Research Roundup - July 2026
- Penn FTD Center
- 2 days ago
- 2 min read
Read the below Research Roundup from Penn FTD Center Research Assistant Professor Katheryn Cousins, PhD.
Terms to Know:
Amyloid PET: a type of brain imaging scan that detects the presence of beta-amyloid plaques, which are a hallmark protein buildup associated with Alzheimer's disease (AD).
Mild Cognitive Impairment (MCI): the in-between stage bridging typical thinking and dementia. MCI generally falls into two categories: Amnestic MCI, which primarily affects memory, and non-amnestic MCI, which primarily affects judgment, decision-making, language, or visual perception.
Plasma biomarker: a measurable substance in blood that serves as a minimally invasive pre-screening tool to aid in diagnosis and assess the risk of cognitive decline.
Phosphorylated tau-217 (p-tau217): a biomarker that reflects the accumulation of amyloid-beta plaques and neurofibrillary tangles in the brain. p-tau217 levels rise in blood plasma and cerebrospinal fluid (CSF) when Alzheimer’s-related brain changes are occurring.
Aβ42 (amyloid-beta 42): is deposited into plaques in the brain which leads to decreased levels in CSF and plasma.
Aβ40 (amyloid-beta 40): another form of the amyloid-beta protein that is measured alongside Aβ42 to determine the risk for amyloid pathology in the brain.
Aβ42/Aβ40 ratio (amyloid-beta 42/amyloid-beta 40): a lower ratio usually indicates the presence of amyloid plaques in the brain and an increased risk of AD while a higher ratio is indicative of a lower likelihood of Alzheimer's.
p-tau217/Aβ42: the ratio of p-tau217 to amyloid-beta 42 that can be measured in CSF or plasma tests. A higher ratio strongly suggests the presence of amyloid pathology in the brain.
What we knew:
Plasma biomarkers generally work well for detecting Alzheimer's disease (AD) pathology and have shown strong diagnostic accuracy in prior studies. However, validation of these tools had mostly occurred in racially homogenous samples. Existing research on biomarker levels and accuracy in a diverse dataset has shown inconclusive results. The validation of plasma biomarkers in a diverse population is needed to ensure accurate interpretation in a larger population.
What we didn’t know:
The study aimed to determine whether p-tau217/Aβ42, p-tau217, or Aβ42/Aβ40 could consistently and accurately detect amyloid pathology equally across racial groups (Black/African American and White participants). Then, the study looks into whether the racial differences in biomarker levels were driven by race itself or by other factors like comorbidities and social determinants of health that are associated with racial identity.
What this research/study shows:
The p-tau217/Aβ42 ratio was the most accurate biomarker for detecting amyloid pathology between participants who self-identified as Black/African American and those who self-identified as White. Where differences did show up, such as the Aβ42/Aβ40 ratio being somewhat higher in Black/African American participants, these seemed to be associated with other factors like diabetes, kidney function, BMI (body mass index), and cognitive status. Additionally, false negatives (missed amyloid-positive cases) were found in women, individuals with normal cognition, those with higher BMIs, and slightly more so among Black/African American participants with normal cognition.
What to do with this information:
The study’s findings support the use of p-tau217/Aβ42 as a primary screening tool for amyloid pathology across diverse populations keeping in mind the caveat of false negative results in specific groups. However, continued efforts in validation studies on a diverse population are still needed.
More information:
