This information is about the drugs used to treat Alzheimer's disease. It discusses how the drugs work, why they are prescribed, their side-effects and alternative treatments.
Alzheimer's disease is only one of many possible causes for memory problems in people. The other causes are described in detail in our information on dementia and memory problems.
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© April 2020 Royal College of Psychiatrists
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Cholinesterase Inhibitors, also known as Acetylcholinesterase Inhibitors, are the main drugs used for Alzheimer's disease in the UK.
Three drugs are licensed:
- Donepezil, also known as Aricept®
- Galantamine, also known as Reminyl®
- Rivastigamine, also known as Exelon®
There are no major differences between these drugs. They are all designed to help the symptoms of Alzheimer's disease - for example, memory loss and anxiety. They are not a cure, though they may help people to keep their independence for longer.
They can improve memory. They can also have general benefits including improving alertness and motivation.
It may take some months for there to be a noticeable improvement or slowing down of memory loss. Some people feel brighter in their mood and will be able to do things that were too hard for them, such as going shopping.
The most common side-effects are feeling sick, loss of appetite, tiredness, diarrhoea, muscle cramps and sometimes poor sleep. These may be reduced or avoided by increasing the dose slowly, or taking the medicine after food.
The side-effects usually fade after a few weeks and will go away if the medicine is stopped. More information about side-effects can be obtained from your doctor or by reading the leaflet that comes with the tablets.
Acetylcholine is a chemical that helps pass messages between certain brain cells involved in memory. In Alzheimer's disease, these brain cells start to die and the amount of acetylcholine is very much reduced.
Memory starts to suffer. Cholinesterase Inhibitors reduce the breakdown of acetylcholine and increases its levels in the brain. This reduces some of the symptoms of Alzheimer's disease.
About 50-60% of people on these drugs show a slight improvement or a stabilisation of their condition over 6 months.
Unfortunately, not everyone benefits from these drugs, and if no improvement or stabilisation is seen in the first few months, then they should be stopped.
It is usual to start on a low dose which is gradually increased.
Don't be put off by any side-effects early on in the treatment as these usually wear off after a few weeks.
It is important to take the drugs every day for them to be effective.
These drugs are usually prescribed for a trial period of 3 to 4 months to see if they show signs of helping.
There is no clear view as to how long they should be taken. If the condition progresses in spite of treatment, there may come a point when you and your doctor decide that there is little point in staying on them.
A specialist, rather than your GP, will prescribe the medicine during this trial period.
You will usually see the specialist in a hospital clinic. You may need blood tests and a brain scan to exclude any other causes for the memory loss.
In some areas, the specialist will continue to prescribe the drug if they conclude that it is working. In other areas, the GP will prescribe it after the trial period.
This drug is also known as Ebixa. It is thought to work by affecting a chemical in the brain called glutamate.
In Alzheimer's disease, too much glutamate leaks out of damaged brain cells and interferes with learning and memory. In some studies, Memantine was shown to improve the memory and behaviour of people with dementia in the medium and later stages.
Memantine can be used for people who find they are intolerant to Cholinesterase Inhibitors.
The main side-effects of Memantine - which are usually mild - are nausea, restlessness, stomach ache and headache.
This drug is used in moderate dementia if the cholinesterase inhibitors cause undue side-effects. It may also help in the more severe stages of the illness.
This is a naturally occurring substance extracted from the Maidenhair tree. It has long been thought to enhance memory.
However, a recent study looked at the effects in Ginkgo in over 3000 people taking it for an average of 6 years. Unfortunately, Ginkgo did not stop dementia developing and, in a small number of people with heart problems, it actually seemed to make their dementia worse.
Another large analysis of Gingko which included patients diagnosed with Alzheimer's disease (925 patients from nine trials) also showed no consistent pattern of benefit associated with Ginkgo biloba. However, Gingko was generally considered to be safe.
This is a natural substance found in oils from soya beans, sunflower seeds, corn and cotton seed, as well as whole-grain foods, fish-liver oils and nuts. Vitamin E has many functions in the body. Vitamin E deficiencies are very rare.
A recent review of several large studies of Vitamin E found that it has no benefits in mild cognitive impairment (a noticeable and measurable decline in cognitive abilities including memory and thinking skills) or Alzheimer's. Of more concern, the review also discovered that high doses of Vitamin E may increase the risk of death.
There are lots of drug trials happening all the time to look for new medications which might help in the treatment of Alzheimer's disease. Currently, there are trials seeking to find new cognitive enhancers; these are drugs or supplements that may improve memory, intelligence, motivation, attention, and concentration.
Other research is seeking to find 'disease modifying' medications which can alter the course of Alzheimer's disease to stop its progression.
In the future there will also be more trials of medications to be used before the disease becomes evident through memory loss. These are called preventative medications, but they have not yet been tried in humans.
It may be possible to try some of these newer treatments by entering into a drug trial. Speak to your GP, a specialist or a national organisation, such as the Alzheimer's Society, for advice.
- Memory problems and dementia. A leaflet by the Royal College of Psychiatrists.
- Donepezil, Galantamine, Rivastigmine (review) and Memantine for the Treatment of Alzheimer's Disease, National Institute for Health and Care Excellence (2011).
- Access to drugs: Alzheimer's Society (2011).
- Ginkgo Biloba - JAMA 2008; 300:2253-62.
- Ginkgo Biloba for cognitive impairment and dementia: Cochrane Review 2009.
- Vitamin E for Alzheimer's disease and Mild Cognitive Impairment, Cochrane Review 2012.
This information was produced by the Royal College of Psychiatrists' Public Education Editorial Board.
- Series editor: Dr Philip Timms
- Expert Review: Dr Thomas Manders and Dr Laura Hill