A 65-year-old male who is being treated for depression visits your emergency room complaining of being unable to urinate. In addition, the patient complains of tachycardia and dry mouth. He has no history of benign prostatic hyperplasia and reports of only being on one psychiatric medication. What type of psychiatric medication would cause such a side effect profile?

Serotonin norepinephrine reuptake inhibitor

Selective serotonin reuptake inhibitor

A 25-year-old woman comes to the physician because of sadness that started 3 weeks after her daughter was born. Her daughter is now 9 months old and usually sleeps through the night, but the patient still has difficulty staying asleep. She has not returned to work since the birth. She is easily distracted from normal daily tasks. She used to enjoy cooking, but only orders delivery or take-out now. She says that she always feels too exhausted to do so and does not feel hungry much anyway. The pregnancy of the patient's child was complicated by gestational diabetes. The child was born at 36-weeks' gestation and has had no medical issues. The patient has no contact with the child's father. She is not sexually active. She does not smoke, drink alcohol, or use illicit drugs. She is 157 cm (5 ft 1 in) tall and weighs 47 kg (105 lb); BMI is 20 kg/m2. Vital signs are within normal limits. She is alert and cooperative but makes little eye contact. Physical examination shows no abnormalities. Which of the following is the most likely diagnosis?

Depression with peripartum-onset

Disruptive mood dysregulation disorder

A 24-year-old woman comes to the physician because she feels sad and has had frequent, brief episodes of crying for the last month. During this period, she sleeps in every morning and spends most of her time in bed playing video games or reading. She has not been spending time with friends but still attends a weekly book club and continues to plan her annual family reunion. She stopped going to the gym, eats more, and has gained 4 kg (8.8 lb) over the past 4 weeks. Three weeks ago, she also started to smoke marijuana a few times a week. She drinks one glass of wine daily and does not smoke cigarettes. She is currently unemployed; she lost her job as a physical therapist 3 months ago. Her vital signs are within normal limits. On mental status examination, she is calm, alert, and oriented to person, place, and time. Her mood is depressed; her speech is organized, logical, and coherent. She denies suicidal thoughts. Which of the following is the most likely diagnosis?

Persistent Depressive Disorder (Dysthymia)

A 42-year-old female presents to her primary care provider for an annual checkup. She reports feeling sad over the past few months for no apparent reason. She has lost interest in swimming, which she previously found enjoyable. Additionally, she has had trouble getting a full night’s sleep and has had trouble concentrating during the day. She has lost 15 pounds since her last visit one year prior. Which of the following sets of neurotransmitter levels is associated with this patient’s condition?

Decreased norepinephrine, decreased serotonin, decreased dopamine

Decreased acetylcholine, normal serotonin, normal dopamine

Decreased GABA, decreased acetylcholine, increased dopamine

Increased norepinephrine, decreased serotonin, decreased GABA

Increased acetylcholine, increased serotonin, decreased dopamine

A 23-year-old woman is brought to the physician by her father because of irritability, mood swings, and difficulty sleeping over the past 10 days. A few days ago, she quit her job and spent all of her savings on supplies for a “genius business plan.” She has been energetic despite sleeping only 1–2 hours each night. She was diagnosed with major depressive disorder 2 years ago. Mental status examination shows pressured speech, a labile affect, and flight of ideas. Throughout the examination, she repeatedly states “I feel great, I don't need to be here.” Urine toxicology screening is negative. Which of the following is the most likely diagnosis?

Attention-deficit hyperactivity disorder

A 24-year-old woman presents to her primary care physician for a wellness exam. She currently has no acute concerns but has been feeling hopeless, has a poor appetite, difficulty with concentration, and trouble with sleep. She says that she has poor self-esteem and that her symptoms have been occurring for the past 3 years. She has had moments where she felt better, but it lasted a few weeks out of the year. She currently lives alone and does not pursue romantic relationships because she feels she is not attractive. She has a past medical history of asthma. Her mother is alive and healthy. Her father committed suicide and suffered from major depressive disorder. On physical exam, the patient has a gloomy demeanor and appears restless and anxious. Which of the following is the most likely diagnosis?

