Annalisa Bosco¹ (), Caterina Foglino^1,2, Lucia Guidi³, Davide Braghittoni³, Greta Venturi³, Luisa Sambati³, Patrizia Fattori¹, Raffaele Lodi^1,3, Caterina Tonon^1,3, Micaela Mitolo⁴; ¹University of Bologna, ²Italian Institute of Technology, ³IRCCS Istituto delle Scienze Neurologiche di Bologna, ⁴University of Parma

Dementia with Lewy Bodies (DLB) is a neurodegenerative disorder marked by alpha-synuclein aggregates in the brain, with early visuospatial deficits distinguishing it from other dementias (Mc Keith et al. 2017). Understanding visuospatial dysfunction in DLB is crucial for diagnostic accuracy, as it often precedes or accompanies hallmark symptoms like visual hallucinations and motor disturbances. This study aims to elucidate such impairments by analyzing measures including movement accuracy, movement and task duration, reaction times, associated ocular patterns and brain volumetry in a pointing to visual targets task. A total of 16 patients with DLB (6F; mean age = 75.416.38) and 16 age-matched healthy controls (HC) (9F; mean age = 67.87 9.63) underwent a pointing task that required them to touch one of four visual target positions displayed on a touchscreen. By application of a linear mixed-effects model, we evaluated the effect of the group (patients vs HC) and the target position on the pointing accuracy, movement duration, task duration, reaction time, saccade duration, saccade amplitude and saccade accuracy. The same model was applied to evaluate the effect of group on the volumetry of the left and right superior parietal lobule (SPL) of the brain, as the SPL plays a critical role in visuospatial processing. A significant group effect was observed across the multiple motor and ocular parameters (F values ranging from 1.16 to 247.84, all p < 0.01), with patients consistently performing worse than controls independent from target position. Moreover, a significant volumetric loss in the left and right SPL was observed in the DLB patients compared to HC (F values ranging from 9.98 to 53.06, p < 0.05). These findings highlight the pervasive visuospatial and motor impairments in DLB, highlighting the importance of assessing both behavioral and neural metrics for improved understanding and differentiation of DLB from other dementia subtypes.

Acknowledgements: This study has been supported by the Italian Ministry of Health (#GR-2019-12369242) and by #NEXTGENERATIONEU (NGEU), National Recovery and Resilience Plan (NRRP), project MNESYS (PE0000006).