Antipsychotic drugs may increase the risk of death in people with Parkinson's disease psychosis (PDP), according to a new study led by researchers from the Institute of Psychiatry, Psychology & Neuroscience (IoPPN) at King's College London.

The study, published in JAMDA, found that people with PDP who were treated with antipsychotics were four times more likely to have died following three to six months of treatment than those who did not receive any antipsychotic medication. They were also more likely to experience serious health issues including cognitive decline, worsening of Parkinson's symptoms, stroke, infections and falls.

Parkinson's disease affects approximately 7-10 million people worldwide and is characterised by progressive loss of motor function, psychiatric symptoms and cognitive impairment. Psychosis is a common and distressing group of psychiatric symptoms affecting people with Parkinson's, usually manifesting as hallucinations and delusions.

PDP affects more than 50 per cent of people with Parkinson's at some point in their condition and antipsychotic drugs are often used to treat this psychosis, yet there is little evidence to support their use.

The researchers examined more than 400 people with PDP, who were taking part in a separate trial, to assess the impact of antipsychotic medications on their overall health and wellbeing. Participants were categorised into two groups -- those receiving antipsychotics and those who did not take any antipsychotic medications at any time during the study.

Professor Clive Ballard from the Wolfson Centre for Age-Related Diseases at the IoPPN, King's College London, said: 'Our findings clearly indicate serious risks associated with antipsychotics and highlight the need for greater caution in treating psychosis in Parkinson's disease.

'Antipsychotics are known to be linked to serious harm in people with Alzheimer's Disease, and these findings show that a similar, although not identical, risk is seen in people with Parkinson's. Our findings therefore strongly suggest that doctors, patients and family members should consider these risks very carefully when considering potential treatments for psychosis and any other behavioural symptom in people with Parkinson's Disease, such as agitation or aggression.

'Further research is required to develop new, better treatments for psychosis and other behavioural symptoms.'

Professor Ballard added: 'For example, a study we published last year showed that a novel antipsychotic, pimavanserin, was effective and had far fewer side effects than traditional antipsychotics.'