Objective: Cognitive impairment is a critical issue in the advanced stages of Parkinson’s disease (PD) [1]. Similar to other neurodegenerative diseases, degeneration of the nucleus basalis of Meynert (NBM) is considered to play a central role in PD-related dementia [2]. However, the relationship between NBM degeneration and peripheral autonomic dysfunction, as assessed by I(123)-metaiodobenzylguanidine (MIBG) myocardial scintigraphy, has not been fully elucidated.

Background: We hypothesized that the correlation between central and peripheral neurodegeneration could be captured by evaluating NBM changes using advanced diffusion MRI (dMRI) and using MIBG scintigraphy as an indicator of peripheral autonomic involvement.

Method: This study included 65 patients with clinically established PD (mean age 64.4 years; 44 males; 15 with cognitive impairment [PD-CI, MMSE < 26]). Within a two-year period, we collected data including advanced dMRI (DTI, DKI, NODDI, FWI), MIBG scintigraphy, DAT-SPECT, cognitive function, MDS-UPDRS, and LEDD. Regions of interest (ROIs) were placed in the NBM. Correlations between dMRI parameters, imaging data, and clinical indices were analyzed using Spearman’s rank correlations. ROC analysis was performed to differentiate PD-CI.

Results: The free-water (FW) values in the NBM showed negative correlations with the MIBG heart-to-mediastinum (H/M) ratio in the early (ρ = –0.53) and delayed (ρ = –0.55) phases. While FW and H/M ratios showed correlations with age (approximately ρ = –0.5), no correlations were found with disease duration or LEDD. Partial correlation analysis with age as a covariate confirmed that the relationship between NBM-FW and the delayed H/M ratio was maintained. ROC analysis using the delayed H/M ratio yielded an AUC of 0.84 for identifying PD-CI, with a specificity of 93% and a sensitivity of 70%.

Conclusion: A reduction in the delayed H/M ratio on MIBG scintigraphy may serve as an indicator reflecting the severity of NBM degeneration. Although various structural brain changes contribute to cognitive impairment in PD, the finding that NBM degeneration is linked to peripheral autonomic decline—manifesting as decreased MIBG uptake—provides valuable information for assessing the risk of dementia. While this study is limited by its sample size, further longitudinal validation is needed.

References: [1] Poewe W, Seppi K, Tanner CM, et al. Parkinson disease. Nat Rev Dis Primers. 2017 Mar 23;3:17013. doi: 10.1038/nrdp.2017.13.
[2] Gratwicke J, Jahanshahi M, Foltynie T. Parkinson’s disease dementia: a neural networks perspective. Brain. 2015 Jun;138(Pt 6):1454-76. doi: 10.1093/brain/awv104.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/reduced-cardiac-mibg-uptake-as-a-biomarker-for-nucleus-basalis-of-meynert-degeneration-and-cognitive-impairment-in-parkinsons-disease/