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Healthy subjects with abnormal levels of amyloid‐B and tau have lower cortical volumes in the mesial temporal region
Author(s) -
Huang Kun,
Dore Vincent,
Li Shenpeng,
Krishnadas Natasha,
Bourgeat Pierrick,
Burnham Samantha C.,
Fripp Jurgen,
Villemagne Victor L.L.,
Rowe Christopher C.
Publication year - 2020
Publication title -
alzheimer's and dementia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.713
H-Index - 118
eISSN - 1552-5279
pISSN - 1552-5260
DOI - 10.1002/alz.045629
Subject(s) - entorhinal cortex , temporal lobe , atrophy , hippocampus , temporal cortex , amygdala , alzheimer's disease , medicine , cortex (anatomy) , psychology , nuclear medicine , pathology , neuroscience , disease , epilepsy
Abstract Background Post‐mortem studies on Alzheimer's disease (AD) have shown that the stereotypical pattern and density of tau deposition is strongly associated with cortical loss. In this study, we investigate if cognitively healthy elderly subjects with abnormal level of tau in the mesial temporal lobe and/or of Ab in the brain as measure with PET have lower cortical volumes in parahippocampal, entorhinal, inferiortemporal, fusiform, hippocampus and amygdala which are the early region of atrophy. Method 232 healthy cognitively normal control (CN) participants from the AIBL cohort underwent an Ab PET scan (18F‐NAV6240) and a tau scan ( 18 F‐MK6240), . Ab and MK6240 scans were spatially normalized and scaled to the cerebellar cortex using CapAIBL. Threshold for Ab abnormality was 20CL, and two standard deviations above the SUVR mean in the mesial temporal region on Ab‐ CN subjects for tau. Three groups were then defined A‐T‐ (n = 180, 74.5 ± 5 yrs), A+T‐(n = 32, 77 ± 6 yrs) and A+T+(n = 16, 78 ± 7 yrs). From T1w MRI, cortical volumes in the parahippocampus, hippocampus, entorhinal, amygdala, inferior temporal and fusiform were computed. Volumes were controlled for intracranial volumes and normal aging and compared between the different group using standard T‐tests. Result There were no significant differences in age between 3 groups. However, A+T+ cohort had lower MMSE scores than A‐T‐. In addition, the CDR scores for A+T+ were significantly higher than in the other two groups. A+T+ had a significant lower cortical volume in all examined regions compared to A‐T‐ and A+T‐, (p < 0.05). There were no significant difference in cortical volumes between A‐T‐ and A+T‐. Conclusion In CN, Ab pathology alone is not associated with lower cortical volumes. However, Ab and tau deposition in the mesial temporal lobe is associated with GM loss, even at the presymptomatic stages.