Some people who look depressed have bipolar disorder. The depressive episodes can look identical to major depressive disorder. The difference is the rest of the picture, which includes episodes of mania or hypomania at some point in life. Telling the two apart matters because treatment is different.
Quick view
- Lifetime prevalence in U.S. adults is about 1.0 percent for bipolar I, about 1.1 percent for bipolar II, and roughly 2.4 percent for subthreshold bipolar (Merikangas et al., 2007).
- Patients spend roughly three times as many weeks depressed as elevated, so a depressive presentation is the rule, not the exception (Judd et al., Arch Gen Psychiatry, 2002).
- Standard antidepressants alone can destabilize bipolar disorder; first-line treatment is a mood stabilizer or an antipsychotic with bipolar-depression evidence.
- Average delay from first symptom to correct diagnosis is roughly 6 to 10 years; screening with the MDQ helps narrow this gap.
DSM-5-TR diagnostic criteria
Bipolar I disorder requires at least one lifetime manic episode, defined as a distinct period of abnormally and persistently elevated, expansive, or irritable mood and increased activity or energy lasting at least one week (or any duration if hospitalization is required), with three or more characteristic symptoms (inflated self-esteem, decreased need for sleep, pressured speech, flight of ideas, distractibility, increased goal-directed activity or psychomotor agitation, and excessive involvement in risky activities). Bipolar II requires at least one hypomanic episode, defined as the same symptom cluster present most of the day, nearly every day, for at least four consecutive days, without the marked impairment or hospitalization that defines mania. Bipolar II also requires at least one major depressive episode. A current bipolar depressive episode meets the same criteria as a unipolar major depressive episode; the difference is the lifetime history.
Bipolar I vs. Bipolar II vs. Cyclothymia
The three bipolar spectrum diagnoses share a pattern of mood elevation but differ in the severity of the elevated episodes, the presence of depression, and the duration required for diagnosis.
| Feature | Bipolar I | Bipolar II | Cyclothymia |
|---|---|---|---|
| Elevated episode required | At least one lifetime manic episode (7 days or more, or any duration if hospitalized) | At least one hypomanic episode (4 days or more), no full manic episode ever | Numerous periods of hypomanic symptoms not meeting full criteria |
| Depressive episode required | Not required for diagnosis, but present in most patients over time | At least one major depressive episode required | Numerous depressive symptoms not meeting full criteria |
| Duration required | Single qualifying manic episode is sufficient | Single qualifying hypomanic plus depressive episode | At least 2 years in adults (1 year in children and adolescents), symptoms present at least half the time |
| Functional impairment in elevated phase | Marked; often hospitalization or psychosis | Noticeable change but not marked; no hospitalization, no psychosis | Subthreshold; impairment driven by chronicity rather than severity |
| Lifetime U.S. prevalence (adults) | About 1.0 percent | About 1.1 percent | About 0.4 to 1 percent |
| First-line maintenance treatment | Lithium, valproate, or atypical antipsychotic; antidepressants only with mood stabilizer | Lithium, lamotrigine, or quetiapine; antidepressant monotherapy is generally avoided | Mood stabilizer (lithium, valproate) plus psychotherapy; treatment evidence is more limited |
Epidemiology
The lifetime prevalence of bipolar I disorder in U.S. adults is about 1.0 percent, bipolar II about 1.1 percent, and subthreshold bipolar another 2.4 percent (Merikangas et al., Arch Gen Psychiatry, 2007). Onset is typically in the late teens to mid-twenties. Approximately 60 percent of bipolar patients begin with a depressive episode, which is part of why the diagnosis is often missed for years. Suicide risk in bipolar disorder is higher than in unipolar depression and warrants explicit attention.
What it can look like
A person describes a long depressive episode and, when asked, also describes earlier periods of unusually elevated mood, decreased need for sleep, racing thoughts, faster speech, riskier decisions, and high energy. Those episodes may have looked like productivity or charisma at the time and may not have been brought up before. The history is the key.
How it shows up in different people
- In adults, the most common presentation at first visit is a depressive episode rather than mania.
- In adolescents, irritability rather than euphoria often dominates manic and hypomanic episodes, which makes the diagnosis harder.
- In older adults, a first manic episode is unusual and warrants a workup for medication-induced or medical causes.
- In women, depressive episodes, mixed features, and rapid cycling are more common; perinatal episodes can be severe.
- In men, manic episodes and substance use comorbidity are somewhat more common.
Why it matters
Standard antidepressants alone can sometimes destabilize bipolar disorder, triggering mood elevation, mixed features, or rapid cycling (Pacchiarotti et al., Am J Psychiatry, 2013). Treatment of bipolar depression usually involves mood stabilizers (lithium, lamotrigine, valproate) or specific antipsychotics with FDA approval for bipolar depression (quetiapine, lurasidone, cariprazine, olanzapine-fluoxetine combination). Antidepressants, when used, are typically added under a clinician's care alongside a mood stabilizer.
Screening
The Mood Disorder Questionnaire (MDQ) is a brief self-report screening tool for bipolar history and should be considered for any patient presenting with a depressive episode, especially with early onset, recurrent episodes, family history of bipolar disorder, or partial response to antidepressants. A positive MDQ is a reason for a careful diagnostic interview, not a diagnosis on its own.
When to seek same-day care
Suicidal thoughts with intent or a plan, mania or psychosis, or inability to keep yourself safe are reasons for same-day care. Call 988, call 911, or go to the nearest emergency department.
Treatment
Mood stabilizers. Lithium remains a first-line agent and has unique evidence for reducing suicide risk in bipolar disorder. Lamotrigine is effective for the depressive pole and for maintenance.
Atypical antipsychotics. Quetiapine, lurasidone, cariprazine, and the olanzapine-fluoxetine combination have FDA approval for bipolar depression.
Therapy and daily anchors. Interpersonal and social rhythm therapy, family-focused therapy, and CBT for bipolar disorder all have evidence. Sleep regularity is unusually important. Substance use, especially alcohol and stimulants, destabilizes the disorder and warrants attention.
Sources
- American Psychiatric Association. DSM-5-TR. 2022.
- Merikangas KR, et al. Lifetime and 12-month prevalence of bipolar spectrum disorder in the National Comorbidity Survey Replication. Arch Gen Psychiatry. 2007.
- Judd LL, et al. The long-term natural history of the weekly symptomatic status of bipolar I disorder. Arch Gen Psychiatry. 2002.
- Pacchiarotti I, et al. The International Society for Bipolar Disorders task force report on antidepressant use in bipolar disorders. Am J Psychiatry. 2013.
- National Institute of Mental Health. Bipolar disorder. Accessed 2026.
Related
Major depressive disorder. Treatment. Bipolar depression (glossary).
