a bipolar spectrum disorder (19.4%) than did individuals with other personality disorders and a higher percentage of individuals with BPD experienced now onsets of bipolar spectrum disorders (8.2%) relative to individuals with other personality disorders over the subsequent four year, the actual association between BPD and bipolar spectrum disorders was modest at best.  In other words, many mental illnesses frequently co-occur, but this does not make them the same thing or even necessarily variants of one another. 

In 2007, Paris, Gunderson, and Weinberg reviewed the literature to determine whether or not BPD should be subsumed under the bipolar disorder category.  Like other studies already mentioned, they found that, while there is some overlap in important characteristics, the relationship between the two is neither consistent nor specific.  Individuals, to some degree, respond differently to different treatments, and the differences in the nature of their mood and behavior problems are substantial.

So, not only can distinctions be made by simply looking at the diagnostic criteria outline in the DSM, but empirical research has come to support the idea that these two phenomena are, in fact, distinct from one another.

Some of you might be wondering whether this distinction is really all that important.  In other words, does it matter that BPD and bipolar spectrum disorders are distinct from one another.  To some degree, I can see the argument that this is just an academic issue - the kind of thing that nerds like myself care about deeply but which matter little to people who do not spend much of their lives treating clients and reading psychology journals.  That being said, let me take a quick moment to explain why I think this is important.  As I have said in other articles on the topic of diagnoses, a proper understanding of mental illness is vital.  Different diagnoses respond differently to different treatments.  Although BPD shows relatively strong responses to mood stabilizing medications and there is preliminary evidence that dialectical behavior therapy (DBT) can be helpful in the treatment of bipolar disorder (Goldstein, Axelson, Birmaher, & Brent, 2007), these disorders do, in fact, respond differently to different treatments.  As a result, assuming that they are the same can cloud treatment decisions.  Additionally, if we made mistakes about the basic nature of a disorder, we are less likely to get the details correct.  In other words, if we can not even fully grasp the fundamental nature of a diagnosis, we are highly unlikely to develop a precise understanding of the more complex components and, as a result, we are unlikely to develop better treatments in the future.  Accuracy is important.  Just as a repeated small error on your paycheck can add up over an extended period of time to cost you a lot of money, errors on abstract concepts like this can keep both researchers and clinicians from maximizing their potential and can set our understanding of mental illness back extensively.

If you would like to learn more about borderline personality disorder and bipolar spectrum disorders, we recommend the following resources, all of which are available through our online store:

• Skills Training Manual for Treating Borderline Personality Disorder by Marsha Linehan

• Cognitive-Behavioral Treatment of Borderline Personality Disorder by Marsha Linehan

• Dialectical Behavior Therapy in Clinical Practice: Applications across Disorders and Settings by Linda Dimeff and Kelly Koerner

• Cognitive-Behavioral Therapy for Bipolar Disorder, Second Edition by Monica Ramirez Basco and John Rush

• Treating Bipolar Disorder: A Clinician's Guide to Interpersonal and Social Rhythm Therapy by Ellen Frank

Mike Anestis is a doctoral candidate in the clinical psychology department at Florida State University