Investigating brain morphometry in prodromal dementia with Lewy bodies. A preliminary MRI-based cortical thickness analysis

Objectives: Prodromal dementia with Lewy bodies (pro-DLB) has gained attention in the field of dementia prevention. However, identifying reliable biomarkers remains a challenge. This ongoing study aims to characterize brain alterations in prodromal DLB (pro-DLB) relative to the healthy population and prodromal Alzheimer’s disease (AD), with a focus on pro-DLB phenotypical onsets: mild cognitive impairment (MCI-DLB) and psychiatric (PSY). Methods: We recruited 54 patients (20 MCI-DLB, 20 MCI-AD, 14 PSY) and 15 healthy controls (HC). Participants underwent structural and functional MRI. A preliminary Voxel-Based Morphometry (VBM) analysis was performed using CAT12 within SPM12. Gray matter volume (GMV) differences among groups were compared via one-way ANOVA. Results: VBM revealed structural damage in both MCI-DLB and PSY patients relative to HC. Frontal atrophy affected the superior frontal gyrus, supplementary motor area, and anterior/middle cingulum. Parietal damage involved the precuneus, with additional atrophy in posterior parietal areas in PSY and the posterior cingulum in MCI-DLB. Temporal atrophy was limited to inferior temporal and fusiform gyri, although PSY patients also exhibited reductions in the left medial temporal lobe. Occipital atrophy was observed in the cuneus, with additional bilateral damage in the early visual cortex in MCI-DLB and middle occipital gyrus in PSY. Subcortical atrophy involved the caudate and olfactory area. No significant GMV differences emerged between pro-DLB subgroups, both showing relative hippocampal preservation compared to MCI-AD. Conclusions: Pro-DLB is characterized by atrophy in frontal, parietal, and occipital areas, aligning with core clinical and neuropsychological features of overt DLB. Structural MRI may aid in distinguishing pro-DLB from healthy aging and prodromal stages of other neurodegenerative disorders, like AD. Lastly, differences between pro-DLB phenotypes might be associated with functional rather than macro-structural alterations.