Parkinson's Disease Behavior Research Articles

Uptake of alpha-synuclein preformed fibrils is suppressed by inflammation and induces an aberrant phenotype in human microglia.

Microglia are brain resident immune cells that maintain proteostasis and cellular homeostasis. Recent findings suggest that microglia dysfunction could contribute to the pathogenesis of Parkinson's disease (PD). One of the hallmarks of PD is the aggregation and accumulation of alpha-synuclein (αSyn) into Lewy bodies inside nerve cells. Microglia may worsen the neuronal microenvironment by persistent inflammation, resulting in deficient clearing of aggregated αSyn. To model microglial behavior in PD, we utilized human induced pluripotent stem cells to generate functionally active microglia. We studied the microglial uptake of alpha-synuclein preformed fibrils (PFFs) and the effect of pro-inflammatory stimulation by interferon gamma. We demonstrate that combined exposure disrupts the phagosome maturation pathway while inflammatory stimuli suppress chaperone mediated autophagy and mitochondrial function. Furthermore, inflammatory stimulation impairs PFF uptake in microglia and increases cytokine production. Moreover, excessive PFF uptake by microglia results in induction of inducible nitric oxide synthase. Taken together, we demonstrate that this model is valuable for investigating the behavior of microglia in PD and provide new insights on how human microglia process aggregated αSyn.

Interaction of motor behaviour, cortical oscillations and deep brain stimulation in Parkinson disease

Abstract Recent progress in the study of Parkinson's disease (PD) has highlighted the pivotal role of beta oscillations within the basal ganglia-thalamo-cortical network in modulating motor symptoms. Predominantly manifesting as transient bursts, these beta oscillations are central to the pathophysiology of PD motor symptoms, especially bradykinesia. Our central hypothesis is that increased bursting duration in cortex, coupled with kinematics of movement, disrupts the typical flow of neural information, leading to observable changes in motor behavior in PD. To explore this hypothesis, we employed an integrative approach, analyzing the interplay between moment-to-moment brain dynamics and movement kinematics, and the modulation of these relationships by therapeutic deep brain stimulation (DBS). Local field potentials were recorded from the hand motor (M1) and premotor cortical (PM) areas, and internal Globus Pallidus (GPi) in 26 PD patients undergoing DBS implantation surgery. Participants executed rapid alternating hand movements in 30-second blocks, both with and without therapeutic pallidal stimulation. Behaviorally, the analysis revealed bradykinesia, with hand movement cycle width increasing linearly over time during DBS-OFF blocks. Crucially, there was a moment-to-moment correlation between M1 low beta burst duration and movement cycle width, a relationship that dissipated with therapeutic DBS. Further analyses suggest that high gamma activity correlates with enhanced motor performance with DBS-ON. Regardless of the nature of coupling, DBS’s modulation of cortical bursting activity appeared to amplify the brain signals’ informational content regarding instantaneous movement changes. Our findings underscore that DBS significantly reshapes the interaction between motor behavior and neural signals in PD, not only modulating specific bands but also expanding the system's capability to process and relay information for motor control. These insights shed light on the possible network mechanisms underlying DBS therapeutic effects, suggesting a profound impact on both neural and motor domains.

Impulse control disorders related cognitive and behavioral features in Parkinson’s disease

Objectives: This study aimed to investigate cognitive and behavioral distinctions in patients with Parkinson's disease (PD) with impulse control disorders (ICDs). Patients and methods: A total of 72 patients (52 males, 20 females; mean age: 60.8±9.2 years; range, 41 to 77 years) with PD (31 with ICD features [PDwIC] and 41 without ICD [PDwoICD]) and 67 healthy controls (35 males, 32 females; mean age: 60.4±10.4 years; range, 36 to 79 years) were included in this prospective cross-sectional study between April 2018 and January 2020. All participants underwent a comprehensive neuropsychometric assessment, including a battery of cognitive and psychiatric tests. Furthermore, the Iowa Gambling Task was employed to evaluate risky decision-making capacities, and the UPPS (Urgency, Premeditation [lack of], Perseverance [lack of], Sensation Seeking) Impulsive Behavior Scale was utilized to assess impulsive personality traits. The Beck Depression Inventory (BDI) was used to assess the presence and severity of depression. Results: The PDwICD, PDwoICD, and healthy control groups showed comparable characteristics in terms of age and education level. Male sex was more prevalent in the PDwICD group than in the control group (p=0.01). The PDwICD group exhibited significantly higher MDS UPDRS I scores and total LEDD compared to the PDwoICD group (p=0.027 and p=0.003, respectively). The PDwICD group also had higher BDI scores and UPPS-Sensation Seeking subscores than the PDwoICD group (p=0.001 and p=0.044, respectively). The multivariate analyses demonstrated an independent association between higher scores of BDI and presence of ICD in PD (p=0.006). Conclusion: In conclusion, comprehensive screening for affective characteristics can help clinicians identify those at higher risk for impulsive behaviors in PD. Prospective studies are needed to better understand the factors leading to ICDs and explore the roles of personality traits, cognitive and behavioral features, and dopaminergic medications.

