Bipolar disorder vs borderline personality disorder

Bipolar disorder and borderline personality disorder (BPD) are two separate conditions that frequently get confused with each other. Some people suffer from both together and for some people there is difficulty in deciding on a diagnosis. One thing that they unfortunately both share is stigma, which hopefully with education will be reduced.

Example of stigma on a comment on an article about BPD (people used to say the same about clinical depression 25 years ago):

​Bipolar disorder is categorised as an 'affective' (mood) disorder whereas borderline personality disorder is categorised as a 'personality' disorder in the Diagnostic and Statistical Manual of Mental Disorders fifth edition (DSM-V). Borderline personality disorder does affect moods but is not episodic like bipolar disorder. Sometimes borderline personality disorder is called emotional dysregulation disorder.

​Bipolar disorder has episodes of elevated, expansive, energetic moods lasting several days or months. These mood episodes can be called mania or hypomania depending on intensity (hypomania is not full mania). (Hypo)manic moods can be euphoric, irritable or angry (depending on a person's personality) during episodes. Most people with bipolar disorder will also have episodes of depressed mood with low energy and numb or sad emotions.  There will also be episodes of 'normal' mood. Mood episodes are like storms that come and go.

Whereas borderline personality disorder has a huge range of intense emotions in one day (or even in an hour) not occurring in episodes of overall elevated or low mood lasting for several days or even months. Some people have rapid cycling bipolar and if they also do not experience full mania, this can be harder to distinguish with borderline personality disorder, but there are other diagnostic criteria. Mood episodes in bipolar disorder are not necessarily 'triggered' by anything, but with BPD, intense emotions are usually 'triggered' by relationship conflict, including from 'reading' into things. People with BPD are emotionally hypersensitive and hyper-reactive.

Emotions can be very intense during bipolar (hypo)mania episodes and there can be more interpersonal conflict during mood episodes which can be like storms. But at other times, people with bipolar disorder will usually be able to manage their interpersonal relationships and emotions in healthy ways. Whereas people with BPD will struggle to manage their intense emotions and conflict in interpersonal relationships (whether in intimate relationships, friendships, workplace) every day, because their core personality is affected. 

Impulsivity can be a part of both conditions, but it is episodic with bipolar - in hypomania or mania episodes. When one is impulsive, they may do risky things without thinking through the consequences, such as spending large amounts of money, driving fast or having sex with strangers.

Pressure of speech is a diagnositic criterion for bipolar (hypo)mania but not for borderline. This is when someone speaks very fast and urgently and no-one else can get a word in. An increase in self-esteem and confidence is common during a bipolar (hypo)mania episode to the extent of grandiosity (where someone believes they have special powers for example). This is not a BPD diagnostic criteron. Changes in sleep patterns (more or less sleep) and appetite are typical with bipolar disorder but is not part of BPD.

Self-harm is listed as a diagnostic criterion for BPD in the DSM-V but not bipolar. Self-harm may include non-suicidal injury to oneself including cutting, burning, binge-eating, eating disorders, abusing alcohol, hitting oneself, putting out hair, scratching oneself until bleeding. Self-harm is used as a coping mechanism.  Suicidal ideation (thoughts of suicide) is common with BPD and also during bipolar depressive episodes.  Both disorders have higher rates of suicide than major depressive disorder.  

BPD typically has an extreme fear of real or perceived abandonment. This could be getting very distressed if someone doesn't return a text for example. People with BPD can be very quick to anger (or even rage) out of proportion to the situation. People with bipolar are more likely to have difficulty managing their anger during manic or mixed episodes. Mixed episodes have some features of mania and depression at the same time. 

People with BPD may dissociate frequently (feeling like they are not real or outside their body). This is not a criterion for bipolar but dissociation can be another symptom of other disorders including post-traumatic stress disorder (PTSD). BPD has been associated with childhood abuse, but this is not always the case. It seems to be an interaction with genetics and environmental factors. Bipolar disorder seems to be genetic.

During severe manic or depressive episodes, people with bipolar disorder or major depression are at risk for psychosis (hallucinations and/or delusions and disconnecting from reality). Under stress, people with BPD may develop mild psychotic-like symptoms.

