Spatial memory deficits in Parkinson's disease: neural mechanisms and assessment

Parkinson's disease (PD) is a progressive neurodegenerative disorder that primarily affects motor function. However, PD may also result in substantial cognitive impairments, including spatial memory deficits. Spatial memory, defined as the ability to encode, store, and retrieve information about environmental spatial orientation, is a critical component of daily functioning. A comprehensive understanding of the neural mechanisms underlying these deficits is imperative for the development of targeted interventions. This narrative review explores the neural basis of spatial memory deficits in PD, summarizing evidence from neuroimaging and neurophysiological studies. In addition, it examines current assessment methods and their clinical applications. Spatial memory is primarily governed by the hippocampus and interconnected cortical and subcortical structures, including the basal ganglia, the prefrontal cortex, and the anterior cingulate cortex. In PD, dopaminergic degeneration in the substantia nigra leads to functional disruptions in these networks. The basal ganglia, particularly the striatum, play a crucial role in procedural aspects of spatial navigation, while the hippocampus is essential for allocentric mapping. The utilization of functional neuroimaging techniques has yielded evidence of altered activity in these regions, which is concomitant with spatial memory deficits. Traditional neuropsychological assessments, laboratory-based tasks, and recent advancements, including virtual reality-based tasks, have been employed in the evaluation of spatial memory. The identification of spatial memory deficits in PD is of significant diagnostic and therapeutic importance. Future research should focus on integrating multimodal assessment tools to enhance diagnostic accuracy and explore novel therapeutic approaches targeting spatial memory dysfunction. The cause of spatial memory deficits in PD is multifactorial, arising from complex interactions between dopaminergic depletion and dysfunction in hippocampal-cortical networks. Advancements in assessment methodologies and targeted interventions hold considerable potential for enhancing spatial cognitive outcomes in patients diagnosed with PD. However, further research is required to refine diagnostic tools and develop effective rehabilitation strategies that are targeted at spatial memory impairments in PD.