[Celyn]

From what I've read (not based on personal experience, sorry!) there definitely can seem to be an overlap between symptoms of Bipolar and Borderline Personality Disorder, so I understand why it is difficult for you to untangle what's what.

My take on what I've read is that symptoms of BPD often appear in the context of personal relationships (friends, family, romantic partner etc), whereas with Bipolar, triggers of symptoms aren't necessarily to do with relationships but may be due to not taking medication correctly, not sleeping enough etc. There's also a difference in that with Bipolar, changes in mood can last for weeks or months at a time, whereas I've had BPD explained to me as very rapid changes (a guest lecturer at uni who treated people with BPD explained it as imagine all the best moments of your life, then all your worst moments, and imagine cycling through those feelings every few minutes/hours all day). Both Bipolar and BPD can effect relationships but again, people with BPD will often have a 'push/pull' type of relationship...small things may cause strong emotions which will push others away but then they get scared of the person leaving them so may cling to them to pull them back (the difference is that it can feel very intense for the person with BPD to the point of feeling suicidal at the thought of a loved one leaving/abandoning them....something that people without mental illness are unlikely to experience). For untreated BPD this may happen on a regular basis, but I imagine that with Bipolar, once the hypo/manic episode has ended (maybe days/weeks/months later), then there may be guilt or shame if the person has treated someone in a way that they wouldn't have if they hadn't experienced an episode.

The same may be said for identity. For people with BPD, they may frequently change their appearance (hairstyle and colour, clothes), their aspirations, and values/beliefs, partly to do with significant people in their lives (maybe if they fell out with someone important they would change everything that reminds them of them or they may change to be more like someone they are idolising). With Bipolar, identity changes may be due to a manic episode, rather than due to the people around them.

Bipolar is more 'biological' which is why medication is often the best route for managing symptoms, whereas BPD is more interpersonal so therapy may be the best route. But I imagine that Bipolar and BPD can interact...for example, if one gets worse, you may notice the other worsens as well.

The problem really is that diagnosing, especially disorders that can seem similar, can be quite subjective, so you may want to talk with your prescriber about what BPD means for you and how you can distinguish the symptoms from Bipolar.

Hope this helps a bit and that others can also help you!