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USMLE STEP3 Exam
Step3 (Page 4 )

Updated On: 1-Feb-2026
Page 4 of 162
PDF with 804 Questions

A 30-year-old married male with a history of depression presents to the family medicine clinic. He appears embarrassed and somewhat anxious during his appointment. He denies significant sadness or crying spells. He is sleeping adequately and eating well, without recent changes in his weight. His energy and concentration are normal, and he denies any suicidal or homicidal ideation. He claims to be compliant with his citalopram (Celexa), which he is taking for his depression, but he complains of "problems with sex."

Which of the following symptoms would this patient most likely exhibit?

  1. decreased libido
  2. painful intercourse
  3. premature ejaculation
  4. priapism
  5. retrograde ejaculation

Answer(s): A

Explanation:

Many psychotropic medications, including most of the antidepressants, cause a variety of sexual dysfunction symptoms. Both painful intercourse and retrograde ejaculation are not seen with antidepressant therapy. These are usually caused by other classes of medications, medical conditions, or surgical procedures. Premature ejaculation is not caused by antidepressants and, in fact, may actually be helped by antidepressants, especially SSRIs. Priapism is an uncommon side effect seen in patients treated with trazodone and even more rarely with the other antidepressants. Decreased libido is a frequent sexual side effect seen in individuals taking antidepressants, especially SSRIs. Other sexual problems caused by these medications include decreased erection and delayed ejaculation.

Almost all of the antidepressants, including the tricyclic antidepressants such as desipramine and the monoamine oxidase inhibitors such as phenelzine, can cause sexual dysfunction. Fluoxetine is a SSRI that commonly causes sexual dysfunction. Venlafaxine is a serotonin and norepinephrine reuptake inhibitor that has also been shown to cause similar problems with sexual performance. Mirtazapine, a novel antidepressant which blocks serotonin and noradrenergic receptors, causes little to no sexual dysfunction. Bupropion has likely dopaminergic properties, and it not only causes little sexual dysfunction, but it also is used to help treat antidepressantinduced sexual dysfunction in some patients.



A 30-year-old married male with a history of depression presents to the family medicine clinic. He appears embarrassed and somewhat anxious during his appointment. He denies significant sadness or crying spells. He is sleeping adequately and eating well, without recent changes in his weight. His energy and concentration are normal, and he denies any suicidal or homicidal ideation. He claims to be compliant with his citalopram (Celexa), which he is taking for his depression, but he complains of "problems with sex."

Consideration is given to switching the patient to another antidepressant in order to minimize his side effects. Which of the following would be the most appropriate medication to choose?

  1. desipramine (Norpramin)
  2. fluoxetine (Prozac)
  3. mirtazepine (Remeron)
  4. phenelzine (Nardil)
  5. venlafaxine (Effexor)

Answer(s): C

Explanation:

Many psychotropic medications, including most of the antidepressants, cause a variety of sexual dysfunction symptoms. Both painful intercourse and retrograde ejaculation are not seen with antidepressant therapy. These are usually caused by other classes of medications, medical conditions, or surgical procedures. Premature ejaculation is not caused by antidepressants and, in fact, may actually be helped by antidepressants, especially SSRIs. Priapism is an uncommon side effect seen in patients treated with trazodone and even more rarely with the other antidepressants. Decreased libido is a frequent sexual side effect seen in individuals taking antidepressants, especially SSRIs. Other sexual problems caused by these medications include decreased erection and delayed ejaculation.

Almost all of the antidepressants, including the tricyclic antidepressants such as desipramine and the monoamine oxidase inhibitors such as phenelzine, can cause sexual dysfunction. Fluoxetine is a SSRI that commonly causes sexual dysfunction. Venlafaxine is a serotonin and norepinephrine reuptake inhibitor that has also been shown to cause similar problems with sexual performance. Mirtazapine, a novel antidepressant which blocks serotonin and noradrenergic receptors, causes little to no sexual dysfunction. Bupropion has likely dopaminergic properties, and it not only causes little sexual dysfunction, but it also is used to help treat antidepressantinduced sexual dysfunction in some patients.



An 86-year-old woman is brought to the emergency room by her daughter. The patient is a poor historian with limited insight. Her daughter understands that she has a history of high BP and is treated with an unknown medication. The patient has been living by herself in a retirement community. The daughter became concerned a year prior, when she noticed that her mother seemed more confused. She had attributed this to "old age," but 2 weeks ago she noticed an abrupt worsening in her condition. Her mother now has difficulty recognizing close relatives and remembering information. For the past 2 weeks, she has been getting lost, forgetting to turn off the stove, and has been unable to bathe herself. The daughter is concerned that she may inadvertently harm herself.

An MRI of the brain would most likely demonstrate which of the following findings?

