According to research from University College London, people diagnosed with psychotic disorders are 2.5 times more likely to develop dementia.
The research, which has been published in Psychological Medicine, has found that people with psychotic disorders such as schizophrenia may be more likely to develop dementia than other mental health disorders like anxiety and depression.
“We found that having a diagnosis of a psychotic disorder is linked to a much higher risk of developing dementia later in life. Our findings add to evidence that protecting people’s mental health throughout life could help to prevent dementia,” said senior author Dr Jean Stafford from the MRC Unit for Lifelong Health & Ageing at University College London (UCL).
The study is the first high-quality systematic review focusing on a range of psychotic disorders and their association with dementia. The researchers looked at psychotic disorders such as schizophrenia that included symptoms such as hallucinations and delusions. Many people with these disorder experience impairments in cognitive functional skills.
The researchers drew on evidence from 11 studies from nine countries across four continents. Close to 13 million people were involved in the study.
People with psychotic disorders are more likely to suffer early onset dementia
The researchers observed that participants with various mental disorders were at a higher risk of dementia later in life, regardless of their age. They also found that people who experienced psychotic disorders were diagnosed at a younger age than those who did not. Results showed that people with psychotic disorders were more likely to be diagnosed with dementia in their 60s.
The findings add to the list of modifiable risk factors for dementia. Previous research from UCL has suggested that four out of ten dementia cases could be prevented or delayed through the treatment of these risk factors. Their research found that the likelihood of dementia was increased by PTSD and that while depression and anxiety increased the risk, psychotic orders have the strongest association.
The cause of the association is unclear
The researchers could not confirm the cause of the association. It is not understood whether the psychotic disorders themselves cause dementia or whether the disorders cause other conditions that in turn increase the risk of dementia.
“People with psychotic disorders are more likely to have other health conditions such as cardiovascular disease or obesity, which can increase the risk 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,” explained Dr Ortega.
“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,” added lead author Sara El Miniawi, from the Division of Psychiatry at UCL.
The researchers were unable to determine whether treatment for psychotic disorders could fight the risk of dementia or whether antipsychotic medication maybe be a cause of dementia. The researchers noted that evidence for both possibilities was limited and conflicting.
“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,” concluded El Miniawi.