How dementia is assessed and diagnosed

Expert reviewer, Dr Rahul Bhattacharya, Consultant Psychiatrist
Next review due, March 2023

Diagnosing dementia can be difficult and take time. You probably won’t get a definite answer immediately. There are many different types of dementia. In older people, other conditions can be confused with dementia, including delirium and depression.

It’s very important to see a health professional if you’re concerned about symptoms such as memory problems in yourself or a loved one. You can’t diagnose dementia on your own.

What to do if you notice dementia symptoms

If you’re worried that you’ve been forgetting things more than usual, it’s worth booking an appointment with your GP. Sometimes, your GP may ask you if you have any concerns about your memory, even if you’re visiting them about something else. This might be if you’re considered to be at increased risk of dementia due to other health conditions. You might also be assessed for dementia if you’ve been admitted to hospital for other reasons.

If you notice a loved one is having problems with their memory or other changes in behaviour, try to encourage them to visit their GP too. It’s a good idea if someone who knows the person well, such as a close family member, goes too. Early symptoms of dementia are often more noticeable to friends and family than the person themselves.

Can I go to a loved one’s GP appointment?

You can go with someone to their GP appointment if they agree. However, everyone has the right to confidentiality from their doctor – it’s up to your loved one if they’d prefer to go alone. If they do go alone, the GP may ask to see you separately or phone you later. Without permission, they usually won’t be able to give you any details about the person’s care, but they can listen to any information that you give them.

You can’t force someone to see their GP. Try to talk to your loved one about why it might be a good idea. If they don’t want to go, you can still contact their GP to tell them about your concerns. If they think necessary, the GP might then speak to your loved one and try to persuade them to come to the surgery.

What will happen at the GP?

It helps to have some idea of what the doctor will ask during the consultation so that you can be prepared. You may also want to jot down any questions you have in advance so you don’t forget at the time.

What the GP will ask

The doctor may ask about the person’s medical history – they’ll want to know about any other conditions they have and medicines they’re taking. They’ll ask about symptoms and whether these have come on gradually or suddenly. They may ask about:

  • memory problems and confusion
  • changes in behaviour and mood, for instance, if the person has felt more depressed, anxious or angry than normal
  • how symptoms are affecting normal daily activities – such as preparing meals, housework and personal hygiene, for instance

The doctor may also use a special questionnaire or tool to assess symptoms. Find out more about this in the section below, Tests for dementia.


As well as asking about dementia symptoms, the doctor will need to do a general health assessment. They’ll carry out an examination and do some basic tests such as blood tests, and sometimes urine tests. This is done to rule out other possible causes of symptoms, such as thyroid problems.

What happens next

The GP should explain their findings so far at the end of their assessment, but they’re unlikely to confirm a diagnosis of dementia on the spot. If they suspect it might be dementia, they’ll make a referral to the local memory clinic or older persons’ mental health team for a fuller assessment.

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Seeing other specialists

Assessment by a specialist aims to confirm a diagnosis of dementia, as well as the type of dementia, when possible. The most common type of dementia is Alzheimer’s disease, and this is usually more straightforward to diagnose. Most people with suspected dementia will be referred by their GP to local mental health services for older people, or the local memory clinic. These services have teams of different health professionals who specialise in helping people with memory problems and suspected dementia.

Sometimes, the GP may refer the person to a consultant in a particular speciality instead – such as a specialist psychiatrist or a neurologist. Neurologists specialise in diseases of the brain or nervous system. This will only be in certain circumstances, such as:

  • the person with suspected dementia is under 65 years old
  • the symptoms seem to be getting worse more quickly than is normal
  • there’s likely to be a genetic cause for dementia
  • there are symptoms affecting a particular region of the body – such as an arm or leg, or vision, hearing or speech problems

These factors often indicate rare types of dementia that tend to be more common in younger people, and are often inherited. These include rare subtypes of Alzheimer’s disease, vascular dementia, dementia with Lewy bodies and frontotemporal dementia. Dementia can also more rarely be caused by certain other conditions, including Parkinson’s disease and Huntington’s disease.