Beta Burst-Driven Adaptive Deep Brain Stimulation Improves Gait Impairment and Freezing of Gait in Parkinson's Disease.

Freezing of gait (FOG) is a debilitating symptom of Parkinson's disease (PD) that is often refractory to medication. Pathological prolonged beta bursts within the subthalamic nucleus (STN) are associated with both worse impairment and freezing behavior in PD, which are improved with deep brain stimulation (DBS). The goal of the current study was to investigate the feasibility, safety, and tolerability of beta burst-driven adaptive DBS (aDBS) for FOG in PD. Seven individuals with PD were implanted with the investigational Summit™ RC+S DBS system (Medtronic, PLC) with leads placed bilaterally in the STN. A PC-in-the-loop architecture was used to adjust stimulation amplitude in real-time based on the observed beta burst durations in the STN. Participants performed either a harnessed stepping-in-place task or a free walking turning and barrier course, as well as clinical motor assessments and instrumented measures of bradykinesia, OFF stimulation, on aDBS, continuous DBS (cDBS), or random intermittent DBS (iDBS). Beta burst driven aDBS was successfully implemented and deemed safe and tolerable in all seven participants. Gait metrics such as overall percent time freezing and mean peak shank angular velocity improved from OFF to aDBS and showed similar efficacy as cDBS. Similar improvements were also seen for overall clinical motor impairment, including tremor, as well as quantitative metrics of bradykinesia. Beta burst driven adaptive DBS was feasible, safe, and tolerable in individuals with PD with gait impairment and FOG.

Effects of Unilateral High Frequency Stimulation of the Subthalamic Nucleus on Risk-avoidant Behavior in a Partial 6-hydroxydopamine Model of Parkinson's Disease.

Deep brain stimulation (DBS) of the subthalamic nucleus (STN) is a well-established treatment for the motor symptoms of Parkinson's disease (PD). While PD is primarily characterized by motor symptoms such as tremor, rigidity, and bradykinesia, it also involves a range of non-motor symptoms, and anxiety is one of the most common. The relationship between PD and anxiety is complex and can be a result of both pathological neural changes and the psychological and emotional impacts of living with a chronic progressive condition. Managing anxiety in PD is critical for improving the patients' quality of life. However, patients undergoing STN DBS can occasionally experience increased anxiety. This study investigates changes in risk-avoidant behavior following STN DBS in a pre-motor animal model of PD under chronic and acute unilateral high frequency stimulation. No significant changes in risk-avoidant behaviors were observed in rats who underwent STN DBS compared with sham stimulation controls. Chronic stimulation prevented sensitization in the elevated zero maze. These results suggest that unilateral stimulation of the STN may have minimal effects on risk-avoidant behaviors in PD. However, additional research is required to fully understand the mechanisms responsible for changes in anxiety during STN DBS for PD.

Prognosis of impulse control disorders in Parkinson's disease: a prospective controlled study.

