Dementia is something many of us worry about as we get older. But what if a blood test could predict your risk of dementia decades before symptoms appear? New research suggests it may one day be possible.
Researchers from the University of California San Diego found that women with higher levels of a protein called p-tau217, which is linked to the brain changes seen in Alzheimer’s disease, were more likely to develop dementia later in life.
The study, published in JAMA Network Open, analysed data from 2,766 participants in the Women’s Health Initiative Memory Study. The women, aged between 65 and 79, were enrolled in the late 1990s and followed for the next 25 years.
At the start of the study, none of the participants had signs of cognitive impairment. Researchers analysed their blood samples for p-tau217 levels and tracked who went on to develop cognitive issues over the following decades.
They found women who had higher levels of p-tau217 in their blood were more likely to develop dementia later in life.
While the research focused on women, the scientists noted the protein is also strongly linked to dementia risk in men.
Lead author Dr Aladdin Shadyab, professor of medicine at UC San Diego’s School of Public Health and Longevity Science, said the research could help doctors identify people at higher risk of dementia long before symptoms appear.
“That kind of long lead time opens the door to earlier prevention strategies and more targeted monitoring, rather than waiting until memory problems are already affecting daily life,” Dr Shadyab said.
“Ultimately, the goal is not just prediction, but using that knowledge to delay or prevent dementia altogether.”
Dementia rates rising in Australia
Dementia is becoming an increasingly urgent health issue in Australia.
According to the Australian Bureau of Statistics and the Australian Institute of Health and Welfare, dementia is now the nation’s leading cause of death in 2025, overtaking heart disease.
In 2024, dementia accounted for 9.4 per cent of all deaths, and over the past decade deaths linked to the condition have increased by 39 per cent.
Women continue to be disproportionately affected, making up 62.4 per cent of dementia deaths – a trend that has remained consistent since 2016.
Professor Tanya Buchanan, CEO of Dementia Australia, says the latest statistics are a wake-up call.
“Dementia is not an inevitable disease of old age,” Professor Buchanan said.
“Whilst we cannot change getting older, genetics or family history, there are things we can do to reduce our risk of dementia.”
In 2026, an estimated 446,500 Australians are living with dementia, and without intervention that number is projected to rise to more than one million by 2065.
What you can do to reduce your dementia risk
Professor Buchanan says dementia is one of the most feared diseases in Australia but also one of the most misunderstood.
A 2024 Dementia Australia survey found more than a quarter of Australians incorrectly believe there is nothing they can do to reduce their risk.
“In Australia, 43 per cent of dementia burden is attributable to six modifiable risk factors that we want all Australians to be aware of – tobacco use, overweight and obesity, physical inactivity, high blood pressure in midlife, high blood plasma glucose and impaired kidney function,” Professor Buchanan said.
These are the steps you can take to help support long-term brain health:
Prioritise sleep
Aim for seven to nine hours of sleep each night and speak with your GP if you regularly struggle with sleep.
Stay physically active
Try to get around 30 minutes of moderate-intensity exercise at least five days a week.
Eat a brain-healthy diet
A Mediterranean-style diet rich in vegetables, fruit, wholegrains, legumes, fish and healthy fats is linked to better brain health.
Stay socially and mentally active
Maintaining friendships, hobbies and learning new skills helps keep the brain engaged.
Protect hearing and vision
Untreated hearing or vision loss has been linked to faster cognitive decline.
Quit smoking and limit alcohol
Both are known risk factors for dementia and other chronic diseases.
Look after your heart
Managing blood pressure, cholesterol and diabetes also helps protect brain health.