You shouldn’t have to wait more than six weeks for a referral. The specialist will carry out more detailed and in-depth assessments and tests, to make a formal diagnosis of dementia. See section below, Tests for dementia, for more information.

In certain cases, they may suggest a brain scan to help with diagnosis. CT and MRI scans are most commonly used for this. For some rarer types of dementia, you may have other types of brain scan that can assess how your brain is functioning.

Tests for dementia

There are a number of different tests doctors use to help diagnose dementia. Some of the names of these tests include the General Practitioner Assessment of Cognition (GPCOG), the Memory Impairment Screen and the Mini-Cog, but they’re all similar. They’re designed to pick up issues around memory, language, understanding and attention.

Some tests are designed to be carried out as an initial assessment by your GP. Others are more in-depth, and will be carried out following referral to a memory clinic or specialist. The person being tested may be asked to do a number of things, including:

  • repeat certain words or phrases, or recall these at the end of the test
  • identify different pictures, or name as many of something as they can (animals, for example)
  • do some simple maths
  • follow simple commands
  • do some simple drawing, such as copying shapes or drawing a clock

The doctor will also ask questions to find out whether the person knows where they are, is aware of recent events, and the time and date.

If your loved one is being tested, it’s important not to jump in to help. The purpose is to see if they can answer the questions themselves. The doctor will be looking at certain things, such as if the person being tested remembers the right words to use and how fluently they can speak. The doctor may talk to you informally about symptoms you’ve noticed in your loved one, or they may ask you to carry out a more structured questionnaire.

Diagnosing dementia is difficult, particularly in the early stages. No single test can provide a definite diagnosis. If a clear diagnosis can’t be made, your doctor might suggest returning in a few months to see whether there is any change in the person’s symptoms.

Can I do an online test for dementia?

You may find quizzes and tools online that claim to be able to spot dementia symptoms. Some may be based around the tests that clinicians use, but it’s important to remember that these don’t work as stand-alone tools. They always need to be delivered and interpreted by a medical professional.

While it’s understandable that many people look for information on how to diagnose dementia, it isn’t possible to diagnose dementia yourself. It’s really important to see a doctor if you’re concerned about yourself or a loved one.

Memory and mental state tests aren’t foolproof. How you perform in them can be affected by many things, including how you feel that day, your language, and other health problems and your education. A doctor will take all this into account. And while tests can help with a diagnosis, they’re not the only thing your doctor will look at. They will also do a physical examination and tests, assess other dementia symptoms, and take into account your past medical history, general mood and appearance. Your doctor will bring all of this information together when making a diagnosis.

If the diagnosis isn’t clear, your doctor can also look at how things are changing over time, rather than at one point in time – as with an online test. Your doctor may also be able to pick up on more subtle changes in your memory, which might be a sign of mild cognitive impairment.

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Related information

    • Making a diagnosis. Alzheimer's Society., accessed 15 January 2020
    • Dementia. NICE Clinical Knowledge Summaries., last revised July 2019
    • Assessment process and test. Alzheimer's Society., accessed 15 January 2020
    • Dementia: assessment, management and support for people living with dementia and their carers. National Institute for Health and Care Excellence (NICE), published June 2018.
    • Memory loss and dementia. Alzheimer's Society., accessed 15 January 2020
    • Confidentiality: good practice in handling patient information. Ethical and legal duties of confidentiality. General Medical Council, published January 2017.
    • Helping you to assess cognition. A practical toolkit for clinicians. Alzheimer's Society, 2015.
    • What causes young-onset dementia? Alzheimer's Society., accessed 12 February 2020
    • Prime Minister's challenge on dementia 2020. Department of Health, February 2015.
  • Reviewed by Pippa Coulter, Freelance Health Editor, Bupa Health Content Team, March 2020
    Expert reviewer Dr Rahul Bhattacharya, Consultant Psychiatrist
    Next review due March 2023