Non-Tremor Motor Dysfunction in Lewy Body Dementias is Associated with AD Biomarkers

Motor features of Parkinson’s disease (PD) are heterogeneous and well-studied; non-tremor features of postural instability and gait dysfunction (PIGD) have been linked to worse outcomes and Alzheimer’s disease (AD) co-pathology. However, these features are understudied in Lewy body dementias (LBD). Here we perform retrospective analysis of a unique cohort of LBD (n=30) with Unified Parkinson’s Disease Rating Scale (UPDRS) data collected at baseline in proximity to cerebrospinal fluid collection to test the hypothesis that LBD patients with a positive AD biomarker profile (LBD+AD=13) would have higher PIGD burden compared with LBD patients without AD biomarker positivity (LBD−AD=17). We find novel evidence for selective impairment of PIGD burden in LBD+AD vs LBD−AD (OR=1.95, 95%CI=1.02-3.70, p=0.04) and a direct association of increasing CSF tau/Aβ(1-42) ratio with increasing PIGD disability in the total cohort (β=0.23, SE=0.08, p=0.01). This unique biomarker stratification approach suggests AD co-pathology may contribute to PIGD motor signs in LBD.