Do cognition and other non-motor symptoms decline similarly among patients with Parkinson's disease motor subtypes? Findings from a 5-year prospective study

Altered connectivity between frontal cortex and supplementary motor area in various types of Parkinson's disease

BACKGROUND

Tremor-dominant (TD) and postural instability/gait difficulty (PIGD) are common subtypes of Parkinson's disease, each with distinct clinical manifestations and prognoses. The neural mechanisms underlying these subtypes remain unclear. This study aimed to investigate the altered connectivity of the frontal cortex and supplementary motor area (SMA) in different types of Parkinson's disease.

METHODS

Data of 173 participants, including 41 TD patients, 65 PIGD patients, and 67 healthy controls, were retrospectively analyzed. All subjects underwent resting-state functional magnetic resonance imaging (rs-fMRI) and clinical assessments. Differences in amplitude of low frequency fluctuation (ALFF), voxel-wise functional connectivity (FC), and functional network connectivity (FNC) among the three groups were compared, followed by partial correlation analysis.

RESULTS

Compared to healthy controls, the left dorsolateral superior frontal gyrus (DLSFG) ALFF was significantly increased in both PIGD and TD patients. The FC between the left DLSFG and the left SMA, as well as between the left paracentral lobule and the right DLSFG, was significantly decreased. Similarly, the FNC between the visual network and the auditory network was reduced. Compared to TD patients, PIGD patients showed a significantly higher ALFF in the left DLSFG and a notably reduced FC between the left DLSFG and left SMA. Additionally, the FC of the left DLSFG-SMA was inversely correlated with the PIGD score exclusively in PIGD patients. The FNC of the visual-auditory network was inversely associated with the tremor score only in TD patients.

CONCLUSION

Decreases in the left DLSFG-SMA connectivity may be a key feature of the PIGD subtype, while reduced VN-AUD connectivity may characterize the TD subtype.

Neuroimaging correlates of postural instability in Parkinson's disease

BACKGROUND

Postural instability (PI) is a common disabling symptom in Parkinson's disease (PD), but little is known on its pathophysiological basis.

OBJECTIVE

In this study, we aimed to identify the brain structures associated with PI in PD patients, using different MRI approaches.

METHODS

We consecutively enrolled 142 PD patients and 45 control subjects. PI was assessed using the MDS-UPDRS-III pull-test item (PT). A whole-brain regression analysis identified brain areas where grey matter (GM) volume correlated with the PT score in PD patients. Voxel-based morphometry (VBM) and Tract-Based Spatial Statistics (TBSS) were also used to compare unsteady (PT ≥ 1) and steady (PT = 0) PD patients. Associations between GM volume in regions of interest (ROI) and several clinical features were then investigated using LASSO regression analysis.

RESULTS

PI was present in 44.4% of PD patients. The whole-brain approach identified the bilateral inferior frontal gyrus (IFG) and superior temporal gyrus (STG) as the only regions associated with the presence of postural instability. VBM analysis showed reduced GM volume in fronto-temporal areas (superior, middle, medial and inferior frontal gyrus, and STG) in unsteady compared with steady PD patients, and the GM volume of these regions was selectively associated with the PT score and not with any other motor or non-motor symptom.

CONCLUSIONS

This study demonstrates a significant atrophy of fronto-temporal regions in unsteady PD patients, suggesting that these brain areas may play a role in the pathophysiological mechanisms underlying postural instability in PD. This result paves the way for further studies on postural instability in Parkinsonism.

Effect of Rhythmically Cued Exercise Interventions on Functions in Patients With Parkinson Disease: A Meta-Analysis

OBJECTIVE

The purpose of this review was to investigate the efficacy of rhythmically cued exercise interventions on motor function, cognition, and mental state in patients with Parkinson disease.

METHODS

PubMed, Cochrane Database, Web of Science, Embase, and CINAHL were searched June 15, 2023. Original studies investigating the efficacy of rhythmically cued exercise interventions on the functions of patients with Parkinson disease were included. The Cochrane risk-of-bias assessment tool was used to evaluate the risk of bias. The protocol was registered in PROSPERO (CRD42022371203).

RESULTS

A total of 38 original studies involving 1486 participants were included. Rhythmically cued exercise interventions demonstrated superior effects on motor function compared to exercise therapy without rhythm (standardized mean difference [SMD] = -0.31). However, no significant improvements were observed in cognition and mental state. Overall, significant improvements were observed in motor examination (SMD = -0.61), Timed "Up & Go" Test (mean difference [MD] = -0.91), activities of daily living (SMD = -0.49), balance (SMD = 0.59), walking velocity (MD = 0.06), step length (MD = 2.65), and stride length (MD = 0.04) following rhythmically cued exercise interventions. No significant improvements were observed in freezing of gait and cadence. Assessment of publication bias showed no significant evidence of publication bias. Meta-regression analyses revealed a significant association between treatment duration and improvement in motor function. Furthermore, adverse events and dropout rates did not significantly differ between the 2 groups.

CONCLUSION

Rhythmically cued exercise interventions are effective in improving motor function in the early to middle stages of Parkinson disease. More than 10 weeks of intervention yielded better results. However, these interventions do not have a significant impact on cognition and mental states. Importantly, rhythmically cued exercise interventions are safe and well tolerated. Large-scale trials are needed for further confirmation.

IMPACT

This study contributes to the development of safe and reliable home rehabilitation programs, aiming to enhance the quality of life for patients with Parkinson disease.

Carpets with visual cues can improve gait in Parkinson's disease patients: may be independent of executive function

BACKGROUND

Gait impairment is common in Parkinson's disease (PD) patients, which greatly reduces their quality of life. Executive dysfunction is associated with gait impairment. Compensatory strategies, including visual cues, have been shown to be effective in improving PD gait. In this study, we aimed to understand whether carpets with visual cues could improve PD gait, and how the improvement varies across patients with different executive function state.

