The study relied on data from brain scans originally used to assess amyloid pathology, widely believed to be a hallmark indication of Alzheimer’s disease. The test used was known as amyloid positron emission tomography (PET).
In totality, 236 people participated in having their amyloid PET scans taken and analyzed by the research team. On average, at least two brain scans were conducted, with about 4 and half years apart of each scan.
“Amyloid accumulation was evaluated in 236 individuals who underwent more than one amyloid PET scan,” the findings state. “The average age was 66.5 ± 9.2 years and twelve individuals (5%) had cognitive impairment at their baseline amyloid PET scan. A tipping point in amyloid accumulation was identified at a low level of amyloid burden, after which nearly all individuals accumulated amyloid at a relatively consistent rate until reaching a high level of amyloid burden.”
The results suggest that the participants who reached the tipping point at a younger age took much longer to present cognitive deficits compared to those who reached it later in life. The participants with a tipping point at age 50 developed symptoms close to 20 years later, while those at age 80 took almost 10 years.
The author’s conclusion of the findings: “The age of symptom onset in sporadic Alzheimer’s disease is strongly correlated with the age that an individual reaches a tipping point in amyloid accumulation.”