By Leah Fein
Penn Memory Center (PMC) researchers found tau, a protein in the brain, may help distinguish Alzheimer’s disease from other forms of cognitive impairment.
Lauren McCollum, cognitive and behavioral neurology clinical fellow; Laura Wisse, PMC Scholar; and David Wolk, PMC co-director presented their poster titled “Cognitive Profiles in Amyloid-Positive MCI & Alzheimer’s Disease with and without Tau” at the American Academy for Neurology Annual Meeting.
Alzheimer’s disease presents itself different in every person, with a lot of variability in cognitive symptoms and progression rates.
When assessing for Alzheimer’s disease, some researchers look for what’s called the “ATN” framework, or amyloid, tau, and neurodegeneration. Amyloid and tau are biomarkers for Alzheimer’s found in an individual’s brain, and neurodegeneration is the progressive loss of brain structure and function of nerve cells as seen in Alzheimer’s disease.
While amyloid may be the first sign of Alzheimer’s disease, people may have amyloid in their brain for years before cognitive changes occur. On the other hand, tau builds up in a person’s brain much later than amyloid. Dr. McCollum and her research team thought if a person could have normal cognition with amyloid, then one could not assume that amyloid is the cause of cognitive decline.
Unlike amyloid, research has shown that tau is directly linked to cognitive decline and neurodegeneration. To better understand the role of tau in developing Alzheimer’s disease, the research team compared cognitive profiles and brain imaging in individuals with elevated amyloid and cognitive impairment, based on the presence or absence of tau.
Their findings suggest that individuals with elevated amyloid but not tau had less “Alzheimer’s-like” cognitive profiles, while those with elevated amyloid and a tau build-up had more “Alzheimer’s-like” profiles. This means individuals with a build-up of tau had more memory loss, a characteristic of Alzheimer’s disease, than those without tau.
Individuals with elevated amyloid but not tau may have a different cognitive impairment diagnosis than Alzheimer’s.
Although more research must be done, these biomarkers may allow people to learn what is driving their cognitive impairment while they are alive. This is unlike other forms of cognitive impairment, like vascular dementia and Lewy body dementia.