People who suffer from psychotic disorders like schizophrenia are 2.5 times more likely to develop dementia eventually than those suffering from other mental disorders, researchers of a recent study said.

The study's findings, which were a systemic review and meta-analysis published in the journal Psychological Medicine recently, found that psychotic disorders may have a stronger link with dementia than other mental health disorders like depression or anxiety.

 “We found that having a diagnosis of a psychotic disorder is linked to a much higher risk of developing dementia later in life,” senior author of the study, Dr Jean Stafford of MRC Unit for Lifelong Health & Ageing at University College of London, said in a statement.

“Our findings add to evidence that protecting people’s mental health throughout life could help to prevent dementia,” she added.

Pointing out that the study is the first high-quality systematic review looking at a range of psychotic disorders and their association with dementia risk, the researchers said that such disorders are severe illnesses that involve symptoms such as hallucinations and delusions, and social withdrawal and many people also experience impairments in cognitive and functional skills.

Scanning over 9000 studies published on the subject, the researchers found that across multiple different psychotic disorders, regardless of the age at which someone first developed their mental illness, there was a higher risk of dementia later in life.

For their final analysis, the researchers collated evidence from 11 studies from nine countries across four continents involving around 13 million participants.

The researchers further found that people who have had a psychotic disorder tend to develop dementia at an earlier and two of the studies included in the analysis found that people with psychotic disorders were much more likely to be diagnosed with dementia while still in their 60s.

Though the researchers could not confirm the cause of the association between psychotic disorders and dementia, they said some of the associations could be because psychotic symptoms could be early markers of dementia for some people but the fact that some of the studies had very long follow-up periods and included people experiencing psychosis at young ages suggests this is not the only explanation.

“People with psychotic disorders are more likely to have other health conditions such as cardiovascular disease or obesity, which can increase the risk said k of dementia, while they are also more likely to have a poor diet, smoke or use drugs, which may harm their health in ways that could increase their likelihood of developing dementia,” current study’s joint senior author, Dr Vasiliki Orgeta, Associate Professor, Mental Health of Older People, Division of Psychiatry at University College of London said.

“Cognitive impairment and hallucinations can be symptoms of both dementia and psychotic disorders, so it is possible there could be a link between the two illnesses. This impairment could also limit people’s cognitive reserve and increase their vulnerability to dementia symptoms,” said the lead author of the study, Sara El Miniawi, who completed the research as her MSc dissertation said.

The researchers said that they were not able to determine whether effective treatment for psychotic disorders could mitigate the dementia risk or whether antipsychotic medication could be a factor, as there was limited and conflicting evidence.

“As people with psychotic disorders face a higher risk of numerous other health conditions, managing their overall physical and mental health is very important, and here we found that health professionals working with them should also be watchful for any signs of cognitive decline,” Miniawi added.