White Matter Hyperintensities, Dopamine Loss, and Motor Deficits in De Novo Parkinson's Disease

Quantitative Analysis of White Matter Hyperintensities as a Predictor of 1-Year Risk for Ischemic Stroke Recurrence

INTRODUCTION

This study evaluates the role of quantitative characteristics of white matter hyperintensities (WMHs) in predicting the 1-year recurrence risk of ischemic stroke.

METHODS

We conducted a retrospective analysis of 1061 patients with ischemic stroke from January 2018 to April 2021. WMHs were automatically segmented using a cluster-based method to quantify their volume and number of clusters (NoC). Additionally, two radiologists independently rated periventricular and deep WMHs using the Fazekas scale. The cohort was divided into a training set (70%) and a testing set (30%). We employed Cox proportional hazards models to develop predictors based on quantitative WMH characteristics, Fazekas scores, and clinical factors, and compared their performance using the concordance index (C-index).

RESULTS

A total of 180 quantitative variables related to WMHs were extracted. A higher NoC in deep white matter and brainstem, advanced age (> 90 years old), specific stroke subtypes, and absence of discharge antiplatelets showed stronger associations with the risk of ischemic stroke recurrence within 1 year. The nomogram incorporating quantitative WMHs data showed superior discrimination compared to those based on the Fazekas scale or clinical factors alone, with C-index values of 0.709 versus 0.647 and 0.648, respectively, in the testing set. Notably, a combined model including both WMHs and clinical factors achieved the highest predictive accuracy, with a C-index of 0.735 in the testing set.

CONCLUSION

Quantitative assessment of WMHs provides a valuable neuro-imaging tool for enhancing the prediction of ischemic stroke recurrence risk.

Predictors associated with the rate of progression of nigrostriatal degeneration in Parkinson's disease

BACKGROUND

Parkinson's disease (PD) manifests as a wide variety of clinical phenotypes and its progression varies greatly. However, the factors associated with different disease progression remain largely unknown.

METHODS

In this retrospective cohort study, we enrolled 113 patients who underwent 18F-FP-CIT PET scan twice. Given the negative exponential progression pattern of dopamine loss in PD, we applied the natural logarithm to the specific binding ratio (SBR) of two consecutive 18F-FP-CIT PET scans and conducted linear mixed model to calculate individual slope to define the progression rate of nigrostriatal degeneration. We investigated the clinical and dopamine transporter (DAT) availability patterns associated with the progression rate of dopamine depletion in each striatal sub-region.

RESULTS

More symmetric parkinsonism, the presence of dyslipidemia, lower K-MMSE total score, and lower anteroposterior gradient of the mean putaminal SBR were associated with faster progression rate of dopamine depletion in the caudate nucleus. More symmetric parkinsonism and lower anteroposterior gradient of the mean putaminal SBR were associated with faster depletion of dopamine in the anterior putamen. Older age at onset, more symmetric parkinsonism, the presence of dyslipidemia, and lower anteroposterior gradient of the mean putaminal SBR were associated with faster progression rate of dopamine depletion in the posterior putamen. Lower striatal mean SBR predicted the development of LID, while lower mean SBR in the caudate nuclei predicted the development of dementia.

DISCUSSION

Our results suggest that the evaluation of baseline clinical features and patterns of DAT availability can predict the progression of PD and its prognosis.

Is white matter hyperintensity burden associated with cognitive and motor impairment in patients with parkinson's disease? A systematic review and meta-analysis

White matter damage quantified as white matter hyperintensities (WMH) may aggravate cognitive and motor impairments, but whether and how WMH burden impacts these problems in Parkinson's disease (PD) is not fully understood. This study aimed to examine the association between WMH and cognitive and motor performance in PD through a systematic review and meta-analysis. We compared the WMH burden across the cognitive spectrum (cognitively normal, mild cognitive impairment, dementia) in PD including controls. Motor signs were compared in PD with low/negative and high/positive WMH burden. We compared baseline WMH burden of PD who did and did not convert to MCI or dementia. MEDLINE and EMBASE databases were used to conduct the literature search resulting in 50 studies included for data extraction. Increased WMH burden was found in individuals with PD compared with individuals without PD (i.e. control) and across the cognitive spectrum in PD (i.e. PD, PD-MCI, PDD). Individuals with PD with high/positive WMH burden had worse global cognition, executive function, and attention. Similarly, PD with high/positive WMH presented worse motor signs compared with individuals presenting low/negative WMH burden. Only three longitudinal studies were retrieved from our search and they showed that PD who converted to MCI or dementia, did not have significantly higher WMH burden at baseline, although no data was provided on WMH burden changes during the follow up. We conclude, based on cross-sectional studies, that WMH burden appears to increase with PD worse cognitive and motor status in PD.

