Psychotic Disorders May Nearly Triple Dementia Risk

According to new research, individuals with nonaffective psychotic disorders are 2.5 times more likely than those without a nonaffective psychotic disorder to eventually develop dementia, representing a new avenue of modifiable risk.¹

In the first high-quality systematic review looking at a range of psychotic disorders and their association with dementia risk, researchers pulled together evidence from close to 13 million participants from 11 studies from 9 countries. The population of interest included adults at least 18 years old with a clinical diagnosis of nonaffective psychosis based on ICD criteria. Results indicated that psychotic disorders may have a stronger link with dementia than other mental health disorders like depression or anxiety. Studies with typical and late-onset psychotic disorders, those with a higher percentage of women, those with a younger minimum age at baseline showed the strongest associations. As such, the study authors wrote, “Our narrative synthesis provided some evidence that people with psychotic disorders tended to be younger at dementia diagnosis and that the association between psychotic disorders and dementia was stronger when the interval between the two diagnoses was shorter.”

Despite speculations of the possible role of antipsychotics in the development of dementia, the investigators only found 2 studies exploring this link. Moreover, those studies showed mixed results. One found a protective effect; the other found an increased risk associated with second generation antipsychotics but a protective effect for first generation antipsychotics.

“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 lead author Sara El Miniawi of University College London.²

Regardless of the age at which an individual first develops their mental illness, those with psychotic disorders are at a higher risk of dementia later in life. Additionally, individuals with a psychotic disorder tend to be younger than average at dementia diagnosis, as young as their 60s.

Previous research indicates that 4 in 10 dementia cases could be prevented or delayed by targeting risk factors from across the lifespan. This study’s findings add to the list of modifiable risk factors for 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,” said Vasiliki Orgeta, PhD, an associate professor at the Division of Psychiatry, Faculty of Brain Sciences at University College London.²

The researchers 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.

References

1. El Miniawi S, Orgeta V, Stafford J. Non-affective psychotic disorders and risk of dementia: a systematic review and meta-analysis. Psychol Med. 2022;1-13.

2. Schizophrenia may increase dementia risk by 2.5 times. UCL News. October 6, 2022. Accessed November 2, 2022. https://www.ucl.ac.uk/news/2022/oct/schizophrenia-may-increase-dementia-risk-25-times