Alzheimer’s disease


Expert reviewer Dr Rahul Bhattacharya, Consultant Psychiatrist
Next review due April 2022

Alzheimer’s disease is a condition that affects the brain. It is the most common cause of dementia: a term used to describe a set of symptoms, which can include problems with memory and thinking. Dementia mainly affects people in older age.

Symptoms of Alzheimer’s disease

Early Alzheimer's symptoms often include difficulty remembering times and dates and taking in new information, such as learning to do something new. Other early Alzheimer's symptoms include memory lapses, such as:

  • forgetting names of people and places
  • difficulty finding words for things
  • not remembering recent events
  • forgetting appointments

There may be signs of changes in behaviour. The person may become more withdrawn and lose interest in their usual activities and hobbies. They may get confused about where familiar places are and start to get lost. In the early stages, people may be aware that they are having memory problems. Understandably, this can cause a lot of anxiety. To try and reassure themselves, they may make things up to fill in the gaps in what they remember.

As the condition worsens, someone with Alzheimer’s may have:

  • greater difficulty planning and making decisions
  • increasing difficulty with language
  • greater memory loss and confusion
  • difficulty thinking logically and carrying out specific tasks

A person with Alzheimer’s may also have difficulties other than thinking and memory problems. As well as the anxiety mentioned above, they may experience depression. In the later stages of the condition, they may start ‘wandering’ out of the house and walking off by themselves.

Other symptoms can include:

  • becoming agitated and aggressive towards others
  • problems going to the toilet (incontinence)
  • loss of interest in eating and drinking
  • hallucinations and delusions

It’s important to remember that changes in behaviour and mood, such as depression or agitation, may be a reaction to living in unsupportive surroundings.

Diagnosing Alzheimer’s disease

Diagnosing dementia can involve tests, assessments and information from family members.

Alzheimer’s disease can be hard to diagnose. In the early stages, symptoms can be subtle and come on slowly, making them difficult to detect. It’s very important for doctors to get as much information as possible from family and friends who see the person regularly. They can help to explain exactly what has changed and over what period of time.

The doctor will also want to know whether anyone else in the family has had any form of dementia. Having Alzheimer’s in the family is a known risk factor, particularly if anyone developed it at a young age (before 60).

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How Alzheimer’s disease develops

Alzheimer’s is a long-term condition that gradually worsens over time. This can be a very slow process in some people, but the progression of Alzheimer's symptoms varies a great deal from person to person. In some cases, it can be as quick as five years. In others, the decline may take closer to 10 years, with long periods where there is no apparent change. Doctors call these periods where the disease doesn’t get worse ‘plateaus’.

You may have heard about different stages of dementia. There are a few staging systems but they were really developed for use in research, so that clinical trial results could be compared. They aren’t a great deal of use in managing or treating dementia day to day.

Early on, people with Alzheimer’s may be able to manage with a little support from family and friends, just needing a bit of supervision with medicines and managing finances. Finding that an older relative’s finances are in a bit of a mess can be the first sign that something is not quite right, leading to the diagnosis of Alzheimer’s disease.

Often, the first activities to become a problem are tasks that need a bit of forward planning, such as cooking and shopping. These problems are caused by difficulties with memory and orientation.

As the condition progresses, the person will have more difficulty managing day-to-day life. They’re likely to need help with more basic daily care, such as washing and dressing. Because the condition worsens over time, eventually many people need to be looked after all the time, which is often only possible in residential care.

As with many long-term illnesses, Alzheimer’s can have complications. People with Alzheimer’s have a higher-than-average risk of infections. They may be prone to urinary infections. Difficulty swallowing can cause people to breathe in (inhale) small amounts of food or drink. This can lead to pneumonia.

People with Alzheimer’s who have an infection may also suddenly become even more confused than usual. If someone suddenly seems more confused than normal, it’s important to quickly investigate whether this is being caused by untreated infection, or by constipation or pain.

Causes of Alzheimer’s disease

Doctors don’t fully understand what causes Alzheimer’s disease. There are some signs that help to explain how it develops.

Alzheimer’s causes some areas of the brain to shrink, while other areas seem normal. The shrinkage is caused by nerve cells dying in some areas of the brain. The brain of someone with Alzheimer’s typically weighs about 100–200 grams (3–7oz) less than a normal average brain.


Image of two brain scans showing changes in the brain during Alzheimer's disease

Two brain scans showing changes in the brain during Alzheimer's disease.
In the right-hand image, the white parts are where cells have died in some areas of the brain.

This brain shrinking offers some insight into what causes Alzheimer's disease. We also know that, inside brain cells damaged by Alzheimer’s, there are twists and knots of protein fibres that usually run in straight lines in normal cells. These fibres are the ‘transport system’ of the cell. Once they become tangled, important molecules can't easily move through the cell and it dies.

The more of these tangles there are, the worse the Alzheimer’s symptoms generally become. So, while doctors still don't know exactly what causes the death of brain cells in Alzheimer’s, they strongly suspect that the tangles are one cause.

Another suspected cause of Alzheimer's disease is an abnormal build-up of a particular type of protein in the brain. Normal nerve cells work by sending chemical signals to each other via ‘chemical messengers’. When you look at brain tissue affected by Alzheimer’s under a microscope, you can see ‘plaques’ of protein and dead cells collecting between the nerve cells. These may block signals between nerve fibres in the brain, so the nerve cells can no longer work.

