There is a lot of research taking place into new drug treatments for Alzheimer’s disease and the other dementias, but currently the medications available are not a cure. They do not slow the progression of the damage to the brain, but can only stabilise some of the symptoms of Alzheimer’s disease for a limited period of time. There are two types of medication currently available, cholinesterase inhibitors and memantine.
The main compounds used are the cholinesterase inhibitors (also known as anti-cholinesterase drugs). Four have been licensed for use in many countries. These drugs work by reducing the breakdown of acetylcholine in the brain. Acetylcholine is a chemical substance that occurs naturally in the brain and enables nerve cells in the brain to pass messages to each other. Research has shown that many people with Alzheimer’s disease have a reduced amount of acetylcholine, and it is thought that the loss of this chemical interferes with memory function.
The cholinesterase inhibitors include donepezil (available with the brand name Aricept®), galantamine (Reminyl®, Razadyne®, Acumor®, Gatalin®), and rivastigmine (Exelon®). An earlier drug of this type was tacrine (Cognex®), which has mostly been superseded by the newer compounds because of its significant side effects. Side effects of these drugs may include diarrhoea, nausea, insomnia or vivid dreams, fatigue and loss of appetite.
NMDA receptor antagonists
Memantine (known as Ebixa®, Axura® or Namenda®) has been licensed in several countries for treatment of moderate to severe Alzheimer’s disease. It is the first drug for people in the later stages of the disease. The drug modifies the function of a receptor in the brain which is involved with the chemical transmitter glutamate, and research has suggested that too much glutamate is damaging or toxic to the nerve cell. Side effects tend to be less severe than for the cholinesterase inhibitors, but can include dizziness, headaches, tiredness, raised blood pressure and constipation.
A number of other treatments, including vitamin E and omega-3 fatty acids, have shown some promising associations, but are not proven for routine use (and high doses of vitamin E can have negative effects). Nootropics, such as Ginkgo Biloba, are available in many countries. Ginkgo seems to improve cerebral blood flow, but improved outcomes with it have not been clinically demonstrated. There is no evidence that coconut oil is beneficial for people with dementia.
Antipsychotic drugs (also known as ‘major tranquillisers’ or ‘neuroleptics’) are usually used to treat people with mental health conditions such as schizophrenia. In some people with dementia antipsychotics can help with certain symptoms such as aggression and psychosis. However, they can cause serious side effects including mobility problems and an increased risk of stroke, particularly when used over longer periods.
The use of antipsychotic drugs should be kept to a minimum. Non-drug approaches should be tried, and if an antipsychotic is prescribed the prescription should be reviewed regularly.