The long-term prognosis of impulsive compulsive disorders (ICD) remains poorly studied in Parkinson's disease (PD). Evaluating the natural history of ICD and its impact on PD symptoms including cognition and treatment adjustments. We assessed PD patients at baseline (BL) with (BL-ICD+) or without (BL-ICD-) ICD despite dopamine agonist (DA) exposure of > 300mg levodopa-equivalent daily dose for > 12months at baseline and after more than two years of follow-up. ICD were assessed using the Ardouin's Scale of Behaviors in PD (ASBPD), cognition using the Mattis scale, and PD symptoms using the UPDRS score. Treatment adjustments, DA withdrawal-associated symptoms, and ICDs social consequences were recorded. 149 patients were included (78 cases and 71 controls), mean duration of follow-up was 4.4 ± 1years. At baseline, psychiatric disorders were more common among BL-ICD + (42.3 vs 12.3% among BL-ICD-, p < 0.01). At follow-up, 53.8% of BL-ICD + were not ICD-free while 21.1% of BL-ICD- had developed ICD. BL-ICD + more frequently experienced akinesia (21.8 vs 8.5%, p = 0.043) and rigidity worsening (11.5 vs 1.4%, p = 0.019) following therapeutic modifications. Decision to decrease > 50% DA doses (12.8 vs 1.4%, p = 0.019) or to withdraw DA (19.2 vs 5.6%, p = 0.025) was more frequently considered among BL-ICD+ . At follow-up, the prevalence of cognitive decline was lower among BL-ICD + (19.2 vs 37.1%, p = 0.025). ICDs were associated with increased psychiatric burden at baseline and better cognitive prognosis. Most patients were still showing ICDs at the follow-up visit, suggesting ICD to be considered as a chronic, neuropsychiatric disorder.

An ensemble of ResNet model for classification of Parkinson disease

Parkinson disease (PD) is one of the neurological illnesses incurred. However, there is a no chance to recognize PD. A fine motor symptom has been identified in this study. A group of patients with PD, as well as the healthy group, is used in the research. The authors have developed a technique that can determine whether a patient has PD or not. Using deep learning methods, the same design generalizing neural networks in the brain can be solved. The categorization of patients with PD and non-PD behavior is found from the analysis of spiral and wave forms using CNN model. Various CNN models were used in the experiment by transfer learning and spiral and wave data sketches. With the help of spiral sketching, the system achieved an accuracy of 96.67% using the ResNet50 model. The main objective of this paper is to explore the application of transfer learning, which improved the performance of the model.

Using 18F-AV-133 VMAT2 PET Imaging to Monitor Progressive Nigrostriatal Degeneration in Parkinson Disease.

There are limited validated biomarkers in Parkinson disease (PD) which substantially hinders the ability to monitor disease progression and consequently measure the efficacy of disease-modifying treatments. Imaging biomarkers, such as vesicular monoamine transporter type 2 (VMAT2) PET, enable enhanced diagnostic accuracy and detect early neurodegenerative changes associated with prodromal PD. This study sought to assess whether 18F-AV-133 VMAT2 PET is sensitive enough to monitor and quantify disease progression over a 2-year window. 18F-AV-133 PET scans were performed on participants with PD and REM sleep behavior disorder (RBD) and neurologic controls (NC). All participants were scanned twice ∼26 months apart. Regional tracer retention was calculated with a primary visual cortex reference region and expressed as the standard uptake volume ratio. Regions of interest included caudate, anterior, and posterior putamen. At the time of scanning, participants underwent clinical evaluation including UPDRSMOTOR test, Sniffin' Sticks, and Hospital Anxiety and Depression Score. Over the 26-month interval, a significant decline in PET signal was observed in all 3 regions in participants with PD (N = 26) compared with NC (N = 12), consistent with a decrease in VMAT2 level and ongoing neurodegeneration. Imaging trajectory calculations suggest that the neurodegeneration in PD occurs over ∼33 years [CI: 27.2-39.5], with ∼10.5 years [CI: 9.1-11.3] of degeneration in the posterior putamen before it becomes detectable on a VMAT2 PET scan, a further ∼6.5 years [CI: 1.6-12.7] until symptom onset, and a further ∼3 years [CI: 0.3-8.7] until clinical diagnosis. Over a 2-year period, 18F-AV-133 VMAT2 PET was able to detect progression of nigrostriatal degeneration in participants with PD, and it represents a sensitive tool to identify individuals at risk of progression to PD, which are currently lacking using clinical readouts. Trajectory models propose that there is nigrostriatal degeneration occurring for 20 years before clinical diagnosis. These data demonstrate that VMAT2 PET provides a sensitive measure to monitor neurodegenerative progression of PD which has implications for PD diagnostics and subsequently clinical trial patient stratification and monitoring. This study provides Class IV evidence that VMAT2 PET can detect patients with Parkinson disease and quantify progression over a 2-year window.

Improving Documentation of Impulse Control Disorders at a Movement Disorder Program During the COVID-19 Pandemic.

