Brain Connectivity Networks Constructed Using MRI for Predicting Patterns of Atrophy Progression in Parkinson Disease.

Background Whether connectome mapping of structural and functional connectivity across the brain could be used to predict patterns of atrophy progression in patients with mild Parkinson disease (PD) has not been well studied. Purpose To assess the structural and functional connectivity of brain regions in healthy controls and its relationship with the spread of gray matter (GM) atrophy in patients with mild PD. Materials and Methods This prospective study included participants with mild PD and controls recruited from a single center between January 2012 and December 2023. Participants with PD underwent three-dimensional T1-weighted brain MRI, and the extent of regional GM atrophy was determined at baseline and every year for 3 years. The structural and functional brain connectome was constructed using diffusion tensor imaging and resting-state functional MRI in healthy controls. Disease exposure (DE) indexes-indexes of the pathology of each brain region-were defined as a function of the structural or functional connectivity of all the connected regions in the healthy connectome and the severity of atrophy of the connected regions in participants with PD. Partial correlations were tested between structural and functional DE indexes of each GM region at 1- or 2-year follow-up and atrophy progression at 2- or 3-year follow-up. Prediction models of atrophy at 2- or 3-year follow-up were constructed using exhaustive feature selection. Results A total of 86 participants with mild PD (mean age at MRI, 60 years ± 8 [SD]; 48 male) and 60 healthy controls (mean age at MRI, 62 years ± 9; 31 female) were included. DE indexes at 1 and 2 years were correlated with atrophy at 2 and 3 years (r range, 0.22-0.33; P value range, .002-.04). Models including DE indexes predicted GM atrophy accumulation over 3 years in the right caudate nucleus and some frontal, parietal, and temporal brain regions (R2 range, 0.40-0.61; all P < .001). Conclusion The structural and functional organization of the brain connectome plays a role in atrophy progression in the early stages of PD. © RSNA, 2024 Supplemental material is available for this article. See also the editorial by Yamada in this issue.

Frequency of C9orf72, GRN, and MAPT pathogenic variants in patients recruited at the Belgrade Memory Center.

Most of the heritability in frontotemporal dementia (FTD) is accounted for by autosomal dominant hexanucleotide expansion in the chromosome 9 open reading frame 72 (C9orf72), pathogenic/likely pathogenic variants in progranulin (GRN), and microtubule-associated protein tau (MAPT) genes. Until now, there has been no systematic analysis of these genes in the Serbian population. Herein, we assessed the frequency of the C9orf72 expansion, pathogenic/likely pathogenic variants in GRN and MAPT in a well-characterized group of 472 subjects (FTD, Alzheimer's disease - AD, mild cognitive impairment - MCI, and unspecified dementia - UnD), recruited in the Memory Center, Neurology Clinic, University Clinical Center of Serbia. The C9orf72 repeat expansion was detected in 6.98% of FTD cases (13.46% familial; 2.6% sporadic). In the UnD subgroup, C9orf72 repeat expansions were detected in 4.08% (8% familial) individuals. Pathogenic variants in the GRN were found in 2.85% of familial FTD cases. Interestingly, no MAPT pathogenic/likely pathogenic variants were detected, suggesting possible geographical specificity. Our findings highlight the importance of wider implementation of genetic testing in neurological and psychiatric practice managing patients with cognitive-behavioral and motor symptoms.

Altered Functional Connectivity of the Subthalamic Nucleus in Parkinson's Disease: Focus on Candidates for Deep Brain Stimulation.

