Cognitive decline during aging can be associated with different objective levels of impairment. Dementia and mild cognitive impairment (MCI) are characterized by objective cognitive impairment, but some individuals experience a subjective decrease in cognitive function (Subjective Cognitive Decline, SCD), even though their assessed cognitive performance does not present objective impairment. Epidemiological data show evidence that the risk for objective cognitive decline increases in individuals with SCD.

We enrolled 33 SCD and 47 MCI subjects. All subjects underwent a brain MR exam at 3T (GE Healthcare). The MRI acquisition protocol included a 1mm-isotropic 3DT1-weighted BRAVO sequence (TR/TE=7/3ms; TI=500ms, NEX=1) and a 3Dpseudo-continuous Arterial Spin Labeling (pCASL) sequence (TR/TE = 4850/10.5 ms, NEX=4, pld=2025 ms, spatial resolution = 3.64 mm, slice thickness = 4 mm).

pCASL data were transformed into cerebral perfusion maps (Cerebral Blood Flow, CBF), using the BASIL methods (Chappell 2009, Alsop 2015).

T1w images were segmented in 68 cortical and 19 subcortical Regions of Interest (ROI), by using FreeSurfer (recon-all) software, according to Desikan-Killiany atlas (Desikan 2006). Thus, for each ROI the mean of the CBF values was extracted.

Group statistical comparisons (ancova analysis, taking into account sex, age and global CBF as covariates) were conducted among CBF measurements between SCD and MCI cohorts.

SCD and MCI cohorts showed statistically significant differences in brain perfusion (SCD > MCI) particularly in the cingulate gyrus (posterior and isthmus components), in the middle and inferior temporal gyrus and in the supramarginal gyrus.

Results confirm that cerebral perfusion in these areas is particularly significant in the onset of objective cognitive impairment.

Acknowledgements

The study was funded by the Italian Ministry of Health: projects GR-2019-12370776 and RC Linea4