FIGURE 8.

The dissociation of tau pathology and neuronal hypometabolism is related to co‐pathologies. (A), Representative ¹⁸F‐FDG SUVR images from six patients. Susceptible patients shown here have imaging findings consistent with co‐pathology (sagittal views are slices through the right hemisphere). The cortical susceptible group (middle) had participants with cingulate island sign, the sparing of posterior cingulate cortex (white arrowheads) relative to cuneus (black arrowheads). The limbic susceptible group (right) had participants with MTL and FSO ¹⁸F‐FDG hypometabolism (white arrowheads) relative to inferior temporal gyrus (I, black arrowheads). Vascular pathology features in susceptible groups included greater (B) vascular risk factors and (C) subcortical infarcts. The cortical susceptible group (D) had higher cingulate island ratio across groups, (E) had significantly worse clock drawing scores, and trended toward (F) greater proportion of participants with hallucinations on the Neuropsychiatric Inventory (NPI) item B and (G) worse ADNI visuospatial scores than the other groups. The limbic susceptible group had larger (H) I/MTL/FSO ¹⁸F‐FDG ratio and worse MTL asymmetry in (I) ¹⁸F‐FDG SUVR and (J) thickness, and significantly worse (K) categorical fluency, (I) language, and (M) memory z scores. Box plots show data points as dots, mean as an X symbol, median as the middle box line, first quartile (Q1) and third quartiles (Q3) as box edges (denoting the IQR), whiskers as the minimum/maximum points and outliers based on thresholds <Q1 − 1.5(IQR) or >Q3 + 1.5(IQR). Cognitive test comparisons included Aβ status, education, sex, and age as covariates. Significant differences in pairwise comparisons by two‐tailed likelihood ratio tests are denoted by *P < 0.05, **P < 0.005. Aβ, amyloid beta; ADNI, Alzheimer's Disease Neuroimaging Initiative; FDG, ¹⁸F‐fluorodeoxyglucose; FSO, frontal supraorbital; IQR, interquartile range; MTL, medial temporal lobe; SUVR, standardized uptake value ratio. Reproduced under open access from Duong et al. ²⁵⁸