TUESDAY, Dec. 26, 2023 (HealthDay News) -- Are you necessarily at higher risk of Alzheimer's disease just because you're 80, and not 75? New research shows it's more complex than that.

The findings suggest that it's the pace of buildup in the brain of Alzheimer's-linked amyloid protein plaques that matters most, not age.

Our findings are consistent with studies showing that the amyloid accumulation in the brain takes decades to develop," said study lead author Dr. Oscar Lopez, a professor of neurology at the University of Pittsburgh.

His team's findings were published Dec. 22 in the journal Neurology.

Neuroscientists have long known that the slow but steady accumulation of amyloid-beta protein plaques within brain tissue is a hallmark of Alzheimer's disease, although whether it actually causes the illness is still debated.

Rates of dementia do rise with advancing age, but is age alone the key factor?

To find out, Lopez' team examined amyloid buildup in the brains of 94 people who were 85 at the time they enrolled in the study. All were tracked for 11 years or until they died, and all received two PET scans of their brains during that time.

The researchers compared levels of amyloid buildup seen in those scans to those seen in scans from a younger group of patients (in their 60s) observed in a prior Australian trial.

As expected, amyloid plaque buildup rose over time, regardless of how much of the protein had infiltrated a participant's brain at the time they joined the Pittsburgh study.

Plaques seemed to accumulate faster among people in their 80s, however, compared to people in their late 60s', Lopez' team reported.

None of the elderly people in Lopez' trial who developed dementia were without some plaque buildup in their brains, confirming its key role in the disease.

Most importantly, when brain plaque buildup began seemed key to how soon dementia set in.

For example, people who were already displaying amyloid buildup in their PET scans at age 80 (when they enrolled in the study) developed dementia two years earlier than folks without such early buildup, the Pittsburgh team found.

Finally, the long-term links between amyloid beta buildup and other brain health indicators was more strongly linked to dementia than just the short-term growth of plaque on its own, Lopez' group added.

That's consistent with other studies, which found that amyloid buildup "takes decades to develop, and occurs in the context of other brain pathologies," Lopez said in a university news release.

Lopez, who also directs Pitts Alzheimer's Disease Research Center, said that "understanding of the timing of the presence of these pathologies will be critical for the implementation of future primary prevention therapies.

More information

Find out more about Alzheimer's disease and the brain at the Alzheimer's Association.

SOURCE: University of Pittsburgh, news release, Dec. 22, 2023

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Brain Plaques Point to Who'll Need Alzheimer's Treatment Most - HealthDay