Musculoskeletal pain in Parkinson's disease: Association with dopaminergic deficiency in the caudate nucleus

BACKGROUND

Musculoskeletal (MSK) pain affects over 80% of People with Parkinson's (PD, PwP) and may, in part, be dopaminergic in origin, as dopaminergic medication often leads to its relief.

METHODS

PwP who underwent striatal dopamine transporter visualization with a radiopharmaceutical DaTscan™ (123 I-Ioflupane Injection) using a single-photon emission computed tomography (SPECT) as a part of their clinical-diagnostic work up were enrolled in the "Non-motor International Longitudinal Study" (NILS; UK National Institute for Health Research Clinical Research Network Number 10084) and included in this cross-sectional analysis. The association between specific DaTscan binding ratios for each striatum, the caudate nucleus and putamen and clinical ratings for MSK pain (assessed using the King's Parkinson's Disease Pain Scale (KPPS)) were analysed.

RESULTS

53 PwP (30.2% female; age: 63.79 ± 11.31 years; disease duration (DD): 3.32 (0.31-14.41) years; Hoehn & Yahr stage (H&Y): 2 (1-4); Levodopa Equivalent Daily Dose (LEDD): 543.08 ± 308.94 mg) were assessed and included in this analysis. MSK pain was highly prevalent (71.7% of all participants, mean KPPS Item 1 score 5.34 ± 4.76) and did not correlate with the motor symptoms burden (SCOPA-Motor total score; p = 0.783) but showed a significant correlation with quality of life (PDQ-8, rs  = 0.290, p = 0.035). z-scores for the caudate nucleus (Exp (B) = 0.367, 95% CI for Exp (B) 0.148-0.910, p = 0.031) and striatum (Exp (B) = 0.338, 95% CI for Exp (B) 0.123-0.931, p = 0.036), adjusted for DD, H&Y and LEDD, were significant determinants of MSK pain.

CONCLUSIONS

Our findings suggest an association between MSK pain in PwP and the severity of dopaminergic deficiency in the caudate nucleus.

SIGNIFICANCE

In People with Parkinson's, musculoskeletal pain does not arise simply as a direct sequel to motor symptoms-instead, it is linked to the severity of dopaminergic depletion in the caudate nucleus.

Association of choroid plexus volume with motor symptoms and dopaminergic degeneration in Parkinson's disease

BACKGROUND

The choroid plexus (CP) is involved in the clearance of harmful metabolites from the brain, as a part of the glymphatic system. This study aimed to investigate the association between CP volume (CPV), nigrostriatal dopaminergic degeneration and motor outcomes in Parkinson's disease (PD).

METHODS

We retrospectively searched drug-naïve patients with early-stage PD who underwent dopamine transporter (DAT) scanning and MRI. Automatic CP segmentation was performed, and the CPV was calculated. The relationship between CPV, DAT availability and Unified PD Rating Scale Part III (UPDRS-III) scores was assessed using multivariate linear regression. We performed longitudinal analyses to assess motor outcomes according to CPV.

RESULTS

CPV was negatively associated with DAT availability in each striatal subregion (anterior caudate, β=-0.134, p=0.012; posterior caudate, β=-0.162, p=0.002; anterior putamen, β=-0.133, p=0.024; posterior putamen, β=-0.125, p=0.039; ventral putamen, β=-0.125, p=0.035), except for the ventral striatum. CPV was positively associated with the UPDRS-III score even after adjusting for DAT availability in the posterior putamen (β=0.121; p=0.035). A larger CPV was associated with the future development of freezing of gait in the Cox regression model (HR 1.539, p=0.027) and a more rapid increase in dopaminergic medication in the linear mixed model (CPV×time, p=0.037), but was not associated with the risk of developing levodopa-induced dyskinesia or wearing off.

CONCLUSION

These findings suggest that CPV has the potential to serve as a biomarker for baseline and longitudinal motor disabilities in PD.

Regional white matter hyperintensity volume in Parkinson's disease and associations with the motor signs

OBJECTIVE

To determine whether white matter hyperintensity (WMH) volumes in specific regions are associated with Parkinson's disease (PD) compared to non-PD controls, and to assess their impact on motor signs through cross-sectional and longitudinal analyses.

METHODS

A total of 50 PD participants and 47 age- and gender-matched controls were enrolled. All PD participants were followed up for at least 2 years. To detect regions of greater WMH in the PD, the WMH volume of each region was compared with the corresponding region in the control group. Linear regression and linear mixed effects models were respectively used for cross-sectional and longitudinal analyses of the impact of increases in WMH volume on motor signs.

