What is the difference between dementia and Alzheimer’s disease?

Dementia is a condition where problems with memory or other types of thinking make it hard for a person to do everyday activities by themselves. It can be caused by several different diseases that affect the brain. Alzheimer’s disease is the most common cause of dementia.

Alzheimer’s disease starts in the brain many years before symptoms start to show. Early symptoms are mild and so don’t stop someone doing their normal everyday activities. It’s only later that symptoms become severe enough to be called ‘dementia’. 

Other common causes of dementia include vascular disease, which prevents blood from getting to the brain properly, and Lewy body disease.

Just as with Alzheimer’s, these diseases develop in the brain over many years. Eventually they lead to vascular dementia and Lewy body dementia.

What is dementia?

Dementia is a group of symptoms. It’s caused by different diseases that damage the brain. The symptoms get worse over time and include: 

  • memory loss 
  • confusion and needing help with daily tasks 
  • problems with language and understanding  
  • changes in behaviour. 

Dementia is progressive, which means symptoms may be relatively mild at first, but they get worse over time.  

What is Alzheimer’s disease?

Alzheimer’s disease is the most common cause of dementia. About two out of three people living with dementia in the UK have Alzheimer’s disease, which is sometimes called “Alzheimer’s”.
Alzheimer’s disease is a physical illness which damages a person’s brain. It starts many years before symptoms start to show.
Early symptoms of Alzheimer’s are mild and don’t prevent someone from doing everyday activities by themselves. This is called mild cognitive impairment (MCI).

It’s often not possible at this stage to say for sure that the person’s symptoms are being caused by Alzheimer’s disease, as there could be many other causes.
Eventually Alzheimer’s disease causes so much damage to the brain that the person develops dementia. Technically this type of dementia is called ‘Alzheimer’s disease dementia’. However, most people – including healthcare professionals – just call it ‘Alzheimer’s disease’.
For most people, Alzheimer’s disease starts in and around the part of the brain involved in memory. However, in some rarer types of dementia the disease starts in a different part of the brain and so causes a different set of symptoms. This is called ‘atypical Alzheimer’s’. For example, posterior cortical atrophy is caused by Alzheimer’s in the back of the brain and mostly causes problems with vision.  

What causes Alzheimer's disease

The causes of Alzheimer’s disease are very complex, but one key part is the build-up of two substances inside the brain called amyloid and tau. When conditions in the brain aren’t right, these clump up and form tiny structures called plaques and tangles. These make it harder for the brain to work properly. 

Over time the disease causes certain parts to become smaller. It also reduces the amount of important chemicals needed to send messages around the brain. 

There is currently no cure for Alzheimer’s disease. However, treatments may temporarily ease some symptoms or slow down their progression in some people. 

What are the main other types of dementia – and what causes them? 

Vascular dementia: this the second most common type of dementia. It is caused by problems with the blood supply to parts of the brain.

Lewy body dementia: Lewy bodies are tiny clumps of protein that build up in the brain. When this happens, it leads to Lewy body disease. There are two main types: 

  • Dementia with Lewy bodies:  When the first signs of Lewy body disease are symptoms of dementia, this is known as ‘dementia with Lewy bodies (DLB)’. 
  • Parkinson’s disease dementia: Lewy body disease can also cause Parkinson’s disease, which mostly involves problems with movement but can also lead to dementia several years later. If it does, this is known as Parkinson’s disease dementia. 

Frontotemporal dementia: this is a less common type of dementia. It can be caused by several different types of disease but they all mostly affect the front or the sides of the brain, known as the frontal and temporal lobes.
Mixed dementia: A diagnosis of mixed dementia is generally used when someone has a mixture of clinical symptoms from two or more different types of dementia – for example, if they have symptoms of both Alzheimer’s disease and dementia with Lewy bodies.  

How do I know what type of dementia I have? 

A diagnosis of dementia needs to be made by a healthcare professional who specialises in dementia, usually following a detailed assessment at a local memory service.  

When someone gets a diagnosis of dementia they should ideally be told by the doctor what type they have. This doesn’t always happen though. Sometimes it’s hard to tell what the cause of a person’s dementia is – particularly during the earlier stages.

It’s not always essential to know straight away what the cause of dementia is, but it can help to make better sense of the person’s symptoms and to get the right treatment.  

Does Alzheimer’s Society support people with dementia, as well as Alzheimer’s disease? 

We support anyone who has dementia. We can help guide people with mild cognitive impairment or who are worried about their memory. Find out how Alzheimer's Society can support you. 

