Objective: To evaluate NMS signal changes in the locus coeruleus (LC) in mild cognitive impairment with Lewy bodies (MCI-LB) as compared to healthy controls (HC) and identify cognitive correlates of the changes. We also aimed at testing the hypothesis of a caudal-rostral direction of α-synuclein pathology spreading in MCI-LB using neuromelanin sensitive (NMS) MRI of the spatially different LC subparts.

Background: While NMS MRI has been particularly used to assess early neurodegeneration of substantia nigra pars compacta (SNc) in Parkinson’s disease, studies evaluating degeneration of the LC subparts are lacking in MCI-LB.

Method: A total of 38 MCI-LB patients and 59 HC underwent clinical and cognitive testing and NMS MRI examination using 3T Siemens Magnetom Prisma. We calculated the contrast ratio of NMS signal (LC-CR) in the whole LC as well as in its caudal, middle and rostral MRI slices and compared the LC-CR values between MCI-LB and HC groups. Correlation analysis was performed to assess relationship between the LC-CR and cognitive outcomes in the patient group.

Results: MCI-LB group showed a significant reduction in the right LC-CR compared to HC (p = 0.021). The right LC-CR decrease was associated with impaired visuospatial memory in the MCI-LB group (BVMT; Brief Visual Memory Test; R = 0.505; p < 0.001). Only the  caudal part of the LC showed significant LC-CR decreases in MCI-LB as compared to HC on both sides (p <0.0001).

Conclusion: This is the first study that focuses on LC-CRs in MCI-LB and analyzes the LC subparts, offering new insights into the LC integrity alterations in the initial stages of DLB and their clinical correlates.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/early-changes-in-the-locus-coeruleus-in-mild-cognitive-impairment-with-lewy-bodies/