Potential utility of salivary gland amyloid uptake as a surrogate marker for adipose tissue and amyloid-beta dynamics based on its association with BMI and cerebral amyloid burden.

Recent studies have noted an unexpected inverse correlation between body mass index (BMI) and cerebral amyloid-beta (Aβ) deposition, suggesting a potential involvement of adipose tissue in AD pathology. Given the adipose-rich nature of salivary glands, we investigated whether Aβ uptake in the salivary glands is associated with the link between BMI and cerebral Aβ deposition usingF-Florbetaben PET/CT. We analyzed data from 187 participants, classified into Aβcognitively normal (AβCN), Aβ mild cognitive impairment (AβMCI), and Aβ AD dementia (AβD) groups. BMI, standardized uptake value ratio of salivary glands (SUVR), and brain (SUVR) were quantified, and their associations were examined using Pearson correlation and multiple regression analyses. Higher BMI was correlated with increased SUVR (r = 0.231, p = 0.0019) and decreased SUVR (r = -0.247, p = 0.0009). SUVR and SUVR were negatively correlated (r = -0.188, p = 0.0102). Multiple regression analysis identified BMI as an independent predictor of composite brain SUVR (β = -0.0168, p = 0.0046), while SUVR was marginally significant (β = -0.0714, p = 0.0701). Regionally, both BMI and SUVR were significantly associated with lower SUVR in the striatum, precuneus, and cingulate cortex. Consistent with previous studies, BMI exhibited an inverse correlation with SUVR. Notably, SUVR was negatively associated with SUVR while demonstrating a positive correlation with BMI. Interpreting SUVR as a fat-related marker, these findings suggest that Aβ sequestration in adipose tissue may contribute to lower cerebral Aβ accumulation. Additional research is necessary to elucidate the underlying mechanism.