We’re a vital source of support, giving help to everyone who needs it today, and hope for everyone in the future. 

This post was first published in July 2018 and most recently updated in February 2023.

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My mother has had dementia for 10 yrs, getting worse all the time. The type of dementia could not be diagnosed by the hospital as it did not fit any of the types exactly. She now recognises no one and sits and stares all day. She is 93 and looks like physically will go on for another 10 years. It is sad to see but at least she is not distressed.

Useful to read other people's comments - my mother-in-law is suffering from Alzheimers

This information is really interesting and informative, I now feel much more comfortable with the differences between dementia and Alzheimer’s disease which I feel will give me a greater understanding of the issues that sufferers and their families have to deal with.

This does explain fully the different types of dementia.

I have been diagnosed with vascular dementia and I've been reading up on your materials and it has been real very supported Jimmy and I understand a lot more now than what I did thank you so much

My mother was diagnosed about 12 years ago with dementia/Alzheimer's. She lives in a assisted living facility and can do everything for herself. She repeats continuously. She has not really gotten any worse. What can I expect after 12 years. Other than this she is very healthy. Takes an Alzheimer's pill at night only.

Fed up hearing and reading the term Your Not Alone
I am looking after my wife who has Alzheimers April 2018 and am left to get on with All the duties ie all the house work, ie washing, ironing, shopping, medication, appointments and cooking. With no help from anyone

I understand what you are going through
My parents are going through the same thing.
If you are not getting help from the local authorities how about advertising for help
Even if it’s just a few hours a day
I volunteer for my local hospice.
Perhaps one of my colleagues could volunteer a few hours with you.
Not sure how to contact you personally on this platform and by the way we are based in North london

James reach out for support
contact Alzheimers society
I feel sure they will be pleased to give you some contacts.

You are not alone means that’s there’s others out there who understand or are going through the same as you.
Unfortunately this is something that as a husband you’ve committed to. Caring for someone you love so much is an important roll. Please take care. And think of her when she used to do it all.. now it’s your turn. Pay her back respectively. :) be happy

Hi if you need help not sure where you live but you can ask for help be contacting adults social services look it up on Google for your area hope this helps

I am in exactly the same position as you, James. I've contacted various local carers groups but they only seem to pay lip service to my problems, suggesting other support groups when what I really need is practical help to understand what is happening. The Covid outbreak has done us no favours, but even before this practical help was impossible to find.
It looks as though we are alone. If not, as you say, it certainly feels like it.

Sorry James but that is what women do. I am sole carer for my husband 82 with alzheimers and have all his care to do as well as all the things you mention and a coal fire to light and clean out daily and am also fed up so know where you are coming from. Being 73 myself and more health issues than my husband, am exhausted.

James I hope you have claimed and your wife is in receipt of Attendance Allowance?
If not definitely claim! Whether you get get lower or higher rate it gives you options and help.
Extra money each week to help you employ a cleaner for a couple of hours, maybe someone to sit with your wife for a couple of hours each week while you go and enjoy some time for yourself.
Citizens advice bureau would help you complete a form.
Contact your local council for a list of services geared towards dementia help, day centres, activities, coffee mornings for the dementia sufferer AND the carer.
You'll probably be surprised just how much help there is out therewife it's just knowing that it's available.
Also asked your local authority for a carer's assessment. It's there to help you, so you are better able to care. With this you may get help with taxi fares if you don't drive, help with housework, someone to take over the care so you can take a break, put you in touch with support groups with other people to talk to you in a similar situation.
Good luck!

Like wise my husband is 80 and I am 79 they tell me to ring several different numbers of I need help but when I ring you get s recorded message that they are extremely busy and will ring back so far no one has

My husband and I are very concerned about his mum, who is 83 in March. We believe that she has the signs of dementia, her memory has got a lot worse over the past year, and she forgets things she has done or people she may have visited that day. She believes that because she can look after herself, keep her flat clean and still drive, that she is fine. My husband has tried to approach her about going to the doctors for tests, as we want her to continue to live as independently for as long as possible, but she insists that she is fine and if she sees a doctor, he will put her in the ‘loony bin’. (Her words, not ours). We are really trying to look for ways to help her and it’s now got to the stage where we would be very grateful of any advice that you may be able to give. Are we right in thinking that a visit to her doctor should be the obvious next step to help her?
Thankyou in anticipation.

Hi , I do believe you should go forward with seeing a geriatric specialist who will be familiar on his or her approach. It's a sensitive subject and personal. However , your instincts are correct , no regrets. I just lost my Mom a bit over a month ago. It was painful , but I feel that we followed our hearts as if she were the one taking care. She did it for all four of us. I would do it again because you don't get that time back. Understand you're doing it out of the well being for your loved one. What else are we here for ??Best of luck to you and your Family .

