This information is for people with dementia and their carers. It tells you about quetiapine (Seroquel), a treatment that is sometimes used for dementia. It's based on the best and most up-to-date research.
Does it work?
We're not certain. There's some evidence to show that quetiapine doesn't help people with dementia who are restless and agitated. And it might make other symptoms worse. But we need to see more research before we can know for certain.
What is it?
Quetiapine is an antipsychotic drug. Antipsychotics are normally used to treat people who have serious mental health problems, like schizophrenia.
Quetiapine comes as tablets. The brand name is Seroquel.
How can it help?
There's no good evidence that quetiapine can help people who have dementia. One study has found that quetiapine doesn't help people with dementia with the symptoms of restlessness and agitation. Also, it made other symptoms of dementia worse. 
How does it work?
Quetiapine works by blocking the action of dopamine. Dopamine is a chemical in the brain that helps electrical signals travel between brain cells (a neurotransmitter).
Symptoms such as delusions (believing things that couldn't be true), aggression, and violence may happen because there is too much dopamine in the brain. Lowering the amount of dopamine may help these symptoms.
Can it be harmful?
Antipsychotics can have dangerous side effects when they're used to treat older people with dementia. People taking these drugs run a higher risk of serious heart problems or a stroke. Antipsychotics can also cause unpleasant but less dangerous problems, like muscle twitches.
Doctors in the UK are advised not to prescribe antipsychotic drugs for people with dementia. 
All antipsychotic drugs can increase the risk of a stroke when they're used to treat older people with dementia.  There's a lower risk with older antipsychotics, like haloperidol, than with the newer ones, which include quetiapine and risperidone.
Another study suggested that the antipsychotic drugs haloperidol (brand name Haldol), olanzapine (brand name Zyprexa), and risperidone (Risperdal) were linked to a rise in the chances of people with dementia dying shortly after starting to take them. But quetiapine did not show this increased risk. 
If you're caring for someone with dementia and their doctor recommends an antipsychotic drug, ask about the risks, and what the benefits of treatment might be.
One study has found that quetiapine can make some of the symptoms of dementia worse.  The patients in this study who were given quetiapine were more likely to score worse in tests of memory and thinking that those given a dummy treatment (called a placebo).
Common side effects reported by people taking quetiapine include:
A big problem with older antipsychotic drugs, such as haloperidol, is that they can give you muscle problems. Some people get stiff or shaking muscles, or unusual movements of their face. These problems are less common with newer antipsychotic drugs like quetiapine.