BACKGROUND: The hypothesis that the effectiveness of deep brain stimulation (DBS) in Parkinson's disease (PD) would be related to connectivity dysfunctions between the site of stimulation and other brain regions is growing. OBJECTIVE: To investigate how the subthalamic nucleus (STN), the most frequently used DBS target for PD, is functionally linked to other brain regions in PD patients according to DBS eligibility. METHODS: Clinical data and resting-state functional MRI were acquired from 60 PD patients and 60 age- and sex-matched healthy subjects within an ongoing longitudinal project. PD patients were divided into 19 patients eligible for DBS and 41 non-candidates. Bilateral STN were selected as regions of interest and a seed-based functional MRI connectivity analysis was performed. RESULTS: A decreased functional connectivity between STN and sensorimotor cortex in both PD patient groups compared to controls was found. Whereas an increased functional connectivity between STN and thalamus was found in PD patient groups relative to controls. Candidates for DBS showed a decreased functional connectivity between bilateral STN and bilateral sensorimotor areas relative to non-candidates. In patients eligible for DBS, a weaker STN functional connectivity with left supramarginal and angular gyri was related with a more severe rigidity and bradykinesia whereas a higher connectivity between STN and cerebellum/pons was related to poorer tremor score. CONCLUSION: Our results suggest that functional connectivity of STN varies among PD patients eligible or not for DBS. Future studies would confirm whether DBS modulates and restores functional connectivity between STN and sensorimotor areas in treated patients.

MRI biomarkers of freezing of gait development in Parkinson's disease.

This study investigated longitudinal clinical, structural and functional brain alterations in Parkinson's disease patients with freezing of gait (PD-FoG) and in those developing (PD-FoG-converters) and not developing FoG (PD-non-converters) over two years. Moreover, this study explored if any clinical and/or MRI metric predicts FoG development. Thirty PD-FoG, 11 PD-FoG-converters and 11 PD-non-converters were followed for two years. Thirty healthy controls were included at baseline. Participants underwent clinical and MRI visits. Cortical thickness, basal ganglia volumes and functional network graph metrics were evaluated at baseline and over time. In PD groups, correlations between baseline MRI and clinical worsening were tested. A ROC curve analysis investigated if baseline clinical and MRI measures, selected using a stepwise model procedure, could differentiate PD-FoG-converters from PD-non-converters. At baseline, PD-FoG patients had widespread cortical/subcortical atrophy, while PD-FoG-converters and non-converters showed atrophy in sensorimotor areas and basal ganglia relative to controls. Over time, PD-non-converters accumulated cortical thinning of left temporal pole and pallidum without significant clinical changes. PD-FoG-converters showed worsening of disease severity, executive functions, and mood together with an accumulation of occipital atrophy, similarly to PD-FoG. At baseline, PD-FoG-converters relative to controls and PD-FoG showed higher global and parietal clustering coefficient and global local efficiency. Over time, PD-FoG-converters showed reduced parietal clustering coefficient and sensorimotor local efficiency, PD-non-converters showed increased sensorimotor path length, while PD-FoG patients showed stable graph metrics. Stepwise prediction model including dyskinesia, postural instability and gait disorders scores and parietal clustering coefficient was the best predictor of FoG conversion. Combining clinical and MRI data, ROC curves provided the highest classification power to predict the conversion (AUC = 0.95, 95%CI: 0.86-1). Structural MRI is a useful tool to monitor PD progression, while functional MRI together with clinical features may be helpful to identify FoG conversion early.

Cerebro-cerebellar motor networks in clinical subtypes of Parkinson's disease.

Parkinson's disease (PD) patients can be classified in tremor-dominant (TD) and postural-instability-and-gait-disorder (PIGD) motor subtypes. PIGD represents a more aggressive form of the disease that TD patients have a potentiality of converting into. This study investigated functional alterations within the cerebro-cerebellar system in PD-TD and PD-PIGD patients using stepwise functional connectivity (SFC) analysis and identified neuroimaging features that predict TD to PIGD conversion. Thirty-two PD-TD, 26 PD-PIGD patients and 60 healthy controls performed clinical/cognitive evaluations and resting-state functional MRI (fMRI). Four-year clinical follow-up data were available for 28 PD-TD patients, who were classified in 10 converters (cTD-PD) and 18 non-converters (ncTD-PD) to PIGD. The cerebellar seed-region was identified using a fMRI motor task. SFC analysis, characterizing regions that connect brain areas to the cerebellar seed at different levels of link-step distances, evaluated similar and divergent alterations in PD-TD and PD-PIGD. The discriminatory power of clinical data and/or SFC in distinguishing cPD-TD from ncPD-TD patients was assessed using ROC curve analysis. Compared to PD-TD, PD-PIGD patients showed decreased SFC in temporal lobe and occipital lobes and increased SFC in cerebellar cortex and ponto-medullary junction. Considering the subtype-conversion analysis, cPD-TD patients were characterized by increased SFC in temporal and occipital lobes and in cerebellum and ponto-medullary junction relative to ncPD-TD group. Combining clinical and SFC data, ROC curves provided the highest classification power to identify conversion to PIGD. These findings provide novel insights into the pathophysiology underlying different PD motor phenotypes and a potential tool for early characterization of PD-TD patients at risk of conversion to PIGD.