Although your post is dated Jan 2020, I just read it. I understand completely what you are going through. Hope its not too late but please ensure she sees a Doctor for further good advice. Driving horrifies me, if she has an accident and kills / hurts someone else you will never forgive yourselves. My mother went through this so I have first hand experience. You love her dearly and your intervention will help her no doubt, see a Doctor they really do try to help, at least give them the opportunity. Take care

If you contact her Doctor they can do a test discreetly and he can explain things. Older people have respect for Doctors. If it's early onset they can give meds to help and she can still live an independent life.
You do need to keep an eye on her driving ability though.

i am studying biomedical science and am trying to gain some more specific information on the different forms of dementia as well as the different the biological affects of each type.
this website has provided me with vital information for my research but if someone could get back to me who is able to answer a few questions it would be greatly appreciated

Hi Claudia,
Thanks for your comment - pleased to hear you've found the website useful.
Could you send us an email explaining a little more about the kind of information you need? Email [email protected] and we'll try to connect you with the right person to help.
Alzheimer's Society blog team

My husband diagnosed with late onset dementia slowly getting worse over 5 years. He is obssessed with time. Flies into rages if clocks are seconds out and Christmas and new year diaries are a source of stress. How is best way to cope woth obsession it is very wearing ?

Hi there,
Sorry to hear about your husband's condition and this new source of stress.
There could be a few different causes of this, so we'd recommend speaking to one of our Dementia advisers who you can talk more about your situation with and get advice from. You can call on 0300 222 11 22 and find more details of how to access phone support here: https://www.alzheimers.org.uk/get-support/national-dementia-helpline
Hope this is helpful,
Alzheimer's Society blog team

My 69yo mother has just been diagnosed with mixed dementia. My sister lives in Kent. I have just moved to to North Norfolk. My mum lives in a one-bed flat in an assisted living complex (warden there 2 hours a week) in Berkshire. Although the diagnosis isn’t a surprise, I feel devastated as I am so far away. I am unable to change my job or move closer to care for my mum and it’s just so upsetting to think that she will have to go through this without seeing us regularly. We have power of attorney for her now so can help with some decisions, but are not able to give her the regular physical love and care she needs. I just feel terrible about this. Should we get a carer for her? What help is available? Do we pay or is there financial help for this? I’d like to try and put some daily help in place to know that she has at least had something to eat and is safe. I don’t know what else to do :(

Hi Camilla, thanks for getting in touch.
We're very sorry to learn about your mother's recent diagnosis.
We recommend calling our National Dementia Helpline to speak with one of our advisers about the situation - they're available to chat seven days a week on 0300 222 11 22 (but opening times may differ over the Christmas period) - https://www.alzheimers.org.uk/get-support/national-dementia-helpline
In the meantime, our Dementia Guide is helpful for anyone who has recently been told they have dementia. It can help to understand more about dementia and the treatments, support and services are available. It includes information about how you can live as well as possible with dementia and about making plans for the future. It also contains helpful information for anyone taking on a caring role, which may be particularly useful for you: https://www.alzheimers.org.uk/publications-about-dementia/the-dementia-…
We hope this helps, Camilla.
Alzheimer's Society blog team

My mother in law has many worsening symptoms and her husband can’t get her to the doctor. Is he able to access any support from your service? Also how would you advise us to support them?

Hi there, thanks for getting in touch.
We're sorry to hear about this. We recommend calling our National Dementia Helpline to speak with one of our advisers about the situation - they're available to chat seven days a week on 0300 222 11 22 (but please be aware availability over the Christmas period may differ) - https://www.alzheimers.org.uk/get-support/national-dementia-helpline
We hope this helps.
Alzheimer's Society blog team

Iv only just been told I have Dementia Hawever I feel very alone Jenny xxxxxxx

I was initially very hesitant to discuss my Alzheimer but i just hope it can still help someone. I feel this will be very important information for all Alzheimer patients, because the most violent element in society today is ignorance. Be it any condition, a healthy diet and natural medicine is a road to fast recovery. I had suffered Alzheimer for many years, I fought for proper medical care and all form of humane treatment with little improvement I went through many sleepless nights and periods of intense grief, as do most families. I was recommended by a friend to use ZOMO herbs for my Alzheimer with high hope and assurance. I finally feel my illness is gone with no more symptoms. Doc email ID [email protected]

Very helpful, thank you!