This research aims 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 dementia with Lewy bodies (DLB) or high-likelihood DLB individuals with mild cognitive impairment (MCI). Additionally, it aims to determine if DaTscan SBR predicts progression of parkinsonian symptoms over 2 years in this patient population.

The criteria for diagnosis of DLB remain predominantly clinical. Striatal dopamine transporter visualization using DaTscan is used to aid in diagnosis when exam findings of parkinsonism are equivocal. Further clinical utility of DaTscan in DLB, such as for screening or confirmatory tests or monitoring of disease progression or response to therapy, remains unclear. 

This is a retrospective cohort study using the Dementia with Lewy Bodies Consortium (DLBC) dataset. The sample group included in this study are individuals with either probable DLB (based on 2017 McKeith Criteria) or high-likelihood DLB individuals with MCI. Each participant had a baseline and 24-month DaTscan analyzed with DaTQUANT software and physical examination scored with MDS-UPDRS-III. Participants without these data were excluded. 

An analysis between 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 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.

These data reveal a significant relationship between DaTscan SBR and motor examination in DLB. Additionally, there is a relationship between baseline SBR and progression of parkinsonian features. We conclude that DaTscan at time of diagnosis could be used to predict progression of parkinsonian symptoms in DLB which can aid in guiding therapies and prognostication of symptom progression.