METHODS

We designed carpets with chessboard and stripe cues. A total of 65 Chinese PD patients were recruited. Movement Disorder Society Unified Parkinson's Disease Rating Scale, L-dopa equivalent daily dosage, Hoehn & Yahr stage, Frontal Assessment Battery, Mini Mental State Examination Scale, Hamilton Anxiety Scale, and Hamilton Depression Scale were evaluated. Gait parameters including stride length, gait speed and fall risk were recorded by a wearable electronic device.

RESULTS

The stride length and gait speed were significantly improved and the fall risk was significantly mitigated when PD patients walked on carpets with chessboard and stripe patterns. Further analysis showed the amelioration of gait parameters was independent of executive dysfunction.

CONCLUSIONS

Our study demonstrates that carpets with visual cues can improve the gait of PD patients even in those with mild executive dysfunction.

Free water imaging unravels unique patterns of longitudinal structural brain changes in Parkinson's disease subtypes

Background

Research shows that individuals with Parkinson's disease (PD) who have a postural instability and gait difficulties (PIGD) subtype have a faster disease progression compared to those with a tremor dominant (TD) subtype. Nevertheless, our understanding of the structural brain changes contributing to these clinical differences remains limited, primarily because many brain imaging techniques are only capable of detecting changes in the later stages of the disease.

Objective

Free water (FW) has emerged as a robust progression marker in several studies, showing increased values in the posterior substantia nigra that predict symptom worsening. Here, we examined longitudinal FW changes in TD and PIGD across multiple brain regions.

Methods

Participants were TD and PIGD enrolled in the Parkinson's Progression Marker Initiative (PPMI) study who underwent diffusion MRI at baseline and 2 years later. FW changes were quantified for regions of interest (ROI) within the basal ganglia, thalamus, brainstem, and cerebellum.

Results

Baseline FW in all ROIs did not differ between groups. Over 2 years, PIGD had a greater percentage increase in FW in the putamen, globus pallidus, and cerebellar lobule V. A logistic regression model incorporating percent change in motor scores and FW in these brain regions achieved 91.4% accuracy in discriminating TD and PIGD, surpassing models based solely on clinical measures (74.3%) or imaging (76.1%).

Conclusion

The results further suggest the use of FW to study disease progression in PD and provide insight into the differential course of brain changes in early-stage PD subtypes.

Unlocking potential: low frequency subthalamic nucleus stimulation enhances executive function in Parkinson's disease patients with postural instability/gait disturbance

Postural instability/gait disturbance (PIGD) is very common in advanced Parkinson's disease, and associated with cognitive dysfunction. Research suggests that low frequency (5-12 Hz) subthalamic nucleus-deep brain stimulation (STN-DBS) could improve cognition in patients with Parkinson's disease (PD). However, the clinical effectiveness of low frequency stimulation in PIGD patients has not been explored. This study was designed in a double-blinded randomized cross-over manner, aimed to verify the effect of low frequency STN-DBS on cognition of PIGD patients. Twenty-nine PIGD patients with STN-DBS were tested for cognitive at off (no stimulation), low frequency (5 Hz), and high frequency (130 Hz) stimulation. Neuropsychological tests included the Stroop Color-Word Test (SCWT), Verbal fluency test, Symbol Digital Switch Test, Digital Span Test, and Benton Judgment of Line Orientation test. For conflict resolution of executive function, low frequency stimulation significantly decreased the completion time of SCWT-C (p = 0.001) and Stroop interference effect (p < 0.001) compared to high frequency stimulation. However, no significant differences among stimulation states were found for other cognitive tests. Here we show, low frequency STN-DBS improved conflict resolution of executive function compared to high frequency. Our results demonstrated the possibility of expanding the treatment coverage of DBS to cognitive function in PIGD, which will facilitate integration of low frequency stimulation into future DBS programming.

Distribution pattern of iron deposition in the basal ganglia of different motor subtypes of Parkinson's disease

OBJECTIVE

The quantitative susceptibility mapping (QSM) technique was used to analyze the distribution pattern of iron deposition in the basal ganglia region of patients with motor subtypes of Parkinson's disease (PD) and to explore the difference in iron content in the basal ganglia region of PD motor subtypes on the major motor symptomatic side.

METHODS

The study included 76 patients with PD and 37 healthy controls (HC). Patients with PD were divided into two groups: postural instability/gait disorder (PIGD)(n = 48), and tremor dominance (TD)(n = 28). We classified patients with PD according to the side of the major motor symptoms as left PIGD (n = 23), left TD (n = 14), right PIGD (n = 25), and right TD (n = 14). All subjects underwent brain magnetic resonance scanning to obtain QSM and susceptibility values in the corresponding regions of interest (ROI).

RESULTS

(1) Compared with the HC, the bilateral SN in the PD-PIGD and TD group showed greater susceptibility values. The susceptibility values in the left CN, bilateral PUT were also greater in the PD-PIGD group than the HC. (2) Compared with the TD, the left PUT susceptibility values were greater in the PIGD group, especially in patients whose major symptomatic side were on the right limb. (3) Correlation analysis showed that in the PD group, bilateral SN was positively correlated with the unified Parkinson's disease rating scale III part scores of the Movement Disorder Society (MDS-UPDRS III) and the Hoehn-Yahr stage. Bilateral dentate nucleus (DN) susceptibility values were significantly positively correlated with TD scores, and left PUT susceptibility values were positively correlated with PIGD scores. The left SN within the PIGD group was positively correlated with the PIGD score.

CONCLUSION

There were different iron deposition patterns in the basal ganglia between the PD-PIGD and TD groups. There also seems to be a difference in iron deposition in PD motor subtypes on different major motor symptom sides.

Speech and gait abnormalities in motor subtypes of de-novo Parkinson's disease

AIM

To investigate the presence and relationship of temporal speech and gait parameters in patients with postural instability/gait disorder (PIGD) and tremor-dominant (TD) motor subtypes of Parkinson's disease (PD).

