Memory Loss

Differential Diagnosis

Occasional Diagnoses

Rare Diagnoses

  • Personality Disorder
  • Malingering
  • Intractable Epilepsy
  • Carbon Monoxide Poisoning
  • Herpes Simplex Encephalitis

Ready Reckoner

Key distinguishing features of the most common diagnoses

Aware of ProblemPossibleNoPossiblePossibleYes
Memory Loss Recent EventsYesYesPossibleYesYes
Memory Loss Remote EventsPossibleNoPossibleNoNo
Neurological SignsPossiblePossiblePossibleNoNo
Sudden OnsetYesNoYesNoNo

Possible Investigations

Likely:(Unless obvious depression or anxiety) FBC, TFT, LFT, calcium.

Possible:B12 and folate levels, CT/MRI scan.

Small Print:Syphilis serology

  • FBC may show raised MCV, suggesting either alcohol abuse or B12/folate deficiency. Check B12 and folate levels if MCV raised.
  • TFT: Hypothyroidism is an important remediable cause of dementia.
  • LFT and γGT will give useful clues to alcohol intake (history likely to be unreliable).
  • Calcium level: May show hypo- or hypercalcaemia.
  • Syphilis serology: For possible neurosyphilis as underlying cause of dementia.
  • CT scan/MRI: Will detect space-occupying lesions, cerebrovascular disease, atrophy and subarachnoid haemorrhage.

Top Tips

  • Patients with dementia are often unaware of, or deny, their memory loss; the problem is more often brought to the GP’s attention by a concerned friend or relative.
  • Patients who present themselves to the GP complaining of memory loss are most likely to be suffering from anxiety or depression.
  • Even if a diagnosis of anxiety or depression seems obvious, patients are likely to be concerned about the possibility of dementia, which will exacerbate the situation; explaining that the problem is more to do with poor concentration than failing memory will help reassure them.
  • Establishing the onset gives valuable clues to the problem – a dementia pattern progressing slowly over a year or two is likely to be Alzheimer’s or multi-infarct dementia; with a shorter history, an underlying cause is possible; and sudden onset of memory loss is likely to be caused by a vascular event or trauma.
  • It can be very difficult to distinguish between depression and dementia – and the two may coexist. Consider a trial of antidepressants.

Red Flags

  • Rapid onset of apparent dementia over 3–6 months or less suggests a possible underlying cause.
  • True memory loss after a head injury suggests significant trauma.
  • Depression in the elderly may mimic dementia (pseudodementia) with behavioural changes like hoarding and bad temper. Do not miss this treatable condition.
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