MRI norm percentile in age‐related atrophy starts from MCI stage

Background Age related atrophy occurs in Alzheimer’s disease and related dementia (ADRD). Although atrophy was reported in early stage as mild cognitive impairment (MCI), the knowledge about earlier changes is limited. To fill this knowledge, we explored the age‐related atrophy in our pilot MRI database when participants at different stages of ADRD. Method MRI data are analyzed using NeuroQuant. We studied MRI data in cognitively healthy (CH, n=74) individuals when their cerebrospinal fluid (CSF) amyloid/tau ratios were normal (CH‐NATs, n=18) or pathological (CH‐PATs, n=41), in participants with impaired or MCI (n=9), and Alzheimer’s disease (AD, n=6), and other dementia (OD, n=6). We explored age, gender‐corrected norm percentiles for atrophy analysis in age‐related structures – (including hippocampal occupancy score (HOC, percent of hippocampi volume relative to inferior lateral ventricle volume), hippocampi, entorhinal cortex, and inferior lateral ventricles) and whole brain, cerebral white matter. We compared the data between CH, MCI, AD, and OD, compared between CH‐NATs and CH‐PATs, and compared between CH with cerebrospinal fluid (CSF) amyloid pathology (ChA+, n=15) and CH without CSF pathology (ChA‐T‐N‐, n=13) based on CSF Aβ42, phosphor‐tau (p‐tau), and total tau (t‐tau). Bonferroni correction was used for Multiple comparisons. Result Analysis of MRIs collected at HMRI show neuro‐quantitative data in CH participants compared to MCI, AD, or OD, and MCI to AD and OD. Compared to CH, MCI have decreased HOC and larger superior lateral ventricle (Table 1, Figure 1), AD have decreased HOC, hippocampi, whole brain, and cerebral white matter, and larger lateral ventricles, OD have similar changes except hippocampi (no change). No significant changes observed between MCI and AD or OD. No significant changes were observed between CH‐NATs and CH‐PATs, or between ChA+ and ChA‐T‐N‐. Conclusion Despite sample size limitation, these results suggest: 1) norm percentile is sensitive to age‐related atrophy at impaired stages, consistent with known changes; Whole brain volume decreases in AD and OD, only AD observed decreased hippocampal atrophy; 2) No apparent age‐related changes were observed in CH stage. Overall, MRI age‐ and gender‐corrected norm percentile for age‐related atrophy analysis is informative in individuals as early as MCI stage.