Major Depressive Disorder vs Bipolar I Disorder
Major Depressive Disorder and Bipolar I Disorder are easy to mix up on the boards. Here's a side-by-side comparison — presentation, workup, imaging, and first-line treatment — drawn from our full outlines.
Major Depressive Disorder vs Bipolar I Disorder at a glance
- Major Depressive Disorder: Persistent depressed mood or anhedonia >=2 weeks with neurovegetative and cognitive symptoms causing functional impairment.
- Bipolar I Disorder: At least one lifetime manic episode; depressive and hypomanic episodes common but not required for diagnosis.
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Side-by-side comparison
| Feature | Major Depressive Disorder | Bipolar I Disorder |
|---|---|---|
| At a glance | Persistent depressed mood or anhedonia >=2 weeks with neurovegetative and cognitive symptoms causing functional impairment. | At least one lifetime manic episode; depressive and hypomanic episodes common but not required for diagnosis. |
| Classic presentation | SIG E CAPS mnemonic — Sleep, Interest, Guilt, Energy, Concentration, Appetite, Psychomotor, Suicidality. Five of nine including depressed mood or anhedonia x… | Manic patient with reduced need for sleep (e.g., sleeping 2-3 hours and feeling rested), spending sprees, hypersexuality, and grandiose business plans.; Manic… |
| Workup / key labs | DSM-5-TR: >=5 of 9 symptoms present for >=2 weeks, with at least one being depressed mood OR anhedonia. Symptoms must cause clinically significant… | DSM-5-TR Bipolar I: At least one lifetime manic episode — distinct period (>=7 days, or any duration if hospitalized) of elevated/expansive/irritable mood AND… |
| Imaging | Neuroimaging not routine; consider MRI brain if new focal neurologic findings, atypical features, or first episode after age 50 | Neuroimaging not routine; consider MRI if atypical features or first episode after age 50 |
| First-line treatment | Psychotherapy — cognitive behavioral therapy (CBT) or interpersonal therapy (IPT); comparable to medication for mild-moderate episodes; SSRI — sertraline,… | Mood stabilizer — lithium (gold standard, anti-suicide effect), valproate, or lamotrigine (bipolar depression and maintenance); Atypical antipsychotic —… |
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