Dementia symptoms and diagnosis

Your health expert: Dr Pravir Sharma, Consultant Psychiatrist
Content editor review by Liz Woolf, December 2022
Next review due December 2025

From time to time, we all forget someone’s name, or why you went into a room. That doesn’t mean you have dementia. But if someone is increasingly forgetful, has difficulty managing, or doesn’t seem to be the person they were, these can be early signs of dementia.

Early symptoms

The four main types of dementia have different early symptoms. Below is a summary of the early symptoms of each.

Alzheimer’s disease usually comes on very slowly and causes:

  • difficulty learning new things
  • confusion about the date or time
  • getting lost, especially in familiar places

Vascular dementia can come on quickly, often after a stroke. Symptoms depend on the part of the brain affected. They can include:

  • emotional or personality changes
  • short temper or crying more easily
  • memory loss or confusion

Dementia with Lewy bodies (DLB) has very specific early symptoms, including:

  • seeing things that aren’t there (visual hallucinations)
  • variable alertness

Frontotemporal dementia usually comes on very slowly. There are three different types. Early signs depend on the type and include:

  • loss of inhibition, odd and inappropriate behaviour and poor self-care
  • speaking more hesitantly and having difficulty understanding long sentences
  • forgetting words, what things are called or what they’re used for

At the GP

If you’re worried that you or a relative have been forgetting things more often than usual, it’s worth seeing the GP. If your relative agrees, it’s a good idea for someone to go with them. Early symptoms of dementia are often more noticeable to friends and family than the person themselves.

The doctor may ask about any other medical conditions they have and medicines they’re taking. They’ll ask about symptoms and how quickly they’ve come on, including:

  • memory problems and confusion
  • behaviour and mood changes – whether they are more depressed, anxious or angry than normal
  • effect on normal daily activities – cooking, housework and bathing, for instance

They may use a special questionnaire or tool to assess symptoms. The doctor will also need to carry out an examination and do some basic tests, such as blood tests, and sometimes urine tests. This rules out other possible causes of symptoms, such as thyroid problems.

The GP should explain their findings at the end of their assessment, but they probably won’t be able to diagnose dementia on the spot. If they suspect it, they’ll refer you (or your relative) to the local memory clinic or older persons’ mental health team for more assessment.

Seeing specialists

Most people with suspected dementia will have Alzheimer’s disease. Their GP will refer them to local mental health services for older people, or the local memory clinic. They can help with memory problems and suspected dementia.

If your GP suspects a rarer type of dementia, they will refer them to a specialist psychiatrist or specialist in diseases of the brain and nervous system (a neurologist). This may be because:

  • they are under 65
  • symptoms are worsening more quickly than normal
  • there are unusual symptoms, for example seizures or a symptom affecting one part of the body
  • the diagnosis is unclear

The specialist can help to diagnose rarer types of dementia. These are more common in younger people and often inherited. This includes rare subtypes of Alzheimer's disease, vascular dementia, dementia with Lewy bodies and frontotemporal dementia. Dementia may also be caused by another medical condition, such as Parkinson's disease or Huntingdon's disease.

A referral should take around six weeks, but could take longer. The specialist will carry out tests. They may suggest a brain scan, which could be a computer tomography (CT) scan, MRI scan or positive emission tomography (PET) scan.

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To help diagnose dementia, the doctor will ask questions to check whether the person knows where they are, the time and date, and about recent events.

They may use a dementia test that takes the form of a questionnaire. This could be the Memory Impairment Screen (MIS) or the 6-item cognitive impairment test (6CIT). These check for issues with memory, language, understanding and attention. They include asking people to:

  • remember words and phrases and repeat them at the end of the test
  • list types of something, such as animals
  • do simple maths, copy shapes or draw a clock
  • follow simple commands

If you're with your loved one, don't try and help. The doctor needs to see whether they can answer themselves. They’ll be checking a number of things, including memory for language and fluency of speech. As a relative, you may also have a questionnaire to fill in or questions about symptoms you've noticed in your loved one.

Diagnosing dementia isn't easy and takes time. The doctor may suggest you come back in a few months to see if anything's changed. Or if you’ve started any other treatment, for depression or anxiety, for example. It's really important to see a doctor if you're concerned about yourself or someone else. You can't diagnose dementia yourself. You may have seen online quizzes that claim to spot dementia symptoms. These don't work on their own. Doctors are trained in assessing mental state and will take other things into account, including physical symptoms, medical history, general mood and appearance.

There are advantages to seeing a doctor early if you suspect you have dementia. Your symptoms may be caused by something else that can be treated – see our information on this page on conditions that can be confused with dementia. If you are found to have dementia, you will be able to access any treatment sooner. You can also get the information and support that’s available. People diagnosed with dementia earlier are also more likely to be able to stay at home and independent for longer.

