Although there are drugs available today which can alleviate the symptoms, there are no drugs yet which are able to cure the disease. To this day, Alzheimer's disease is not curable. Depending on the drug, only the period in which the patient is still independent can be prolonged. In general, it is also not true that these drugs could prolong the lives of patients.
One main group of drugs used are the anti-dementia drugs:
There are 3 categories of anti-dementia drugs:
(1) NMDA receptor antagonists
(2) Acetylcholinesterase inhibitors
In order to describe the effect of the drugs a brief review of the causes of the disease must be made. Alzheimer's patients have a disorder of the neurotransmitters glutamate and acetylcholine. These are chemical messengers in the central nervous system. The acetylcholine level is too low, while the glutamate level is too high.
The aim of the drugs must therefore be the regulation of concentrations of the chemical messengers so that the degradation of nerve cells is prevented as long as possible.
(1) NMDA antagonists (memantines)
NDMA antagonists are named after the active substance memantine. This type of drugs are used to affect the glutamate concentration. Glutamate is deposited on N-methyl-D-aspartate receptors. However, an over-concentration of glutamate must be avoided so the nerve cells don't get destroyed. The taking of memantine generally improves the patient's behavior in everyday situations, he has fewer delusions and decreased aggressiveness. The taking is recommended when the patient is already in a moderate to severe disease state.
The following figures describe the process and the effect of the NDMA antagonists schematically. The term NMDA derives from the NDMA receptors on the nerve cells in the brain which are responsible for the reception of learning signals.
For patients suffering, the problem is, that in resting state the release of glutamate is increased, which acts as a messenger and delivers signals to the nerve cells. Therefore a certain amount of background noise is present. This means that the nerve cell receives signals permanently, although no learning signals should be transferred. If a learning signal arrives now, it can not be distinguished from the normal level. The consequence is that the nerve cell thinks that it doesn't receive signals any more and so it dies.
To prevent the process of dying NMDA antagonists are used. Assuming the same starting position as in the previous figure, it is the memantine which embeds itself as a protective effect into the NMDA receptor, which is responsible for the reception of signals. The level of background noise then goes back to normal. If a learning signal arrives now, the memantine in the NMDA receptor is replaced by this signal. The signal is detected once again and the nerve cell doesn't die.
(2) Acetylcholinesterase inhibitors
Acetylcholine is a neurotransmitter for the transmission of nerve signals between nerve cells. In the case of Alzheimer's patients its concentration is too low or it is no longer produced in sufficient quantities. This applies specifically to the synapses, the communication points between the nerve cells. But if is there is not enough acetylcholine available, the nerve cells stop receiving the signals and the cells die slowly.
Normally, a splitting of acetylcholine into acetate and choline is done by the enzyme acetylcholinesterase. This splitting process is done in Alzheimer's patients just as often as in healthy people, although the former have less acetylcholine. So, acetylcholine is missing for transmitting signals.
The approach of the drugs is to slow down the degradation and to prevent the death of neurons that are responsible for the production of acetylcholine.
The taking of the drugs results in an improvement in information transmission and an improvement in cognitive abilities. Acetylcholinesterase inhibitors are only effective in the early stages of the disease. The further the disease has progressed, the more the drug loses its effect, because the brain is damaged more and more.
And so, one can see that even this drug does not cure the disease, but merely can reduce the symptoms.
Nootropics are drugs that stimulate the brain metabolism and promote the blood circulation in the brain. There are herbal and chemical drugs in this group. The effect of nootropics is controversial. In Germany they are used relatively much, while they are clearly used less e.g. in the United States.
Advantages of anti-dementia drugs
Anti-dementia drugs are supposed to preserve the patients' quality of life longer and shorten the time spent in a nursing home. Positive side effects are also better concentration ability of patients and the reduction of depression. Therefore, additional anti-depressants possibly don't need to be taken any more. The patients also have less difficulties with speech and have less panic attacks
Disadvantages of anti-dementia drugs
But there are not only positive effects. It may well be that the patients show intolerance for drugs and experience side effects such as indigestion. If you read the advantages and have the impression of anti-dementia drugs being a miracle cure, this is not the case. Anti-dementia drugs can not bring back the logical thinking and decision-making ability of the patients. In principle, anti-dementia drugs do not cause any reversal effect or cure the disease, they merely reduce the symptoms.
The use of antipsychotics is not aimed directly at the Alzheimer's disease, but rather at accessory symptoms. Alzheimer's patients often suffer from delusions or anxiety. These come up when the patients are no longer able to correctly classify situations. Due to the decreased ability to concentrate there is also an unease among the patients that, depending on the type, may lead to sleeping problems. Antipsychotic drugs can counter these accessory symptoms. The prescription must, as with the other drugs, also be done by the doctor. Especially patients with stroke risk should be careful with the use.
As previously mentioned in other sections of this information portal, Alzheimer's patients often have either aggressions or depressions, possibly even both. To counter the depressions, antidepressants can be taken. However, an impairment of dementia may occur as a side effect.
Anxiolytics are mild sedatives and can possibly be used in patients who can not otherwise be controlled and show potential for aggression.
The effects of Neuroleptics are similar to those of antipsychotics. Neuroleptics are used to reduce delusions, to compensate anxiety and to reduce aggressiveness.