10 acute confusion facts
Here we provide 10 medical revision notes about acute confusion (also known as delirium or acute confusional state, ACS), distinguishing it from chronic confusion (e.g. dementia).
Key Points
- Acute confusion is an acute, transient, and typically reversible disturbance in attention, cognition, and consciousness
- Common causes include almost any infection, metabolic disorder, or drug
- Diagnosis is clinical, supported by blood tests and imaging to identify the cause
- Treatment involves correcting the underlying cause and providing supportive care.
1. Definition
- Acute confusion is a mental state characterised by confusion, disorientation, and impaired thinking or memory. Patients may be unable to think clearly or remember recent events
- Affects 1 in 5 elderly patients on wards.
Types: hyperactive (agitation, delusions, hallucinations, wandering, aggression); and hypoactive (lethargy, slow tasks, excessive sleeping, inattention).
2. Epidemiology
- Acute confusion can affect people of any age but is more common in older adults
- At least 20% of older patients admitted to hospital experience ACS; 15-50% will develop delirium during hospitalisation
- It’s common post-operatively, in nursing home residents, and in ICU patients
- In younger people, it’s usually due to drug use (recreational or prescribed) or a serious systemic condition.
3. Risk Factors
- Advanced age
- Pre-existing cognitive impairment (especially dementia)
- Multiple chronic illnesses
- Sensory impairment (vision or hearing)
- History of previous delirium.
4. Causes (‘SIDMADS’)
There are seven main groups of causes:
- Surgery (especially post-op)
- Infection (UTI, pneumonia, wound infections)
- Dehydration (pre-renal AKI)
- Medication (e.g. opiates, psychotropics; changes in dose or withdrawal)
- Alcohol or drug withdrawal/excess
- Diabetes and metabolic imbalances (e.g. hypo/hyperglycaemia, hyponatraemia, hypercalcaemia)
- Systemic failures (e.g. renal, liver, heart, or lung)
Notes:
- Acute confusion is often multifactorial, e.g. an elderly post-op patient with pneumonia and dehydration.
- Alcohol withdrawal delirium is also called ‘delirium tremens’ or DTs.
- Acute confusion rarely results from new brain pathology (e.g. stroke), though encephalitis can cause it.
5. Symptoms
- Altered consciousness, disorientation, impaired attention, hallucinations, agitation, or lethargy
- Symptoms of the underlying cause may dominate (e.g. pneumonia)
- Onset is rapid, often within hours or days, and symptoms may fluctuate, often worsening at night.
6. Diagnosis
- Primarily clinical, based on history, physical examination, and cognitive assessment. Use the 10-question Mental Test Score (MTS)
- Key investigations include:
- Bloods: FBC, clotting, CRP, U&Es, LFTs, bone profile (?calcium), glucose
- Urine: dipstick
- ABG: May make a diagnoses like DKA or hypercalcaemia, or indicate severity (lactate or acidosis)
- Cultures: Blood, MSU, sputum, wound
- Imaging: CXR is essential; consider CT head if no improvement in 3 days or if otherwise indicated.
Top Tip:
If you can’t recall the full MTS (!), use the simple 3-question assessment:
- “Is the patient oriented in place, time, and person?”
A score of 3/3 (knowing where they are, the day, and their full name) and/or knowing the date, usually indicates they are not confused.
Differential diagnosis
- Acute confusional state and dementia are the most common causes of cognitive impairment, although mental health disorders (e.g. depression) can also disrupt cognition
- Acute confusion and dementia are separate disorders but are sometimes difficult to distinguish. In both, cognition is disordered. However, the following helps distinguish them:
- ACSs affects mainly attention and awareness
- Dementia affects mainly memory and other cognitive function
- An ACS is typically caused by acute illness or a medication/recreational drug toxicity (sometimes life threatening) and is usually reversible
- Dementia is typically caused by anatomical changes in the brain, has slower onset, and is generally irreversible.
Note. Mistaking delirium for dementia in an older patient is a common clinical error. This can have serious long-term social implications. So you should try not to make this error.
7. Treatment
- Treat the underlying cause (review drug chart carefully)
- Supportive care: safe environment, reorientation, hydration, nutrition
- Consider medications for severe agitation or psychosis (e.g. haloperidol or lorazepam) – only if necessary.
Top Tip:
Always ask yourself: Why am I not giving IV fluids and antibiotics? Have I checked the drug chart thoroughly? What does the CXR show?
8. Complications
If not treated promptly, acute confusion can lead to longer hospital stays, prolonged cognitive impairment, and increased mortality, particularly in older adults.
9. Outlook
With timely and appropriate treatment, acute confusion is usually reversible, and patients typically return to their baseline cognitive function.
10. Prevention
Preventive strategies include:
- Managing risk factors (hydration, nutrition)
- Promoting sleep and minimising high-risk medications
- Early mobilisation in hospitalised patients, especially post-operatively.
Summary
We have described 10 revision facts about acute confusion, focusing on its causes, symptoms and treatment options. We hope this information helps you! 😊