Functional connectivity in Parkinson's disease candidates for deep brain stimulation.

This study aimed to identify functional neuroimaging patterns anticipating the clinical indication for deep brain stimulation (DBS) in patients with Parkinson's disease (PD). A cohort of prospectively recruited patients with PD underwent neurological evaluations and resting-state functional MRI (RS-fMRI) at baseline and annually for 4 years. Patients were divided into two groups: 19 patients eligible for DBS over the follow-up and 41 patients who did not meet the criteria to undergo DBS. Patients selected as candidates for DBS did not undergo surgery at this stage. Sixty age- and sex-matched healthy controls performed baseline evaluations. Graph analysis and connectomics assessed global and local topological network properties and regional functional connectivity at baseline and at each time point. At baseline, network analysis showed a higher mean nodal strength, local efficiency, and clustering coefficient of the occipital areas in candidates for DBS over time relative to controls and patients not eligible for DBS. The occipital hyperconnectivity pattern was confirmed by regional analysis. At baseline, a decreased functional connectivity between basal ganglia and sensorimotor/frontal networks was found in candidates for DBS compared to patients not eligible for surgery. In the longitudinal analysis, patient candidate for DBS showed a progressively decreased topological brain organization and functional connectivity, mainly in the posterior brain networks, and a progressively increased connectivity of basal ganglia network compared to non-candidates for DBS. RS-fMRI may support the clinical indication to DBS and could be useful in predicting which patients would be eligible for DBS in the earlier stages of PD.

Neurogenetic traits outline vulnerability to cortical disruption in Parkinson's disease.

The genetic traits that underlie vulnerability to neuronal damage across specific brain circuits in Parkinson's disease (PD) remain to be elucidated. In this study, we characterized the brain topological intersection between propagating connectivity networks in controls and PD participants and gene expression patterns across the human cortex - such as the SNCA gene. We observed that brain connectivity originated from PD-related pathology epicenters in the brainstem recapitulated the anatomical distribution of alpha-synuclein histopathology in postmortem data. We also discovered that the gene set most related to cortical propagation patterns of PD-related pathology was primarily involved in microtubule cellular components. Thus, this study sheds light on new avenues for enhancing detection of PD neuronal vulnerability via an evaluation of in vivo connectivity trajectories across the human brain and successful integration of neuroimaging-genetic strategies.

Longitudinal clinical, cognitive, and neuroanatomical changes over 5 years in GBA-positive Parkinson's disease patients.

