Dementia is differentiated from the normal ageing process by the severity and widespread nature of cognitive decline. Cognitive function refers to a group of mental processes including attention, memory, learning, reasoning, thinking, problem solving, decision making, and producing and understanding language. Healthcare professionals should refer individuals showing signs of mild cognitive impairment (MCI) to memory assessment services to aid early identification of dementia. Currently, more than 50 per cent of people with MCI go on to develop dementia. NHS health checks on people aged 65-74 must raise awareness of the signs and symptoms of dementia, and signpost people to memory services as appropriate.

Early recognition and diagnosis, alongside effective intervention and support, can enable dementia patients to live well by improving their quality of life, or delaying or preventing care home admission. It also allows patients and their families to prepare and make any advance decisions about the care they wish to receive in the later stages of the disease. It is therefore important to make the diagnosis, explain the diagnosis to the patient and their family, and provide both verbal and written support and information during the diagnosis. Forgetfulness and confusion can be symptoms of another condition, or have a modifiable cause. These include:

• Depression and anxiety
• Brain tumour
• Hypothyroidism
• Vitamin B deficiency
• Pain
• Impaired vision or hearing
• Stress
• A sudden life change
• Delirium, possibly due to:
  
  • Anaemia
  • Low blood sugar
  • Diarrhoea or constipation
  • Medication
  • Infection
  • Post surgery.

Therefore, at the time of MCI presentation, the following screening should be carried out:

• Haematology, including vitamin B12 and folate serum levels
• Biochemistry tests, including electrolytes, calcium, glucose, and renal and liver function
• Thyroid function tests
• A midstream urine test, if delirium is a possibility
• A medication review to identify and minimise drug use, including OTC products that could affect cognitive function.

Once any MCI causes have been eliminated, a dementia specialist should assess the patient. There is no single laboratory test for this, but a clinical diagnosis can be made by a combination of the following:

• History taking
• Cognitive and mental state examination
• Physical examination
• Brain scan €“ usually MRI.

A diagnosis of a subtype of dementia should be made by a healthcare professional who has expertise in differential diagnosis using international standardised criteria. Confirmation of the suspected cause can only be made postmortem or, in very rare cases, through a brain biopsy.