RESULTS

The PD group had greater WMH volume in the occipital region compared with the control group. Cross-sectional analyses only detected a significant correlation between occipital WMH volume and motor function in PD. Occipital WMH volume positively correlated with the severity of tremor, and gait and posture impairments, in the PD group. During the follow-up period, the participants' motor signs progressed and the WMH volumes remained stable, no longitudinal association was detected between them. The baseline occipital WMH volume cannot predict the progression of signs after adjustment for baseline disease duration and the presence of vascular risk factors.

INTERPRETATION

PD participants in this study were characterized by greater WMH at the occipital region, and greater occipital WMH volume had cross-sectional associations with worse motor signs, while its longitudinal impact on motor signs progression was limited.

Dual-task gait and white matter hyperintensities in Lewy body diseases: An exploratory analysis

Background

Parkinson’s disease (PD) and dementia with Lewy bodies (DLB) are part of a spectrum of Lewy body disorders, who exhibit a range of cognitive and gait impairments. Cognitive-motor interactions can be examined by performing a cognitive task while walking and quantified by a dual task cost (DTC). White matter hyperintensities (WMH) on magnetic resonance imaging have also been associated with both gait and cognition. Our goal was to examine the relationship between DTC and WMH in the Lewy body spectrum, hypothesizing DTC would be associated with increased WMH volume.

Methods

Seventy-eight participants with PD, PD with mild cognitive impairment (PD-MCI), PD with dementia or DLB (PDD/DLB), and 20 cognitively unimpaired participants were examined in a multi-site study. Gait was measured on an electronic walkway during usual gait, counting backward, animal fluency, and subtracting sevens. WMH were quantified from magnetic resonance imaging using an automated pipeline and visual rating. A median split based on DTC was performed. Models included age as well as measures of global cognition and cardiovascular risk.

Results

Compared to cognitively unimpaired participants, usual gait speed was lower and DTC was higher in PD-MCI and PDD/DLB. Low DTC participants had higher usual gait speed. WMH burden was greater in high counting DTC participants. Frontal WMH burden remained significant after adjusting for age, cardiovascular risk and global cognition.

Conclusion

Increased DTC was associated with higher frontal WMH burden in Lewy body disorders after adjusting for age, cardiovascular risk, and global cognition. Higher DTC was associated with age.

Striatal fibrinogen extravasation and vascular degeneration correlate with motor dysfunction in an aging mouse model of Alzheimer’s disease

Introduction: Alzheimer’s Disease (AD) patients exhibit signs of motor dysfunction, including gait, locomotion, and balance deficits. Changes in motor function often precede other symptoms of AD as well as correlate with increased severity and mortality. Despite the frequent occurrence of motor dysfunction in AD patients, little is known about the mechanisms by which this behavior is altered.

Methods and Results: In the present study, we investigated the relationship between cerebrovascular impairment and motor dysfunction in a mouse model of AD (Tg6799). We found an age-dependent increase of extravasated fibrinogen deposits in the cortex and striatum of AD mice. Interestingly, there was significantly decreased cerebrovascular density in the striatum of the 15-month-old as compared to 7-month-old AD mice. We also found significant demyelination and axonal damage in the striatum of aged AD mice. We analyzed striatum-related motor function and anxiety levels of AD mice at both ages and found that aged AD mice exhibited significant impairment of motor function but not in the younger AD mice.

Discussion: Our finding suggests an enticing correlation between extravasated fibrinogen, cerebrovascular damage of the striatum, and motor dysfunction in an AD mouse model, suggesting a possible mechanism underlying motor dysfunction in AD.

White and gray matter alterations in de novo PD patients: which matter most?

OBJECTIVES

This paper aimed to identify white matter (WM) and gray matter (GM) abnormalities in a sample of early PD patients, and their correlations with motor and non-motor symptom severity.

METHODS

We enrolled 62 de novo PD patients and 31 healthy subjects. Disease severity and non-motor symptom burden were assessed by the Unified Parkinson's Disease Rating Scale part III and the Non-Motor Symptoms Scale, respectively. Cognitive performance was assessed using Montreal Cognitive Assessment and Frontal Assessment Battery. All subjects underwent a 3-Tesla MRI protocol. MRI analyses included tract-based spatial statistics, cortical thickness, and subcortical and cerebellar volumetry.

RESULTS

In comparison to control subjects, PD patients exhibited lower fractional anisotropy and higher mean, axial, and radial diffusivity in most WM bundles, including corticospinal tracts, the internal and external capsule, the anterior and posterior thalamic radiations, the genu and body of the corpus callosum, cerebellar peduncles, and superior and inferior longitudinal and fronto-occipital fasciculi. Correlations between Montreal Cognitive Assessment scores and fractional anisotropy values in the right posterior thalamic radiation, left superior corona radiata, right inferior-fronto-occipital fasciculus, left inferior longitudinal fasciculus, bilateral anterior thalamic radiations, and bilateral superior longitudinal fasciculi were found. Smaller cerebellar volumes in early PD patients in the left and right crus I were also found. No GM changes were present in subcortical or cortical regions.

