Akinetic-rigid Parkinson's Disease Patients Research Articles

Different functional connectivity modes of the right fronto-insular cortex in akinetic-rigid and tremor-dominant Parkinson's disease.

Patients with akinetic-rigid Parkinson's disease (AR-PD) are more prone to cognitive decline and depressive symptoms than tremor-dominant PD (TD-PD) patients. The right fronto-insular cortex (rFIC), as a key node of salience network, plays a critical role in the switching between central executive network and default mode network. In this study, we explored the functional connectivity mode of rFIC with triple-brain networks, namely default mode network, salience network, and central executive network, in two motor subtypes of PD. We recruited 44 PD patients (including the TD-PD group and AR-PD group) and 18 age-matched healthy controls (HCs). We performed functional connectivity (FC) analysis of resting-state functional MRI. Compared with TD-PD, decreased FC were found in the right insular cortex and bilateral anterior cingulate gyrus in AR-PD. Compared with HCs, decreased FC in the bilateral insula, the anterior cingulate gyrus, the precentral gyrus, and the right medial frontal gyrus were found; therein, the FC value of rFIC-precentral gyrus was positively correlated with the Unified Parkinson's Disease Rating Scale-II score in AR-PD (p = 0.0482, r = 0.4162). While TD-PD showed decreased FC in the left insula as well as bilateral anterior cingulate gyrus when compared with HCs, and the FC value of the rFIC-left insula was positively correlated with its Hamilton Depression Rating Scale score (p = 0.02, r = 0.50). The functional connectivity mode of rFIC in AR-PD differed from that in TD-PD. The decreased rFIC FC with the other nodes of salience network might be a potential indicator for AR-PD patients prone to develop cognitive decline and depressive symptoms.

Association of grey matter changes with stability and flexibility of prediction in akinetic-rigid Parkinson's disease.

Parkinson's disease (PD), which is caused by degeneration of dopaminergic neurons in the midbrain, results in a heterogeneous clinical picture including cognitive decline. Since the phasic signal of dopamine neurons is proposed to guide learning by signifying mismatches between subjects' expectations and external events, we here investigated whether akinetic-rigid PD patients without mild cognitive impairment exhibit difficulties in dealing with either relevant (requiring flexibility) or irrelevant (requiring stability) prediction errors. Following our previous study on flexibility and stability in prediction (Trempler et al. J Cogn Neurosci 29(2):298-309, 2017), we then assessed whether deficits would correspond with specific structural alterations in dopaminergic regions as well as in inferior frontal cortex, medial prefrontal cortex, and the hippocampus. Twenty-one healthy controls and twenty-one akinetic-rigid PD patients on and off medication performed a task which required to serially predict upcoming items. Switches between predictable sequences had to be indicated via button press, whereas sequence omissions had to be ignored. Independent of the disease, midbrain volume was related to a general response bias to unexpected events, whereas right putamen volume correlated with the ability to discriminate between relevant and irrelevant prediction errors. However, patients compared with healthy participants showed deficits in stabilisation against irrelevant prediction errors, associated with thickness of right inferior frontal gyrus and left medial prefrontal cortex. Flexible updating due to relevant prediction errors was also affected in patients compared with controls and associated with right hippocampus volume. Dopaminergic medication influenced behavioural performance across, but not within the patients. Our exploratory study warrants further research on deficient prediction error processing and its structural correlates as a core of cognitive symptoms occurring already in early stages of the disease.

Effects of progressive resistance exercise in akinetic-rigid Parkinson's disease patients: a randomized controlled trial.

