Step 2 CK · Psychiatry

Mood Disorders

Name: Mood Disorders
Creator: Veli Bakalov, MD

Diagnosing depression and mania and choosing the drug that fits

Psychiatry·Mood & Anxiety Disorders·5 min read·9 high-yield points·Reviewed by Veli Bakalov, MD @HemeOncBuddy

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High-yield

MDD = ≥5 SIGECAPS symptoms for ≥2 weeks including depressed mood or anhedonia; persistent depressive disorder = depressed mood ≥2 years (1 year in children) plus ≥2 symptoms.
First-line depression: SSRI/SNRI plus CBT; judge response at 4–6 weeks; continue 6–12 months after a first episode, longer if recurrent or severe.
Bupropion: no sexual side effects or weight gain and aids smoking cessation, but lowers the seizure threshold (avoid in seizure and eating disorders); mirtazapine boosts appetite and sleep.
Nonresponse → switch or augment (aripiprazole, lithium, T3); ECT is the most effective and fastest option for severe, psychotic, catatonic, suicidal, or food-refusing depression (main side effect: transient amnesia).
Bipolar I = ≥1 manic episode (≥1 week, or any duration if hospitalized); bipolar II = hypomania (≥4 days, no psychosis or hospitalization) plus major depression, never full mania.
Bipolar disorder needs a mood stabilizer (lithium, valproate, carbamazepine, lamotrigine, quetiapine); never antidepressant monotherapy, which can trigger a manic switch.
Lithium 0.6–1.2 mEq/L: nephrogenic DI, hypothyroidism, hypercalcemia (hyperparathyroidism), small Ebstein anomaly risk; dehydration, thiazides, NSAIDs, and ACE inhibitors raise levels; uniquely lowers suicide risk.
Postpartum: blues (days 2–5, resolve by 2 weeks, reassure), depression (SSRI plus therapy), psychosis (delusions, infanticide risk → emergency hospitalization).
A prior attempt is the strongest predictor of completed suicide; women attempt more, men complete more (firearms); hospitalize when intent, plan, and means signal imminent risk.

Depressive disorders: diagnosis

Major depressive disorder (MDD) requires ≥5 of 9 symptoms for at least 2 weeks with functional impairment, and at least one must be depressed mood or anhedonia. The mnemonic SIGECAPS covers the rest: Sleep change, loss of Interest, Guilt or worthlessness, low Energy, poor Concentration, Appetite or weight change, Psychomotor agitation or slowing, and Suicidality.

Rule out mimics first. Check TSH, review medications and substances, and always ask about past manic or hypomanic episodes. A patient who presents depressed may have bipolar disorder, and an antidepressant alone can then trigger a manic switch.

Persistent depressive disorder (dysthymia) is depressed mood most of the day, more days than not, for ≥2 years (1 year in children), plus ≥2 of appetite change, sleep change, low energy, poor concentration, low self-esteem, or hopelessness, never symptom-free for more than 2 months. It is milder but chronic; treat with an SSRI plus psychotherapy.

Seasonal pattern. Recurrent major depressive episodes tied to a season, typically fall and winter with spring remission, often with atypical features such as hypersomnia and hyperphagia. Treat with bright light therapy and SSRIs; bupropion started before the season helps prevent episodes.

Treating depression

First line. Start an SSRI or SNRI plus psychotherapy (CBT). Allow 4–6 weeks at an adequate dose before judging response. After a first episode, continue the antidepressant for 6–12 months after remission to prevent relapse; recurrent or severe disease warrants longer, sometimes indefinite, maintenance.

SSRI/SNRI plus CBTFirst-line; reassess at 4–6 weeks.
Switch or augmentAripiprazole (atypical antipsychotic), lithium, or T3.
Treatment-resistantEsketamine, further trials.
ECTMost effective for severe or refractory depression.

Depression treatment ladder

Choose the agent by side-effect profile.

SSRIs: first line; sexual dysfunction and GI upset are the common complaints.
SNRIs (venlafaxine, duloxetine): also relieve neuropathic pain; venlafaxine can raise blood pressure.
Bupropion (norepinephrine-dopamine reuptake inhibitor): no sexual side effects or weight gain and aids smoking cessation, but lowers the seizure threshold, so avoid it in seizure disorders and eating disorders.
Mirtazapine (α2 antagonist): boosts appetite and sleep, useful with cachexia, weight loss, or insomnia.

Antidepressants carry a boxed warning for increased suicidal thinking under age 25. Energy often returns before mood lifts, so monitor closely in the first weeks, and avoid TCAs in suicidal patients because they are lethal in overdose.

When first-line fails. After an adequate trial, switch agents or augment with aripiprazole, lithium, or T3. Intranasal esketamine (an NMDA antagonist) is an option for treatment-resistant depression. Psychotic depression needs an antidepressant plus an antipsychotic, or ECT.