CONCLUSION

The combined evaluation of WM and GM in the same patient sample demonstrates that WM microstructural abnormalities precede GM structural changes in early PD patients.

Evolution characteristics of dynamic balance disorder over the course of PD and relationship with dopamine depletion

Objective

This study aimed to assess the evolution of dynamic balance impairment during the course of Parkinson's disease (PD) and to clarify the contribution of striatal dopaminergic innervation to poor dynamic balance.

Methods

In our study, 89 patients with PD (divided into 2 groups according to the H-Y stage) and 39 controls were included. Kinematic data were recorded by a portable inertial measurement unit system. Dopaminergic loss in the striatal subregion was verified through the ¹¹C-CFT PET examination. The severity of white matter hyperintensities (WMHs) was assessed by the Scheltens scale. The correlation between dynamic kinematic parameters and dopamine transporter availability was analyzed by multivariate regression analysis.

Results

Patients with early PD presented with imbalance featured by smaller three-dimensional trunk ROM with reduced trunk coronal angular velocity during walking and with reduced trunk sagittal angular velocity during the stand-to-sit task (all p < 0.05). These abnormalities were not more severe at a later stage. The ROM in the coronal and transverse planes during walking correlated with caudate DAT uptake (β = 0.832, p = 0.006, Q = 0.030, and β = 0.890, p = 0.003, Q = 0.030) after controlling for age, gender, and WMHs. As the disease progressed, the trunk sagittal and transverse angular velocities during walking and trunk sagittal angular velocity when turning and sitting-to-standing were slower, which was accompanied by reduced gait velocity gradually (all p < 0.05). These parameters related to disease progression have no association with striatal DAT uptake (all p > 0.05).

Conclusion

The dynamic balance in PD was impaired from the early stages, and the characteristics of the impairment changed differently as the disease progressed. Dopaminergic denervation has a lower contribution to dynamic balance disorders throughout PD.

Clinical characteristics of late-onset neuromyelitis optica spectrum disorder

BACKGROUND

Anti-aquaporin-4 (AQP-4) immunoglobulin G (IgG) is a major autoimmune antibody that contributes to the pathogenesis of neuromyelitis optica spectrum disorder (NMOSD). NMOSD often presents as disability, severe sensory impairment, and sleep disorders, which can cause anxiety and depression and further affect the quality of life. The age of onset is a key factor influencing the prognosis of NMOSD. However, this result was based on studies involving only anti-aquaporin-4 (AQP4) immunoglobulin G (IgG)-seropositive NMOSD patients or studies using the 2006 NMOSD diagnosis criteria. Therefore, further study of the age of onset of NMOSD is valuable. This study aimed to describe the clinical and magnetic resonance imaging (MRI) differences between early-onset neuromyelitis optica spectrum disorder (EO-NMOSD) and late-onset (LO)-NMOSD patients.

METHODS

Fifty patients were enrolled, their anti-AQP4-IgG titers were measured, and brain and spinal cord MRIs were obtained. Additionally, several questionnaires related to disease severity, anxiety, depression, cognition, sleep, pain, and fatigue were collected.

RESULTS

Higher AQP4-IgG seropositivity, higher AQP4-IgG titer, frequency of thoracic myelitis, and white matter hyperintensities (WMH), as well as greater severity of disability, greater severity of sleep disorders, higher anxiety, poorer cognitive function, and higher clinical dementia rating (CDR)-community affairs scores were observed in late-onset (LO)-NMOSD patients than those in early-onset (EO)-NMOSD. AQP4-IgG titer positively correlated with age, annual relapse rate, Expanded Disability Status Scale (EDSS) sensory scores, Activity of Daily Living Scale (ADL) scores, and Pittsburgh Sleep Quality Index (PSQI) scores. The EDSS-sensory scores positively correlated with age, relapse time, Hamilton Depression Rating Scale, Hamilton Anxiety Rating Scale, PSQI, ADL, and CDR. WMH was positively correlated with age, EDSS-sensory scores, PSQI scores, and CDR scores and negatively correlated with the California Verbal Learning Test scores.

CONCLUSION

LO-NMOSD patients have worse prognoses than those of EO-NMOSD patients. Higher AQP4-IgG titers, more WMHs, thoracic myelitis, and severe sensory symptoms are associated with cognition, depression, anxiety, and sleep disorders.

White matter hyperintensities burden in the frontal regions is positively correlated to the freezing of gait in Parkinson's disease

Objective

Previous studies have reported that white matter hyperintensities (WMHs) are associated with freezing of gait (FOG), but it is not clear whether their distribution areas have correlations with FOG in Parkinson's disease (PD) and the potential influencing factors about WMHs.