OBJECTIVE: To study the longitudinal disease course of Parkinson's disease (PD) patients with glucocerebrosidase (GBA) mutation (GBA-positive) compared to PD non-carriers (GBA-negative) along a 5-year follow-up, evaluating changes in clinical and cognitive outcomes, cortical thickness, and gray-matter (GM) volumes. METHODS: Ten GBA-positive and 20 GBA-negative PD patients underwent clinical, neuropsychological, and MRI assessments (cortical thickness and subcortical, hippocampal, and amygdala volumes) at study entry and once a year for 5 years. At baseline and at the last visit, each group of patients was compared with 22 age-matched healthy controls. Clinical, cognitive, and MRI features were compared between groups at baseline and over time. RESULTS: At baseline, GBA-positive and GBA-negative PD patients had similar clinical and cognitive profiles. Compared to GBA-negative and controls, GBA-positive patients showed cortical thinning of left temporal, parietal, and occipital gyri. Over time, compared to GBA-negative, GBA-positive PD patients progressed significantly in motor and cognitive symptoms, and showed a greater pattern of cortical thinning of posterior regions, and frontal and orbito-frontal cortices. After 5 years, compared to controls, GBA-negative PD patients showed a pattern of cortical thinning similar to that showed by GBA-positive cases at baseline. The two groups of patients showed similar patterns of subcortical, hippocampal, and amygdala volume loss over time. CONCLUSIONS: Compared to GBA-negative PD, GBA-positive patients experienced a more rapid motor and cognitive decline together with a greater, earlier and faster cortical thinning. Cortical thickness measures may be a useful tool for monitoring and predicting PD progression in accordance with the genetic background.

Longitudinal White Matter Damage Evolution in Parkinson's Disease.

BACKGROUND: White matter hyperintensities (WMHs) have a role in cognitive impairment in normal brain aging, while the effect on Parkinson's disease (PD) progression is still controversial. OBJECTIVE: To investigate the longitudinal evolution of micro- and macrostructural damage of cerebral white matter (WM) and its relationship with the clinical picture in PD. METHODS: A total of 154 PD patients underwent clinical, cognitive, and magnetic resonance imaging (MRI) assessment once a year for up to 4 years. Sixty healthy controls underwent the same protocol at baseline. WMHs were identified and total WMH volume was measured. WMHs were also used as exclusion masks to define normal-appearing white matter (NAWM). Using tract-based spatial statistics, diffusion tensor (DT) MRI metrics of whole-brain WM and NAWM were obtained. Linear mixed-effects models defined the longitudinal evolution and association between variables. WM alterations were tested as risk factors of disease progression using linear regression and Cox proportional hazards models. RESULTS: At baseline, PD patients showed alterations of all DT MRI measures compared to controls. Longitudinally, DT MRI measures did not vary significantly and no association with clinical variables was found. WMH volume changed over time and was associated with impairment in global cognition, executive functions, and language. Baseline WMH volume was a moderate risk factor for progression to mild cognitive impairment. CONCLUSIONS: Our study suggests an association between WMHs and cognitive deterioration in PD, whereas WM microstructural damage is a negligible contributor to clinical deterioration. WMHs assessed by MRI can provide an important tool for monitoring the development of cognitive impairment in PD patients. © 2021 International Parkinson and Movement Disorder Society.

Longitudinal brain connectivity changes and clinical evolution in Parkinson's disease.

Longitudinal connectivity studies might guide our understanding of the underlying neurodegenerative processes. We report the results of a longitudinal study in patients at different stages of Parkinson's disease (PD), who performed motor and non-motor evaluations and serial resting state (RS) functional MRI (fMRI). Cluster analysis was applied to demographic and clinical data of 146 PD patients to define disease subtypes. Brain network functional alterations were assessed at baseline in PD relative to 60 healthy controls and every year for a maximum of 4 years in PD groups. Progression of brain network changes were compared between patient clusters using RS fMRI. The contribution of network changes in predicting clinical deterioration was explored. Two main PD clusters were identified: mild PD (86 patients) and moderate-to-severe PD (60 patients), with the latter group being older and having earlier onset, longer PD duration, more severe motor, non-motor and cognitive deficits. Within the mild patient cluster, two clinical subtypes were further identified: mild motor-predominant (43) and mild-diffuse (43), with the latter being older and having more frequent non-motor symptoms. Longitudinal functional connectivity changes vary across patients in different disease stages with the coexistence of hypo- and hyper-connectivity in all subtypes. RS fMRI changes were associated with motor, cognitive and non-motor evolution in PD patients. Baseline RS fMRI presaged clinical and cognitive evolution. Our network perspective was able to define trajectories of functional architecture changes according to PD stages and prognosis. RS fMRI may be an early biomarker of PD motor and non-motor progression.

