Effects of Alzheimer's disease drugs

Are drugs effective for everyone with Alzheimer's disease? We explain the benefits, how addictive the drugs are, and what the side effects might be.

Donepezil, rivastigmine and galantamine

NICE guidance recommends that donepezil, rivastigmine or galantamine is offered as part of NHS care for people with mild to moderate (early to middle stage) Alzheimer’s disease. There is good evidence (especially for donepezil) that these cholinesterase inhibitors also help people in the later stages of Alzheimer’s disease (see ‘Stopping treatment’).

40–70% of people with Alzheimer’s disease who take a cholinesterase inhibitor find it helps them. Doctors cannot reliably know in advance whether the medication will help a specific person. Where the treatment helps someone, symptoms improve temporarily (usually for between six and 12 months). This effect then wears off a bit, so symptoms gradually get worse over the following months (even though the person is still taking the medication). People who take a cholinesterase inhibitor may find it helps with:

  • anxiety
  • motivation
  • memory and concentration
  • ability to continue daily activities (such as managing money, shopping or cooking).

It is not clear whether the cholinesterase inhibitors also help with behavioural changes such as agitation or aggression. Research hasn’t given a clear answer one way or the other.

Drugs for behavioural and psychological symptoms

Learn about how drugs can help with behavioural and psychological symptoms of dementia.

Read more

Memantine

NICE guidance recommends using memantine as part of NHS care for people with severe (late stage) Alzheimer’s disease. NICE also recommends memantine for people with moderate (middle stage) Alzheimer’s disease who cannot take the cholinesterase inhibitor drugs – this is usually because of side effects.

Memantine is licensed for the treatment of moderate to severe Alzheimer’s disease. In people in the middle and later stages of the disease, memantine can slow down the progression of symptoms. These include worsening mental abilities (such as disorientation) and problems carrying out daily activities such as getting dressed. There is some evidence that memantine may also help with symptoms such as delusions, aggression and agitation. For more information see Drugs for behavioural and psychological symptoms in dementia, and Aggressive behaviour.

If the person is taking memantine and has also been kept on a cholinesterase inhibitor, this means they will get both drugs together. There is now evidence that this combination treatment is better for someone with late-stage Alzheimer’s than the cholinesterase inhibitor alone. This may be because the drugs work in different ways.

Are there any side effects?

Most people can take cholinesterase inhibitors and memantine without too many side effects. Not everyone has the same side effects, or has them for the same length of time.

The most common side effects of donepezil, rivastigmine and galantamine are:

  • loss of appetite
  • nausea
  • vomiting
  • diarrhoea.

Other side effects include muscle cramps, headaches, dizziness, fatigue and insomnia. Side effects can be less likely for people who start treatment by taking the lower prescribed dose for at least a month (see ‘Taking the drugs’).

The side effects of memantine are less common and less severe than for the cholinesterase inhibitors. They include:

  • dizziness
  • headaches
  • tiredness
  • raised blood pressure
  • constipation.

Talk to the doctor or the pharmacist about any side effects. None of these drugs are addictive.

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