Methods

Two hundred and forty-six patients with PD who underwent brain MRI were included. Participants were divided into PD with FOG (n = 111) and PD without FOG (n = 135) groups. Scheltens score was used to assess the WMHs burden in the areas of deep white matter hyperintensities (DWMHs), periventricular hyperintensities (PVHs), basal ganglia hyperintensities (BGHs), and infratentorial foci of hyperintensities (ITF). Whole brain WMHs volume was evaluated by automatic segmentation. Binary logistic regression was used to evaluate relationships between WMHs and FOG. The common cerebrovascular risk factors that may affect WMHs were evaluated by mediation analysis.

Results

There were no statistical differences between PD with and without FOG groups in whole brain WMHs volume, total Scheltens score, BGHs, and ITF. Binary logistic regression showed that the total scores of DWMHs (OR = 1.094; 95% CI, 1.001, 1.195; p = 0.047), sum scores of PVHs and DWMHs (OR = 1.080; 95% CI, 1.003, 1.164; p = 0.042), especially the DWMHs in frontal (OR = 1.263; 95% CI, 1.060, 1.505 p = 0.009), and PVHs in frontal caps (OR = 2.699; 95% CI, 1.337, 5.450; p = 0.006) were associated with FOG. Age, hypertension, and serum alkaline phosphatase (ALP) are positively correlated with scores of DWMHs in frontal and PVHs in frontal caps.

Conclusion

These results indicate that WMHs distribution areas especially in the frontal of DWMHs and PVHs play a role in PD patients with FOG.

Association of cholesterol level with dopamine loss and motor deficits in Parkinson disease: A cross-sectional study

BACKGROUND AND PURPOSE

Cholesterol is vital in neuronal function; however, the influence of cholesterol levels on parkinsonism is unclear. This study investigated the relationship between baseline total cholesterol (TC) levels, dopamine loss, and motor symptoms in drug-naïve Parkinson disease (PD).

METHODS

This cross-sectional study enrolled 447 drug-naïve patients with PD who underwent dopamine transporter (DAT) imaging. Multivariate linear regression was used to investigate the effect of cholesterol levels on Unified Parkinson's Disease Rating Scale Part III (UPDRS-III) total score and each subscore after adjusting for the covariates. An interaction analysis was performed to examine the interaction between TC levels and statin use on the UPDRS-III scores.

RESULTS

No significant correlation was found between TC levels and DAT availability after adjusting for potential confounders. Multivariate linear regression showed that TC levels were significantly and negatively associated with the UPDRS-III total score (β = -0.116, p = 0.013) and bradykinesia subscore (β = -0.145, p = 0.011). Dichotomized analysis according to TC levels showed that TC levels were significantly associated with UPDRS-III total score, and rigidity, bradykinesia, and axial subscores only in the low TC group. There was an interaction effect between TC levels and statin use for the axial subscores (β = -0.523, p = 0.025). Subgroup analysis showed that TC levels were significantly and negatively associated with the axial subscore in statin users; however, no association was found in statin nonusers.

CONCLUSIONS

This study suggests that TC levels affect parkinsonian motor symptoms, especially in subjects with low cholesterol status, whereas the severity of axial motor symptoms is negatively associated with TC levels only in statin users.

White matter hyperintensity presence, quantity, and location exhibits no association with motor and non-motor manifestations of PD

INTRODUCTION

Nonspecific areas of brain white matter hyperintensity (WMH) are commonly found in the elderly. Some studies have shown that the presence, quantity, and location of WMHs may be associated with the development of cognitive and motor decline in patients with Parkinson's disease (PD), but the results remain controversial. This study aimed to evaluate the relationship of WMH to motor and non-motor symptoms, including dysautonomia and rapid eye movement sleep behavior disorder (RBD), in patients with PD.

METHODS

Brain magnetic resonance images were acquired from 120 patients diagnosed with PD and analyzed for WMH classification and quantification. Motor symptoms were quantified using sub-scores of the Movement Disorder Society-Unified Parkinson Disease Rating Scale (MDS-UPDRS)-III. Dysautonomia was evaluated by autonomic reactivity tests, and polysomnography was used for the diagnosis of RBD.

RESULTS

Age, total value of the MDS-UPDRS-III tremor sub-score, and the presence of dysautonomia were found to be linearly positively associated. Specifically, the duration of PD was positively associated with rigidity, bradykinesia, axial symptoms, prevalence of dysautonomia, and RBD sub-scores. However, in the multivariate analysis adjusted for variables of interest, no statistical significance was found for any of the models.

CONCLUSION

The presence, quantity, and location of WMH were not associated with the analyzed motor and non-motor manifestations of PD.