After diagnosis

A dementia diagnosis can be overwhelming. Of course, it's upsetting for both the person and their loved ones. But the diagnosis can be a relief. Everyone can now make sense of distressing symptoms and behaviours, which can make them easier to cope with.

Unfortunately, there's no cure for dementia, but there are treatments that can help. The doctor will monitor how well the person responds to their care and treatment. For Alzheimer's disease and dementia with Lewy bodies, medicines are usually started straightaway. If these help, the dose will be gradually increased.

As well as medicines, the specialist or memory clinic may suggest group therapy. Groups can provide mental stimulation as well as opportunities to reminisce and talk about the past. They could take the form of bingo, art or music therapy, or gardening. Planning regular activities can help to build a routine for the person with dementia.

There are also decisions to make about future treatment and support. It’s best to discuss these things when the person with dementia is still able to take part.

Power of Attorney

It’s best to arrange this as soon as possible. It gives carers legal power to make decisions about healthcare and finances. You do this through a solicitor while the person is still able to agree to it.

You can do this if they can no longer make decisions for themselves, but it's more complicated. How you apply varies between countries of the UK. You can find out more on (England and Wales), the Office of the Public Guardian (Scotland) or NI Direct (Northern Ireland).


You may be able to claim Attendance Allowance, Personal Independence Payment (PIP) or Carer’s Allowance. The Alzheimer’s Society has useful benefits information.

Making care decisions

If they're well enough, the person with dementia can make an 'advanced decision' or 'advanced statement'. An advanced decision is sometimes called a ‘living will’.

These detail how people would like to be medically treated and cared for when no longer able to decide for themselves. There's good information about these on the Alzheimer's Society website.


You must tell the Driver and Vehicle Licensing Agency (DVLA) if you've been diagnosed with dementia. They will send you a questionnaire and ask for a medical report from your doctor. As long as your doctor agrees, you can still legally drive while they make a decision. You may be able to keep driving, but this will be reviewed yearly. If they decide you can no longer drive, you have to stop. You can appeal but have to stop driving until the appeal is heard.

Conditions that may be mistaken for dementia

It’s easy to mistake dementia signs for another problem or health condition, or vice versa.

  • Delirium can cause confusion and problems with memory and understanding. But it's usually temporary and comes on quickly. In older people it can be caused by sudden illness – an infection or heart attack.
  • Depression is often mistaken for dementia and may appear before dementia develops. As well as low mood and poor self-care, older people may be disorientated and have memory loss.
  • Generalised anxiety disorder is extreme and long-lasting anxiety. Symptoms similar to dementia include restlessness, poor concentration and disturbed sleep.
  • Hormone conditions that can cause dementia symptoms include an under-or-overactive thyroid gland and an underactive pituitary gland.
  • Head injury or repeated small head injuries over time can cause memory problems, mental slowness and being up and down emotionally. This can be because of a history of contact sports, like rugby.
  • Hearing or sight problems can affect your ability to take in information and make it look as if mental ability is affected.
  • Low levels of B vitamins can cause symptoms similar to dementia. These include confusion, memory loss, irritability and a change in mental state. You need vitamin B12 and thiamine to keep your nervous system healthy.
  • Drinking too much alcohol can cause symptoms similar to dementia. If you do this regularly over a long period, it can cause brain damage and lead to dementia.
  • Reactions to medicines can affect the brain and cause confusion, including painkillers, antidepressants, anxiety medicines and steroids. This is more likely in older people on multiple medications.
  • Mild cognitive impairment (MCI) means problems with memory and thinking that are not bad enough to affect daily life. MCI means you're more likely to develop dementia, but it's not inevitable. It may improve or stay stable.

Of course, memory naturally gets a little worse with age. These memory lapses are normal, but if they get worse or affect everyday life, they may be a sign of dementia. The Alzheimer’s Society has some information comparing normal ageing changes and dementia symptoms that you may find useful.

Different types of dementia have different early symptoms. Memory problems are often among the first signs. People with Alzheimer’s often have trouble learning new things (using a new microwave, for example) and may get confused about the date or get lost in familiar places.

See our section on Early dementia symptoms for more information.

All of us have the occasional memory lapse as we get older. Forgetting someone’s name or the name of a film you’ve seen, but remembering it later, is perfectly normal. But if memory problems become more frequent or start to disrupt your daily life, it’s best to see your GP.

See our section on Early dementia symptoms for more information.

Dementia can be difficult to diagnose. Doctors use questionnaires that are specially designed to pick up problems with memory and confusion. They will also do other basic tests, such as blood tests, to rule out other causes of confusion.

See our sections on Seeing the GP and Seeing a specialist for more information.

If your GP suspects you have Alzheimer’s disease, they’ll refer you to a memory clinic or elderly mental health service. If you might have a rarer type of dementia, they will refer you to another specialist, such as a neurologist.

See our section on Seeing a specialist for more information.

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