A mental health volunteer is interviewing locals as part of a community outreach program. A 46-year-old man discloses that he has felt sad for as long as he can remember. He feels as though his life is cursed and if something terrible can happen to him, it usually will. He has difficulty making decisions and feels hopeless. He also feels that he has had worsening suicidal ideations, guilt from past problems, decreased energy, and poor concentration over the past 2 weeks. He is otherwise getting enough sleep and able to hold a job. Which of the following statement best describes this patient's condition?

The patient has double depression.

The patient may have symptoms of mania or psychosis.

The patient is likely to show anhedonia.

The patient likely has paranoid personality disorder.

The patient should be started on an SSRI.

A 38-year-old man comes to the physician because of persistent sadness and difficulty concentrating for the past 6 weeks. During this period, he has also had difficulty sleeping. He adds that he has been “feeling down” most of the time since his girlfriend broke up with him 4 years ago. Since then, he has only had a few periods of time when he did not feel that way, but none of these lasted for more than a month. He reports having no problems with appetite, weight, or energy. He does not use illicit drugs or alcohol. Mental status examination shows a depressed mood and constricted affect. Which of the following is the most likely diagnosis?

Adjustment disorder with depressed mood

A 29-year-old man comes to the physician with his wife because she has noticed a change in his behavior over the past 2 weeks. His wife reports that he is very distracted and irritable. His colleagues have voiced concerns that he has not been turning up for work regularly and behaves erratically when he does. Previously, her husband had been a reliable and reasonable person. The patient says that he feels “fantastic”; he only needs 4 hours of sleep each night and wakes up cheerful and full of energy each morning. He thinks that his wife is overreacting. The patient has been healthy except for a major depressive episode 5 years ago that was treated with paroxetine. He currently takes no medications. His pulse is 98/min, respirations are 12/min, and blood pressure is 128/62 mm Hg. Mental status examination shows frenzied speech and a flight of ideas. Which of the following is the strongest predisposing factor for this patient's condition?

Maternal obstetric complications

A 33-year-old woman comes to the emergency department for the evaluation of a headache and increased sweating for the last two hours. The patient also reports palpitations and nausea. Yesterday, she was started on venlafaxine for treatment-resistant depression. She took citalopram for four weeks, but stopped three days ago because her symptoms of depression did not improve. She does not smoke or drink alcohol. Her temperature is 39°C (102.2°F), pulse is 120/min, and blood pressure is 150/90 mm Hg. On mental status examination, the patient is only oriented to person, but not to place or time. Examination shows tremors in all extremities. She has impaired gait. Deep tendon reflexes are 3+ bilaterally. Which of the following is the most likely cause of this patient's symptoms?

Increased CNS serotonergic activity

A 28-year-old male presents to his primary care physician with complaints of intermittent abdominal pain and alternating bouts of constipation and diarrhea. His medical chart is not significant for any past medical problems or prior surgeries. He is not prescribed any current medications. Which of the following questions would be the most useful next question in eliciting further history from this patient?

"Can you tell me more about the symptoms you have been experiencing?"

"Does the diarrhea typically precede the constipation, or vice-versa?"

"Is the diarrhea foul-smelling?"

"Please rate your abdominal pain on a scale of 1-10, with 10 being the worst pain of your life"

"Are the symptoms worse in the morning or at night?"

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

Mood disorders due to medical conditions — USMLE Lesson

Etiology & Pathophysiology - The Body's Blues

Direct Physiological Consequence: Symptoms are a direct result of a general medical condition, not just a psychological reaction to illness.
Key Mechanisms:
- HPA Axis Dysregulation: ↑ Cortisol (e.g., Cushing's, steroid use).
- Inflammatory Cytokines: ↑ IL-6, TNF-α can ↓ serotonin synthesis.
- Neurotransmitter Disruption: Direct brain lesions or metabolic changes.
Common Medical Culprits:
- Neurologic: Stroke, Parkinson's, Huntington's, MS, TBI.
- Endocrine: Hypothyroidism, Cushing's disease, Addison's disease.
- Medication-Induced: 📌 PROMS (Propranolol, Reserpine, Oral contraceptives, Methyldopa, Steroids), Interferon-α.

⭐ Post-stroke depression is most common with lesions in the left frontal lobe or basal ganglia.

HPA axis, inflammation, and gut-brain axis in depression

Diagnosis & Clinical Features - Spotting the Imposter

Core Criterion: A prominent, persistent mood disturbance (depressive or bipolar-like) that is the direct pathophysiological result of a specific medical condition.
Key Suspicion Triggers:
- Atypical age of onset (e.g., first mania at age 60).
- Presence of physical exam findings or lab abnormalities linked to a medical cause.
- Mood symptoms appear after the onset of the medical condition.

⭐ Exam Favorite: Always consider hypercortisolism (Cushing's syndrome) or hypothyroidism in patients presenting with new-onset depression, especially with atypical features.

Common Medical Causes - The Usual Suspects

Neurological Disorders
- Cerebrovascular accidents (esp. left frontal lobe)
- Parkinson's & Huntington's disease
- Multiple sclerosis
- Traumatic brain injury (TBI)
- Epilepsy (esp. temporal lobe)
Endocrinopathies
- Hypothyroidism & Hyperthyroidism ("apathetic hyperthyroidism")
- Cushing's disease (↑cortisol)
- Addison's disease (↓cortisol)
- Hyper/hypoparathyroidism
Infectious & Inflammatory
- HIV, Neurosyphilis, Systemic Lupus Erythematosus (SLE)
Nutritional Deficiencies
- Vitamin B12, folate, or D deficiency
Medication-Induced
- Corticosteroids, Interferon-α, Levodopa, some antihypertensives (e.g., reserpine)

⭐ New-onset depression in an older patient with weight loss and vague abdominal pain should raise suspicion for pancreatic cancer.

The mood disturbance must be a direct physiological result of another medical condition, not a psychological reaction.

A clear temporal relationship between the onset of the medical condition and the mood symptoms is essential for diagnosis.

Hypothyroidism and pancreatic cancer are classic causes of secondary depression.

Cushing's disease, multiple sclerosis, and strokes can present with either depression or mania.

Always treat the underlying medical condition as the primary intervention strategy.

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