Progressive resistance exercise (PRE) can have a positive effect in individuals with Parkinson's disease (PD). However, the effect of PRE may vary with the clinical subtype of PD. To date, no study has assessed the effects of PRE in the different subtypes of PD. The aim of the present study was to assess the effects of PRE in PD patients with akinesia and rigidity (AR-subtype). A randomized controlled trial was conducted. Outpatients clinics of the Bierzo Parkinson Association (Ponferrada, Spain) and the Asturias Parkinson Association (Oviedo, Spain). Twenty-eight patients with AR-subtype PD were randomized into an Experimental Group (EG, N.=13) and Control Group (CG, N.=15). Static posturography (Centre of Pressure -CoP- parameters), gait (the Ten-Meter Walk Test [TMWT]), freezing of gait (the Freezing of Gait Questionnaire [FOG-Q]), the motor portion of the Movement Disorders Society-Unified Parkinson's Disease Rating Scale (MDS-UPDRS) and patient-perceived quality of life (the 39-item Parkinson's disease Questionnaire [PDQ39]), were assessed at pre-test, post-test, and re-test. Ratings of perceived exertion (RPE) (Borg >6-20 Scale) were recorded at the end of each PRE training session. The EG displayed significant ameliorations in Length (CoP parameters) from pre- to post-test (P=0.048), in speed of fast rhythm walking (TMWT) from pre- to post-test (P=0.000), and from pre- to re-test (P=0.027), and in the PDQ39 Score from pre- to post-test (P=0.024). No significant differences were detected in Area or Speed (CoP parameters), speed of preferred rhythm walking (TMWT), FOG-Q scores, or the motor portion of the MDS-UPDRS scores. The EG reported a mean RPE of 9.95 (between "very light" and "fairly light") for the whole training program. These findings provide support for the use of PRE training in the rehabilitation of individuals with AR-subtype PD, as it can improve static posturography, gait, and quality of life. Furthermore, RPE scores showed that individuals with AR-subtype PD consider that PRE training require only light efforts. The PRE training can be a helpful and fruitful rehabilitation tool for AR-subtype PD patients.

Decreased interhemispheric functional connectivity in subtypes of Parkinson's disease.

Parkinson's disease (PD) can be classified into tremor-dominant (TD) subtype and akinetic-rigid (AR) subtype, which exhibit different clinical courses and prognoses. However, the neural mechanisms underlying different subtypes of PD are not well understood. Using voxel-mirrored homotopic connectivity (VMHC), we examined the homotopic resting-state functional connectivity patterns in akinetic-rigid PD (AR-PD) and tremor-dominant PD (TD-PD) to study the neural basis for these disparate manifestations of PD. Twenty-one TD-PD patients, 29 AR-PD patients and 26 normal control subjects participated in this study. Resting-state fMRI data were analyzed using VMHC. Correlations between VMHC values and each clinical characteristic were also calculated. Compared with normal control subjects and subjects with AR-PD, subjects with TD-PD exhibited significantly lower VMHC values in the posterior lobe of the cerebellum. Moreover, tremor scores and VMHC values for the cerebellum were found to be significantly negatively correlated in TD-PD patients. By contrast, subjects with AR-PD exhibited lower VMHC values in the precentral gyrus compared with normal control subjects. These findings suggest that functional coordination between homotopic brain regions is impaired in AR-PD and TD-PD patients. This study provides evidence of both cerebellum-related connectivity deficits in TD-PD. The finding that VMHC values and tremor scores were significantly correlated suggests that VMHC measurements may be of potential clinical relevance in TD-PD.

Differential effects of dopaminergic medication on basic motor performance and executive functions in Parkinson's disease

BackgroundPatients with Parkinson's disease (PD) often show deficits in the self-initiation and selection of movements, which can be partly compensated for by external cues. We here investigated impairments in the initiation and selection of self-initiated or externally cued movements in PD. Specifically, we assessed how behavioral changes relate to medication, disease severity, and basic motor or cognitive deficits. MethodsSeventeen akinetic-rigid PD patients and 16 healthy controls (HC) performed a computerized motor task assessing differences between internally and externally triggered movements and reaction times. Patients performed the task twice in a randomized fashion, once with their regular dopaminergic medication and once 12h after withdrawal of medication. Additionally, all subjects underwent comprehensive neuropsychological and motor assessments. ResultsCompared to HC, patients showed a significant slowing across all tasks. Furthermore, patients showed a selective deficit of movement initiation as indexed by longer reaction times when movement lateralization was internally chosen as opposed to being externally cued. This deficit correlated significantly with motor scores of the Unified Parkinson's Disease Rating Scale (UPDRS). Notably, there was no main effect of dopaminergic medication (“ON”/”OFF”) on internally and externally triggered movements despite significant improvement of UPDRS and maximum finger tapping frequency in the “ON” state. DiscussionOur results suggest that disease severity in PD patients is related to disturbances in internal action initiation, selection and simple decision processes. Moreover, the data add further support to the notion that dopaminergic medication differentially affects motor and cognitive performance in PD. These findings imply that disturbances in executive functions in PD are also influenced by factors other than reduced dopaminergic activity.