METHODS

Speech samples and instrumented walkway system assessments were acquired from a total of 60 de-novo PD patients (40 in TD and 20 in PIGD subtype) and 40 matched healthy controls. Objective acoustic vocal assessment of seven distinct speech timing dimensions was related to instrumental gait measures including velocity, cadence, and stride length.

RESULTS

Compared to controls, PIGD subtype showed greater consonant timing abnormalities by prolonged voice onset time (VOT) while also shorter stride length during both normal walking and dual task, while decreased velocity and cadence only during dual task. Speaking rate was faster in PIGD than TD subtype. In PIGD subtype, prolonged VOT correlated with slower gait velocity (r = -0.56, p = 0.01) and shorter stride length (r = -0.59, p = 0.008) during normal walking, whereas relationships were also found between decreased cadence in dual task and irregular alternating motion rates (r = -0.48, p = 0.04) and prolonged pauses (r = -0.50, p = 0.03). No correlation between speech and gait was detected in TD subtype.

CONCLUSION

Our findings suggest that speech and gait rhythm disorder share similar underlying pathomechanisms specific for PIGD subtype.

Impacts of motor phenotype on cognitive function in patients with Parkinson's disease 1 year after subthalamic-nucleus deep brain stimulation

BACKGROUND

Parkinson's disease (PD) is a neurological disorder that affects both motor and cognitive functioning. This study aimed to examine the impact of motor phenotype on cognitive function 1 year after subthalamic-nucleus deep brain stimulation (STN-DBS).

METHODS

The prospectively collected data of 37 patients with PD were retrospectively analyzed. The patients were divided into two group according to their motor phenotype: the postural instability and gait disturbance (PIGD) group comprised 16 patients, and the tremor-dominant (TD) group comprised 21 patients. The clinical characteristics and cognitive functions of all patients were examined at baseline and at the 1-year follow-up after STN-DBS.

RESULTS

The data showed that STN-DBS significantly improved motor functions (P < 0.05). A repeated-measures analysis of variance indicated a considerable group × time interaction impact on the memory quotient score (P < 0.001) and T_min (P = 0.033).

CONCLUSIONS

A distinct relationship between the neuropsychological spectrum and motor phenotype of PD patients was observed at the 1-year follow-up after STN-DBS, with worse cognitive outcomes in patients with the PIGD phenotype. Geriatr Gerontol Int 2023; 23: 85-90.

Bilateral globus pallidus interna deep brain stimulation in Parkinson's disease: Therapeutic effects and motor outcomes prediction in a short-term follow up

Objective

We aimed to compare the motor effect of bilateral globus pallidus interna (GPi) deep brain stimulation (DBS) on motor subtypes of Parkinson's disease (PD) patients and identify preoperative predictive factors of short-term motor outcome.

Methods

We retrospectively investigated bilateral GPi DBS clinical outcomes in 55 PD patients in 1 year follow up. Motor outcome was measured by the Movement Disorder Society Unified Parkinson's Disease Rating Scale (MDS-UPDRS) part III before and 1 year after surgery. Clinical outcomes were compared among different motor subtypes. Preoperative predictors of motor outcome were assessed by performing univariate and multivariate linear regression and logistic regression analyses.

Results

At 1 year following implantation, GPi DBS significantly improved the off-medication MDS-UPDRS III scores in all motor subtype cohorts, with prominent improvement in tremor. No significant difference of postoperative motor symptoms changes was found except greater tremor improvement achieved in both the tremor-dominant (TD) and indeterminate (IND) patients compared to the postural instability and gait difficulty (PIGD) patients. High percentage of PIGD patients were weak responders to DBS. Better levodopa responsiveness and more severe tremor predicted greater overall improvement of motor function in the entire cohort. Similarly, both levodopa responsiveness and tremor improvement were confirmed as predictors for motor improvement in PIGD patients.

Conclusion

Bilateral GPi DBS could effectively improve motor outcomes in PD patients regardless of motor subtypes. Both TD and IND patients obtained larger tremor improvement. The intensity of levodopa responsiveness and the severity of tremor could serve as predictors of motor improvement 1 year after GPi DBS.

Laterality in Parkinson's disease: A neuropsychological review

Laterality of motor symptom onset in Parkinson's disease is both well-known and under-appreciated. Treatment of disorders that have asymmetric pathological features, such as stroke and epilepsy, demonstrate the importance of incorporating hemispheric lateralization and specialization into therapy and care planning. These practices could theoretically extend to Parkinson's disease, providing increased diagnostic accuracy and improved treatment outcomes. Additionally, while motor symptoms have generally received the majority of attention, non-motor features (e.g., autonomic dysfunction) also decrease quality of life and are influenced by asymmetrical neurodegeneration. Due to the laterality of cognitive and behavioral processes in the two brain hemispheres, analysis of hemibody side of onset can potentially give insight into expected symptom profile of the patient and allow for increased predictive accuracy of disease progression and outcome, thus opening the door to personalized and improved therapy in treating Parkinson's disease patients. This review discusses motor and non-motor symptoms (namely autonomic, sensory, emotional, and cognitive dysfunction) of Parkinson's disease in respect to hemispheric lateralization from a theoretical perspective in hopes of providing a framework for future research and personalized treatment.

