Professor Steven Marwaha, Professor of Psychiatry at the Institute for Mental Health at the University of Birmingham, answers your questions to help clear up the confusion between bipolar and BPD.
What is bipolar?
Bipolar is a severe mental illness (SMI) where someone experiences extreme changes in mood and energy that are much more intense than just feeling a bit sad or happy. Someone with bipolar usually needs to monitor and manage their moods daily otherwise they can experience symptoms of hypomania/mania or depression.
Symptoms of bipolar for most people are episodic. In other words, people living with the condition can go through periods when they’re unwell (known as an episode or relapse) and they can also go through periods when they’re stable for weeks, months or sometimes years.
Bipolar affects people from all backgrounds, making little distinction across the world between social class, sexuality, ethnicity and gender.
What is a personality disorder?
Borderline Personality Disorder, or BPD, is a common type of personality disorder.
According to the World Health Organisation (ICD-11) a personality disorder is an ‘enduring pattern of disturbance’ characterised by problems in functioning of:
- the self (eg. identity, self-worth, accuracy of self-view, self-direction)
and/or
- relationships (eg. ability to develop and maintain close and mutually satisfying relationships, ability to understand others’ perspectives and to manage conflict in relationships).
For someone to get a diagnosis of a personality disorder, the pattern of disturbance needs to:
- happen over a long time (years)
- show up in unhelpful patterns, such as being inflexible, feeling emotions very strongly, finding it hard to calm down or reacting in intense ways
- negatively affect a range of personal and social situations
- cause substantial distress or significant problems in relationships, studying, work and/or other important areas of functioning.
There are different types of personality disorders, each affecting how a person interacts with others and sees themselves.
Symptoms can range from mild to severe and may overlap with other conditions like depression or substance abuse.
What is BPD?
Borderline personality disorder (BPD), also known as emotionally unstable personality disorder (EUPD), is a category of personality disorder often characterised by mood swings and impulsivity.
The World Health Organisation has recently moved away from a diagnosis of specific types of personality disorder, focusing instead on how much impact the disorder has in a person’s life. However, doctors often still use a description of ‘borderline pattern’ to help guide treatment.
Experiences of BPD are different for different people, but the condition typically affects someone’s emotional functioning, behaviours, how they feel about themselves and how they interact with others.
Symptoms of BPD can include mood instability where someone experiences emotions that are very intense, overwhelming and changeable. This typically happens several times a day.
Someone with BPD can also experience outbursts of intense anger, impulsivity and often suicidal or self-harm behaviours. They may also experience disturbed thinking/perception, difficulties with their sense of identity, and intense but unstable relationships.
What is the difference between BPD and bipolar?
Bipolar is a mood disorder where someone experiences extreme changes in mood, energy and activity that are more intense than just feeling a bit sad or happy. Usually lots of symptoms happen at the same time and last many days or weeks.
BPD is a personality disorder that mostly affects how someone relates to other people and how they manage their emotions. It involves intense and unstable emotions, difficulties in maintaining relationships and a fear of abandonment.
The mood changes that people with BPD typically experience are intense and short-lived (several times a day), whereas the mood changes in bipolar typically last a number of days or often weeks in between periods of stability.
Do symptoms of bipolar and BPD overlap?
Yes, there are many overlaps between BPD and bipolar, including mood instability, impulsive behaviour, depression and impacts on day-to-day functioning.
The overlaps seem to be particularly widespread early on when the conditions are developing in young people.
Why is it important to tell the difference between BPD and bipolar?
It’s important to tell the difference between BPD and bipolar because they need different treatments.
In January 2025, The American Psychiatric Association issued ‘Practice Guidelines’ with updated recommendations for treating borderline personality disorder (BPD). The guidelines emphasise that BPD is best managed with psychotherapy, such as Dialectical Behaviour Therapy (DBT), which is a form of Cognitive Behaviour Therapy (CBT) adapted for people who feel emotions very intensely.
No medication has been approved specifically for the treatment of BPD, but some people may be prescribed antidepressants or other medication, such as low dose anti-psychotics to help with symptoms.
Bipolar treatment may include a mix of medications like lithium, other mood stabilisers, anti-psychotics, and antidepressants. Many people with bipolar also find that psychotherapy – especially psychoeducation – can help to manage the condition, enabling someone to understand what triggers episodes and how to manage symptoms.
The psychological treatment for bipolar and BPD are distinct, based on different models, and target different aspects of psychological functioning.
Careful expert treatment is needed for people who have either bipolar or BPD. Getting the wrong diagnosis means someone isn’t getting the right treatment, support and knowledge they need to manage the symptoms and live well.
What causes BPD?
Like bipolar, BPD doesn't have a single cause but most likely results from a combination of factors.
We know that that early adverse experiences have a negative impact on brain development, including on the brain areas that affect emotional functioning. This means that traumatic life experiences whilst growing up, such as abuse, neglect or loss, may contribute to the development of BPD, leading to ‘attachment’ problems to other people.
Genetics may also make someone more prone to BPD and problems with brain chemicals or changes in brain function may also play a role. Our knowledge in both these areas is limited.
These genetic, biological and environmental factors can combine, making it difficult for individuals to manage their emotions and relationships. Ongoing research is needed to better understand how these factors interact and contribute to BPD.
When do symptoms of BPD typically start?
Like with bipolar, symptoms of BPD usually start when someone’s in their late teens or early 20s, though signs such as mood swings and relationship problems can show up during the earlier teenage years. These symptoms are often mistaken for ‘typical’ teen behaviour, which can sometimes delay getting help.
Can someone have both bipolar and BPD?
Yes, according to some research, about 20% of people with bipolar type 2 and 10% of people with bipolar type 1 also have BPD. The Bipolar Commission survey found that 8.9% of respondents currently had a diagnosis of BPD alongside their diagnosis of bipolar.
When someone has both bipolar and BPD, they often experience more severe problems with regulating emotions, impulsivity and focus than if they had just one of these conditions, which may increase the risk of self-harm or suicidal behaviour.
Are people sometimes misdiagnosed with BPD when they have bipolar?
Because the conditions of bipolar and BPD are so widely misunderstood, misdiagnosis can happen.
Getting the right diagnosis is vital to ensure someone gets the correct treatment and support.
What can someone do if they suspect they’ve been misdiagnosed with BPD or bipolar?
If someone has been misdiagnosed, they might find that:
- their symptoms have been getting worse since they started medication and/or therapy
- they are experiencing symptoms that don’t match their current diagnosis
- they aren’t experiencing the typical symptoms of their current diagnosis
If you suspect you’ve been misdiagnosed, speak to your GP or mental health team.
There’s more information about getting a bipolar diagnosis here
Last updated: 20th January 2025