Patterns of striatal dopamine depletion and motor deficits in de novo Parkinson's disease

The background of this study is to investigate whether striatal dopamine depletion patterns (selective involvement in the sensorimotor striatum or asymmetry) are associated with motor deficits in Parkinson's disease (PD). We enrolled 404 drug-naïve patients with early stage PD who underwent dopamine transporter (DAT) imaging. After quantifying DAT availability in each striatal sub-region, principal component (PC) analysis was conducted to yield PCs representing the spatial patterns of striatal dopamine depletion. Subsequently, multivariate linear regression analysis was conducted to investigate the relationship between striatal dopamine depletion patterns and motor deficits assessed using the Unified PD Rating Scale Part III (UPDRS-III). Mediation analyses were used to evaluate whether dopamine deficiency in the posterior putamen mediated the association between striatal dopamine depletion patterns and parkinsonian motor deficits. Three PCs indicated patterns of striatal dopamine depletion: PC1 (overall striatal dopamine deficiency), PC2 (selective dopamine loss in the sensorimotor striatum), and PC3 (symmetric dopamine loss in the striatum). Multivariate linear regression analysis revealed that PC1 (β = - 1.605, p < 0.001) and PC2 (β = 3.201, p < 0.001) were associated with motor deficits (i.e., higher UPDRS-III scores in subjects with severe dopamine depletion throughout the whole striatum or more selective dopamine loss in the sensorimotor striatum), whereas PC3 was not (β = - 0.016, p = 0.992). Mediation analyses demonstrated that the effects of PC1 and PC2 on UPDRS-III scores were indirectly mediated by DAT availability in the posterior putamen, with a non-significant direct effect. Dopamine deficiency in the posterior putamen was most relevant to the severity of motor deficits in patients with PD, while the spatial patterns of striatal dopamine depletion were not a key determinant.

Local striatal volume and motor reserve in drug-naïve Parkinson's disease

Motor reserve (MR) may explain why individuals with similar pathological changes show marked differences in motor deficits in Parkinson's disease (PD). In this study, we investigated whether estimated individual MR was linked to local striatal volume (LSV) in PD. We analyzed data obtained from 333 patients with drug naïve PD who underwent dopamine transporter scans and high-resolution 3-tesla T1-weighted structural magnetic resonance images. Using a residual model, we estimated individual MRs on the basis of initial UPDRS-III score and striatal dopamine depletion. We performed a correlation analysis between MR estimates and LSV. Furthermore, we assessed the effect of LSV, which is correlated with MR estimates, on the longitudinal increase in the levodopa-equivalent dose (LED) during the 4-year follow-up period using a linear mixed model. After controlling for intracranial volume, there was a significant positive correlation between LSV and MR estimates in the bilateral caudate, anterior putamen, and ventro-posterior putamen. The linear mixed model showed that the large local volume of anterior and ventro-posterior putamen was associated with the low requirement of LED initially and accelerated LED increment thereafter. The present study demonstrated that LSV is crucial to MR in early-stage PD, suggesting LSV as a neural correlate of MR in PD.

Association between white matter lesions and Parkinson's disease: an impact on Postural/Gait difficulty phenotype and cognitive performance

BACKGROUND

White matter hyperintensities (WMHs) may be observed on Magnetic Resonance Imaging (MRI) in patients with Parkinson disease with or without vascular risk factors. Whether WMHs may influence motor and non-motor aspects of Parkinson disease is a subject of debate. The aim of this study is to evaluate the impact of WMH severity on various aspects of Parkinson disease in combination to the estimation of the impact of cerebrovascular risk factors.

MATERIALS AND METHODS

We included a cohort of patients with Parkinson's disease who underwent MRI examination. The Fazekas visual rating scale was used to assess the severity and location of WMHs, and patient clinical characteristics were correlated with MRI data.

RESULTS

All vascular risk factors were associated with higher Fazekas score in both periventricular and deep white matter. Periventricular white matter hyperintensities (PWMHs) and deep white matter hyperintensities (DWMHs) were associated with lower scores in the ACE-R cognitive assessment scale (p < 0.001). Furthermore, PWMHs and DWMHs severity was associated with higher UPDRS motor score (p < 0.001), while the Postural Instability Gait Difficulty (PIGD) phenotype was correlated with higher burden of WMHs.

CONCLUSIONS

Comorbid WMHs may contribute to multi-dimension dysfunction in patients with Parkinson disease and consequently the management of vascular risk factors may be crucial to maintain motor and non-motor functions in PD.

