5.10 Mood Disorders (Depression and Bipolar)
Psychiatry Review for the USMLE Step 1 exam
- Mood disorders are persistent disruptions in emotion, categorized into bipolar disorders and depressive disorders.
- Bipolar disorders are characterized by manic or hypomanic episodes, while depressive disorders feature periods of depression.
- Major Depressive Disorder (MDD) is characterized by feelings of sadness, guilt, worthlessness, and anhedonia lasting for at least two weeks.
- SIG E CAPS is an acronym used to remember the symptoms of depression: Sleep changes, Interest loss, Guilt, Energy loss, Concentration difficulties, Appetite changes, Psychomotor retardation, and Suicidal ideation.
- In MDD, at least 5 of the SIG E CAPS symptoms must persist for more than 2 weeks.
- Persistent Depressive Disorder (dysthymia) is a chronic, low-grade form of MDD that lasts for at least two years.
- Mania is a symptom common to all bipolar disorders, characterized by elevated or irritable mood and increased activity or energy.
- Mania lasting for at least 1 week is called a manic episode, while hypomania is a less severe form lasting longer than 4 days.
- The symptoms of mania can be remembered using the mnemonic DIG FAST: Distractibility, Irritable mood/insomnia, Grandiosity, Flight of ideas, Agitation/increased activity, Speedy thoughts/speech, and Thoughtlessness.
- Bipolar I involves manic episodes, and bipolar II involves hypomanic episodes and major depressive episodes.
- Bipolar I requires at least one manic episode, while bipolar II requires depressive episodes.
- Mood stabilizers such as lithium, valproate, carbamazepine, and lamotrigine are used to treat bipolar disorders. Litium is the best (notable exeptions however).
- Antidepressants are contraindicated for bipolar patients due to the risk of flipping into mania.
- The risk of suicide is high in bipolar patients, with 25-50% attempting suicide and 10-15% dying by suicide.
- Cyclothymia is a less common form of bipolar disorder characterized by cycling between hypomania and mild depression over many years.
