Tests for dementia

A GP often carries out initial tests, which should include taking a history of symptoms, a physical health check, blood tests and cognitive tests. Cognitive tests may include questions about the date, the location and a short-term memory test.

The cognitive tests assess a number of different things including:

  • short- and long-term memory
  • concentration and attention span
  • language and communication skills
  • awareness of time and place (orientation)

Many carers we interviewed witnessing these tests reported being amazed to discover just how much memory loss there was. A GP may make a diagnosis or refer the person for further tests. Usually further tests are carried out in a specialist department. The decision as to whether the ongoing referral is to memory assessment service, a neurologist, psychiatrist, geriatrician or psycho-geriatrician will depend on the nature of the symptoms, especially in younger people where dementia is rare and neurological or psychiatric problems may need to be excluded first. For a lot of the people we talked with, in 2003/4, it was not uncommon that the diagnostic process including waiting for a specialist referral took at least a year; this has hopefully improved since initiatives such as the National Dementia Strategy for England (Department of Health 2009) and others were introduced.

A complete assessment will include taking a thorough history of the symptoms, talking to friends/relatives/carers where possible, and carrying out investigations for any conditions that might have caused the symptoms described. This may include blood tests, urine tests and a physical examination, and a medicine review to check for any medicines that may impair cognitive functioning.

The blood tests help to exclude other causes of symptoms that can be confused with dementia. In most cases, these blood tests will check:

  • liver function
  • kidney function
  • thyroid function
  • haemoglobin A1c (to check for diabetes)
  • vitamin B12 and folate levels

If your GP thinks you may have an infection, they may also ask for a urine test or other investigations.

Specific tests for dementia always include cognitive tests. A doctor usually refers the patient to the Memory Clinic where medical specialists in dementia work together. The patient has a brain scan, usually a CT scan, and sometimes an MRI scan. A CT scan takes only a few minutes and does not require the patient to actually go inside the scanner, so is acceptable to most people. Other types of scan, such as a SPECT scan or a PET scan, may be recommended if the result of the MRI or CT scan are uncertain. They may also do further, more detailed memory tests.

Some carers are anxious that a scan may be frightening, however, so in some cases a diagnosis may be made without supporting evidence of a scan.

Describes how the diagnosis of Alzheimer’s disease was made.

The diagnostic process should involve taking a thorough history from the carer as well as the person with dementia. In some cases, particularly where an elderly couple are living independently, another family member may be needed to give a clear picture of the situation. Several people expressed concern that they were not included in the process of taking a history. Doctors did not ask for the carer’s account of their day to day existence and their abilities and accepted the patient’s account of things, which people felt bore no relation to reality. Some specialists appeared to forget that once they had made their diagnosis the problems of the person living with dementia and of the person supporting them had not necessarily been resolved.

Describes why he feels it was inappropriate to refuse to include him in the investigation of his wife’s problems.


Since the National Dementia Strategy for England was launched in 2009-2014, the process of diagnosing dementia seems to be quicker for many than it was for the people we interviewed in 2003/4, but services do differ across the country.

Diagnosis of dementia

When there are symptoms suggesting the onset of dementia, an accurate diagnosis is wanted from carers so that they can understand what is going on...

Getting the diagnosis of dementia

Carers may have very different feelings about how to break the news when a diagnosis of Alzheimer's disease or another type of dementia has been...