HAI Book 2025 - Flipbook - Page 426
Houlihan, Hannah
107
Annual percent change of microglia density in relation to tau
accumulation in older adults
Hannah Houlihan1, Aubrey Johnson1, Anna Smith1, Diana Guzman1, Amarachukwu Okafor1,
Lauren Heuer1, Thairi Sanchez1, Daniel Talmasov1, Ndubisi Chikwem1, Dina Dass1, James
Noble1, William Kreisl1, Scott Small1, Patrick Lao1
1
Columbia University Medical Center, New York, NY, US
Background: We sought to quantify regional annual percent change in ER176, a novel TSPO PET radiotracer, and
tau accumulation in older adults.
Methods: Participants (n=13 amyloid-negative controls without cognitive impairment; n=1 amyloid-positive
individual with Posterior Cortical Atrophy (PCA); Table 1) from the Longitudinal Imaging of Microglial Activation in
Different Clinical Variants of Alzheimer9s Disease study underwent amyloid (Florbetaben), tau (MK6240), and TSPO
PET (ER176). Annual percent change in partial volume corrected TSPO and tau SUVR for 13 AD-related ROIs were
assessed by demographic characteristics and baseline biomarker values in controls.
Results: TSPO change ranged from -4.6±2% in hippocampus to +3.3±2% in superior temporal lobe for controls,
and from -5.8% in hippocampus to +4.1% in middle inferior temporal lobe in PCA (Figure 1A). Tau change ranged
from -0.4±5% in inferior parietal cortex to +5.2±3% in entorhinal cortex in control, and from -1.4% in hippocampus
to +9.5% in entorhinal cortex in PCA (Figure 1B). Older age was associated with a greater TSPO change in lingual
(0.17 [0.01, 0.33], p=0.04) and fusiform gyrus (0.6 [0.07, 1.1], p=0.03). Greater baseline MK6240 was associated with
a greater TSPO change in lingual gyrus (5.5 [1.7, 9.2], p=0.01). Greater baseline TSPO was associated with greater
MK6240 change in superior parietal cortex (42 [24, 60], p=0.001) and cingulate gyrus (66 [2.2, 129], p=0.04).
Conclusion: Compared to previous generation TSPO tracers, ER176 had a similar but slightly greater range in
percent change per year and had the added benefit of including low affinity binders. Longitudinally, TSPO
demonstrated both increases and decreases across the brain in controls and one individual with PCA, whereas tau
demonstrated mostly increases, which was greatest in the entorhinal cortex. These longitudinal ER176 PET data
relative to tau PET reflect the dynamic role of TSPO in aging and disease.
HAI2025 - 426