Disruptive mood dysregulation disorder

Depression with atypical features for USMLE Step 2 CK: High-Yield Psychiatry Lessons

Atypical Depression - The 'Reversed' Blues

A subtype of major depression where mood improves with positive events (mood reactivity).
Characterized by "reversed" vegetative symptoms. Diagnosis requires mood reactivity plus ≥2 of the following:
- Hyperphagia (↑ appetite) & weight gain.
- Hypersomnia (↑ sleep).
- Leaden paralysis: heavy, leaden feeling in arms or legs.
- Long-standing sensitivity to interpersonal rejection.

⭐ High-Yield: While SSRIs are first-line, Monoamine Oxidase Inhibitors (MAOIs) are particularly effective for treatment-resistant atypical depression.

Common Signs of Atypical Depression

Clinical Features - Mood-Brightening Misery

Mood Reactivity (Mood Brightening): Core feature. Mood temporarily lifts with positive events (e.g., good news). Contrasts with the pervasive low mood of melancholic depression.
Weight Gain or ↑ Appetite: A distinct feature compared to the typical loss of appetite and weight.
Hypersomnia: Sleeping >10 hours/day or at least 2 hours more than baseline when not depressed.
Leaden Paralysis (Leaden Fatigue): Profound physical exhaustion; limbs feel heavy, leaden, and difficult to move.
Interpersonal Rejection Sensitivity: Long-standing pattern of overreacting to perceived social rejection or criticism.

⭐ Key Differentiator: The presence of mood reactivity is essential for diagnosis. A patient who enjoys a social event but feels depressed again the next morning is a classic vignette.

Differential Dx - Distinguishing Despair

Bipolar Disorder: Must rule out; screen for prior manic/hypomanic episodes. Antidepressant monotherapy risks inducing mania.
Persistent Depressive Disorder (Dysthymia): Chronic low-grade depression for ≥2 years; less intense than a full MDE.
Adjustment Disorder: Emotional/behavioral symptoms develop within 3 months of a stressor; marked distress but doesn't meet full MDE criteria.
Medical Conditions: Always consider hypothyroidism, anemia, Cushing's syndrome, and neurological disorders.
Substance/Medication-Induced: Check for drug/alcohol use or offending medications.

⭐ Always screen for bipolar disorder before initiating antidepressants. Misdiagnosing bipolar depression as unipolar can lead to treatment-induced mania or hypomania.

MAOIs are highly effective for atypical depression, often used after failed trials of other agents like SSRIs.
Agents:
- 📌 TIPS: Tranylcypromine, Isocarboxazid, Phenelzine, Selegiline.
Mechanism: Inhibit monoamine oxidase, ↑ levels of serotonin, norepinephrine, and dopamine.
⚠️ Major Risks:
- Hypertensive Crisis: Triggered by ingesting tyramine-rich foods.
- Serotonin Syndrome: Risk when combined with SSRIs, SNRIs, or TCAs. Requires a 2-week washout period ( 5 weeks for fluoxetine).

⭐ Exam Favorite: Patients on MAOIs must avoid tyramine-rich foods like aged cheese, cured meats (salami, pepperoni), red wine, and fava beans to prevent a life-threatening hypertensive crisis.

Tyramine-rich foods to avoid with MAOIs

High‑Yield Points - ⚡ Biggest Takeaways

The hallmark is mood reactivity: mood temporarily brightens in response to positive events.

Instead of typical neurovegetative symptoms, look for ↑ appetite or weight gain and hypersomnia.

Leaden paralysis (a heavy feeling in arms/legs) is a classic, specific symptom.

Features a long-standing pattern of interpersonal rejection sensitivity, causing significant impairment.

SSRIs are first-line, but MAOIs are highly effective for treatment-refractory atypical depression.

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