Tracking Cortical Changes Throughout Cognitive Decline in Parkinson's Disease.

BACKGROUND: The objectives of this study were to investigate progressive cortical thinning and volume loss in Parkinson's disease (PD) patients with different longitudinal patterns of cognitive decline: with stable normal cognition, with stable mild cognitive impairment, with conversion to mild cognitive impairment, and with conversion to dementia. METHODS: We recruited 112 patients (37 Parkinson's disease with stable normal cognition, 20 Parkinson's disease with stable mild cognitive impairment, 36 Parkinson's disease with conversion to mild cognitive impairment, 19 Parkinson's disease with conversion to dementia) and 38 healthy controls. All patients underwent at least 2 visits within 4 years including clinical/cognitive assessments and structural MRI (total visits, 393). Baseline cortical thickness and gray matter volumetry were compared between groups. In PD, gray matter changes over time were investigated and compared between groups. RESULTS: At baseline, compared with Parkinson's disease with stable normal cognition cases, Parkinson's disease with conversion to mild cognitive impairment patients showed cortical atrophy of the parietal and occipital lobes, similar to Parkinson's disease with stable mild cognitive impairment and Parkinson's disease with conversion to dementia patients. The latter groups (ie, patients with cognitive impairment from the study entry) showed additional involvement of the frontotemporal cortices. No baseline volumetric differences among groups were detected. The longitudinal analysis (group-by-time interaction) showed that, versus the other patient groups, Parkinson's disease with stable mild cognitive impairment and Parkinson's disease with conversion to dementia cases accumulated the least cortical damage, with Parkinson's disease with conversion to dementia showing unique progression of right thalamic and hippocampal volume loss; Parkinson's disease with conversion to mild cognitive impairment patients showing specific cortical thinning accumulation in the medial and superior frontal gyri, inferior temporal, precuneus, posterior cingulum, and supramarginal gyri bilaterally; and Parkinson's disease with stable normal cognition patients showing cortical thinning progression, mainly in the occipital and parietal regions bilaterally. CONCLUSIONS: Cortical thinning progression is more prominent in the initial stages of PD cognitive decline. The involvement of frontotemporoparietal regions, the hippocampus, and the thalamus is associated with conversion to a more severe stage of cognitive impairment. In PD, gray matter alterations of critical brain regions may be an MRI signature for the identification of patients at risk of developing dementia. © 2020 International Parkinson and Movement Disorder Society.

Progressive brain atrophy and clinical evolution in Parkinson's disease.

Clinical manifestations and evolution are very heterogeneous among individuals with Parkinson's disease (PD). The aims of this study were to investigate the pattern of progressive brain atrophy in PD according to disease stage and to elucidate to what extent cortical thinning and subcortical atrophy are related to clinical motor and non-motor evolution. 154 patients at different PD stages were assessed over time using motor, non-motor and structural MRI evaluations for a maximum of 4 years. Cluster analysis defined clinical subtypes. Cortical thinning and subcortical atrophy were assessed at baseline in patients relative to 60 healthy controls. Longitudinal trends of brain atrophy progression were compared between PD clusters. The contribution of brain atrophy in predicting motor, non-motor, cognitive and mood deterioration was explored. Two main PD clusters were defined: mild (N = 87) and moderate-to-severe (N = 67). Two mild subtypes were further identified: mild motor-predominant (N = 43) and mild-diffuse (N = 44), with the latter group being older and having more severe non-motor and cognitive symptoms. The initial pattern of brain atrophy was more severe in patients with moderate-to-severe PD. Over time, mild-diffuse PD patients had the greatest brain atrophy accumulation in the cortex and the left hippocampus, while less distributed atrophy progression was observed in moderate-to-severe and mild motor-predominant patients. Baseline and 1-year cortical thinning was associated with long-term progression of motor, cognitive, non-motor and mood symptoms. Cortical and subcortical atrophy is accelerated early after the onset of PD and becomes prominent in later stages of disease according to the development of cognitive, non-motor and mood dysfunctions. Structural MRI may be useful for monitoring and predicting disease progression in PD.

