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Antipsychotics pose previously unknown risks to dementia patients, NIHR study finds

Published: 19 April 2024

An NIHR-funded study has found that the use of antipsychotic medication to treat symptoms of dementia is associated with higher risks of a wide range of serious health outcomes.

The study, which was funded by NIHR Greater Manchester Patient Safety Research Collaboration (PSRC), has found that the risks for patients are highest soon after they start taking the drugs. This suggests that more caution is needed around prescribing. 

What is dementia?

Dementia describes a set of symptoms that over time can affect memory, problem-solving, language and behaviour. Symptoms may be mild at first but get worse over time. Caring for dementia patients in the later stages of the condition can be very challenging. 

When are antipsychotic drugs prescribed to people with dementia? 

Despite safety concerns, antipsychotics are prescribed for 

  • Symptoms such as hallucinations, delirium and psychosis
  • Persistent distress, agitation and anxiety
  • Persistent aggression and un-cooperativeness

For many years there have been safety concerns about the use of antipsychotics for dementia patients. Increased risk of stroke and death has been reported. 

Large analysis based on reliable health data 

The observational study investigated the association between antipsychotic drugs in patients with dementia and a range of serious health outcomes. 

The study linked primary care, hospital and mortality data in England between January 1998 and May 2018. The researchers identified 173,910 people diagnosed with dementia who had not been prescribed an antipsychotic in the year before their diagnosis. 35,339 patients were prescribed an antipsychotic on or after the date of their dementia diagnosis. 

These prescribed antipsychotics accounted for almost 80% of all prescriptions: 

  • Risperidone
  • Quetiapine
  • Haloperidol
  • Olanzapine 

These patients were then matched with up to 15 randomly selected patients who had not used antipsychotics. Patient lifestyle, pre-existing medical conditions and prescribed drugs were taken into account. 


The researchers compared the health outcomes of the non-use group to the group who had antipsychotics. The results, published in the BMJ, show that within the group who had been prescribed an antipsychotic, there were higher rates of 

  • stroke
  • blood clots
  • heart attack
  • heart failure
  • fracture
  • pneumonia
  • acute kidney injury 

This is a wider range of harms than previously known. The researchers observed for almost all outcomes that the risks were highest during the first week of antipsychotic treatment. This was particularly true for pneumonia.

Rates of pneumonia among antipsychotic users 

When looking at pneumonia, the researchers noted that:

  • The rates in the first 3 months were 4.48% vs 1.49% for non-users.
  • In one year, this rose to 10.41% for antipsychotic users vs 5.63% for non-users. 

The researchers estimate that over the first six months of treatment, antipsychotic use might be associated with one additional case of pneumonia for every 9 patients treated. 


Because it was an observational study, no firm conclusions can be drawn about cause and effect. And although a range of factors have been adjusted for, the possibility that other unmeasured variables may have affected the results can’t be ruled out.

Senior author Professor Darren M. Ashcroft, Director of the NIHR Greater Manchester PSRC and NIHR Senior Investigator said: “In recent years, it has become clear that more people with dementia are being prescribed antipsychotic drugs, despite existing regulatory safety warnings. It is important that any potential benefits of antipsychotic treatment are weighed carefully against the risk of serious harm, and treatment plans need to be regularly reviewed in all health and care settings.”

With the number of people living with dementia forecast to increase greatly in the coming years, further research into safer drugs and more efficacious non-drug treatments for behavioural and psychological symptoms of dementia are needed. 

The NIHR PSRCs bring patient safety discoveries to frontline NHS services.

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