PET scan reveals new protein’s role in Alzheimer’s disease

Sam Lockhart/Courtesy

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A recent study published Wednesday by UC Berkeley researchers demonstrates the ability of PET scans to track the gradual progression of Alzheimer’s disease in cognitively healthy adults.

Campus professor William Jagust, visiting scholar Michael Scholl and postdoctoral fellow Samuel Lockhart led a team of scientists that used PET scans to produce the first images of tau, a protein in the brain that accumulates with age, in living patients.

Tau, which stabilizes brain neurons, is found in the parts of the brain associated with memory. Yet, when tau spreads out into other areas of the brain as a person ages, an individual may begin to experience difficulties with cognition and memory.

PET scans have previously been used to image beta-amyloid, a protein in the brain that has long been associated with the development of Alzheimer’s disease. Older adults who have increased levels of beta-amyloid often experience memory impairment.

According to Jagust, although scientists know that beta-amyloid accumulation in the brain correlates to the onset of Alzheimer’s disease, arguments persist about how the protein actively causes the disease, because adults may have beta-amyloid in their brains and still remain cognitively healthy.

“Tau may be the missing link between amyloid and cognitive ability,” Jagust said. Though the exact relationship between the two proteins is not yet known, tau tends to spread in the brain when beta-amyloid is present, Jagust added.

In conducting its research, the team carried out PET scans on 53 adults. The group of test subjects included five healthy young adults, 33 cognitively healthy older adults and 15 patients with Alzheimer’s disease. All the subjects were given memory tests to examine their cognitive abilities, then scanned for the presence of beta-amyloid and tau proteins in their brains, Jagust noted.

Prior to this research, studying tau accumulation in the brain could only be done through autopsies on people suspected to have had Alzheimer’s, according to Lockhart. With tau imaging, doctors can now track the additional information of the brain of an adult without Alzheimer’s disease, which would enable scientists to predict who might have a higher chance of accumulating Alzheimer’s later in life, Jagust said.

According to Lockhart, current treatments for Alzheimer’s are mainly symptomatic and therapy-based, although there have been some advancements in “disease-modification treatments” — drugs that aim to reduce beta-amyloid levels in the brain — in the past few years.

The development of tau imaging will help researchers track the progression of the proteins to develop more treatments against the disease, according to a press release.

“This research doesn’t offer people who have Alzheimer’s disease anything very concrete treatment-wise,” Jagust said. “But it will allow us to assess and diagnose people in terms of how progressed they might be (in the disease).”

Contact Jessie Qian at [email protected] and follow her on Twitter at @jessieq96.