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

The guidance from NICE (2011) recommends that donepezil, rivastigmine or galantamine is offered as part of NHS care for people with mild-to-moderate Alzheimer's disease.

There is good evidence (strongest for donepezil) that these cholinesterase inhibitors also help people with more severe Alzheimer's disease.

Between 40 and 70 per cent of people with Alzheimer's disease benefit from taking a cholinesterase inhibitor. In cases where the treatment shows benefit, symptoms improve temporarily (for between six and 12 months in most cases) and then gradually worsen over the following months.

People taking a cholinesterase inhibitor can experience

  • reduced anxiety
  • improvements in motivation, memory and concentration
  • improved ability to continue daily activities.

It is not clear whether the cholinesterase inhibitors also bring benefits for behavioural changes such as agitation or aggression. Trials in this area have given mixed results.

Drugs used to relieve behavioural and psychological symptoms

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

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The NICE guidance (2011) recommends use of memantine as part of NHS care for severe Alzheimer's disease.

NICE also recommends memantine for people with moderate 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, it can slow down the progression of symptoms, including disorientation and difficulties carrying out daily activities.

There is some evidence that memantine may also help with symptoms such as delusions, aggression and agitation.

Are there any side effects?

Generally, cholinesterase inhibitors and memantine can be taken without too many side effects. Not everyone experiences the same side effects, or has them for the same length of time (if they have them at all).

The most frequent side effects of donepezil, rivastigmine and galantamine are loss of appetite, nausea, vomiting and 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.

The side effects of memantine are less common and less severe than for the cholinesterase inhibitors. They include dizziness, headaches, tiredness, raised blood pressure and constipation.

It is important to discuss any side effects with the GP and/or the pharmacist.

None of these drugs are addictive.

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