title: Diffusion alterations associated with Parkinson's disease symptomatology: A review of the literature.
abstract: Parkinson's disease (PD) is a heterogeneous neurological disorder with a variety of motor and non-motor symptoms. The underlying mechanisms of these symptoms are not fully understood. An increased interest in structural connectivity analyses using diffusion tensor imaging (DTI) in PD has led to an expansion of our understanding of the impact of abnormalities in diffusivity on phenotype. This review outlines the contribution of these abnormalities to symptoms of PD including bradykinesia, tremor and non-tremor phenotypes, freezing of gait, cognitive impairment, mood, sleep disturbances, visual hallucinations and olfactory dysfunction. Studies have shown that impairments in cognitive functioning are related to diffusion abnormalities in frontal and parietal regions, as well as in the corpus callosum and major fibres connecting midbrain and subcortical structures with the neocortex. However, the impact of diffusion alterations on motor, mood and other symptoms of PD are less well understood. The findings presented here highlight the challenges faced and the potential areas of future research avenues where DTI may be beneficial. Larger cohort studies and standardized imaging protocols are required to investigate current promising preliminary findings.
authors.affiliation: Brain and Mind Centre, University of Sydney, Sydney, Australia; School of Social Sciences and Psychology, Western Sydney University, Sydney, Australia.
authors.forename: Julie M
authors.initials: JM
authors.lastname: Hall
authors.affiliation: Brain and Mind Centre, University of Sydney, Sydney, Australia.
authors.forename: Kaylena A
authors.initials: KA
authors.lastname: Ehgoetz Martens
authors.affiliation: Brain and Mind Centre, University of Sydney, Sydney, Australia.
authors.forename: Courtney C
authors.initials: CC
authors.lastname: Walton
authors.affiliation: Brain and Mind Centre, University of Sydney, Sydney, Australia; Behavioural and Clinical Neuroscience Institute, University of Cambridge, Cambridge, United Kingdom; Department of Psychology, University of Cambridge, Cambridge, UK.
authors.forename: Claire
authors.initials: C
authors.lastname: O'Callaghan
authors.affiliation: MARCS Institute, Western Sydney University, Sydney, Australia.
authors.forename: Peter E
authors.initials: PE
authors.lastname: Keller
authors.affiliation: Brain and Mind Centre, University of Sydney, Sydney, Australia. Electronic address: simonl@med.usyd.edu.au.
authors.forename: Simon J G
authors.initials: SJ
authors.lastname: Lewis
authors.affiliation: School of Social Sciences and Psychology, Western Sydney University, Sydney, Australia; MARCS Institute, Western Sydney University, Sydney, Australia.
authors.forename: Ahmed A
authors.initials: AA
authors.lastname: Moustafa
mesh_terms: D001921:Brain / Q000000981:diagnostic imaging*; D016206:Databases, Bibliographic / Q000706:statistics & numerical data; D056324:Diffusion Tensor Imaging; D006801:Humans; D010300:Parkinson Disease / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D066127:White Matter / Q000000981:diagnostic imaging
keywords: Diffusion tensor imaging; Heterogeneity; Parkinson's disease; White matter tracts