title: Neuroimaging correlates of cognitive impairment and dementia in Parkinson's disease.
abstract: There has been a gradual shift in the definition of Parkinson's disease, from a movement disorder to a neurodegenerative condition affecting multiple cognitive domains. Mild cognitive impairment (PD-MCI) is a frequent comorbidity in PD that is associated with progression to dementia (PDD) and debilitating consequences for patients and caregivers. At present, the pathophysiology underpinning cognitive impairment in PD is not established, although emerging evidence has suggested that multi-modal imaging biomarkers could be useful in the early diagnosis of PD-MCI and PDD, thereby identifying at-risk patients to enable treatment at the earliest stage possible. Structural MRI studies have revealed prominent grey matter atrophy and disruptions of white matter tracts in PDD, although findings in non-demented PD have been more variable. There is a need for further longitudinal studies to clarify the spatial and temporal progression of morphological changes in PD, as well as to assess their underlying involvement in the evolution of cognitive deficits. In this review, we discuss the aetiology and neuropsychological profiles of PD-MCI and PDD, summarize the putative imaging substrates in light of evidence from multi-modal neuroimaging studies, highlight limitations in the present literature, and suggest recommendations for future research.
authors.affiliation: Department of Psychiatry, University of Cambridge, UK. Electronic address: fkm24@medschl.cam.ac.uk.
authors.forename: Elijah
authors.initials: E
authors.lastname: Mak
authors.affiliation: Department of Psychiatry, University of Cambridge, UK. Electronic address: ls514@cam.ac.uk.
authors.forename: Li
authors.initials: L
authors.lastname: Su
authors.affiliation: Wolfson Brain Imaging Centre, UK. Electronic address: gbw1000@wbic.cam.ac.uk.
authors.forename: Guy B
authors.initials: GB
authors.lastname: Williams
authors.affiliation: Department of Psychiatry, University of Cambridge, UK. Electronic address: john.obrien@medschl.cam.ac.uk.
authors.forename: John T
authors.initials: JT
authors.lastname: O'Brien
mesh_terms: D001921:Brain / Q000473:pathology*; D060825:Cognitive Dysfunction / Q000175:diagnosis* / Q000209:etiology; D003704:Dementia / Q000175:diagnosis* / Q000209:etiology; D018450:Disease Progression; D006801:Humans; D059906:Neuroimaging / Q000379:methods*; D010300:Parkinson Disease / Q000150:complications / Q000175:diagnosis*
keywords: Cognitive impairment; Lewy bodies; MRI; Neuroimaging; Parkinson's disease