APOE genotype helps p-tau217 predict who may develop cognitive impairment sooner

by · News-Medical

A pooled analysis across seven multiethnic cohorts examines whether the same p-tau217 reading carries the same prognostic meaning for people with different APOE backgrounds.

Study: Plasma phosphorylated tau 217 concentrations, APOE genotype, and timing of cognitive impairment in individuals across diverse racial and ethnic groups: a pooled analysis of prospective cohort studies. Image Credit: Nanzeeba / Shutterstock

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A recent pooled analysis published in The Lancet Neurology suggests that higher plasma phosphorylated tau 217 (p-tau217) levels are associated with a greater risk of cognitive impairment, especially among adults carrying the apolipoprotein E ε4 (APOE-ε4) allele.

Plasma p-tau217, an established biomarker of neuropathological changes associated with Alzheimer’s disease (AD), can increase in the blood during the early stages of the condition, even before the onset of overt symptoms. People with equivalent p-tau217 levels can still follow different clinical trajectories, with genetic background likely contributing to this variation.

About the study

In the present study, researchers explored the influence of p-tau217 and APOE genotype on the risk and onset of cognitive impairment across diverse racial and ethnic groups. To do so, they analyzed participant-level data from seven multiethnic prospective cohort studies of older adults.

The studies included the AD Neuroimaging Initiative (ADNI), the Health & Aging Brain Study-Health Disparities (HABS-HD), the Estudio Familiar de Influencia Genética en Alzheimer (EFIGA), and the Washington Heights, Hamilton Heights, Inwood Columbia Aging Project (WHICAP).

Data were also obtained from the Religious Orders Study/Rush Memory and Aging Project (ROSMAP), the Wisconsin Registry for Alzheimer's Prevention (WRAP), and the Wisconsin Alzheimer's Disease Research Center (Wisconsin-ADRC).

The included studies comprised individuals without cognitive impairment who were at increased risk of dementia, while people with mild cognitive impairment (MCI) or dementia were also included. Participants had been recruited through community-based settings and academic research centers in the Dominican Republic, Canada, and the United States (US).

Using observed clinical follow-up data instead of predicted age at onset, the team evaluated the risk and timing of cognitive impairment. Regression and survival models adjusted for sociodemographic factors were used to examine whether baseline p-tau217 concentrations were associated with existing or future cognitive impairment.

Results

The study sample comprised 8,582 individuals (66% female and 34% male) with a mean age of 70 years. Non-Hispanic Whites accounted for 47% of the cohort (n=4,056), while Black participants accounted for approximately 16% (n=1,380). The remaining 37% (n=3,146) were Hispanic or from other ethnic groups. The longitudinal analyses included 4,569 participants (53%) who had no cognitive impairment at the study's commencement and had at least one follow-up clinical assessment.

In the primary analysis of continuous, log-transformed, and within-cohort-standardized p-tau217 values, higher concentrations were associated with higher odds of cognitive impairment at baseline. This association was stronger among participants carrying the APOE-ε4 allele than among non-carriers.

In addition to improving risk assessment, the APOE-ε4 status also helped estimate the timing of cognitive impairment. Among people with the APOE-ε4 allele, each one-standard-deviation rise in plasma p-tau217 corresponded to a 24% shorter time to cognitive impairment. For those without the allele, the time was 13% shorter.

Conclusion

The study was limited by single-timepoint p-tau217 measurements in most cohorts, assay and follow-up differences, an outcome that combined cognitive impairment of any type, combined racial and ethnic categories, and incomplete renal function data.

Broader global validation, repeated biomarker measurements, and studies incorporating polygenic risk scores are needed to test generalizability and refine risk estimates.

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