Low skull bone density is associated with poor motor prognosis in women with Parkinson’s disease

Parkinson’s disease (PD) and osteoporosis are degenerative diseases that have shared pathomechanisms. To investigate the associations of skull bone density with nigrostriatal dopaminergic degeneration and longitudinal motor prognosis in female patients with PD. We analyzed the data of 260 drug-naïve female PD patients aged ≥50 years old who were followed-up for ≥3 years after their first visit to the clinic with baseline dopamine transporter (DAT) imaging. We measured skull bone density as a surrogate marker for systemic bone loss by calculating the Hounsfield unit (HU) in computed tomography scans. A Cox proportional hazard model was built to compare the rates of levodopa-induced dyskinesia (LID) or wearing-off according to skull HU. Longitudinal changes in levodopa-equivalent dose (LED) during a 3-year follow-up were assessed using a linear mixed model. A lower skull HU was associated with lower baseline DAT availability in striatal subregions; however, this relationship was not significant after adjusting for age, disease duration, body mass index, and white matter hyperintensities. After adjusting for confounding factors, a lower skull HU was significantly associated with an increased risk of LID development (hazard ratio = 1.660 per 1 standard deviation decrease, p = 0.007) and wearing-off (hazard ratio = 1.613, p = 0.016) in younger (&lt;67 years) but not in older patients. Furthermore, a lower skull HU was associated with a steeper increase in LED during follow-up in younger patients only (β = –21.99, p &lt; 0.001). This study suggests that baseline skull bone density would be closely linked to motor prognosis in drug naïve women with PD.

Technology-based therapy-response evaluation of axial motor symptoms under daily drug regimen of patients with Parkinson’s disease

Background

Axial disturbances are the most disabling symptoms of Parkinson’s disease (PD). Kinect-based objective measures could extract motion characteristics with high reliability and validity.

Purpose

The present research aimed to quantify the therapy–response of axial motor symptoms to daily medication regimen and to explore the correlates of the improvement rate (IR) of axial motor symptoms based on a Kinect camera.

Materials and methods

We enrolled 44 patients with PD and 21 healthy controls. All 65 participants performed the Movement Disorder Society-Sponsored Revision of the Unified Parkinson’s Disease Rating Scale part III and the Kinect-based kinematic evaluation to assess arising from a chair, gait, posture, and postural stability before and after medication. Spearman’s correlation analysis and multiple linear regression model were performed to explore the relationships between motor feature IR and clinical data.

Results

All the features arising from a chair (P = 0.001), stride length (P = 0.001), velocity (P < 0.001), the height of foot lift (P < 0.001), and turning time (P = 0.001) improved significantly after a daily drug regimen in patients with PD. In addition, the anterior trunk flexion (lumbar level) exhibited significant improvement (P = 0.004). The IR of the axial motor symptoms score was significantly correlated with the IRs of kinematic features for gait velocity, stride length, foot lift height, and sitting speed (r_s = 0.345, P = 0.022; r_s = 0.382, P = 0.010; r_s = 0.314, P = 0.038; r_s = 0.518, P < 0.001, respectively). A multivariable regression analysis showed that the improvement in axial motor symptoms was associated with the IR of gait velocity only (β = 0.593, 95% CI = 0.023–1.164, P = 0.042).

Conclusion

Axial symptoms were not completely drug-resistant, and some kinematic features can be improved after the daily medication regimen of patients with PD.

Associations between white matter hyperintensities, striatal dopamine loss, and cognition in drug-naïve Parkinson's disease

INTRODUCTION

This study investigated the relationship between white matter hyperintensities (WMHs), nigrostriatal dopamine deficits, and cognitive decline in patients with drug-naïve early-stage Parkinson's disease (PD).

METHOD

This cross-sectional study enrolled 309 non-demented patients with de novo PD who underwent [¹⁸F] N-(3-fluoropropyl)-2β-carbonethoxy-3β-(4-iodophenyl) nortropane positron emission tomography, brain magnetic resonance imaging, and a detailed neuropsychological test at baseline. We quantified dopamine transporter (DAT) availability in each striatal sub-region and applied the Scheltens scale to assess the severity of periventricular and deep WMHs. The relationships between WMHs, DAT availability, and cognition in PD were assessed using multivariate linear regression and mediation analyses while adjusting for age at parkinsonian symptom onset, sex, disease duration, and vascular risk factors.

RESULTS

The severities of periventricular and frontal WMHs were associated with striatal DAT availability. Periventricular WMHs affected the level of cognitive performance in all cognitive domains, while frontal WMHs affected the attention/working memory and frontal/executive function domains. The effects of WMHs on attention/working memory and frontal/executive dysfunction were mostly direct with minimal mediating effects through striatal DAT availability. Meanwhile, striatal DAT availability fully mediated the association between WMHs and cognitive impairment in the visuospatial and memory function domains.

CONCLUSION

This study demonstrated the different effects of WMHs on cognitive impairment depending on the cognitive domains in PD. These findings suggest a close link between comorbid WMHs, striatal dopamine depletion, and cognition in patients with PD.

