Published by the Clinical Team at My Limitless Journeys. Reviewed under board-certified psychiatric oversight.
Why these two get confused
Both involve mood that moves more than other people’s, impulsivity that damages careers and relationships, and elevated risk of self-harm. And both are frequently described by the person living with them in the same three words: “my moods swing.” That phrase is where the confusion begins, because it flattens two very different phenomena into one sentence.
The cost of getting it wrong is not academic. A person with BPD treated as bipolar may spend years cycling through mood stabilisers that were never going to address the mechanism. A person with bipolar disorder treated as a personality problem may get skills training while an untreated manic vulnerability is repeatedly triggered. Meanwhile alcohol or stimulants are quietly doing the regulating, and nobody can read the underlying picture at all.
Bipolar disorder: episodes, not moods
Bipolar disorder is defined by discrete episodes. A manic episode is a sustained period of elevated, expansive or irritable mood with increased energy, lasting at least a week, accompanied by features such as reduced need for sleep, pressured speech, racing thoughts, grandiosity and impulsive activity with painful consequences. Hypomania is the shorter, less severe version, and depressive episodes are sustained lows lasting two weeks or more. Bipolar I requires at least one manic episode; bipolar II involves hypomania with depression; cyclothymic disorder describes chronic, sub-threshold fluctuation.
The National Institute of Mental Health puts past-year prevalence among US adults at 2.8%, with a lifetime figure of 4.4%, and reports that an estimated 82.9% of those with past-year bipolar disorder had serious impairment. The key clinical feature for our purposes is persistence. An episode does not lift because the argument resolved or the text was answered. It runs its course, largely independent of what happens on any given afternoon. Our page on bipolar disorder treatment covers the management in detail.
BPD: dysregulation, and what it responds to
Borderline personality disorder is characterised by pervasive instability in emotion, relationships, self-image and behaviour. NIMH describes it as an illness that severely affects a person’s ability to regulate their emotions, with heightened impulsivity, an unstable sense of self and elevated risk of self-harm. Diagnostic features include frantic efforts to avoid abandonment, intense and unstable relationships, chronic emptiness, difficulty controlling anger, and stress-related paranoid ideation or dissociation. Past-year prevalence in US adults is around 1.4%.
The mood movement here is fast and reactive. Someone can go from settled to devastated in ten minutes because a message went unanswered, and back toward baseline within hours if the rupture is repaired. That reactivity — and the fact that it is usually interpersonal — is the most useful distinguishing feature in a clinical interview, and why a day-by-day account beats any checklist. If you are supporting someone through these moments, our guide on navigating a BPD episode is written for exactly that.
The “types” of BPD, and what they are actually for
People searching this topic quickly encounter four subtypes: impulsive, self-destructive, discouraged and petulant. They are worth understanding correctly. They are descriptive clinical presentations drawn from theoretical work on personality, not categories in the DSM-5. No one is diagnosed with “petulant BPD.” What they capture is that the same criteria can look strikingly different from the outside.
The impulsive presentation is outward and often charismatic: thrill-seeking, reckless driving, spending, substance use, anger that arrives without a brake. The self-destructive presentation turns the same pain inward through self-harm, health neglect and a deep sense of worthlessness. The discouraged or quiet presentation internalises almost everything — dependency, passivity, suppressed feeling, intense fear of abandonment behind an outwardly composed surface, which is why it is so often missed entirely. The petulant presentation oscillates between clinging and resentment: irritability, difficulty trusting, passive-aggression, and relationships that swing between need and anger.
Their real value is in treatment planning. The impulsive picture calls for early emphasis on distress tolerance and consequence-mapping. The self-destructive picture calls for safety planning and work on self-worth before anything else. The quiet picture calls for building assertiveness in someone whose instinct is to disappear. The petulant picture calls for sustained work on trust and on repairing ruptures rather than escalating them. Same diagnosis, four different opening moves — and the same substance serving four different functions, which is why we assess function rather than quantity.
Six differences that matter clinically
Duration. Bipolar episodes last days to weeks. BPD states last minutes to hours, occasionally a day.
Trigger. Bipolar episodes often begin without a proportionate external cause, though sleep disruption, travel and substances can precipitate them. BPD shifts almost always have an interpersonal trigger, and the person can usually name it.
Self-image. In bipolar disorder, self-image changes with the episode and returns between them. In BPD, the instability of identity is chronic and present between crises.
Relationships. Bipolar disorder strains relationships largely through the consequences of episodes. In BPD, the relationships themselves are the terrain on which the disorder plays out, with abandonment fear at the centre.
Sleep. In mania, reduced sleep comes with increased energy — someone functions on three hours and feels excellent. In BPD, poor sleep produces ordinary exhaustion.
First-line treatment. Bipolar disorder is managed primarily with medication — mood stabilisers, certain antipsychotics — plus psychoeducation and rhythm stability. BPD responds primarily to structured psychotherapy, with dialectical behaviour therapy the best-established. Medication in BPD targets co-occurring symptoms rather than the disorder itself.
Where they genuinely overlap
This is not a clean either-or. In the Collaborative Longitudinal Personality Disorders Study, bipolar I and II were significantly more common among patients with BPD than among patients with other personality disorders — 19.4% against 7.9% — and new bipolar diagnoses emerged over four years in 7.9% of the BPD group against 3.1% of comparison groups. The authors read this as a modest association rather than evidence of a single spectrum, which is roughly where the field has settled. Someone can have both, and when they do, both need treating.
Substance use is not a side issue here
In BPD it is close to the norm. A 2018 review by Trull and colleagues in Borderline Personality Disorder and Emotion Dysregulation found 75.28% of people with BPD met criteria for a lifetime substance use disorder and 45.46% for a current one, with lifetime alcohol use disorder at 59.46%. A German review by Kienast and colleagues in Deutsches Ärzteblatt International reports around 78% developing a substance-related disorder in their lifetime, and — the figure that should shape any treatment plan — remission rates roughly four times lower over six years for people with both conditions than for BPD alone.
In bipolar disorder the association is also strong. SAMHSA’s advisory on bipolar disorder and co-occurring substance use disorders reports lifetime co-occurrence ranging from 21.7% to 59% across studies, with twelve-month figures from 4% to more than 25%, and notes that people with bipolar disorder show markedly higher rates of co-occurrence than people with other mental disorders. Substances also distort the diagnostic picture directly: stimulant intoxication mimics hypomania, withdrawal mimics depression, and alcohol amplifies impulsivity in a way that can make anyone look borderline.
Treating both, and in what order
The sequencing that fails most reliably is “get sober first, then we will look at the psychiatry.” For someone whose drinking is the only regulation strategy they have, removing it without replacing it is not a neutral act. Kienast and colleagues recommend evidence-based psychotherapies delivered for both disorders simultaneously, including dialectical behaviour therapy adapted for substance use, and note that pharmacological relapse prevention works about as well in people with a personality disorder as without one.
In practice: medical stabilisation first, because withdrawal has to be managed safely; then a diagnostic period long enough to see what is substance-driven; then integrated treatment with one team. For BPD that centres on DBT — mindfulness, distress tolerance, emotion regulation and interpersonal effectiveness — applied to both the self-harm and the using, as we describe in DBT for substance use recovery. For bipolar disorder it centres on medication adherence, sleep and routine stability, and early identification of prodromal signs. Where both are present the plan holds both, which is the argument of levels of care for co-occurring disorders and of our BPD treatment program.
Frequently asked questions
Can someone have both bipolar disorder and BPD?
Yes. In the CLPS data, roughly one in five patients with BPD also had bipolar I or II. Having both is not a contradiction; it means the treatment plan needs a medication strategy and a structured psychotherapy running in parallel rather than one instead of the other.
Is BPD a permanent diagnosis?
No, and this is one of the most important things we tell families. Longitudinal research has consistently found that a substantial proportion of people with BPD no longer meet criteria after several years, particularly with structured treatment. It has a considerably better long-term trajectory than its reputation suggests.
Which BPD “type” do I have?
Most people recognise themselves in more than one, and the presentation shifts with circumstances and over time. Treat them as a way of describing where your difficulties currently sit, useful for deciding what to work on first, rather than as a diagnostic result.
Do I have to be abstinent before a diagnosis can be made?
A period of stability makes any diagnosis far more reliable, because intoxication and withdrawal imitate both conditions. That does not mean waiting to be treated — safety, stabilisation and skills work all begin immediately; it is the formal diagnostic conclusion that benefits from a clearer window.
How do I support someone without making it worse?
Validate the feeling before you address the facts, keep your own limits consistent rather than moving them under pressure, and do not attempt to be the clinician. Family involvement is a genuine predictor of how well these treatments hold, which is why we build family support into the plan rather than offering it as an extra.
If you have been given two different diagnoses in two years and neither treatment held, the missing piece may be the substance use nobody assessed alongside them. We can look at all of it at once.
Keep reading: Bipolar disorder treatment · BPD treatment · Navigating a BPD episode · DBT for substance use recovery · Co-occurring disorders