APOE E4 is associated with impaired self-declared cognition but not disease risk or age of onset in Nigerians with Parkinson's disease

The relationship between APOE polymorphisms and Parkinson's disease (PD) in black Africans has not been previously investigated. We evaluated the association between APOE polymorphic variability and self-declared cognition in 1100 Nigerians with PD and 1097 age-matched healthy controls. Cognition in PD was assessed using the single item cognition question (item 1.1) of the MDS-UPDRS. APOE genotype and allele frequencies did not differ between PD and controls (p > 0.05). No allelic or genotypic association was observed between APOE and age at onset of PD. In PD, APOE ε4/ε4 conferred a two-fold risk of cognitive impairment compared to one or no ε4 (HR: 2.09 (95% CI: 1.13-3.89; p = 0.02)), while APOE ε2 was associated with modest protection against cognitive impairment (HR: 0.41 (95% CI 0.19-0.99, p = 0.02)). Of 773 PD with motor phenotype and APOE characterized, tremor-dominant (TD) phenotype predominated significantly in ε2 carriers (87/135, 64.4%) compared to 22.2% in persons with postural instability/gait difficulty (PIGD) (30/135) and 13.3% in indeterminate (ID) (18/135, 13.3%) (p = 0.037). Although the frequency of the TD phenotype was highest in homozygous ε2 carriers (85.7%), the distribution of motor phenotypes across the six genotypes did not differ significantly (p = 0.18). Altogether, our findings support previous studies in other ethnicities, implying a role for APOE ε4 and ε2 as risk and protective factors, respectively, for cognitive impairment in PD.

Pedunculopontine Nucleus Dysconnectivity Correlates With Gait Impairment in Parkinson’s Disease: An Exploratory Study

Background

Gait impairment is a debilitating and progressive feature of Parkinson’s disease (PD). Increasing evidence suggests that gait control is partly mediated by cholinergic signaling from the pedunculopontine nucleus (PPN).

Objective

We investigated whether PPN structural connectivity correlated with quantitative gait measures in PD.

Methods

Twenty PD patients and 15 controls underwent diffusion tensor imaging to quantify structural connectivity of the PPN. Whole brain analysis using tract-based spatial statistics and probabilistic tractography were performed using the PPN as a seed region of interest for cortical and subcortical target structures. Gait metrics were recorded in subjects’ medication ON and OFF states, and were used to determine if specific features of gait dysfunction in PD were related to PPN structural connectivity.

Results

Tract-based spatial statistics revealed reduced structural connectivity involving the corpus callosum and right superior corona radiata, but did not correlate with gait measures. Abnormalities in PPN structural connectivity in PD were lateralized to the right hemisphere, with pathways involving the right caudate nucleus, amygdala, pre-supplementary motor area, and primary somatosensory cortex. Altered connectivity of the right PPN-caudate nucleus was associated with worsened cadence, stride time, and velocity while in the ON state; altered connectivity of the right PPN-amygdala was associated with reduced stride length in the OFF state.

Conclusion

Our exploratory analysis detects a potential correlation between gait dysfunction in PD and a characteristic pattern of connectivity deficits in the PPN network involving the right caudate nucleus and amygdala, which may be investigated in future larger studies.

The emerging postural instability phenotype in idiopathic Parkinson disease

Identification of individuals at high risk for rapid progression of motor and cognitive signs in Parkinson disease (PD) is clinically significant. Postural instability and gait dysfunction (PIGD) are associated with greater motor and cognitive deterioration. We examined the relationship between baseline clinical factors and the development of postural instability using 5-year longitudinal de-novo idiopathic data (n = 301) from the Parkinson’s Progressive Markers Initiative (PPMI). Logistic regression analysis revealed baseline features associated with future postural instability, and we designated this cohort the emerging postural instability (ePI) phenotype. We evaluated the resulting ePI phenotype rating scale validity in two held-out populations which showed a significantly higher risk of postural instability. Emerging PI phenotype was identified before onset of postural instability in 289 of 301 paired comparisons, with a median progression time of 972 days. Baseline cognitive performance was similar but declined more rapidly in ePI phenotype. We provide an ePI phenotype rating scale (ePIRS) for evaluation of individual risk at baseline for progression to postural instability.

Distinct hippocampal subfield atrophy in Parkinson's disease regarding motor subtypes

INTRODUCTION

Global hippocampal atrophy has been repeatedly reported in patients with Parkinson's disease (PD). However, there is limited literature on the differential involvement of hippocampal subfields among PD motor subtypes. This study aimed to investigate hippocampal subfield alterations in patients with PD based on their predominant symptoms.

METHOD

We enrolled 31 PD patients with the tremor-dominant (TD) subtype, 27 PD patients with postural instability and gait disturbance-dominant (PIGD) subtype, and 40 healthy controls (HCs). All participants underwent high-spatial-resolution T1-weighted magnetic resonance imaging. The volume of hippocampal subfields was measured using FreeSurfer software, compared across groups, and correlated with clinical features.

RESULTS

We found volumetric reductions in the hippocampal subfield in both patient subtypes compared to HCs, which were more pronounced in the PIGD subtype. The PIGD subtype had accelerated age-related alterations in the hippocampus compared to the TD subtype. Bilateral hippocampal volumes were positively associated with cognitive performance levels, but not with disease severity and duration in patients.

CONCLUSIONS

Alterations in the hippocampal subfields of patients with PD differed based on their predominant symptoms. These findings are of relevance for understanding the pathophysiology of the increased risk of cognitive impairment in PIGD.

Optimizing Cognitive Training for the Treatment of Cognitive Dysfunction in Parkinson's Disease: Current Limitations and Future Directions

Cognitive dysfunction, primarily involving impairments in executive function, visuospatial function and memory, is one of the most common non-motor symptoms of Parkinson’s disease (PD). Currently, the only pharmacological treatments available for the treatment of cognitive dysfunction in PD provide variable benefit, making the search for potential non-pharmacological therapies to improve cognitive function of significant interest. One such therapeutic strategy may be cognitive training (CT), which involves the repetition of standardized tasks with the aim of improving specific aspects of cognition. Several studies have examined the effects of CT in individuals with PD and have shown benefits in a variety of cognitive domains, but the widespread use of CT in these individuals may be limited by motor impairments and other concerns in study design. Here, we discuss the current state of the literature on the use of CT for PD and propose recommendations for future implementation. We also explore the potential use of more recent integrative, adaptive and assistive technologies, such as virtual reality, which may optimize the delivery of CT in PD.