Neurotoxicity induced by toluene: In silico and in vivo evidences of mitochondrial dysfunction and dopaminergic neurodegeneration

Toluene is an air pollutant widely used as an organic solvent in industrial production and emitted by fossil fuel combustion, in addition to being used as a drug of abuse. Its toxic effects in the central nervous system have not been well established, and how and which neurons are affected remains unknown. Hence, this study aimed to fill this gap by investigating three central questions: 1) How does toluene induce neurotoxicity? 2) Which neurons are affected? And 3) What are the long-term effects induced by airborne exposure to toluene? To this end, a Caenorhabditis elegans model was employed, in which worms at the fourth larval stage were exposed to toluene in the air for 24 h in a vapor chamber to simulate four exposure scenarios. After the concentration-response curve analysis, we chose scenarios 3 (E3: 792 ppm) and 4 (E4: 1094 ppm) for the following experiments. The assays were performed 1, 48, or 96 h after removal from the exposure environments, and an irreversible reduction in neuron fluorescence and morphologic alterations were observed in different neurons of exposed worms, particularly in the dopaminergic neurons. Moreover, a significant impairment in a dopaminergic-dependent behavior was also associated with negative effects in healthspan endpoints, and we also noted that mitochondria may be involved in toluene-induced neurotoxicity since lower adenosine 5'-triphosphate (ATP) levels and mitochondrial viability were observed. In addition, a reduction of electron transport chain activity was evidenced using ex vivo protocols, which were reinforced by in silico and in vitro analysis, demonstrating toluene action in the mitochondrial complexes. Based on these findings model, it is plausible that toluene neurotoxicity can be initiated by complex I inhibition, triggering a mitochondrial dysfunction that may lead to irreversible dopaminergic neuronal death, thus impairing neurobehavioral signaling.

Premorbid Educational Attainment and Long-Term Motor Prognosis in Parkinson's Disease

BACKGROUND

Premorbid educational attainment is a well-known proxy of reserve, not only with regard to cognition, but also to motor symptoms.

OBJECTIVE

In the present study, we investigated the relationship between educational attainment and long-term motor prognosis in patients with Parkinson's disease (PD).

METHODS

We analyzed 466 patients with de novo PD without dementia who underwent dopamine transporter (DAT) scans and were followed up more than 2 years. Patients were divided into three groups: low education (years-of-education ≤6, n = 125), intermediate education (6 <years-of-education < 12, n = 108), and high education (years-of-education ≥12, n = 233). The effects of educational attainment on the development of levodopa-induced dyskinesia (LID), wearing-off, and freezing-of-gait, and longitudinal increase in levodopa-equivalent doses (LEDs) were assessed.

RESULTS

Multiple regression analysis showed that higher education was associated with milder parkinsonian symptoms after adjusting for DAT availability in the posterior putamen. Survival analysis showed that the rate of LID was significantly lower in the high education group than in the low education group (HR = 0.565, p = 0.010). A linear mixed model showed that the high education group had lower LED than the low education group until a period of 30 months; however, this difference in LED was not observed thereafter.

CONCLUSION

The present study demonstrated that premorbid educational attainment has protective effects on the development of LID in patients with PD and has sparing effects on LED during the early treatment period. These results suggest that high educational attainment has a beneficial effect on motor outcomes in patients with PD.

Total Cerebral Small Vessel Score Association With Hoehn and Yahr Stage in Parkinson's Disease

Background: This study aimed to evaluate the total cerebral small vessel disease (CSVD) score in patients with Parkinson’s disease (PD) at different stages and related factors.

Methods: A 100 and seven patients with idiopathic PD and 62 normal controls (NCs) who underwent brain magnetic resonance imaging (MRI) were enrolled. PD patients were divided into two groups: early PD [(Hoehn and Yahr (H&Y) 1–1.5, n = 36)] and advanced PD (H&Y 2–4, n = 71) groups. We calculated the total CSVD score for each participant based on lacunes, high-grade white matter hyperintensities (WMH), enlarged perivascular spaces (EPVS), and cerebral microbleeds (CMBs). Differences in total CSVD score between the PD and NCs and between the two subgroups were compared. In addition, a multivariate logistic regression analysis was conducted to investigate the association between CSVD markers and clinical variables in PD.

Results: Lacunes were found in 9.3% of patients with PD, periventricular WMH (PVWMH) in 89.7%, deep WMH (DWMH) in 81.3%, EPVS in 85%, and CMBs in 2.8%. Compared with NCs, patients with PD showed higher PVWMH and DWMH scores. Advanced PD patients exhibited greater PVWMH (P = 0.041), DWMH (P = 0.046), and total CSVD score (P = 0.044) than the early PD group. After adjusting for multiple variables, higher H&Y stage was independently correlated with increased total CSVD score (OR = 2.667, 95% CI 1.154–2.266) and PVWMH score (OR = 2.237, 95% CI 1.084–1.696).

Conclusions: CSVD may play a critical role in patients with PD. The total CSVD score is a potential neuroimaging marker for monitoring the progression of PD.