Electroconvulsive therapy (ECT) is the most effective treatment for severe, refractory, or psychotic depression and is first-line when a rapid response is needed: acute suicidality, catatonia, refusal to eat or drink, or severe depression in pregnancy. It is given under general anesthesia with a muscle relaxant. The main side effect is transient anterograde and retrograde amnesia, and there are no absolute contraindications.

Bipolar spectrum

Mania (DIGFAST): Distractibility, Impulsivity or Indiscretion (spending sprees, risky sex), Grandiosity, Flight of ideas, increased goal-directed Activity or energy, decreased need for Sleep, and Talkativeness (pressured speech). Psychosis can occur. Exclude stimulants, corticosteroids, and hyperthyroidism as secondary causes.

Bipolar I vs bipolar II vs cyclothymia

Feature	Bipolar I	Bipolar II	Cyclothymic disorder
Defining episode	≥1 manic episode	≥1 hypomanic plus ≥1 major depressive episode	≥2 years of subthreshold hypomanic and depressive symptoms
Elevated-mood duration	≥1 week (any duration if hospitalized)	≥4 days	Recurrent, subthreshold
Severity	Marked impairment; psychosis or hospitalization possible	No marked impairment, psychosis, or hospitalization	Milder, chronic
Depression	Common but not required	Required	Subthreshold only
Full mania ever	Yes	Never	Never

Bipolar II patients usually present in the depressive phase, so screen for past hypomania before prescribing any antidepressant.

Mood stabilizers and lithium

A mood stabilizer is the base. Treat bipolar disorder with lithium, valproate, carbamazepine, lamotrigine, or an atypical antipsychotic such as quetiapine. NEVER use antidepressant monotherapy, which can precipitate a manic switch.

Mood stabilizers at a glance

Drug	Best use	Key toxicities
Lithium	Mania and maintenance; reduces suicide	Nephrogenic DI, hypothyroidism, hyperparathyroidism, tremor, Ebstein anomaly
Valproate	Acute mania, maintenance	Hepatotoxicity, pancreatitis, neural tube defects, weight gain
Carbamazepine	Mania (alternative)	Agranulocytosis, SIADH, SJS, CYP450 induction, teratogen
Lamotrigine	Bipolar depression maintenance	SJS; requires slow titration
Quetiapine	Mania and bipolar depression	Sedation, weight gain, metabolic syndrome

0.6–1.2 mEq/Llithium therapeutic range: narrow, so levels are monitored

Lithium monitoring. Lithium has a narrow therapeutic index. Chronic effects are nephrogenic diabetes insipidus and hypothyroidism, and lithium can cause hyperparathyroidism with hypercalcemia, so follow creatinine, TSH, and calcium (with a pregnancy test at baseline and an ECG when indicated). First-trimester exposure raises the risk of Ebstein anomaly (tricuspid malformation), but the absolute risk is low; lithium is not absolutely contraindicated in pregnancy, so weigh relapse risk against stopping it and offer fetal echocardiography. Dehydration, thiazides, NSAIDs, and ACE inhibitors raise levels; toxicity brings coarse tremor, ataxia, and confusion, and severe cases need hemodialysis. Its unique benefit is a proven anti-suicidal effect.

Postpartum mood disorders

The postpartum spectrum

Feature	Baby blues	Postpartum depression	Postpartum psychosis
Onset	Days 2–5	Within weeks to months	Days to weeks, abrupt
Features	Tearfulness, mood swings, no impairment	Full depressive episode with functional impairment	Delusions, hallucinations; infanticide and suicide risk
Course	Resolves within 2 weeks	Persists without treatment	Psychiatric emergency
Management	Reassurance, supportive care	SSRI plus psychotherapy	Hospitalize; antipsychotics, mood stabilizers, or ECT

Practical points. Screen with the Edinburgh Postnatal Depression Scale; "blues" persisting beyond 2 weeks or causing impairment should be reassessed as postpartum depression. Sertraline is a preferred SSRI during breastfeeding. Postpartum psychosis is often the first presentation of bipolar disorder.

Suicide risk assessment

Ask directly. Asking about suicidal thoughts does not plant the idea. Assess ideation, intent, plan, access to means, and protective factors.

Risk factors. The strongest single predictor is a prior attempt. Others follow SAD PERSONS: male Sex, Age (older), Depression, Previous attempt, Ethanol or drug use, Rational thinking loss (psychosis), Social support lacking, Organized plan, No spouse, and Sickness; add hopelessness and access to firearms. Women attempt more often, but men complete suicide more often because they use more lethal means such as firearms.

Disposition. Hospitalize when intent, plan, and means indicate imminent risk, involuntarily if necessary. Lower-risk patients get a safety plan, means restriction (removing firearms, limiting pill supplies), close follow-up, and treatment of the underlying disorder.