Amnesia, dissociative disorders and delirium: Pathology review

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Amnesia, dissociative disorders and delirium: Pathology review

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Amnesia, dissociative disorders and delirium: Pathology review

USMLE® Step 1 questions

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USMLE® Step 1 style questions USMLE

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A 72-year-old woman is brought to the emergency department by their son for evaluation of confusion. The patient's son reports that he went to the patient’s apartment to check on the patient and found her lying on the ground. The son explains that “She couldn’t tell me what happened, so I called 911.” The patient’s past medical history includes hypertension, hyperlipidemia, diabetes, and a recent left femoral neck fracture. The patient’s current medications include lisinopril, metformin, atorvastatin, ibuprofen, and acetaminophen. The patient is currently employed as a lawyer and has been working at home since the fracture. Temperature is 38.3°C (100.9°F), pulse is 104/min, respirations are 22/min, blood pressure is 107/70 mmHg, and O2 saturation is 93% on room air. Initial assessment demonstrates an elderly female who appears confused. The patient states, “What you are trying to do to me here is illegal. You are trying to lock me up and throw away the key!” Physical examination reveals a left lower extremity in a cast with adequate capillary refill and without other signs of injury or trauma. The patient is not physically abusive and follows directions given by the physician and nurses. A chest X-ray is demonstrated below.  Which of the following best describes the etiology of this patient’s confusion?

Reproduced from: wikipedia


78 year old Joanne is brought in by her son, who is worried because Joanne seems to forget things all the time.

You start by introducing yourself, and then explain to Joanne the reason she’s in the hospital.

You then ask her a few things about herself.

She looks confused and tells you that she used to be a Broadway singer before retiring and she has travelled all around Europe.

Her son tells you she used to work as a sales woman and she’s never been to Europe in her entire life.

A few minutes later, Joanne asks her son where they are and who you are.

On physical examination, you notice a strong alcoholic odor, so her son reluctantly tells you that Joanne has a history of chronic alcohol abuse.

Next to her, a 66 year old man is also brought to the hospital, after being found by the police wandering in the streets, with a battered suitcase.

He doesn’t seem to know his name, location, or where he was going, and stares blankly when you ask him anything.

The only thing he is able to tell you is that he is going on a business trip.

When you contact his relatives, they tell you that his name is Matthew, and that he was recently fired from his job.

Physical examination is unremarkable.

Based on the initial presentation, both Joanne and Matthew seem to have some form of amnesia, dissociative disorder, or delirium.

Okay, starting with amnesia, this can be categorized into two types.

The first type is anterograde amnesia, which refers to an inability to form new memories, often forgetting what happened hour to hour.

The second and probably most high yield type of amnesia is retrograde amnesia, and it refers to an inability to recall old memories.

As a result, they may completely forget important people or moments in their life, which can cause anxiety for the individual experiencing retrograde amnesia, as well as their friends and family.

Both anterograde and retrograde amnesia can be caused by acute and chronic conditions.

Acute causes include traumatic brain injury or infections that may cause brain inflammation, such as herpes simplex.

On the other hand, chronic causes include brain tumors and neurodegenerative diseases, including Alzheimer disease or other forms of dementia.

For your exams, what’s extremely high yield to remember is that amnesia can also result from vitamin B1 or thiamine deficiency.


Pathologically, amnesia is defined as a loss of memory despite otherwise normal cognitive function. It can be due to damage to the brain like in stroke, or degenerative diseases that affect the brain. Dissociative disorders are a group of conditions that involve disruptions in consciousness, identity, and/or memory. Delirium is a mental state characterized by alteration of attention, consciousness, and cognition.

Amnesia can be divided into three subtypes: anterograde amnesia, retrograde amnesia, and transient global amnesia. Anterograde amnesia is the inability to form new memories following the onset of amnesia. Retrograde amnesia is the inability to recall memories that were formed before the onset of amnesia. Transient global amnesia is a brief episode of complete or nearly complete memory loss.


  1. "Robbins Basic Pathology" Elsevier (2017)
  2. "Harrison's Principles of Internal Medicine, Twentieth Edition (Vol.1 & Vol.2)" McGraw-Hill Education / Medical (2018)
  3. "Pathophysiology of Disease: An Introduction to Clinical Medicine 8E" McGraw-Hill Education / Medical (2018)
  4. "Dissociative disorders in DSM-5" Depression and Anxiety (2011)
  5. "Prevalence of dissociative disorders among women in the general population" Psychiatry Research (2007)

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