People with BPD have very intense interpersonal relationships with high conflict - an emotional rollercoaster. People with bipolar are able to manage healthy relationships between mood episodes or when stabilised on medications.  People with BPD tend to 'split' people - idealise them and then devalue them - often in the same day. They see people as all good then if offended, they see them as all bad. Whereas most people with bipolar can see people have a mixture of qualities.

People with BPD typically have an unstable sense of self, identity, emotions and behaviours. They will have a strong urge to act on impulse, even if it hurts others and themselves. Then they feel shame and then fear that they will be abandoned. They lack the skills to self-soothe with intense emotional states.  They can feel chronic emptiness inside.

The main reason for a correct diagnosis is to decide on appropriate treatment. Bipolar disorder is treated with mood stabilisers and sometimes antipsychotics. Antidepressants may be used with caution with mood stabilisers (antidepressants may trigger mania episodes). Whereas borderline personality disorder is treated with psychotherapy. Dialectical behavioural therapy (DBT) has been shown to be the most effective treatment for DBT. 

Both conditions are chronic and not 'cured' but they can both be managed with appropriate treatment and support. A psychiatrist and a psychologist can diagnose both conditions but a psychiatrist will prescribe medication where appropriate. Whereas a psychologist can provide therapy. 

In summary, borderline personality disorder is a instability of emotions, self, identity along with a fear of abandonment and lack of healthy coping mechanisms (self-harm is used as a coping mechanism to try to ease internal distress). Whereas bipolar disorder is extreme shifts in energy and episodic elevated and low moods.  Most experts see the two conditions as separate, but some people argue that BPD should be part of the bipolar 'spectrum' with BPD as an extremely rapidly cycling bipolar. I can see the case for both viewpoints. 

I have been diagnosed with bipolar 1 disorder, PTSD and anxiety and a psychiatrist and psychologist have ruled out BPD for me. I have hypersensitive, intense emotions during mood episodes, have racing thoughts and either talk excessively (mania) or hardly at all. My sleep and appetite are affected.  During 'stable' times, I am still sensitive, but not hypersensitive and reactive. I am able to 'bite my tongue' if someone offends me. Less so if I'm in a mood episode. I can feel 'brave' enough to be combative with someone (I have a fear of conflict which is trauma related).

I was devastated by a relationship breakup, but I did not fear every moment that I was going to be abandoned if I did not get a text immediately. I do not self-harm (unless over-indulging in chocolate and ice-cream during 'crashes' is counted as mild self-harm. Or if risk-taking during mania could be considered to be a form of self-harm). I have relatively 'healthy' self-coping mechanisms and a strong sense of self and identity. I do dissociate sometimes (which has been attributed to my PTSD diagnosis). I do think my bipolar can look similar to BPD during 'crashes' from mania into depression or during mixed episodes - under extreme stress I can have 'meltdowns' with a lot of crying and irritability. Medication has been helping stabilise my moods, although I do still get breakthrough hypomania and mild depressive episodes.

I am having trauma therapy and learning to express strong emotions rather than shutting them down. Anger is an emotion I very rarely feel, even during mania (anger is a trauma trigger for me). I have felt 'alive' though to express it. Even with my extreme mood episodes which have been like electric storms, I am still 'me' - just an 'augmented' me with mania with impaired judgement, impulsivity and no filter doing things I would not normally do. And a 'diminished' me in depression with depleted energy. My underlying personality is still there, even though I seem and behave differently during episodes.  My cognition is severely impaired during severe episodes - my thinking becomes disorganised and I have made decisions with poor judgement. My PTSD flares up bad during episodes. So bad that I changed my name as my former name became a trigger.

Please note that I am not an expert in this area and this summary of information from my independent research and personal experiences is no substitute for independent professional advice. I have been diagnosed with bipolar disorder and have been learning about my condition and I often see it confused with BPD. There is a myth that BPD is only diagnosed in women.

Some recommended video links by experts are below:

A psychiatrist explains the difference between BPD and bipolar disorder:

A psychologist explains the characteristics of BPD (with some comparison with bipolar):