Impulse control disorders (ICD) are a group of behaviors in Parkinson disease (PD), (compulsive buying, gambling, binge eating, craving sweets, and hypersexuality) that occur in up to 20% of individuals with PD, sometimes with devastating results. We sought to determine the rate of ICD screening based on 2020 quality measures for PD care by the American Academy of Neurology. We conducted a quality improvement project to document and improve physician ICD screening in a tertiary movement disorder program. Serial medical records were reviewed for 5 weeks before and 13 weeks after an educational session and documentation tool deployments in 2020. Inclusion criteria included the following: idiopathic PD, PD dementia (PDD), or dementia with Lewy bodies (DLB). Individual encounters for 109 patients preintervention and 276 patients postintervention were reviewed. There was no difference between the preintervention and postintervention (pre-IG vs post-IG, respectively) in terms of age, male to female ratio, proportion of patients with PD, PDD, or DLB, duration of diagnosis, or levodopa equivalents. There was a shift to increased ICD queries above the median for the study period (28.8%) for 7 consecutive weeks in post-IG. The frequency of ICD diagnosis was not different from pre-IG to post-IG (95% confidence interval, 0-32.6 vs 2.7-13.4%, p = 0.444). ICD queries immediately after ICD education and dissemination of documentation tools increased. Both preintervention and postintervention groups were similar in demographic and clinical characteristics. This program was instituted at the height of wave 2 of the COVID-19 pandemic in Alberta during staff redeployment and 100% shift to telemedicine ambulatory care. Our results demonstrate that amid a crisis, quality improvement can still be effective with education and provision of tools for clinicians.

Physiological measures and anatomical correlates of subthalamic deep brain stimulation effect on gait in Parkinson's disease

We examined whether conflicting visual and non-visual information leads to gait abnormalities and how the subthalamic deep brain stimulation (STN DBS) influences gait dysfunction in Parkinson's disease (PD). We used a motion capture system to measure the kinematics of the lower limbs during treadmill walking in immersive virtual reality. The visual information provided in the virtual reality paradigm was modulated to create a mismatch between the optic-flow velocity of the visual scene and the walking speed on the treadmill. In each mismatched condition, we calculated the step duration, step length, step phase, step height, and asymmetries. The key finding of our study was that mismatch between treadmill walking speed and the optic-flow velocity did not consistently alter gait parameters in PD. We also found that STN DBS improved the PD gait pattern by changing the stride length and step height. The effects on phase and left/right asymmetry were not statistically significant. The DBS parameters and location also determined its effects on gait. Statistical effects on stride length and step height were noted when the DBS volume of activated tissue (VTA) was in the dorsal aspect of the subthalamus. The statistically significant effects of STN DBS was present when VTA significantly overlapped with MR tractogrphically measured motor and pre-motor hyperdirect pathways. In summary, our results provide novel insight into ways for controlling walking behavior in PD using STN DBS.

Seasonal variations of nonmotor symptoms in patients with Parkinson's disease in Southeast China.

Studies suggest seasonal fluctuations of symptoms in Parkinson's disease (PD) patients in Western countries. However, the association between seasonal change and variation in nonmotor symptoms (NMS) in Chinese PD patients is unclear. Here, we studied whether there is a change rule with annual cycle with severity of NMS for patients with PD in Southeast China. We studied 1005 PD patients between April 2008 and October 2020. Patients were classified into four seasons according to the 24 Chinese solar terms, based on assessment date. We compared comprehensive NMS scales and polysomnography parameters among groups and conducted further analysis of disease severity. Among the 1005 patients studied, the mean age was 64.2 ± 9.7 years and 569 (56.6%) of them were men. Relative to the summer group, patients assessed during winter had higher Scales for Outcomes in Parkinson's disease-Autonomic Dysfunction (SCOPA-AUT) scores ( P = 0.045). The sleep efficiency factor scores of Pittsburgh Sleep Quality Index in patients were higher during spring than summer ( P = 0.009). Among patients who completed polysomnography during the same period ( n = 135), compared with summer follow-ups, we observed a higher percentage of NREMS1 in winter and spring follow-ups ( P = 0.042, P = 0.011), a higher NREMS1 time in spring follow-ups ( P = 0.0024), a lower NREMS2 time in winter follow-ups ( P = 0.007), and a higher percentage of phasic RSWA in autumn and winter follow-ups ( P = 0.026 and P = 0.020, respectively). In a subset of patients with PD and REM sleep behavior disorder (RBD; n = 182), those visited during winter had higher scores for RBD questionnaire- Hong Kong and its factor 1 (dream-related sub-score) than those visited during summer ( P = 0.034, P = 0.020). We observed similar findings for SCOPA-AUT and sleep efficiency factor scores in early stage patients in subgroup analysis. PD patients assessed for follow-up during summer showed less severe symptoms of autonomic dysfunction and RBD symptoms than those assessed in winter, and less sleep disturbance than those in spring and winter, suggesting that seasonal change and NMS fluctuation are related, especially in patients with early stage PD.

