A Clue To Dementia Could Show Up As Early As 45

One in 11 people aged 65 and over have dementia in the UK, the NHS said. And according to Alzheimer’s Society, a person’s risk “roughly doubles” every five years after around 70.

But while it might take decades for symptoms to show, researchers increasingly think markers of coming dementia can begin years before diagnosis.

And a recent paper in Springer Nature has suggested that a biomarker in people’s blood – pTau181, which is linked to a higher dementia risk – might hint at a greater likelihood of developing the condition when seen in 45-year-olds.

“Although plasma pTau181 has been shown to accurately discriminate patients with Alzheimer’s disease from healthy older adults, there are few studies of plasma biomarkers among middle-aged populations,” the paper reads.

45-year-olds with elevated pTau181 were more likely to say they had concerns about their cognition than adults of the same age with lower pTau181 levels in this study.

They tended to be more worried about their memory and thinking, though this didn’t show up on cognitive scores.

Researchers call this phenomenon – the “self-reported persistent decline in cognitive performance with normal performance on objective cognitive tests, in the absence of another explanation” – subjective cognitive decline (SCD).

Scans and other investigations didn’t show any structural brain changes, usually linked to dementia, among those with more pTau181.

Speaking to the University of Otago, the study’s lead author, Dr Ashleigh Barrett-Young, said that this might mean signs of higher dementia risk begin years before the changes we associate with the condition start.

“This means there may be an important window for prevention, which remains one of the most promising approaches for Alzheimer’s disease,” she said.

Dr Barrett-Young added that their results might mean small changes in cognition –SCD – combined with elevated pTau181 aged 45 could hint at measurable issues later on.

“This highlights the need for careful research to understand how early changes relate to later outcomes.”

Dr Barrett-Young stressed that this theory needs more research.

She said “Understanding the earliest stages of disease development is essential for designing effective prevention and treatment strategies, even if clinical tools are still some way off.

“Importantly, biomarkers like pTau181 reflect risk, not certainty”.

We don’t know for sure whether those with a combination of higher pTau181 and SCD aged 45 will definitely face a higher dementia risk, either.

Writing for The Conversation, Dr Barrett-Young said: “Perhaps pTau181 increases during the earliest stages of Alzheimer’s disease, when people first start to notice their memory worsening, but no changes are shown yet in MRI scans.

“Or it could be that elevated pTau181 is not related to Alzheimer’s disease risk in midlife, and the protein is only useful for detecting Alzheimer’s in older adults. We don’t know enough yet, but will be following the same group of people as they get older to continue this research.”