The Impact of Sex on the Neurocognitive Functions of Patients with Parkinson's Disease

This study aimed to understand the impact of sex on the neurocognitive function of patients with Parkinson's disease (PD). Ninety-four participants with idiopathic PD and 167 age-matched healthy individuals as normal controls (NCs) were recruited and underwent comprehensive neuropsychological assessments. Sex differences were found in NCs, but not in patients with PD. Among male participants, patients with PD showed worse performance on the Digit Symbol Substitution (DSS) (p < 0.001) test and Symbol Search (SS) (p < 0.001) than NCs. Among female participants, patients with PD showed worse performance on the category score of the Modified Wisconsin Card Sorting Test (p < 0.001), SS (p < 0.001), and pentagon copying (p < 0.001) than NCs. After controlling for the effects of age and years of education, Hoehn and Yahr stage was found to predict the performance of the Color Trails Test part A (βA = 0.241, pA = 0.036), Stroop Color and Word Test (β = -0.245, p = 0.036), and DSS (β = -0.258, p = 0.035) in men with PD. These results indicate the differential effect of sex on the neurocognitive function among healthy aging and PD populations. The disappearance of sex differences, which is present in healthy aging, in patients with PD suggests a gradual loss of the neuroprotective effect of estrogen after the initiation of the neurodegenerative process. This study also found mental flexibility and visuospatial function to be the susceptible cognitive domains in women with PD, while the disease severity could predict the working memory and processing speed in men with PD.

Cortical Serotonergic and Catecholaminergic Denervation in MPTP-Treated Parkinsonian Monkeys

Decreased cortical serotonergic and catecholaminergic innervation of the frontal cortex has been reported at early stages of Parkinson's disease (PD). However, the limited availability of animal models that exhibit these pathological features has hampered our understanding of the functional significance of these changes during the course of the disease. In the present study, we assessed longitudinal changes in cortical serotonin and catecholamine innervation in motor-symptomatic and asymptomatic monkeys chronically treated with low doses of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). Densitometry and unbiased stereological techniques were used to quantify changes in serotonin and tyrosine hydroxylase (TH) immunoreactivity in frontal cortices of 3 control monkeys and 3 groups of MPTP-treated monkeys (motor-asymptomatic [N = 2], mild parkinsonian [N = 3], and moderate parkinsonian [N = 3]). Our findings revealed a significant decrease (P < 0.001) in serotonin innervation of motor (Areas 4 and 6), dorsolateral prefrontal (Areas 9 and 46), and limbic (Areas 24 and 25) cortical areas in motor-asymptomatic MPTP-treated monkeys. Both groups of symptomatic MPTP-treated animals displayed further serotonin denervation in these cortical regions (P < 0.0001). A significant loss of serotonin-positive dorsal raphe neurons was found in the moderate parkinsonian group. On the other hand, the intensity of cortical TH immunostaining was not significantly affected in motor asymptomatic MPTP-treated monkeys, but underwent a significant reduction in the moderate symptomatic group (P < 0.05). Our results indicate that chronic intoxication with MPTP induces early pathology in the corticopetal serotonergic system, which may contribute to early non-motor symptoms in PD.

Progression in Parkinson's Disease: Variation in Motor and Non-motor Symptoms Severity and Predictors of Decline in Cognition, Motor Function, Disability, and Health-Related Quality of Life as Assessed by Two Different Methods

Background

Parkinson's disease (PD) is multi-symptom disease with variable progression.

Objectives

We performed a longitudinal study to address the evolution of motor symptoms (MS) and non-motor symptoms (NMS), predictors of motor-, cognitive-, disability-, and health-related quality of life (HRQL) status and the relative usefullness of a battery of separate NMS scales (BSS) versus the Non-Motor Symptom Scale (NMSS).

Methods

Seventy-two patients were assessed at baseline and 4 years later with the NMSS and BSS. We assessed the following outcomes: cognition (Montreal Cognitive Assessment scale [MoCA]), disability (Unified Parkinson's Disease Rating Scale Part II [UPDRS II], Schwab and England [S&E]), motor dysfunction (Unified Parkinson's Disease Rating Scale Part III [UPDRS III], Hoehn and Yahr [HY]), and HRQL (EuroQol [EQ] EQ-vertical visual analogue scale [VAS] and EQ-Index). Statistical analysis included a comparison between scales scores at both time points and multivariate regression analysis to calculate the impact of each baseline symptom in outcomes. NMSS and BSS were introduced in separate models.

Results

NMSS Domain 4: perception/hallucinations, Parkinson's Psychosis Questionnaire, Apathy Scale, NMSS Domain 7: urinary, S&E, UPDRS II, HY, and MoCA scores worsened significantly. Dementia increased to a 4-year prevalence of 39.8%. In the multivariate model using BSS, cognitive state variation was significantly predicted by baseline HY, EQ-Index, and S&E. Using the NMSS, MoCA change was significantly associated with NMSS Domain 4: perceptions/hallucination score, cognitive status with UPDRS III score, HRQL with NMSS Domain 4: perception/hallucinations score, and S&E.

Conclusion

Our study suggests that NMS progress heterogeneously, BSS approach being more sensitive to change than NMSS. The multivariate analysis has shown that S&E and NMSS Domain 4: perception/hallucinations scores are the stronger predictors of HRQL and cognitive dysfunction variation, favoring NMSS over the BSS approach.

Cross-sectional associations between cognition and mobility in Parkinson's disease

Cross-sectional studies show an association of decline in mental flexibility and inhibitory control with reduced gait speed and falls, as well as divided attention deficit and difficulty in initiating gait.

Effect of nutritional risk on cognitive function in patients with chronic obstructive pulmonary disease

Objective

We aimed to clarify the cognitive function of patients with chronic obstructive pulmonary disease (COPD) and different nutritional status.

Methods

Among 95 patients with COPD in this retrospective study, we administered the Nutritional Risk Screening 2002 (NRS 2002) and Mini-Mental State Examination (MMSE). We recorded patients’ clinical characteristics, comorbidities, and laboratory measurements. According to NRS 2002 scores, patients were divided into two groups: no nutritional risk with NRS 2002 < 3 (n = 54) and nutritional risk, with NRS 2002 ≥ 3 (n = 41).

