Posterior cingulate cortex atrophy across the Alzheimer's disease spectrum: A cross-sectional MRI study linking volumetrics to cognitive decline

Background The posterior cingulate cortex (PCC) is a metabolic hub within the default-mode network and an early target of Alzheimer's disease (AD) pathology, yet its quantitative relationship with cognition across the normal aging–mild cognitive impairment (MCI)–AD continuum remains incompletely defined. Objective In this study we aimed to compare PCC volumes across AD, MCI, and controls, and assess their relationship with cognitive performance. Methods In this single-center cross-sectional study, 161 participants (NL = 30, MCI = 60, AD = 71) underwent structural MRI. PCC volumes were automatically segmented and summed. Linear regressions adjusted for age and sex were performed to examine associations between PCC volumes and cognitive measures. False discovery rate correction was applied to multiple comparisons. Additional subgroup analyses were conducted by gender and education level using Mann–Whitney U tests, and ordinary least squares regression models tested for group × education interactions. Results Mean Post-cin-T volume declined step-wise from NL (6.05 ± 0.21cm 3 ) to MCI (5.64 ± 0.63cm 3 ) to AD (4.98 ± 1.01cm 3 ; p < 0.001). Post-cin-R and Post-cin-L showed parallel gradients. Higher MoCA scores correlated with larger PCC volumes (e.g., total: β = 0.069, p < 0.001), whereas higher CDR scores were linked to smaller volumes (total: β = –0.705, p < 0.001). Subgroup analyses revealed that higher-education participants showed broader PCC–cognition associations. Interaction analyses indicated no significant moderating effect of education on group–volume relationships. Conclusions Quantitative PCC atrophy differentiates NL, MCI and AD and correlates robustly with cognitive performance, particularly in educated individuals. PCC volumetry may serve as a non-invasive MRI biomarker for early diagnosis and disease staging in the AD spectrum.