Subtype-specific statistical causalities in parkinsonian tremor

Tremor is one of the cardinal symptoms of Parkinson's disease. Up to now, however, its pathophysiology remains poorly understood. Previously, oscillatory coupling at tremor frequency between the subthalamic nucleus und affected muscles was shown. In these studies, however, causality of coupling could not be demonstrated. Thus, we analyzed the statistical causality between intraoperatively recorded local field potentials in the subthalamic area and affected arm muscles during tremor episodes, using squared partial directed coherence, a recently developed causality measure. The analysis identified differential statistical causality patterns for Parkinson's disease patients of the akinetic-rigid subtype during tremor episodes (n=6) versus patients of the tremor-dominant subtype (n=8): for the akinetic-rigid Parkinson's disease patients significantly more cases of the subthalamic region were found to be statistically causal for electromyographic-tremor activity, a result in accordance with the standard basal ganglia model. In contrast, for the tremor-dominant patients, significantly more instances of electromyographic tremor activity turned out to be causal for activity of the subthalamic region. Furthermore, the clinical effective stimulation site coincided with the location of most input causalities from the periphery in seven out of eight tremor-dominant patients. The data suggest that, although tremor activity in tremor-dominant and akinetic-rigid Parkinson's disease patients was clinically similar, statistical causality between tremor electromyogram (EMG) and the subthalamic nucleus was fundamentally different. Therefore, we hypothesize different pathophysiological mechanisms to underlie the generation of tremor in the two subtypes of Parkinson's disease.

117 Diagnostic FP-CIT SPECT and clinical progression in Parkinson's disease

BackgroundFunctional imaging of striatal dopamine transporters (DaT) is abnormal at presentation in Parkinson's disease (PD). While there is a cross-sectional relationship between the severity of bradykinesia and rigidity, and the...

Quantitative Bewegungsanalyse der Rumpfmotorik von Parkinsonpatienten mittels dreidimensionaler Kinematik und Oberflächenelektromyografie

Hintergrund Im Krankheitsverlauf der Parkinsonerkrankung (PD) werden axiale Defizite als Ausdruck einer reduzierten Rumpfmotorik prominent. Obwohl die Rumpfmotorikstörung progressiv verläuft und die tägliche Aktivität der Patienten beeinträchtigt wird, ist die quantitative Beurteilung noch nicht standardisiert und üblich. Methode Wir verglichen die Rumpfmotorik im 3-dimensionalen Raum mit synchroner Oberflächenelektromyografie (oEMG) von 19 PD-Patienten vom akinetisch-rigiden Subtyp (Hoehn & Yahr: 2–3, UPDRS motor score: 25,5 ± 10,7 in „on” Phase) mit einer altersgemachten Kontrollgruppe. Ergebnisse Die Rumpfbeweglichkeit (Range of Motion) war in frontaler, sagittaler und transversaler Ebene in der PD-Gruppe signifikant reduziert (Mittelwerte für alle Bewegungsrichtungen p < 0,001) mit jeweils signifikant erhöhter Bewegungsvariabilität (p < 0,001) bei reduzierter muskulärer Aktivität (oEMG). Die kinematischen Daten korrelierten nicht mit der täglichen L-Dopa-Dosis in mg. Schlussfolgerung Die 3-dimensionale Rumpfkinematik und die analoge Oberflächenelektromyografie ermöglichen den Klinikern und Therapeuten eine quantitative und objektive Beurteilung der Rumpfmotorik bei PD-Patienten. Der fehlende Einfluss von L-Dopa auf die Rumpfkinematik zeigt die unabhängige Kontrolle des axialen Tonus gegenüber des Extremitätentonus.

PATH50 Novelty-seeking and risk-taking behaviour in subtypes of Parkinson's disease

Why do some patients with Parkinson's disease develop risk-taking behaviour? We assessed responses to novelty and willingness to take risks in 29 patients with idiopathic Parkinson's disease (PD), compared to...