There is a known genetic link for early onset dementia (before the age of 60). There may also be a link with having had a previous head injury or a history of depression. There is also some evidence that there are particular lifestyle risk factors for Alzheimer’s disease. See our Prevention section below for more details.

Treatment of Alzheimer's disease

Unfortunately, there is currently no cure for Alzheimer’s disease. There are medicines to treat the symptoms of Alzheimer’s, but they don’t treat the underlying progressive illness. The aim of this treatment is to help to slow down memory loss, and to allow people with Alzheimer’s to manage their daily lives for as long as possible.

Medicines for early-stage Alzheimer’s

The doctor is likely to prescribe one of the three medicines available:

  • donepezil (Aricept)
  • galantamine (Reminyl)
  • rivastigmine (Exelon)

The names in brackets are the brand names. These are all the same type of drug, called acetylcholinesterase inhibitors (pronounced asset-isle-coleen-ester-aze). These drugs stop an enzyme from breaking down the ‘chemical messenger’ acetylcholine in the brain. This helps the nerve cells in the brain to continue to communicate with each other.

All these medicines seem to work as well as each other. There’s evidence that they can slow down the development of Alzheimer’s symptoms for a year or two. There can be a noticeable improvement in memory, but this won’t be the case for most people.

It is best to start taking these medicines as soon as Alzheimer’s is diagnosed, in the early stages.

The medicines have to be prescribed by a specialist and are tablets or capsules that you swallow. You take donepezil once daily and the other two medicines twice daily. Rivastigmine also comes as a stick-on patch that needs to be changed every 24 hours. This can be easier for some families to manage than tablets. You may find it helpful to download our medicines planner for dementia carers (PDF, 0.8MB).

The dose of all these medicines is gradually increased over the first month. This is to try and get the most benefit with the fewest side-effects. The most common side-effects are generally feeling sick, vomiting and diarrhoea. Skin patches may cause fewer side-effects than tablets or capsules.

It isn’t recommended to stop dementia medicines solely because the dementia is becoming more advanced. The medicine may still be slowing down the dementia. It is best for a dementia specialist to make the decision to stop treatment.

Medicines for later stage Alzheimer’s

There is another medicine available for moderate-to-severe Alzheimer’s, called memantine (Ebixa). It doesn’t help with early Alzheimer’s, so isn’t usually prescribed until later in the course of the disease. If the medicines someone is taking for earlier stage dementia no longer seem to be helping, the doctor may suggest taking memantine as well, or instead.

Memantine is a type of drug called an NMDA inhibitor. It works by helping to block signals from a ‘chemical messenger’ called glutamate, which can be overactive in Alzheimer’s. Memantine is a tablet that you take once a day. It can have side-effects, including headache, constipation and dizziness.

Other medicines that may be used in Alzheimer’s

More than eight out of 10 people diagnosed with Alzheimer’s will have some sort of emotional distress or behavioural disturbance at some point.

Doctors used to treat agitation and aggressive behaviour with drugs used in psychiatric care, called anti-psychotics. We have since found that the risk of serious side-effects with these drugs is much higher in older people. This means they’re now less likely to be used. Doctors are more likely to prescribe the existing dementia drugs listed above and suggest other therapies for calming (see the Other therapies section below for examples).

As many as half of people diagnosed with dementia will also have depression. In around two out of every 10 Alzheimer’s patients, depression is severe enough to need treating. The doctor may suggest trying a course of antidepressants for three to six months. It’s important not to overprescribe medicines in older people, so doctors should not do this lightly and ought to stop the tablets if they think they’re not helping.

Dementia symptoms can cause a lot of stress and upset for carers. If you’re looking after someone with dementia, there’s lots of support available to dementia carers.

Other therapies for Alzheimer’s disease

There are several other ways that life with Alzheimer’s disease can be improved. This may be through a person’s environment, or by helping them treat or manage other health problems that are affecting their quality of life.

Keeping active and doing as much as possible for themselves can help people to sleep better, stay mobile and look after themselves for longer. Similarly, mental activity and interacting with others can help to maintain memory and social skills.

At earlier stages, talking therapies enable people with dementia to come to share their feelings and can help with anxiety and depression. Complementary therapies can aid relaxation and in later stages of dementia help with management of difficult symptoms such as agitation. There isn’t a great deal of research evidence about the benefits of these kinds of therapies for people with dementia, but some people do find that they help.

Preventing Alzheimer's disease

Some risk factors for dementia are unavoidable. But there are changes you can make that may help reduce your risk of dementia later in life. It may help to avoid:


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Related information

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      • Carers of people with dementia. Health Talk Online. www.healthtalk.org, last updated July 2018
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      • Dementia. NICE Clinical Knowledge Summaries. cks.nice.org.uk, last updated May 2017
      • O'Brien JT, Holmes C, Jones M, et al. Clinical practice with anti-dementia drugs: a revised (third) consensus statement. British Association of Psychopharmacology. bap.org.uk, published 2017
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  • Reviewed by Graham Pembrey, Lead Editor, Bupa Health Content Team, April 2019
    Expert reviewer Dr Rahul Bhattacharya, Consultant Psychiatrist
    Next review due April 2022



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