  1. caudate nucleus atrophy
  2. dilated ventricles without atrophy
  3. frontotemporal atrophy
  4. generalized atrophy
  5. white matter infarcts

Answer(s): E

Explanation:

This is a case of dementia, vascular type (multiinfarct dementia), caused by poorly controlled hypertension. Atrophy of the caudate nucleus is seen in Huntington chorea, which accounts for the movement disorder and dementia that are seen in that illness. Dilated ventricles without atrophy are characteristic of normal pressure hydrocephalus (NPH), one of the potentially reversible causes of dementia. The triad seen in NPH consists of dementia, gait disturbance, and urinary incontinence. Pick's disease is a gradually progressing dementia, displaying marked but preferential atrophy of the frontal and temporal lobes of the brain. Generalized atrophy can often be seen with neuroimaging in Alzheimer dementia. Vascular dementia classically will show lacunar infarcts of the white matter on MRI. With the exception of reversible causes (e.g., NPH, metabolic causes, or heavy metal toxicity), improvement is unusual in dementing illnesses. A rapid decline is common in dementias due to prion infection, such as Creutzfeldt-Jakob disease. Stable dementias are also unusual, most notably seen in dementia due to a head injury. Both Alzheimer's and Pick's dementias demonstrate a steady worsening of the illness over many years. The multiple small infarcts causing vascular dementia correspond to a stepwise deterioration in functioning of the patient.



An 86-year-old woman is brought to the emergency room by her daughter. The patient is a poor historian with limited insight. Her daughter understands that she has a history of high BP and is treated with an unknown medication. The patient has been living by herself in a retirement community. The daughter became concerned a year prior, when she noticed that her mother seemed more confused. She had attributed this to "old age," but 2 weeks ago she noticed an abrupt worsening in her condition. Her mother now has difficulty recognizing close relatives and remembering information. For the past 2 weeks, she has been getting lost, forgetting to turn off the stove, and has been unable to bathe herself. The daughter is concerned that she may inadvertently harm herself.

Which of the following will be the most likely course of her illness?

  1. gradual improvement
  2. rapid decline
  3. stable course
  4. steady worsening
  5. stepwise deterioration

Answer(s): E

Explanation:

This is a case of dementia, vascular type (multiinfarct dementia), caused by poorly controlled hypertension. Atrophy of the caudate nucleus is seen in Huntington chorea, which accounts for the movement disorder and dementia that are seen in that illness. Dilated ventricles without atrophy are characteristic of normal pressure hydrocephalus (NPH), one of the potentially reversible causes of dementia. The triad seen in NPH consists of dementia, gait disturbance, and urinary incontinence. Pick's disease is a gradually progressing dementia, displaying marked but preferential atrophy of the frontal and temporal lobes of the brain. Generalized atrophy can often be seen with neuroimaging in Alzheimer dementia. Vascular dementia classically will show lacunar infarcts of the white matter on MRI. With the exception of reversible causes (e.g., NPH, metabolic causes, or heavy metal toxicity), improvement is unusual in dementing illnesses. A rapid decline is common in dementias due to prion infection, such as Creutzfeldt-Jakob disease. Stable dementias are also unusual, most notably seen in dementia due to a head injury. Both Alzheimer's and Pick's dementias demonstrate a steady worsening of the illness over many years. The multiple small infarcts causing vascular dementia correspond to a stepwise deterioration in functioning of the patient



A 67-year-old man is seen in the clinic for a scheduled visit. He complains of walking difficulties that have progressively worsened over many months. He also has noticed "shaking" of his hands, resulting in his dropping objects occasionally. He is greatly upset by these problems and admits to frequent crying spells. His only chronic medical illnesses are gastroesophageal reflux disease and hyperlipidemia. He is currently prescribed a proton pump inhibitor and cholesterol-lowering agent. His MSE is notable for little expression or range of affect. His vitals signs are within normal limits. On physical examination, there is a noticeable coarse tremor of his hands, left greater than right. His gait is slow moving and broad-based.

Which of the following brain structures is most likely affected in this man's condition?

  1. caudal raphe nuclei
  2. hippocampus
  3. locus ceruleus
  4. nucleus basalis of Meynert
  5. substantia nigra

Answer(s): E

Explanation:

This patient suffers from Parkinson's disease, a disorder involving decreased dopaminergic transmission. The nigrostriatal system originates in the substantia nigra. It is the primary dopaminergic tract in the central nervous system and is significantly affected in Parkinson's disease. The caudal raphe nuclei are the origin of the serotonergic system in the brain. The hippocampus is responsible for emotional and memory processing. The locus ceruleus is the location of the norepinephrine cell bodies. The nucleus basalis of Meynert is where the neurotransmitter acetylcholine originates.

The concern with treating agitation and psychosis in patients with Parkinson's disease is that antipsychotics block certain dopamine receptors, which can subsequently worsen the Parkinson's symptoms. While clozapine has minimal extrapyramidal symptoms (EPS), its risk of agranulocytosis and need for regular blood monitoring make it less practical as a first-line agent. Haloperidol is a high potency neuroleptic. It is efficacious in treating psychotic symptoms and reducing agitation, but its potency also presents a significant risk of worsening the Parkinson's disease. Risperidone is an atypical, or second-generation, antipsychotic. Although the risk of EPS at low doses is less than with haloperidol, risperidone tends to still be more of a problem when compared with other atypical medications. Thioridazine is another older antipsychotic. While its lower potency creates less EPS and, therefore, less likelihood of worsening Parkinson symptoms, it has significant anticholinergic side effects that may worsen the confusion. A more concerning risk is prolongation of the QTc interval on ECG, potentially causing a ventricular arrhythmia. Quetiapine is a second-generation antipsychotic medication with essentially no EPS. This gives it a unique advantage in treating the psychosis and/or agitation in Parkinson's patients without also worsening the movement disorder.



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