Early Changes in the Locus Coeruleus in Mild Cognitive Impairment with Lewy Bodies

Background: Although neuromelanin-sensitive magnetic resonance imaging (NM-MRI) has been used to evaluate early neurodegeneration in Parkinson's disease, studies concentrating on the locus coeruleus (LC) in pre-dementia stages of dementia with Lewy bodies (DLB) are lacking. Objectives: The aims were to evaluate NM-MRI signal changes in the LC in patients with mild cognitive impairment with Lewy bodies (MCI-LB) compared to healthy controls (HC) and to identify the cognitive correlates of the changes. We also aimed to test the hypothesis of a caudal-rostral alpha-synuclein pathology spread using NM-MRI of the different LC subparts. Methods: A total of 38 MCI-LB patients and 59 HCs underwent clinical and cognitive testing and NM-MRI of the LC. We calculated the contrast ratio of NM-MRI signal (LC-CR) in the whole LC as well as in its caudal, middle, and rostral MRI slices, and we compared the LC-CR values between the MCI-LB and HC groups. Linear regression analyses were performed to assess the relationship between the LC-CR and cognitive outcomes. Results: The MCI-LB group exhibited a significant reduction in the right LC-CR compared to HCs (P = 0.021). The right LC-CR decrease was associated with impaired visuospatial memory in the MCI-LB group. Only the caudal part of the LC exhibited significant LC-CR decreases in MCI-LB patients compared to HCs on both sides (P < 0.0001). Conclusions: This is the first study that focuses on LC-CRs in MCI-LB patients and analyzes the LC subparts, offering new insights into the LC integrity alterations in the initial stages of DLB and their clinical correlates. (c) 2024 The Author(s). Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.