Dynamics of impulsive-compulsive behaviors in early Parkinson's disease: a prospective study.

INTRODUCTION: Impulsive compulsive behaviors (ICBs) in Parkinson's disease (PD) are debilitating disorders of repetitive, excessive, and compulsive nature affecting up to one third of PD patients. Objectives are to address clinical, psychiatric, and cognitive characteristics of ICBs and to define risk factors in PD patients in the initial motor stage, followed up for 5 years. METHODS: We analyzed 106 consecutive PD outpatients at Hoehn and Yahr disease stage 1 and 125 healthy controls. The participants were assessed for the presence of any ICB using the current clinical criteria and underwent comprehensive clinical, psychiatric, and neuropsychological evaluations. The patients completed the same protocol at Years 1, 2, 3, and 5. RESULTS: ICBs were present in 21 (19.8%) PD patients and 13 (10.4%) healthy controls at baseline. Prevalence of ICBs increased to 29.2% at Year 5, significantly after Year 2. Multiple ICBs were present in 4,7% and 61.9% of PD-ICBs at the baseline and Year 5, respectively. ICBs resolved in 30% of cases (most often compulsive eating). Dopamine agonist treatment at the baseline carried five times higher risk of having or developing ICB(s) anytime during follow-up. We identified risk factors for compulsive eating (dopamine agonist treatment at baseline), hypersexuality (males), compulsive buying (depression and younger age), and punding (younger age and higher levodopa dose at baseline). Significant interaction of rate of motor progression and ICB diagnosis was shown. CONCLUSIONS: PD patients showed increasing frequency of most ICBs during the 5-year follow-up. Specific risk factors were identified for different types of ICBs.

Longitudinal assessment of autonomic dysfunction in early Parkinson's disease.

INTRODUCTION: Clinical correlates of autonomic nervous system (ANS) dysfunction in early Parkinson's disease (PD) have been addressed mainly in a cross-sectional way. METHODS: This is a combined cross-sectional and longitudinal prospective study of ANS dysfunction using the SCOPA-AUT in PD patients at the Hoehn and Yahr stage 1 with disease duration <2 years. PD patients (n = 107) were compared to healthy controls (HC, n = 79), and then followed-up for over 3 years. The severity of PD, depression, anxiety, apathy and cognitive impairment were evaluated using rating scales. RESULTS: At least one symptom of ANS dysfunction was present in 71% of PD patients in comparison to 30.4% of HC, and in all PD patients after three years. The overall severity of dysautonomia symptoms was mild (SCOPA-AUT mean ±â€¯SD; 4.16 ±â€¯5.0), but worsened by 23%, 86% and 0.3% during the 1st, 2nd and 3rd year respectively. Nighttime voiding (38.3%), constipation (30.8%) and straining for defecation (29%) were the most common symptoms. Prevalence and severity of urinary, gastrointestinal, and orthostatic symptoms increased, in contrast to thermoregulatory and pupillomotor symptoms. Frequency of symptoms suggestive of multi-domain ANS dysfunction rose from 49% to 79%. Psychiatric symptoms and age, but not motor impairment, were associated with dysautonomia symptoms. CONCLUSION: Symptoms of ANS dysfunction were frequent in the initial motor stage of PD and progressed, yet remaining mild, within 3 years. An independent progression of dysautonomia symptoms from motor disability and its associations with non-motor, mainly psychiatric symptoms and age support the non-motor clustering in PD.

Functional and structural brain networks in posterior cortical atrophy: A two-centre multiparametric MRI study.

