Memory Loss
Differential Diagnosis
Common Diagnoses
- Anxiety/Stress
- Depressive Illness
- Dementia (Multi-infarct, Alzheimer’s Disease and Dementia with Underlying Cause, Such as Tumour, Neurosyphilis, Hypothyroidism, Vitamin B12 and Folate Deficiency)
- Trauma: Head Injury
- CVA (Infarct in Posterior Cerebral Artery Territory)
Occasional Diagnoses
- Chronic Excess Alcohol Intake (Thiamine Deficiency: Korsakoff’s Syndrome)
- Subarachnoid haemorrhage
- Other Thiamine Deficiency: Malabsorption, Carcinoma Stomach, Hyperemesis Gravidarum
- Transient global amnesia
- Fugue States and Psychogenic Amnesia
- Tumour of Third Ventricle or Hypothalamus
Rare Diagnoses
- Personality Disorder
- Malingering
- Intractable Epilepsy
- Carbon Monoxide Poisoning
- Herpes Simplex Encephalitis
Ready Reckoner
Key distinguishing features of the most common diagnoses
| Trauma | Dementia | CVA | Depression | Anxiety | |
|---|---|---|---|---|---|
| Aware of Problem | Possible | No | Possible | Possible | Yes |
| Memory Loss Recent Events | Yes | Yes | Possible | Yes | Yes |
| Memory Loss Remote Events | Possible | No | Possible | No | No |
| Neurological Signs | Possible | Possible | Possible | No | No |
| Sudden Onset | Yes | No | Yes | No | No |
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.