Abstract
ObjectiveWe evaluated disruption of the white matter (WM) network related with Alzheimer's disease (AD) and Lewy body disease (LBD), which includes Parkinson's disease and dementia with Lewy bodies.MethodsWe consecutively recruited 37 controls and 77 patients with AD‐related cognitive impairment (ADCI) and/or LBD‐related cognitive impairment (LBCI). Diagnoses of ADCI and LBCI were supported by amyloid PET and dopamine transporter PET, respectively. There were 22 patients with ADCI, 19 patients with LBCI, and 36 patients with mixed ADCI/LBCI. We investigated the relationship between ADCI, LBCI, graph theory‐based network measures on diffusion tensor images, and cognitive dysfunction using general linear models after controlling for age, sex, education, deep WM hyperintensities (WMH), periventricular WMH, and intracranial volume.ResultsLBCI, especially mixed with ADCI, was associated with increased normalized path length and decreased normalized global efficiency. LBCI was related to the decreased nodal degree of left caudate, which was further associated with broad cognitive dysfunction. Decreased left caudate nodal degree was associated with decreased fractional anisotropy (FA) in the brain regions vulnerable to LBD. Compared with the control group, the LBCI group had an increased betweenness centrality in the occipital nodes, which was associated with decreased FA in the WM adjacent to the striatum and visuospatial dysfunction.ConclusionConcomitant ADCI and LBCI are associated with the accentuation of LBCI‐related WM network disruption centered in the left caudate nucleus. The increase of occipital betweenness centrality could be a characteristic biologic change associated with visuospatial dysfunction in LBCI.
Highlights
Alzheimer's disease (AD) and dementia with Lewy bodies (DLB) are the first and second most common causes of degenerative dementia, respectively
Compared with the control group, the pure Lewy body disease (LBD)-related cognitive impairment (LBCI) group had an increased betweenness centrality in the left inferior occipital gyrus, which was associated with decreased fractional anisotropy (FA) in the white matter (WM) adjacent to the bilateral striatum and visuospatial dysfunction
Our findings suggest that concomitant AD-related cognitive impairment (ADCI) and LBCI are associated with the accentuation of LBCI-related WM network disruption centered in the left caudate nucleus, and occipital increase of betweenness centrality could be a characteristic biologic change associated with visuospatial dysfunction in pure LBCI
Summary
Alzheimer's disease (AD) and dementia with Lewy bodies (DLB) are the first and second most common causes of degenerative dementia, respectively. Cognitive impairment is common in patients with Parkinson's disease (PD), which comprises Lewy body (LB) disease (LBD) together with DLB. Previous autopsy studies have shown that LBD and AD pathologies frequently co-occur (Hamilton, 2000; Irwin et al, 2017). In vivo amyloid imaging and dopamine transporter imaging, which have contributed to more accurate antemortem diagnosis of AD and LBD, revealed frequent co-occurrence of the two diseases in cognitively impaired patients Donaghy et al, 2015; Gomperts et al, 2008; S. W. Kang et al, 2019)
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