This study identified structural and functional brain connectivity alterations in two independent samples of patients along the posterior cortical atrophy (PCA) disease course. Twenty-one PCA patients and 44 controls were recruited from two expert centres. Microstructural damage of white matter (WM) tracts was assessed using probabilistic tractography; resting state (RS) functional connectivity of brain networks was explored using a model free approach; grey matter (GM) atrophy was investigated using voxel-based morphometry. Compared with controls, common patterns of damage across PCA patients included: GM atrophy in the occipital-temporal-parietal regions; diffusion tensor (DT) MRI alterations of the corpus callosum and superior (SLF) and inferior longitudinal fasciculi (ILF) bilaterally; and decreased functional connectivity of the occipital gyri within the visual network and the precuneus and posterior cingulum within the default mode network (DMN). In PCA patients with longer disease duration and greater disease severity, WM damage extended to the cingulum and RS functional connectivity alterations spread within the frontal, dorsal attentive and salience networks. In PCA, reduced DMN functional connectivity was associated with SLF and ILF structural alterations. PCA patients showed distributed WM damage. Altered RS functional connectivity extends with disease worsening from occipital to temporo-parietal and frontostriatal regions, and this is likely to occur through WM connections. Future longitudinal studies are needed to establish trajectories of damage spreading in PCA and whether a combined DT MRI/RS functional MRI approach is promising in monitoring the disease progression.

Exploring the relationship between motor impairment, vascular burden and cognition in Parkinson's disease.

OBJECTIVE: To determine frequency and type of cognitive disorders in cross-sectional analysis of a Parkinson's disease (PD) cohort, and explore its relations to motor symptoms, modifiable vascular risk factors and white matter lesions (WML) volume. METHODS: In a group of 133 PD patients, mild cognitive impairment (PD-MCI) and dementia (PDD) were diagnosed according to Movement Disorders Society Task Force criteria (level 2 for PD-MCI). Detailed motor measurements were applied, including rigidity, axial, bradykinesia, tremor and postural instability gait disorders (PIGD) scores. Vascular risk was estimated by the Framingham General Cardiovascular Disease risk scoring algorithm and WML volume was measured for whole brain and frontal lobe. RESULTS: Sixty-one (46.9%) patients fulfilled criteria for PD-MCI, and 23 (17.7%) for PDD. Non-amnestic multiple domain MCI was most frequent (52% of PD-MCI patients). Motor scores were significantly higher in cognitively impaired patients, but only axial score discriminated between MCI and dementia. High vascular risk was related to impaired cognition, bradykinesia, axial, PIGD and freezing of gait (FOG) score, while whole brain WML volume was associated with PDD, FOG and attention deficits. Furthermore, high vascular risk was identified as a potential predictor of both MCI and dementia in PD. Additionally, age and bradykinesia score were independently associated with PD-MCI and age, axial score and whole brain WML volume with PDD. CONCLUSION: Cognitive disorders in PD are associated with more severe, predominantly axial motor deficits and increased, but partly modifiable vascular burden, thus opening a possibility for development of preventive strategies in PD.

White matter tract alterations in Parkinson's disease patients with punding.

OBJECTIVE: To assess brain white matter tract alterations in patients with Parkinson's disease and punding (PD-punding) compared with controls and PD cases without any impulsive-compulsive behaviour. METHODS: Forty-nine PD patients (21 PD-punding and 28 PD with no impulsive-compulsive behaviours) and 28 controls were consecutively recruited. Clinical, cognitive and psychopathological evaluations were performed. Diffusion tensor MRI metrics of the main white matter tracts were assessed using a tractography approach. RESULTS: Compared with controls, both PD groups showed white matter microstructural alterations of the left pedunculopontine tract and splenium of the corpus callosum. PD-punding patients showed a further damage to the right pedunculopontine tract and uncinate fasciculus, genu of the corpus callosum, and left parahippocampal tract relative to controls. When adjusting for depression and/or apathy severity, a greater damage of the genu of the corpus callosum and the left pedunculopontine tract was found in PD-punding compared with patients with no impulsive-compulsive behaviours. CONCLUSIONS: PD-punding is associated with a disconnection between midbrain, limbic and white matter tracts projecting to the frontal cortices. These alterations are at least partially independent of their psychopathological changes. Diffusion tensor MRI is a powerful tool for understanding the neural substrates underlying punding in PD.