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Probability diagnosis

Severe anxiety/stress

Major depression esp. post ECT


Head injury

Alcohol excess incl. Korsakoff syndrome

Iatrogenic e.g. ECT, cardiac bypass surgery

Serious disorders not to be missed


  • Cerebral haemorrhage/subarachnoid

  • Cerebral infarction esp. vertebrobasilar


  • Cerebral e.g. meningitis, abscess

  • Viral encephalitis e.g. Herpes Simplex

  • Syphilis



  • Cerebral tumour

  • Paraneoplasia


  • Anoxia/hypoxia

  • Hypothermia

  • Electrolyte disturbance esp. hyponatraemia

  • Dehydration

  • Post-ictal state

Pitfalls (often missed)

Transient global amnesia

B1 deficiency incl. alcohol abuse

Dissociative fugue states

Depersonalisation disorder


  • Wernicke’s encephalopathy

  • Carbon monoxide poisoning

Masquerades checklist

Depression esp. major

Diabetes: hypoglycaemia

Drugs: various e.g. Cannabis, amphetamines (see list)


Thyroid/other endocrine: hypercalcaemia/hypothyroid?

Is the patient trying to tell me something?

Conversion reaction (hysterical fugue)

Psychogenic amnesia/malingering

Key history

A careful history is required recording the nature of memory loss incl. onset, duration, fluctuation and associations. Interview family members and check for possible bizarre behaviour. The key history should incl. past medical history including diabetes, hypertension, cerebrovascular disease; drug history esp. alcohol, smoking or illicit drugs (cannabis, amphetamines, opioids, solvent sniffing), lithium, barbiturates, benzodiazepines, anticonvulsants, digoxin, OTC drugs, etc.; and psychiatric history, incl. severe anxiety, stress, depression, fugue features, dissociation or personality disorder.

Key examination

  • General features: appearance of patient incl. central cyanosis, hydration status, vital signs

  • Psychiatric assessment and mental state examination

  • Neurological examination

Key investigations

First line:

  • urinalysis

  • blood sugar

  • pulse oximetry

  • FBE & ESR

  • LFTs (γGT)

  • Others according to history and findings


  • blood gases

  • TFTs

  • syphilis serology

  • CXR

  • imaging: cerebral CTscan or MRI

Diagnostic tips

Consider memory loss as a presenting feature of severe stress, anxiety or depression (which can present as pseudo dementia in the elderly).

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