Results

We found a negative correlation between NRS 2002 and MMSE scores in participants with COPD (r = −0.313). Patients with nutritional risk were more likely to be cognitively impaired than those with no nutritional risk. Multivariate logistic regression analysis indicated that malnutrition was an independent risk factor for cognitive impairment, after adjusting for confounders (odds ratio [OR] = 4.120, 95% confidence interval [CI]: 1.072–15.837). We found a similar association between NRS 2002 and MMSE scores at 90-day follow-up using a Pearson’s correlation test (r = −0.493) and logistic regression analysis (OR = 7.333, 95% CI: 1.114–48.264).

Conclusions

Patients with COPD at nutritional risk are more likely to have cognitive impairment.

Efficacy of short-term multidisciplinary intensive rehabilitation in patients with different Parkinson's disease motor subtypes: a prospective pilot study with 3-month follow-up

Parkinson's disease (PD) can be classified into three motor-based subtypes: postural instability/gait difficulty (PIGD), tremor dominant (TD), and indeterminate. The neuropathophysiological mechanisms of the three motor subtypes are different, which may lead to different responses to therapy. Sixty-nine patients with idiopathic Parkinson's disease (Hoehn-Yahr stage ≤ 3) were screened from 436 patients with Parkinsonism recruited through outpatient services and the internet. According to the Movement Disorder Society Unified Parkinson's Disease Rating Scale (MDS-UPDRS) TD/PIGD ratio, the patients were divided into PIGD (TD/PIGD ≤ 0.09; n = 36), TD (TD/PIGD ≥1.15; n = 19), and indeterminate (TD/PIGD = 0.90-1.15; n = 14) groups. All patients received 2 weeks of multidisciplinary intensive rehabilitation treatment (MIRT) during hospitalization, as well as a remote home rehabilitation health education class. Compared with the scores at admission, all patients showed significant improvements in their MDS-UPDRS III score, walking ability, balance, and posture control at discharge. Moreover, the MDS-UPDRS III score improvement was greater in the PIGD group than in the TD group. The follow-up data, collected for 3 months after discharge, showed that overall symptom improvement in each group was maintained for 1-3 months. Furthermore, there were no significant differences in the duration or grade effects of symptom improvement among the three groups. These findings suggest that 2 weeks of MIRT is effective for improving motor performance in all three motor subtypes. Patients in the PIGD group had a better response after hospitalization than those in the TD group. This study was approved by the Institutional Ethics Committee of Beijing Rehabilitation Hospital of Capital Medical University of China (approval No. 2018bkky022) on May 7, 2018 and registered with the Chinese Clinical Trial Registry (registration No. ChiCTR1900020771) on January 19, 2019.

Transcranial direct current stimulation combined with physical or cognitive training in people with Parkinson's disease: a systematic review

BACKGROUND

Pharmacologic therapy is the primary treatment used to manage Parkinson's disease (PD) symptoms. However, it becomes less effective with time and some symptoms do not respond to medication. Complementary interventions are therefore required for PD. Recent studies have implemented transcranial direct current stimulation (tDCS) in combination with other modalities of interventions, such as physical and cognitive training. Although the combination of tDCS with physical and cognitive training seems promising, the existing studies present mixed results. Therefore, a systematic review of the literature is necessary.

AIMS

This systematic review aims to (i) assess the clinical effects of tDCS when applied in combination with physical or cognitive therapies in people with PD and; (ii) analyze how specific details of the intervention protocols may relate to findings.

METHODS

The search strategy detailed the technique of stimulation, population and combined interventions (i.e. cognitive and/or physical training). Only controlled studies were included.

RESULTS

Seventeen of an initial yield of 408 studies satisfied the criteria. Studies involved small sample sizes. tDCS protocols and characteristics of combined interventions varied. The reviewed studies suggest that synergistic effects may be obtained for cognition, upper limb function, gait/mobility and posture when tDCS is combined with cognitive and/or motor interventions in PD.

CONCLUSION

The reported results encourage further research to better understand the therapeutic utility of tDCS and to inform optimal clinical use in PD. Future studies in this field should focus on determining optimal stimulation parameters and intervention characteristics for maximal benefits in people with PD.

Parkinson's disease motor subtypes and bilateral GPi deep brain stimulation: One-year outcomes

OBJECTIVE

We aimed to explore the differences in motor symptoms and quality of life (QOL) outcomes following bilateral globus pallidus internus deep brain stimulation (GPi DBS), across well-defined motor subtypes of Parkinson's disease (PD), to improve clinical decision making.

METHODS

This single-center retrospective study investigated bilateral GPi DBS outcomes in 65 PD patients. Outcome measures included the Unified Parkinson's Disease Rating Scale (UPDRS) and Parkinson's Disease Questionnaire (PDQ-39) before and one year after surgery. Outcomes were compared between the tremor-dominant (TD) and postural instability and gait difficulty (PIGD) subtypes and between the TD and akinetic-rigid (AR) subtypes.

RESULTS

For the entire cohort, motor function (UPDRS III) in the Off-medication state, motor complications (UPDRS IV), activities of daily living (ADL, UPDRS II), and the ADL and discomfort domains of PDQ-39 significantly improved one year following GPi implantation compared to baseline (effect size = 1.32, 1.15, 0.25, 0.45, and 0.34, respectively). GPi DBS improved the Off-medication UPDRS III scores regardless of the motor subtypes. However, compared to the PIGD and AR patients, the TD patients showed greater improvement in overall UPDRS III postoperatively primarily due to greater tremor improvement in the Off-medication state. The outcomes in akinesia, rigidity, axial symptoms and QOL were similar among all subtypes.

CONCLUSION

Bilateral GPi DBS was effective for advanced PD patients regardless of motor subtypes. Greater tremor improvement in the TD patients accounted for greater Off-medication motor improvement. Longer-term GPi DBS outcomes across different motor subtypes and brain targets should be further studied.

