Tests and scans used to diagnose dementia

A dementia diagnosis can be based on several tests, scans and assessments. This page describes the tests and scans you might have if your GP refers you to a specialist.

How will a specialist test for dementia?

Going to a specialist appointment can feel scary and confusing if you have possible symptoms of dementia.

But a specialist’s assessment will be similar to those you have already done at your GP surgery. It will just be more detailed to give them as much information as possible. This includes taking a history, and physical examinations and tests.

The specialist may ask you questions that feel quite personal, about your life, relationships, home environment and mental health. They need as much information about you as possible to understand what could be causing your symptoms.

Talking to your GP about dementia

If you're preparing to talk to your GP about memory problems, read our advice to help you make the most of your conversation.

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Mental ability tests

You will have a more detailed assessment to understand your mental abilities. The specialist will see how you answer different types of questions – for example:  

  • using your memory to recall a list of items
  • factual information, for example about the time and place
  • interpreting shapes
  • solving problems.

If you are having an appointment by video call, you can write answers on a piece of paper and hold this up to the screen to show the specialist.

There are different versions of these tests, which have different names.

The Mini-Mental State Examination (MMSE) used to be the most commonly used test. Other versions of this test include MoCA (Montreal Cognitive Assessment) and ACE-III. These tests have slightly different questions, but are all designed to check your mental abilities in the same way. 

You do not need to prepare for any tests. It’s understandable to want to do ‘well’ in the test, but it’s very important that your health professional understands how your mind is working. Feeling as relaxed as possible will help you to complete the test as well as you can.  

These tests cannot be used on their own to diagnose dementia. But they can help the specialist work out the type of problem you may have, particularly in the early stages of your symptoms.

The assessment can also be used to compare with later tests you may do, to see if anything has changed.

Brain scans

Some people may have a scan to check for changes in the brain. Not everyone needs a scan, especially if it is already clear what is causing your symptoms. Brain scans do not hurt, and you will not need time to recover. The health professional will explain what these different scans involve.

CT (computerised tomography) and MRI (magnetic resonance imaging) are the most common scans used to check for changes in the brain.

CT scans

CT scans can check for signs of stroke or a brain tumour. But they cannot provide detailed information about the structure of the brain.

MRI scans

MRI scans can help confirm the type of disease causing a person’s dementia. It can do this by: 

  • showing if blood vessels are damaged, which happens in vascular dementia 
  • showing which parts of the brain are shrinking (getting smaller). This helps find out which type of dementia a person has, as different diseases that cause dementia affect different parts of the brain.  

The MRI machine can be very loud so you may be offered earplugs. You will also have to stay as still as you can. If you are uncomfortable with loud noises, or have trouble staying still, you should discuss this with your doctor before your appointment.

Other specialist brain scans

If the result of your MRI or CT scan is not clear, you may have another type of scan called a SPECT scan or a PET scan.

These scans can show if there are problems with the blood flow in the brain. If the specialist thinks you could have dementia with Lewy bodies or Parkinson’s disease dementia, you may have a scan of the brain called a DAT scan.

These scans involve the injection of liquid and special scanning equipment that can look at how the brain is working, rather than what it looks like.

It can take a long time to get an appointment for a brain scan, so the specialist may give you a temporary diagnosis while you wait. 

Your scan may not show any unusual changes in your brain. This could mean that you do not have dementia, but does not rule it out. If your dementia is in an early stage, it may not be seen on the scan.

How we can support you

Call our support line for advice, or connect with people in similar situations through our online community

Dementia Connect support line
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