Thousands of elderly people with Alzheimer's disease or other types of dementia take antipsychotic medicines. But these drugs are controversial, because research has shown that some of them increase the risk of a stroke for people with dementia. Now, new research has looked in more detail at which antipsychotic drugs increase the chances of having a stroke, and who is at most risk.
What do we know already?
Antipsychotic drugs were developed to treat people with serious mental illnesses, such as schizophrenia. They calm people down when they’re agitated, and help with symptoms where people lose touch with reality (for example, hearing voices or seeing things that aren't really there).
There are two main types of antipsychotic drugs. The newer type are called atypical antipsychotics. Two examples are olanzapine (brand name Zyprexa) and risperidone (Risperdal). The older type are called typical antipsychotics. One of these is haloperidol (brand names include Haldol and Seranace). The main differences between older and newer drugs are in the type of side effects people get.
As well as being used for people with schizophrenia, antipsychotic drugs have been widely used for elderly people with dementia. They are used to calm people down if they are agitated or aggressive.
But since 2004, doctors have been told not to use olanzapine and risperidone for people with dementia. People with dementia taking these drugs are more likely to have a stroke.
Despite the risks, olanzapine and risperidone are still sometimes used for people with dementia. If you have cared for a relative with dementia, you’ll know how upsetting it can be to see them agitated, distressed or having frightening delusions. Doctors may think it’s worth using the drugs to control these symptoms, despite the dangers.
Researchers wanted to find out whether other types of antipsychotic drugs could also cause strokes. So, they trawled through thousands of old medical records to find out about people who’d had strokes, and who’d taken any type of antipsychotic drug. They wanted to find out whether people were more likely to have had their stroke while taking antipsychotic drugs.
What does the new study say?
All elderly people had an increased risk of having a stroke while they were taking an antipsychotic drug. The risk was higher for atypical antipsychotics such as olanzapine and risperidone.
The risk of a stroke while taking antipsychotic drugs was higher for elderly people with dementia, compared with elderly people who didn't have dementia.
Tell me more about the study’s findings
People who’d been diagnosed with dementia were more than three times more likely to have a stroke while taking any type of antipsychotic drug, compared to while they weren't taking the drugs.
Elderly people are more at risk of strokes than younger people. About 2 in every 100 people over 75 have a stroke each year. So, drug side effects that make a stroke more likely are particularly dangerous for the elderly.
Where does the study come from?
The study was carried out at the London School of Hygiene and Tropical Medicine. It was published in the BMJ (British Medical Journal), which is owned by the British Medical Association. It was paid for by the Wellcome Trust and the Medical Research Council.
How reliable are the findings?
The study was carried out carefully and looked at medical records for nearly 7,000 people. The results are clear that people’s risk of having a stroke went up while they were taking antipsychotics, and went down again after they stopped taking them.
What does this mean for me?
If you are a close relative or carer for someone with dementia, you’ll probably want to know which drugs they have been prescribed, and why. Olanzapine and risperidone aren't recommended for people with dementia, but the study suggests that there's still a risk with other antipsychotic drugs.
The average age of people in the study was 80 when they first started taking antipsychotic drugs, and nearly 81 when they first had a stroke. The youngest person in the study was 71. That’s probably because strokes are less common in younger people. So, this study doesn’t tell us anything about the risk of stroke for younger people taking antipsychotic drugs for mental illnesses such as schizophrenia.
What should I do now?
If you are concerned about a relative with dementia, it's okay to ask their doctor what medicines they are taking and for what reasons. If you’re not happy with the answers, ask the doctor why they think antipsychotic drugs are right for your relative, and whether the benefits are likely to outweigh the risks.
It's worth remembering that all drugs have side effects as well as benefits. You’ll need to weigh these up with your relative’s doctor.
From:
Douglas I, Smeeth L. Exposure to antipsychotics and risk of stroke: self-controlled case series study. BMJ. 2008; 337: a1227.
To find out more, see our information on dementia.