Correlations between blood lipid, serum cystatin C, and homocysteine levels in patients with Parkinson's disease

AIM

The aim was too study the correlations between blood lipid, serum cystatin C (Cys C) and homocysteine (Hcy) levels in patients with Parkinson's disease (PD).

METHODS

A total of 322 PD patients and 214 healthy subjects were selected as case and control groups, respectively. The risk factors were explored by logistic regression analysis. The case group was subtyped according to main motor symptoms and age of onset. The correlations of significantly different indices with age, duration of disease, and equivalent dose of levodopa were studied by Spearman's correlation analysis. Receiver operating characteristic curves were plotted to analyze diagnostic values.

RESULTS

Compared to the control group, the PD group had lower serum total cholesterol, triglyceride, and apolipoprotein B (Apo B) levels and higher high-density lipoprotein cholesterol (HDL-C), Hcy, and Cys C levels (P < 0.05). Decreased Apo B level and increased HDL-C and Hcy levels were independent risk factors (P < 0.05). The Cys C level of early-onset patients was lower than of late-onset patients (P < 0.05). Hcy (r = 0.198, P < 0.05) and Cys C (r = 0.281, P < 0.05) levels were positively correlated with age. Triglyceride level was negatively correlated with age (r = -0.202, P < 0.05) and disease duration (r = -0.198, P < 0.05). Unified Parkinson's Disease Rating Scale III score was positively correlated with disease duration (r = 0.435, P < 0.05) and equivalent dose of levodopa (r = 0.423, P < 0.05). The areas under the curve for Apo B, HDL-C, and Hcy levels were 0.341, 0.588, and 0.643, respectively (P < 0.05). The combination of Apo B, HDL-C, and Hcy levels showed high diagnostic value, with a sensitivity of 76.4% and specificity of 69.5%.

CONCLUSIONS

Low serum levels of total cholesterol, triglyceride, and Apo B, and high levels of HDL-C, Hcy, and Cys C may be correlated with PD onset and progression. Decreased Apo B level and elevated HDL-C and Hcy levels are independent risk factors. Early-onset and late-onset PD may have different progression mechanisms.

Relationship between cognitive performance and mobility in patients with Parkinson's disease: A cross-sectional study

Gait disorders may be associated with cognitive impairment, and slow speed predicts cognitive impairment and dementia. Objective: To investigate the relationships between cognitive function and gait performance in patients with Parkinson’s disease (PD) who attended a hospital neurorehabilitation program. Methods: Descriptive and inferential statistics (Pearson’s correlation) were used for data analysis. The cognitive functions were evaluated through Digit Span, Mental Control, Trail Making Test, Phonemic Verbal Fluency Task, and Addenbrooke’s Cognitive Examination III. The motor function was assessed through 10-meter walk test, Mini BESTest and Timed Up and Go Test. Results: A total of 65 patients were included in this study. Of these, 66.15% were males, mean age was 61.14 (8.39) years, mean educational was 12 (8) years, disease progression time was 5.45 (4.37) years. 64.61% were in stages I and II of the Hoehn and Yahr stage. The correlation analyses showed that balance skills are significantly correlated with the ability to switch attention between two tasks and visuospatial function. The function mobility showed a significant correlation with cognitive tests. Conclusion: Data suggest the importance of the aspects of switch attention and mental flexibility in gait, evidencing the greater difficulty for double tasks.

Falls in persons with Parkinson's disease: Do non-motor symptoms matter as much as motor symptoms?

ABSTRACT Falls are common among persons with Parkinson's disease (PD). On the other hand, predicting falls is complex as there are both generic and PD-specific contributors. In particular, the role of non-motor symptoms has been less studied. Objective: The objective of this study was to identify the role of non-motor predictors of falling in persons with PD (PwP). Methods: A cross-sectional study was carried out in PwP recruited from a movement disorders clinic. Clinical and demographical data were collected. All PwP were assessed using the Movement Disorders Society Unified Parkinson's Disease Rating Scale (MDS-UPDRS) and the Non-Motor Symptoms Scale (NMSS). Variables were assessed at the bivariate level. Significant variables were put into a logistic regression model. Results: A total of 179 PwP were included. Overall, 16.8% of PwP had fallen in the past 12 months, with 53.3% of them being recurrent fallers. The mean number of monthly falls was 2.5 ± 3.3. Factors associated with falling in the bivariate analysis included the disease duration, Hoehn and Yahr stage, MDS-UPDRS part I and II, postural instability/gait disturbance (PIGD) subtype, NMSS urinary domain, NMSS miscellaneous domain, and non-motor severity burden (all p-values < 0.05). After multivariate analysis, only the disease duration (p = 0.03) and PIGD (p = 0.03) remained as independent risk factors. Conclusion: Disease duration and the PIGD subtype were identified as relevant risk factors for falls in PwP Non-motor symptoms appear to have a less important role as risk factors for falls.

Motor function and the probability of prodromal Parkinson's disease in older adults

BACKGROUND

Identification and characterization of Parkinson's disease (PD) in its prodromal stage is crucial.

OBJECTIVE

The objective of this study was to investigate the association between motor function and the probability of prodromal PD in a community-dwelling older population.

METHODS

We used data from a population-based cohort of older adults (HELIAD study). Subjective motor function was evaluated with a 12-item motor symptoms questionnaire and objective motor function indirectly with a physical activity questionnaire and two gait speed tests. The probability of prodromal PD was calculated according to the Movement Disorder Society research criteria for n = 1731 without PD. Regression multiadjusted models were used to investigate the associations between each motor measure and prodromal PD probability.

RESULTS

For each unit increase in motor symptoms score and for each kcal/kg/day lower energy expenditure (corresponding to 20 minutes of light walking/day for a 75-kg man) there was a 27% and 3% higher probability for prodromal PD, respectively (P < 0.001). Having at least one subjective motor symptom increased the odds of having possible/probable prodromal PD (n = 49; P < 0.05). Including subjective and indirect motor variables in the same model showed that both (symptoms and physical activity) contributed significantly to the model (P < 0.01). Excluding subthreshold parkinsonism from the calculation showed that gait speed less than 0.8 m/s was also associated with a higher prodromal PD probability score (P < 0.001).

