A new genetic study, the largest of its kind to date, has found that a gene already associated with Alzheimer’s disease also independently increases the risk of Delirium. Researchers analysed DNA data from more than one million individuals across several major global cohorts, including participants from the UK, the US, and Finland.
The gene in question, APOE. and especially its variant APOE ε4 — is already known for raising Alzheimer’s risk because of its role in lipid (fat) transport in the blood. But this study shows that even when accounting for dementia, the APOE gene variant still significantly elevates the risk of developing delirium. In other words, the increased risk cannot be explained simply by the gene’s link to Alzheimer’s — APOE appears to have a separate, direct effect on delirium risk.
Delirium — typically a rapid change in brain function leading to confusion and disorientation — is common among hospitalized older adults and is associated with worse outcomes such as longer hospital stays, higher mortality, and increased risk of later dementia.
In addition to the genetic analysis, researchers dug deeper using blood samples from about 32,000 individuals who later developed delirium, collected up to 16 years ahead of diagnosis. These analyses uncovered several blood-based proteins that may serve as biomarkers — including markers associated with brain vulnerability, inflammation, and immune response — which might predict delirium risk long before symptoms begin.
The findings challenge conventional thinking by demonstrating that delirium may have a substantial genetic component, not simply as a byproduct of dementia risk, but as a condition with its own genetic and biological underpinnings.
Ultimately, this discovery could pave the way for improved risk screening, early identification of susceptible individuals, and potentially new approaches to preventing or managing delirium — shifting the focus beyond just cognitive decline and dementia.
