Medications for the treatment of Alzheimer’s disease
There is currently no cure for Alzheimer’s disease. Various medications can somewhat delay the loss of cognitive performance and independence in people who have mild or moderate Alzheimer's. But they can also have side effects. It isn’t clear whether any of the medications are better than the others.
People who have Alzheimer's become forgetful and find it increasingly difficult to understand complex issues or express themselves in words. Their orientation in space and time gets worse and they need more and more support in everyday life. The speed at which the disease progresses varies greatly from person to person.
Alzheimer’s disease is the most common cause of dementia. More and more brain cells are lost as time goes by. There is currently no way to cure the disease or stop it from progressing. But there are various medications which aim to maintain people’s memory and independence in everyday life for longer. There are also non-drug interventions, including things like memory training or encouraging social activities.
Cholinesterase inhibitors are believed to be able to reduce the symptoms of Alzheimer’s by increasing communication between nerve cells in the brain. These medications have been approved for use in mild to moderate Alzheimer’s disease. Three different cholinesterase inhibitors are currently available in Germany: donepezil, galantamine and rivastigmine. They are taken in the form of tablets. Rivastigmine is also available in a patch. Here the drug is absorbed into the body through the skin.
Cholinesterase inhibitors can slightly delay the loss of brain function. What is known so far: Some people who have Alzheimer's are somewhat better able to remember things if they take cholinesterase inhibitors. It isn’t clear whether any of the three medications is more effective than the others.
There is no proof that people who take cholinesterase inhibitors can manage their everyday lives for longer. It's also not clear whether these drugs
- can improve quality of life,
- reduce accompanying psychological problems such as depression or anxiety, or
- delay the point at which people need full-time care (for example, at a nursing home).
Donepezil already has a beneficial effect at smaller doses, whereas galantamine and rivastigmine only have an effect at a medium or higher dose. All three medications can cause side effects like nausea, vomiting, dizziness or diarrhea. The higher the dose, the more likely they are to occur. Depending on which medication they take, about 1 to 3 out of 10 people feel nauseous or vomit.
Rivastigmine patches are available in various doses. Unlike for rivastigmine capsules, there is only weak evidence suggesting that the patch improves brain function. But this is only true for higher-dose patches that release 9.5 mg of rivastigmine in 24 hours. Most side effects are equally common, regardless of whether the medication is used in the form of a patch or capsule. But gastrointestinal (stomach and bowel) problems are less common in people who use patches rather than capsules. Instead, they may cause skin problems such as itching and redness.
Medications containing the drug memantine have been approved for the treatment of moderate to severe Alzheimer’s disease in Germany. They are thought to prevent an excess amount of the substance glutamate from damaging the brain. Glutamate is a chemical messenger that carries nerve signals and helps us to remember things. It is thought that people with Alzheimer’s disease have too much glutamate in their brains, causing their nerve cells to die.
Memantine can somewhat delay the deterioration of cognitive performance in some people. Expressed in numbers: memantine can delay the deterioration of cognitive performance in about 1 out of 10 people over a time period of six months. There is also some evidence to suggest that people who take memantine can carry on doing everyday activities like brushing their teeth, getting dressed or using public transport somewhat longer. The studies also suggest that it can relieve severe restlessness.
It isn’t known whether memantine affects how long people with Alzheimer's can still be cared for at home. There is also no evidence that this treatment helps family members or loved ones, for example by lessening the emotional burden or lowering the need for care.
Memantine seems to be well tolerated overall. But side effects might still very rarely occur.
Ginkgo is a herbal product based on extracts from the leaves of the Ginkgo biloba tree. It is believed to have various effects, such as improving blood circulation and protecting nerve cells. Ginkgo is available without a prescription. In Germany and other countries, doctors can also prescribe it for people who have Alzheimer’s disease.
Some studies have shown that people who have mild or moderate Alzheimer’s disease and take the highest tested dose of Ginkgo (240 mg per day) might be better able to perform everyday activities such as household chores and washing themselves again. The studies also suggested that, when taken at high doses, Ginkgo could reduce mental health problems and improve people’s ability to remember things. But it isn’t clear how big this effect is.
Gingko is generally quite well tolerated. Sometimes people stop taking Gingko because they experience side effects, such as stomach ache or headache. It can’t be ruled out that Ginkgo may interact with other medications, such as blood-thinning medication.
Alzheimer’s disease often leads to considerable changes in people’s personality and behavior. For example, they might be unusually anxious, distrustful, passive, restless or aggressive. These changes in behavior could be part of the disease, but they might also be a totally normal reaction to their environment or to the limitations and losses associated with Alzheimer’s. Aggression, for instance, might be a normal reaction if someone who has Alzheimer's feels patronized. Depression and sleep problems are also common in people who have Alzheimer’s.
For this reason, many people with Alzheimer’s also take medication to reduce mental health problems and abnormal behavior. This may include things like sedatives, antidepressants or antipsychotics. Although these medications might relieve the symptoms, they can also lead to serious side effects such as confusion or a higher risk of falling.
So it is important to first look for the causes of the problems and try to solve them without using these medications, known as psychotropic medications, if possible. They should only be used if there are no other suitable treatment options. Taking several medications at the same time can lead to drug-drug interactions too. Before doctors prescribe a new medication, it is important that they carefully check whether such side effects or interactions are possible, and point out alternative treatment options if necessary.
The treatment of physical symptoms such as pain may be an issue in Alzheimer’s disease too. Pain is sometimes the cause of restlessness and unusual behavior – something which people with advanced Alzheimer’s are often unable to communicate.
Medications – yes or no?
The currently available medications can’t greatly influence the course of Alzheimer’s disease. This makes good-quality social and nursing support all the more important. So far, research has shown that particular medications can temporarily relieve some symptoms or delay their onset somewhat in mild to moderate Alzheimer’s. These medications include cholinesterase inhibitors, memantine and possibly Ginkgo too.
It isn’t possible to say whether one of these types of medications is better than others. Hardly any studies have compared the various medications with each other. There has also been hardly any research on the long-term effects of the medications – most of the studies done so far lasted half a year at the most.
The decision whether or not to take any of these medications can be discussed with a doctor. But it remains a personal decision that will depend on things like how someone feels about the possible advantages and side effects. One person may consider the prospect of small improvements to be a good reason to take medication on a daily basis. Another might be put off by the limited benefits and the potential side effects. Further factors that play a role in the decision include whether or not someone has other medical conditions, whether they are already taking medication and, last but not least, how far the disease has already progressed.
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Institute for Quality and Efficiency in Health Care (IQWiG, Germany). Responder analyses for memantine in Alzheimer´s disease - Rapid report; commission A10-06. March 28, 2011. (IQWiG reports; Volume 84).
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