Some of the examples of antidementia drugs include Donepezil (Aricept), Rivastigmine and Galantamine. There are no major differences between these medications. All three of these are known as acetyl cholinesterase inhibitors. They are typically the medication used for patients with early signs of Alzheimer’s dementia in particular. There is another medication called Memantine (in the class of drugs called NMDA antagonists) which is usually reserved for more advanced cases of dementia when symptoms are worsening.
What do antidementia drugs they do?
Antidementia medication is not a cure for dementia. However they may help to stabilise the illness or improve it for a while. Dementia medication can sometimes help improve memory. They can also have general benefits including improving alertness and motivation. More often carers see general improvements in behaviour or mood in patients with more advanced or severe dementia. The drugs are usually given as tablets or capsules. Galantamine can be given in liquid form. Rivastigmine is available in liquid form and also patches (where the medication is absorbed through your skin).
How effective are antidementia drugs?
Research studies have shown that 40–50% of people who have taken these drugs have shown some improvement or stabilisation of their condition over a period of six months.
How do antidementia drugs work?
Mechanism of action of dementia treatment: In Alzheimer’s disease, one of the chemicals in the brain called acetylcholine, which is important for learning and memory, is in short supply. So if you have less acetylcholine activity, then you may have less memory ability and reduced learning. The medications act by increasing the brain levels of acetylcholine and thus help to stabilise or improve memory, learning and functioning. All three of the “acetylcholinesterase inhibitor” medications namely Donepezil, Rivastigmine and Galantamine work in this way.
How are antidementia drugs started?
Firstly the specialist will see the patient in the Memory Clinic. Different memory screening tests are completed. But before that, we have to find out if the drug suits a particular patient. A detailed history is taken, including a medical history to rule out heart, kidney or liver problems or breathing problems. We will need to do relevant investigations necessary to rule out any treatable causes for the memory problems. Then we will also do a formal assessment of daily living skills and finally decide if an antidementia medication is appropriate.
What dose of medication is used?
Patients are initially started on a low dose of these medications. The drugs take at least 4 weeks to show their full effect at the starting dose. After 4 weeks, we may increase the dose depending on the response and how a patient has tolerated the medication. Initially we usually prescribe these antidementia drugs for a trial period of 3 months to see if there has been a beneficial effect. If not we may discontinue the medication. If a patient does show improvement, they can remain on this for a longer period of time assuming ongoing benefit. We would usually review a patient every 6 months thereafter.
Adverse side-effects of antidementia drugs
All medicines have side-effects; some patients may not experience any side-effects. The most common adverse effects with dementia treatment are feeling nauseous (sickness), vomiting, diarrhoea, poor sleep, muscle cramp. These effects if they occur tend to be mild and temporary. The uncommon and rare side effects are urinary retention and seizures. The medication can be stopped immediately if it causes any problematic side-effects. These medications are not addictive and there is no evidence of withdrawal symptoms if the medication is being stopped.
Drowsiness is not a main side effect of these drugs but if you do feel drowsy you should not drive or operate dangerous machinery. You should take extra care as they may affect your reaction times. The combination of Donepezil and alcohol may cause drowsiness. However, patients on Donepezil can have an occasional drink, if they wish. There is no evidence of withdrawal symptoms.