Tau positron emission tomography better predicts cognitive decline in patients with Alzheimer’s disease

In patients with Alzheimer’s disease (AD), tau positron emission tomography (PET) was superior to magnetic resonance imaging (MRI) or amyloid PET in predicting cognitive changes. These results were published in JAMA Neurology.

For this study, we analyzed data (N = 1431) collected between 2014 and 2021 for an ongoing study on AD conducted in South Korea, Sweden, and the United States. Cognitive changes were assessed annually by tau-PET, amyloid-PET, and MRI.

Participants had a mean age of 71.2 (SD, 8.8) years, 52.5% were men, 44.7% were positive for apolipoprotein E (APOE) e4 and the baseline value of the Mini-Mental State Examination (MMSE) was 26.7 (SD, 3.9).

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The mean annual decrease in the MMSE score was -1.01 (SD, 1.61). Patients with amyloid-b (Ab) -positive AD dementia (n = 315) had a faster annual decline in MMSE scores (mean -2.42; SD 1.87) compared to Ab-positive mild cognitive impairment (MCI ; n = 271; mean -1.38; SD 1.84) Ab-negative MCI (n = 172; mean -0.74; SD 1.31) Ab-positive cognitively unimpaired (CU; n = 253; mean – 0.37; SD 0.84) or Ab-negative CU (n = 420; mean -0.19; SD 0.55).

The decline in MMSE over time was more strongly associated with [18F]Flortaucipir uptake as measured by tau-PET (R2, 0.35) compared to MRI (R2, 0.24; p <0.001). Stratified by AD subtype, the same pattern was observed for both CU groups and the Ab-positive MCI cohort (all P <0.001), and the opposite pattern in which MRI outperformed tau-PET was observed for Ab- negative MCI and AD dementia groups were observed (both P <.001).

Similar results were obtained with a. observed [18F]RO948 replication cohort (R2, Tau-PET: 0.49 vs. MRI: 0.34; P <0.001). For the AD dementia replication cohort, tau PET outperformed MRI (R2, 0.26 vs. 0.17; P <0.001)

In models that predicted MMSE trajectories over time, models with confounders (age, gender, educational level, cohort assignment) with Tau-PET plus MRI outperformed models that included co-founders with MRI plus Tau-PET. Especially for all Ab-positive persons (R2, 0.561; b, -0.21 vs. R2, 0.546; b, 0.27), the Ab-positive AD dementia cohort (R2, 0.425; b, -0, 17 vs. R2, 0.414; b, 0.23), Ab-positive MCI group (R2, 0.390; b, -0.26 vs. R2, 0.356; b, 0.24) and Ab-positive CU cohort (R2, 0.188; b, -0.18 vs R2, 0.180; b, 0.10).

The decline in MMSE over time was more strongly associated with [18F]Flortaucipir uptake as measured by tau-PET (R2, 0.35) compared to amyloid-PET (R2, 0.17; P <0.001). Stratified by AD subtype, the same pattern was observed for AD dementia, Ab-positive MCI, and both CU cohorts (all P <0.001).

Similar results were found for the [18F]RO948 replication cohort (R2, tau PET: 0.49 vs. amyloid PET: 0.25; P <0.001).

This study was limited by the short follow-up period (mean 22.7; SD 9.8 months).

These data showed that tau PET tracers had superior prognostic utility in predicting cognitive decline in patients with AD when compared to MRI or amyloid PET.

Disclosure: Some authors stated links with biotech, pharmaceutical, and / or device manufacturers. For a full list of the author’s disclosures, see the original reference.

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R. Ossenkoppele, R. Smith, N. Mattsson-Carlgren, et al. Accuracy of tau positron emission tomography as a prognostic marker in preclinical and prodromal Alzheimer’s disease: a direct comparison with amyloid positron emission tomography and magnetic resonance imaging. JAMA Neurol. doi: 10.1001 / jamaneurol.2021.1858

This article originally appeared on Psychiatry Advisor