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Bipolar? Borderline Personality Disorder? NOT the same thing.

Bipolar vs. BPD infographic

One of the most common mistakes people make about mental illnesses is assuming that bipolar disorder and borderline personality disorder (BPD) are the same. There is so much nuance and definitional ambiguity in mental health sometimes that confusion can be totally understandable, but by the end of this article, hopefully the difference between bipolar disorder and BPD will be clear!

Their Symptoms

The National Institute of Mental Health defines bipolar disorder as a lifelong “brain disorder that causes unusual shifts in mood, energy, activity levels, and the ability to carry out day-to-day tasks.” Bipolar disorder is also known as manic-depressive illness, and consists of episodes of mania (or hypomania) and depression. Manic and hypomanic episodes typically see emotional highs (such as feeling like one is at the top of the world, being unusually productive and energetic, and engaging in risky behavior like sudden excessive spending or reckless sex), while depressive episodes can cause one to lose all energy and productivity, feel incapable and empty, eat/sleep too much or too little, and/or even engage in suicidal thinking/action.

These episodes and symptoms manifest in different ways for different people, but generally can be described as one of four types of bipolar disorder (yes, bipolar disorder is just a broader term, and people are diagnosed with more specific illnesses!):

Bipolar I Disorder

This is usually what people think of when they hear “bipolar disorder.” Those with Bipolar I experience manic episodes lasting at least a week (or, if shorter, extremely severe manic episodes) and depressive episodes lasting at least two weeks. It is also possible for high and low symptoms to exist within one “episode"--for the symptoms to "mix."

Bipolar II Disorder

Similar to Bipolar I Disorder, except people with Bipolar II experience hypomanic episodes, a less severe version of manic episodes, instead of manic episodes.

Cyclothymic Disorder (cyclothymia)

Characterized by a continuous pattern of hypomanic and depressive symptoms for at least two years (one year for children and adolescents) without meeting the diagnostic requirements to have such symptoms named hypomanic and depressive episodes.


There may be other specific cases where symptoms of bipolar disorder emerge, but which do not meet the definitions of the three cases above. These require special diagnoses.

Borderline personality disorder (BPD), on the other hand, is defined by the National Institute of Mental Health as “a serious mental disorder marked by a pattern of ongoing instability in moods, behavior, self-image, and functioning.” Like bipolar disorder, people with BPD also experience severe mood swings that may lead to reckless behavior and even suicide. However, unlike bipolar disorder, wherein there are defined manic/hypomanic and depressive episodes, BPD consists of drastic swings in not only mood and behavior but also in all aspects of the individual's life, often times undergoing such chaotic spectrums in the span of just a few hours to days. BPD can severely cripple relationships the person has with others around them, and can lead to unstable, intense emotions that induce a high risk of self-harm and suicide.

Most mental health professionals agree that BPD is a misnomer, and BPD can in fact be often misdiagnosed or underdiagnosed because many of its symptoms overlap with other mental illnesses.

Their Causes

Mental illnesses are almost never caused by one single factor alone, but certain situations can increase the risk of mental illness.

Both bipolar disorder and BPD are more likely to manifest in those whose family member(s) have such disorders, and in fact, BPD is five times more likely to occur in someone whose first-degree biological relative(s) have BPD.

The two's differences begin to emerge more clearly when looking at other potential causes. For example: scientists aren’t yet sure of the exact links between bipolar disorder and abnormal brain structures, whereas there is clearer evidence supporting the idea that BPD leads to “structural and functional changes in the brain, especially in the areas that control impulses and emotional regulation.” Nonetheless, a change in brain structure and/or functioning cannot be used as clear-cut proof for someone having bipolar disorder or BPD since much research remains to be done.

In addition, people with BPD seem to have a higher chance of having experienced some sort of trauma in their life, especially during childhood. Abuse, abandonment, wildly unstable relationships, and hostile conflicts can all increase one’s risk of BPD. However, trauma is not a requirement for BPD, and not all people with BPD have experienced prior trauma.

Their Treatments

While both bipolar disorder and BPD can be treated with psychotherapy (commonly known as talk therapy), it is important to note that the two have very different treatment plans. For one, psychotherapy or any sort of treatment plan cannot guarantee 100% effectiveness in combating the disorder, so those with bipolar disorder typically add medication to their treatment plan for better results. Such medication may include antidepressants, mood stabilizers, and/or atypical antipsychotics. Because bipolar disorder can sometimes be misdiagnosed as depression, which may require different types of medication for treatment, it is important that one seeks help from a licensed health professional to ensure that they have a better chance of receiving effective and appropriate medication. Especially as medication may have adverse side effects, figuring out a plan that works takes time and professionalism.

BPD, on the other hand, is notoriously difficult to treat and usually does not come with medication. This is in part because the risk of self-harm is so high among those with BPD that health professionals must be extra careful about prescribing drugs that could be lethal in case of overdose. Therefore, the primary way to treat BPD is with psychotherapy. In fact, a specific form of psychotherapy known as Dialectical Behavior Therapy (DBT) was created to better treat BPD, though it is now being used to treat other mental illnesses and disabilities as well. DBT fosters the idea that both acceptance and change must be combined for treatment to be effective. It utilizes awareness and mindfulness to encourage oneself to be more attuned to their current mood and situation, emphasizing control of emotions, reduction of self-harm, and better interpersonal relationships. Essentially, it integrates the more traditional psychotherapy methods of illuminating false perceptions one may hold for themselves and/or their surroundings with the concept that it is important for oneself to accept their emotional distresses while also learning how to regulate and tolerate them. Family therapy sessions are also often recommended for those with BPD as BPD can create severe stress on those in close relations with the individual. Furthermore, those with BPD sometimes experience symptoms severe enough to require intensive inpatient care, which is seemingly but not necessarily less often the case for those who are bipolar.


Bipolar disorder and BPD can be wildly confusing. Both deal with dangerous swings between highs and lows. However, though the two share some symptoms, they are very different disorders with their own treatment methods.

If you or a loved one may be suffering from bipolar disorder or BPD, please visit our “Resources” page to determine the best way you can seek support. We also highly recommend visiting your doctor and informing them of your concerns so that you can be referred to a licensed health professional who will be able to provide you with more information.

Para saber más sobre el trastorno bipolar en español, por favor lea esto y esto.

Please note that this article is not meant to be used as a method of diagnosis and is strictly for educational purposes only. Letters to Strangers is not a replacement for therapy or consultation with a licensed mental health professional.

All information, quotes, and links come from the National Institute of Mental Health’s webpage on Bipolar Disorder and Borderline Personality Disorder, except for the section on DBT, which also includes information from WebMD.


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