Pattern of Reduced Functional Connectivity and Structural Abnormalities in Parkinson’s Disease: An Exploratory Study

Abstract

BackgroundMRI brain changes in Parkinson’s disease (PD) are controversial.ObjectivesWe aimed to describe structural and functional changes in PD.MethodsSixty-six patients with PD (57.94 ± 10.25 years) diagnosed according to the UK Brain Bank criteria were included. We performed a whole brain analysis using voxel-based morphometry (VBM–SPM 8 software), cortical thickness (CT) using CIVET, and resting-state fMRI using the Neuroimaging Analysis Kit software to compare patients and controls. For VBM and CT we classified subjects into three groups according to disease severity: mild PD [Hoehn and Yahr scale (HY) 1–1.5], moderate PD (HY 2–2.5), and severe PD (HY 3–5).ResultsWe observed gray matter atrophy in the insula and inferior frontal gyrus in the moderate PD and in the insula, frontal gyrus, putamen, cingulated, and paracingulate gyri in the severe groups. In the CT analysis, in mild PD, cortical thinning was restricted to the superior temporal gyrus, gyrus rectus, and olfactory cortex; in the moderate group, the postcentral gyrus, supplementary motor area, and inferior frontal gyrus were also affected; in the severe PD, areas such as the precentral and postentral gyrus, temporal pole, fusiform, and occipital gyrus had reduced cortical thinning. We observed altered connectivity at the default mode, visual, sensorimotor, and cerebellar networks.ConclusionSubjects with mild symptoms already have cortical involvement; however, further cerebral involvement seems to follow Braak’s proposed mechanism. Similar regions are affected both structurally and functionally. We believe the combination of different MRI techniques may be useful in evaluating progressive brain involvement and they may eventually be used as surrogate markers of disease progression.

Emergent Functional Network Effects in Parkinson Disease

“…For example, dysfunction of somatomotor networks is not surprising, given the characteristic motor manifestations of PD (Jankovic 2008) and previous reports of their disruptions (Hacker et al 2012;Gottlich et al 2013;Olde Dubbelink et al 2014;Campbell et al 2015;Canu et al 2015;Gorges et al 2015;Tan et al 2015;Guimaraes et al 2016;Koshimori et al 2016;Peraza et al 2017). However, we show disruptions of internetwork somatomotor interactions.…”

“…These internetwork differences included somatomotor to cortical sensory and association systems and subcortical systems, like the cerebellum and thalamus. Interestingly, lower internetwork FC of the motor system weakly mirrored that found in other sensory systems (visual, auditory, seen also in (Olde Dubbelink et al 2014;Canu et al 2015;Guimaraes et al 2016;Ma et al 2017;Peraza et al 2017)). Reduced internetwork FC between somatomotor and sensory networks in PD may relate to reports of impaired sensory processing and sensorimotor integration (Abbruzzese and Berardelli 2003;Patel et al 2014;Richards et al 1993), as further suggested by the relationship between visual-cerebellar FC and visuospatial performance reported here.…”

“…The large, prominent, intranetwork and internetwork disruptions of the cerebellar and thalamic systems are particularly interesting. Although known to have central roles in motor function as well as important processing and gating roles for many other cortical networks (Alexander et al 1990;Middleton and Strick 2000;Saalmann and Kastner 2011;Buckner 2013;Hwang et al 2017), few prior studies comprehensively included these regions in studies of connectome-wide disruption in PD (although for cerebellum see (Onu et al 2015;Guimaraes et al 2016;Ma et al 2017) and for thalamus see (Baggio et al 2014;Gorges et al 2015;Vervoort et al 2016)). Our findings indicate that the cerebellum and thalamus may be key sites of dysfunction in PD.…”

Behavioral and Neuroanatomical Account of Impulsivity in Parkinson's Disease

“…These findings also indicate that patients without ICD have some brain pathology in regions relevant for impulsivity. This corresponds with previous MRI research conducted on the general PD population (42,(97)(98)(99)(100).…”

ALFF and ReHo Mapping Reveals Different Functional Patterns in Early- and Late-Onset Parkinson’s Disease

“…Occipital gyrus, FFG, and LING play important roles in the visual processing circuits (Machielsen et al, 2000;Stoeckel et al, 2009;Weiner and Zilles, 2016). Several studies have reported anatomical atrophy and lower functional activity in FFG, LING, and occipital gyrus in hallucinatory PD than non-hallucinatory PD and HC (Watanabe et al, 2013;Goldman et al, 2014;Yao et al, 2015;Guimaraes et al, 2016). In the current study, we identified the impaired function in FFG and LING in the LOPD group, which may imply that the risk of hallucinations increases with age in LOPD (Fenelon et al, 2000).…”