123I‐Ioflupane SPECT Striatal Binding Ratio Predicts Progression of Parkinsonism in a Dementia with Lewy Bodies Cohort

Abstract

AbstractBackgroundThe criteria for diagnosis of dementia with Lewy bodies (DLB) remain predominantly clinical. However, use of striatal dopamine transporter visualization is suggested as an “indicative” biomarker for DLB under the most recent published DLB criteria (McKeith, Neurology, 2017). The objective of this study is to determine if 123I‐ioflupane SPECT (DaTscan) striatal binding ratio (SBR) correlates with parkinsonian symptoms measured on the Movement Disorder Society – Unified Parkinson’s Disease Rating Scale Part III (MDS‐UPDRS‐III) in patients with either probable DLB or high‐likelihood DLB individuals with mild cognitive impairment (MCI). A secondary aim of this study is to determine if DaTscan SBR measured at baseline can predict progression of parkinsonian symptoms over 2 years in this study population.MethodsThis is a retrospective cohort study using the U.S. Dementia with Lewy Bodies Consortium (DLBC) dataset (U01 NS100610). The sample group included in this study are individuals with either probable DLB (McKeith, Neurology, 2017) or MCI‐LB (McKeith, 2020). Each participant had a baseline DaTscan analyzed with DaTQUANT software and physical examination scored with MDS‐UPDRS‐III. Participants without these data were excluded. Mixed effect models were fit with UPDRS score as the dependent variable and SBR z‐score as the primary independent variable. Data were adjusted for age, gender, diagnosis, and dopaminergic medication at time of examination.ResultsAn analysis between 53 participants’ baseline MDS‐UPDRS‐III and SBR z‐scores revealed a moderate negative correlation, indicating SBR is a significant predictor of baseline MDS‐UPDRS‐III score. An analysis between 23 participants’ baseline SBR z‐scores and 24‐month MDS‐UPDRS‐III revealed a moderate negative correlation, indicating that baseline SBR is a significant predictor of 24‐month MDS‐UPDRS‐III scores.ConclusionThese data reveal a significant relationship between DaTscan SBR and motor examination in DLB. Additionally, there is a significant relationship between baseline SBR and progression of parkinsonian features. We conclude that in DLB, DaTscan at time of diagnosis could be used to confirm underlying dopamine deficiency in the context of clinical parkinsonism and predict progression of parkinsonian symptoms in DLB. This could aid in guiding therapies and prognostication of symptom progression.