DSM Criteria for Delirium

Delirium, not to be confused with dementia.

The DSM criteria for delirium:

  1. Disturbance of consciousness
  2. Change in cognition
  3. Develops over a short period of time (hours to days) and fluctuates
  4. There is an identifiable general medical condition (or is substance induced)

It is important to recognize a delirium so that the underlying condition can be treated. It is also important because the delirium itself can be harmful to the patient, for example if someone who is delirious walks out into the cold with only a housecoat.

The longer one has delirium, the longer is takes to resolves, even after the underlying condition is treated.

If someone asks you to asses the level of competency of a person with delirium, it’s best to defer. Competency is both TIME- and QUESTION-dependent, so if you are asking someone when they are lucid, they could still be deemed competent, even if they are likely going to return to being delirious.

Mnemonic for delirium: I WATCH DEATH

  1. Infectious: UTIs, pneumonia, meningitis
  2. Withdrawal: alcohol, benzos
  3. Acute metabolic: liver or kidney failure, electrolytes
  4. Trauma: post-op, head injury
  5. CNS pathology: tumor, stroke, seizure
  6. Hypoxia: anemia, PE, heart failure
  7. Deficiencies in vitamins: thiamine, B12, folate
  8. Endocrine: Glucose, thyroid, adrenal, parathyroid (hypercalcemia)
  9. Acute vascular: shock, hypertensive ecephalopathy
  10. Toxins: alcohol, benzos, anticholinergics, opioids, anesthetics, anticonvulsants, dopaminergic agents, steroids, insulin, antibiotics (quinolines), NSAIDs
  11. Heavy metals: lead, arsenic, mercury

Work up


  1. CBC, BUN, Creatinine
  2. Extended electrolytes (Na, K, HCO3, Ca, PO, Mg)
  3. Glucose
  4. Liver function tests
  5. Albumin
  6. Urine culture
  7. TSH
  8. Vitamin B12 & folate

And maybe

  • ECG
  • CXR
  • Blood cultures
  • CT head
  • Heavy metal screen
  • Lumbar puncture
  • EEG

But I want to earn the radiologist tons of money…
Only if they have:

  • Focal neurological deficit
  • Acute change in status
  • Anticoagulant use
  • Acute incontinence
  • Gait abnormality
  • History of cancer

Parkinson’s Disease

Parkinson’s Disease is a degenerative movement disorder resulting from the death of the dopaminergic neurons in the substantia nigra.

There aren’t any definitive blood tests or imaging for Parkinson’s, so it really comes down to a solid neurological examination.

Generally bradykinesia (slow movement) plus one of the other two cardinal signs

  1. Rigidity (cogwheel)
  2. Tremor (pill rolling)

The other movement signs seen in Parkinson’s

  1. Shuffling gait
  2. Mask-like expression
  3. Postural instability: this is tested with the “pull test” – the examiner stands behind the patient and firmly pulls the patient by the shoulders. Someone with normal postural reflexes should only need to take one step back, someone with postural instability will fall or need to take multiple steps backwards.

Differentiating types of psychosis

Note: my example of a non-bizarre delusion can also be classified as an idea of reference (in which you think that TV or songs are talking about you)

Many psychiatric and general medical conditions can have symptoms of psychosis and mood disorders. The way to figure them out is to look at the timeline and the onset of the psychotic vs. mood symptoms (which came first, are they always at the same time, was there something else going on)

Disorder Duration Psychotic Symptoms Mood Disorder
Schizophrenia More than 1 month of symptoms, disturbance persisting for more than 6 months Present (delusions, hallucinations) Brief duration of mood symptoms
Schizoaffective Disorder Same as schizophrenia Present all along (with and in the absence of a mood disorder) Brief and only at time of psychotic symptoms
Mood Disorder with Psychotic Features Meeting the criteria for depression or bipolar I/II Only at time of mood disorder Present in the absence of psychotic symptoms
Schizophreniform Disorder More than 1 month of symptoms, disturbance persisting less than 6 months Present Brief duration of mood symptoms
Substance-Induced Psychosis During or within 1 month of intoxication or withdrawal (longer implies underlying psychotic disorder) Prominent hallucinations or delusions May exist concurrently
Delusional Disorder At least 1 month Non-bizarre delusions (has never met criterion A in DSM for schizophrenia) Brief in relation to the duration of delusional period

*Brief psychotic disorder: symptoms more than 1 day, less than 1 month and not better accounted for by another psychotic disorder

Hallmarks of Alzheimer’s Dementia

For a dementia to be considered to be Alzheimer’s, it must meet specific criteria

  1. Memory impairment
  2. 1 or more of:
    • Aphasia: language disturbance
    • Apraxia: inability to carry out motor activities despite intact motor function
    • Agnosia: can’t identify objects despite intact motor function
    • Disturbance in executive functioning (SOAP – sequencing, organizing, abstracting, planning)
  3. Cognitive deficits (in 1 and 2) are a decline from functioning and cause impairment in social or occupational functioning
  4. Gradual onset with ongoing decline
  5. Cognitive decline not due to other processes, medical illness (thyroid, B12, folate, hypercalcemia, HIV), substance
  6. Not due to delirium
  7. Not due to mood, anxiety or psychotic disorder