CONCLUSIONS

Subjective motor symptoms as well as simple objective motor measures of physical activity or gait speed are associated with a higher probability of prodromal PD in older adults. These data may serve to enable the early identification of prodromal PD cohorts, particularly if they are confirmed in longitudinal studies. © 2019 International Parkinson and Movement Disorder Society.

Gait impairments in Parkinson's disease

Gait impairments are among the most common and disabling symptoms of Parkinson's disease. Nonetheless, gait is not routinely assessed quantitatively but is described in general terms that are not sensitive to changes ensuing with disease progression. Quantifying multiple gait features (eg, speed, variability, and asymmetry) under natural and more challenging conditions (eg, dual-tasking, turning, and daily living) enhanced sensitivity of gait quantification. Studies of neural connectivity and structural network topology have provided information on the mechanisms of gait impairment. Advances in the understanding of the multifactorial origins of gait changes in patients with Parkinson's disease promoted the development of new intervention strategies, such as neurostimulation and virtual reality, aimed at alleviating gait impairments and enhancing functional mobility. For clinical applicability, it is important to establish clear links between specific gait impairments, their underlying mechanisms, and disease progression to foster the acceptance and usability of quantitative gait measures as outcomes in future disease-modifying clinical trials.

Postural Dynamics Are Associated With Cognitive Decline in Parkinson's Disease

Early features of Parkinson's disease (PD) include both motor and cognitive changes, suggesting shared common pathways. A common motor dysfunction is postural instability, a known predictor of falls, which have a major impact on quality of life. Understanding mechanisms of postural dynamics in PD and specifically how they relate to cognitive changes is essential for developing effective interventions. The aims of this study were to examine the changes that occur in postural metrics over time and explore the relationship between postural and cognitive dysfunction. The study group consisted of 35 people (66 ± 8years, 12 female, UPDRS III: 22.5 ± 9.6) diagnosed with PD who were recruited as part of the Incidence of Cognitive Impairment in Cohorts with Longitudinal Evaluation—PD Gait (ICICLE-GAIT) study. Postural and cognitive assessments were performed at 18, 36, and 54 months after enrolment. Participants stood still for 120 s, eyes open and arms by their side. Postural dynamics were measured using metrics derived from a single tri-axial accelerometer (Axivity AX3, York, UK) on the lower back. Accelerometry metrics included jerk (derivative of acceleration), root mean square, frequency, and ellipsis (acceleration area). Cognition was evaluated by neuropsychological tests including the Montreal Cognitive Assessment (MoCA) and digit span. There was a significant decrease in accelerometry parameters, greater in the anteroposterior direction, and a decline in cognitive function over time. Accelerometry metrics were positively correlated with lower cognitive function and increased geriatric depression score and negatively associated with a qualitative measure of balance confidence. In conclusion, people with PD showed reduced postural dynamics that may represent a postural safety strategy. Associations with cognitive function and depression, both symptoms that may pre-empt motor symptoms, suggest shared neural pathways. Further studies, involving neuroimaging, may determine how these postural parameters relate to underlying neural and clinical correlates.

Depressive symptoms may increase the risk of the future development of freezing of gait in patients with Parkinson's disease: Findings from a 5-year prospective study

INTRODUCTION

Prospective studies identifying predictors of freezing of gait (FOG) in Parkinson's disease (PD) are limited. We aim to explore which symptoms are associated with future development of FOG in non-freezers.

METHODS

Fifty-seven PD patients without FOG at baseline were re-evaluated after a mean of five years. At baseline, disease severity [Unified Parkinson's Disease Rating Scale (MDS-UPDRS)], gait under single and dual-tasking, balance, cognition and other non-motor symptoms were assessed. The new-FOG-questionnaire (NFOG-Q) determined FOG. Multivariate binary logistic regression determined independent predictors of FOG.

RESULTS

At follow-up, 26 subjects (46%) had FOG while 31 remained non-freezers. At baseline, non-freezers (FOG-) and future freezers (FOG+) were similar (p > 0.10) with respect to age, gender, disease duration, dopaminergic medications, and cognitive function. However, FOG + had significantly worse scores on the Geriatric Depression Scale (GDS) (FOG+:5.2 ± 3.7; FOG-:2.4 ± 2.0, p = 0.005), PDQ-39, the NMS-questionnaire, UPDRS-part I, UPDRS-part III (off), and the Berg Balance Scale. In binary logistic regression, GDS, gait speed and UPDRS-III (on vs. off) were the only significant independent predictors of future FOG (GDS: OR = 10.93, p = 0.003, ΔUPDRS-III: OR = 1.34, p = 0.006). Moreover, 80% of the subjects who had marked depressive symptoms at baseline (GDS≥5) developed FOG at follow-up. In contrast, only 27% of those with few depressive symptoms at baseline became freezers (p < 0.001).

CONCLUSIONS

Depressive symptoms apparently precede the development of FOG. While elucidation of the relationship between depression and FOG needs further study, our findings offer another perspective regarding the pathophysiology of FOG and may help clinicians to estimate the risk of developing this debilitating phenomenon.

Who will remain tremor dominant? The possible role of cognitive reserve in the time course of two common Parkinson's disease motor subtypes

In a prospective 5-year study among Parkinson's disease (PD) tremor-dominant (TD) patients, we investigated who will remain TD and who will later convert into the postural instability gait difficulty (PIGD) phenotype. At follow-up, 38% were still considered TD. At baseline the TD non-convertors had more years of education and better cognitive function than the convertors and significantly smaller deterioration in gait, balance, cognitive function and other non-motor symptoms. These results highlight the potential role of cognition in protecting against the development of PIGD symptoms.