A new study, published in Alzheimer’s & Dementia: The Journal of the Alzheimer’s Association, has found that early symptoms of dementia may appear in two “windows,” years before diagnosis.
They found that cognitive tests, blood biomarkers, and brain scans changed beginning from people’s late 50s.
Dr Mingzhao Hu, an assistant professor in Mayo Clinic’s Department of Quantitative Health Sciences and first author of the study, said: “By estimating the ages when changes in health markers become more noticeable, the results show that many of these shifts tend to happen from late 50s through early 70s.”
What did the research show?
Using data from 2,082 participants in the Mayo Clinic Study of Ageing, the researchers tracked data from people’s blood, brain scans, and cognitive tests.
The study is long-running and “provides an integrated view of age-related patterns across multiple Alzheimer’s biomarkers measured in blood and imaging, plus cognition,” Dr Hu said.
Cognition scores among those who went on to develop dementia began to decline at 50, followed by a sudden accumulation of amyloid plaques in the brain in people’s 60s.
Then, in their late 60s and early 70s, people who went on to develop dementia saw more signs of tau accumulation, “pointing to an early 60s window when cognitive and amyloid changes become more pronounced”, the Mayo Clinic said in a press release.
Alzheimer’s, the most common form of dementia in the UK, is associated with the buildup of amyloid plaques and tau tangles. They’ve been compared to the “trigger and bullet” in the development of the condition.
Some blood markers, like plasma GFAP, NfL and p-tau, tended to change between 68-72, along with brain atrophy, particularly in the parts of the brain responsible for memory.
The Mayo Clinic’s release continued, “Two broad windows emerged, around the early 60s for cognition and amyloid PET, and around the late 60s to early 70s for several blood and neurodegeneration markers.”
Researchers hope this will lead to earlier detection
Spotting dementia early is key to better care and outcomes. But there’s no single test for dementia at the moment, and most cases are diagnosed years after symptoms begin (3.5 years on average, according to UCL).
The researchers think these “breakpoints” might be useful in dementia diagnosis going forward, as well as blood tests.
Dr Jonathan Graff-Radford, the chair of Behavioural Neurology at Mayo Clinic and senior author of the study, said: “As Alzheimer’s research shifts toward prevention and earlier treatment, blood biomarkers will play a central role in identifying who is best suited for these therapies.
“Knowing when these biomarkers start to change, and when they relate to cognitive impairment, helps point us to the ages when prevention screening could have the greatest impact.”