What is mixed dementia?

‘Mixed dementia’ is a condition in which a person has more than one type of dementia. Alzheimer’s disease and vascular dementia is the most common type.

Other combinations of dementias are also possible – particularly Alzheimer’s disease and dementia with Lewy bodies.

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A mixed dementia diagnosis

At least one in every ten people with dementia is diagnosed as having more than one type. Mixed dementia is much more common in older age groups, such as those over 75 years.

Despite many older people having both Alzheimer’s disease and vascular problems, relatively few are diagnosed with ‘mixed dementia’. Doctors tend to only use the term ‘mixed dementia’ when a person has clear clinical features of two types of disease that directly contribute to dementia symptoms.

What are the symptoms of mixed dementia?

Symptoms of mixed dementia vary depending on the types of dementia a person has. Often someone will have a greater amount of one type of dementia than another. In such cases, we talk about this type being ‘predominant’.

Common types of mixed dementia

Occasionally, mixed dementia can be a combination of three types of dementia-causing disease. But most diagnoses tend to be a mixture of two types. Here, we look at two common types of mixed dementia – Alzheimer's disease and vascular dementia, and Alzheimer’s disease and Lewy body disease.

Alzheimer’s disease and vascular dementia

This is the most common type of mixed dementia. The person affected has two different diseases in their brain that contribute to their dementia symptoms.

Understanding Alzheimer’s disease

Alzheimer’s disease is caused by a build-up of faulty proteins in and around brain cells – particularly cells that help to form memories. Earlier stages of Alzheimer’s disease are strongly associated with memory problems, language difficulties, and becoming confused more easily.

Understanding vascular dementia

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The ‘vascular’ part of mixed dementia is caused by problems with the supply of blood throughout the brain. Sometimes this can be caused by having a stroke or a series of mini-strokes. In other cases it can be due to a more gradual deterioration of small blood vessels over many years. Vascular disease prevents brain cells from getting enough oxygen and nutrients.

These are needed to function properly. The symptoms of vascular dementia depend on what part of the brain is affected. Generally, the condition tends to result in much slower processing of thoughts and information, difficulties with planning or problem-solving, and trouble concentrating for more than a short period.

Alzheimer’s disease and Lewy body disease

Less often, dementia can be caused by a mixture of Alzheimer’s disease and Lewy body disease.

Understanding Lewy body disease

Lewy bodies are the clumps of faulty proteins that build up in the brain cells of people who have Parkinson’s disease or dementia with Lewy bodies. Lewy body disease has quite distinct features not seen in the other dementias.

It tends to affect different parts of the brain that control body movement and processing of sensory information. People with Lewy body disease often have very disturbed sleep and visual hallucinations. They may also experience rapid ‘fluctuations’ in their ability to function properly, feeling confused or disorientated quite suddenly. Memory tends to be less affected than in people with Alzheimer’s disease.

What are the treatments for mixed dementia?

There is currently no cure for any type of dementia, including mixed dementia. Drugs and other treatments can help maintain a better level of cognitive function for longer. This does not stop the underlying damage happening in the brain.

Medication for mixed dementia

The most common kinds of medication used to treat mixed dementia are cholinesterase inhibitors. These boost levels of a chemical in the brain that helps cells communicate with each other. Unfortunately, there’s currently no medication that can improve the symptoms of vascular dementia. However, someone with vascular disease may be able to prevent strokes or other ‘events’ by continuing to take their medication for high blood pressure or diabetes.

Therapies for mixed dementia

As well as drug treatments, there are other therapies that may help to improve function or quality of life. These include cognitive behavioural therapy, cognitive stimulation therapy, cognitive rehabilitation, and reminiscence therapy. Learn more about the different approaches for coping with memory loss. A person with mixed dementia involving Lewy body disease may be offered physiotherapy to help with movement problems.

More practical and emotional support near you

There are dementia services and support groups in your area. Find out what's available where you are.

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Mum is 90 and has been diagnosed with Alzeimers and Vacular dementia. The local Iccles team have prescribed Memantine about 6 weeks ago. This has resulted in mum being comatose most of the time. She was admitted to hospital as the nurses in the nursing home couldn't wake her. She spent 5 days there.

My sister and I are worried stiff as no one seems to be helping mum return to how she was before she was prescribed with Memantine. We accept she was noisy and challenging but now she is zombie like. Please help with advice if you can. Kind regards Kathy Sawdon

Hello Kathy.

We’re very sorry to hear your family are going through such a stressful time. As requested, an adviser from our Helpline team will be contacting you privately with the email address you provided.

We hope this helps.

We sometimes prescribe Memantin at eveningtime, and only half dose (10 mg) for better quality of life.

Hi my name is Debbie I live in Ruabon near Wrexham North Wales my mum and dad both suffer with this problem and a group of us are doing the memory walk on Sunday the 2nd of September 2018 from Trevor basin to LLangollen love Mrs da Evans xx

My husband sleeps 14 hrs a night and then during the day as well is this normal behaviour ?

Hi Sylvia, thanks for your comment.

It is quite common for people with dementia, especially in the later stages, to spend a lot of their time sleeping. As dementia progresses even simple tasks (such as communicating or eating) can become exhausting. The task takes more and more out of them, and as a result the person sleeps more and more.

It is also worth noting that the quality of sleep someone has deteriorates as they get older. So a 90-year-old person may sleep for 14-15 hours a day, but it is unlikely to be good quality sleep. It is not the same as a 25-year-old sleeping for 14-15 hours.

It can also be influenced by people’s sleeping patterns before they had dementia, some people need more sleep than others.
If the person is in the later stages and the have gradually started sleeping more and more, it is likely to be due to the dementia progressing. However, if it has come on suddenly or the person doesn’t seem well it may have another cause. It may be worth speaking to the GP, to rule out any infections or conditions that could be having an impact. It may also be worth asking for a medication review with the GP or speaking to a pharmacist as medication can cause a range of side effects.

If the person is sleeping a lot but it isn’t having a negative impact on them it is often best to just go with it. If you need any more advice or support with your husband's care don't hesitate to contact our helpline: https://www.alzheimers.org.uk/get-support/national-dementia-helpline


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