Depression

SIGECAPS mnemonic

Sleep, Interest, Guilt, Energy, Concentration, Appetite, Psychomotor changes, Suicidal ideation.

DSM-5 criteria for Major Depressive Disorder

≥5 symptoms for ≥2 weeks, including depressed mood or anhedonia(low interest), causing functional impairment. SIGECAPS

High‑risk features for suicide in MDD

Older age, male, living alone, SUD, hopelessness.

Differential diagnosis for depression

Bipolar disorder, Persistent Depressive Disorder (PDD), PMDD, adjustment disorder, substance‑induced depression, depression due to medical condition.

Persistent Depressive Disorder definition

Depressed mood continuously for ≥2 years (≥1 year adolescents) or most days for 2+ years with ≥2 associated symptoms.(never symptom free for 2+months); SIGECAPS symptoms

Difference between MDD and PDD

MDD = episodic, severe; PDD = chronic, long‑standing low mood with fewer symptoms.

Premenstrual Dysphoric Disorder (PMDD) definition

≥5 symptoms in the week before menses, improving after onset, minimal post‑menses.

Premenstrual Dysphoric Disorder (PMDD) required symptom categories

Mood lability, irritability, depressed mood, anxiety + somatic/behavioral symptoms 5+ symptoms present in final week before onset of menses; go away/minimal after menses

Premenstrual exacerbation (PME)

Worsening of existing psychiatric symptoms(ex: anxiety) around menses; not PMDD.

Depressive disorder due to medical condition

Depression caused by physiological effects of illness (e.g., hypothyroidism, hyperglycemia).

Monoamine hypothesis

Depression linked to low serotonin, norepinephrine, and dopamine.

Receptor hypothesis

Upregulated, hypersensitive 5HT‑1A receptors contribute to depressive symptoms.

SSRI mechanism summary

Block SERT → ↑ serotonin → downregulate autoreceptors → ↑ neuronal firing → ↑ synaptic serotonin.

First‑line treatments for MDD

SSRIs, SNRIs, psychotherapy.

Fluoxetine (Prozac) clinical pearl

Long half‑life; good for patients prone to missed doses or withdrawal.

Bupropion(Wellbutrin) clinical pearl

NDRI(works on NE); useful for ADHD, smoking cessation; no sexual side effects; no increased risk of serotonin syndrome

Duloxetine(Cymbalata) clinical pearl

SNRI useful for neuropathic pain and fibromyalgia.

Mirtazapine(Remeron) clinical pearl

Improves appetite and sleep; helpful in underweight or insomnia‑dominant depression.

Black box warning for antidepressants

Increased suicidality risk in individuals under age 24.

SSRI side effects

Nausea, headache, sexual dysfunction, activation/anxiety, insomnia.

SSRI trial duration

Requires 6+ weeks at therapeutic dose; evaluate response at 10–12 weeks.

When to switch antidepressants

No meaningful response after 10–12 weeks at therapeutic dose.