Visuospatial and visuoperceptual impairment and its structural correlates as measures of cognitive decline in Parkinson’s disease
Year: 2018
Type: dissertation
Study design: Observational Study
Abstract: Parkinson’s disease is a common neurodegenerative disorder that manifests with a wide range of non-motor symptoms. Among them, cognitive impairment is present in a high proportion of patients, having a great impact on quality of life and prospective outcome. Initiatives have aimed to describe the features of cognitive impairment in Parkinson’s disease and, although findings are not conclusive, the visuospatial and visuoperceptual neuropsychological domain can be impaired early in the disease course, and these deficits sustain a relationship with disease severity and progression. Moreover, posterior cortically-based deficits are prognostic markers of the emergence of dementia in Parkinson’s disease. Hence, their early identification is an important undertaking in clinical settings.\n\t\t\t\t In our studies, we have investigated visuospatial and visuoperceptual impairment in Parkinson’s disease patients, as well as its evolution over time. We assessed 121 Parkinson’s disease patients and 41 healthy matched control subjects, applying well-validated and widely used neuropsychological tests, and followed the sample for an approximate period of four years. We identified the neuroanatomical substrates of these deficits using surface-based cortical thickness measures and tract-based spatial statistics for white matter microstructure integrity parameters. \n\t\t\t\t Parkinson’s disease patients exhibit a posterior temporo-parieto-occipital pattern of cortical thinning that is related to the impairment of visual cognition processes; however, these correlates do not appear to follow the classical dissociation described in the current literature of the healthy visual system pathways. In Parkinson’s disease patients with mild cognitive impairment, this degeneration is more pronounced and widespread, and follows a posterior-anterior pattern of cortical thinning. Moreover, after a four-year follow-up, Parkinson’s disease patients with mild cognitive impairment exhibit a differential pattern from cognitively normal patients, that involves temporo-parieto-occipital regions, and is related to changes over time in visuospatial and visuoperceptual measures. Conversely, white matter microstructure appears altered in the posterior corpus callosum in Parkinson’s disease, whereas visuospatial, visuoperceptual and visuoconstructive measures exhibit widespread long- and short-range correlates with white matter degeneration. \n\t\t\t\t Our results give support to the hypothesized relationship between impairment in visuospatial and visuoperceptual functions and the degeneration of predominantly posterior cortices over time, establish-ing the structural basis of cognitive decline in Parkinson’s disease. These findings could have translational implications and contribute to the validation of the use of these tests in clinical as well as research settings. Further research involving multimodal approaches of structural and functional neuroimaging techniques in longitudinal settings could shed light on the characterization of the neuroanatomical substrate of cognitive decline in Parkinson’s disease.
Authors: García Díaz, Anna Isabel
Language: English
Subfield: Clinical Neurology
Field: Medicine
Domain: Health Sciences
Open Access status: green
OpenAlex ID: W2907960116