Motivational and myopic mechanisms underlying dopamine medication-induced impulsive-compulsive behaviors in Parkinson's disease.

Dopaminergic medications can trigger impulsive-compulsive behaviors (ICBs) in pre-disposed patients with Parkinson's disease (PD), but what this implies on a neurocognitive level is unclear. Previous findings highlighted potentially exacerbated incentive motivation (willingness to work for rewards) and choice impulsivity (preferring smaller, immediate rewards over larger, delayed rewards) in PD patients with ICBs (PD + ICBs). To deeply understand this evidence, we studied 24 PD + ICBs and 28 PD patients without ICBs (PD-ICBs). First of all, patients underwent the assessment of impulsivity traits, mood, anxiety, and addiction condition. We further administered robust objective and subjective measures of specific aspects of motivation. Finally, we explored whether these processes might link to any heightened antisocial behavior (aggression and risky driving) in PD + ICBs. High levels of positive urgency trait characterized PD + ICBs. They choose to exert more effort for rewards under the conditions of low and medium reward probability and as reward magnitude increases. Findings on choice impulsivity show a great tendency to delay discounting in PD + ICBs, other than a high correlation between delay and probability discounting. In addition, we found what appears to be the first evidence of heightened reactive aggression in PD patients with ICBs. Exacerbated incentive motivation and delay discounting trended toward positively predicting reactive aggression in PD + ICBs. Our promising results suggest that there might be immense value in future large-scale studies adopting a transdiagnostic neurocognitive endophenotype approach to understanding and predicting the addictive and aggressive behaviors that can arise from dopaminergic medication in PD.

Validation of the Japanese Version of the Questionnaire for Impulsive-Compulsive Disorders in Parkinson's Disease-Rating Scale (QUIP-RS).

Introduction The Questionnaire for Impulsive-Compulsive Disorders in Parkinson's Disease (PD)-Rating Scale (QUIP-RS) was developed to assess the severity of impulsive and compulsive behaviors (ICBs) in PD. We aimed to validate the Japanese version of QUIP-RS and determine the characteristics of ICBs in Japan. Methods We translated the QUIP-RS into Japanese, back-translated it to English, and obtained confirmation from the original author that the questionnaire remained appropriate. The participants for the validation study were 161 PD patients, identified by continuous sampling at two institutions, who were diagnosed with ICBs through a semistructured interview and completed the QUIP-RS-J. Sensitivity, specificity, and cutoff values were calculated using receiver operating characteristic (ROC) curves. Interinstitutional reliability and test-retest reliability were also assessed for a subset of participants. Results Twenty-six (16.1%) participants were diagnosed with ICB. The optimal cutoff value of the QUIP-RS-J total score was 6, with area under the curve (AUC) = 0.889 and sensitivity/specificity of 0.92/0.71. Each subscale also showed high AUC (0.89–1.00), sensitivity (0.92–1.00), and specificity (0.71–1.00). Compared with the English version, the optimal cutoff point for binge eating was higher and hypersexuality lower. The total score tended to be higher when described by an informant. Conclusion The present study validated the Japanese version of QUIP-RS. Use of QUIP-RS-J enables standardized assessment of ICBs and can be used in clinical research, including international multicenter studies.

Neuropeptide-S affects cognitive impairment and depression-like behavior on MPTP induced experimental mouse model of Parkinson’s disease

The present study proposes to investigate the effect of neuropeptide–S (NPS) on cognitive functions and depression-like behavior of MPTP-induced experimental model of Parkinson’s disease (PD). Three-month-old C57BL/6 mice were randomly divided into three groups as; Control, Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) and MPTP + NPS 0.1 nmol (received intraperitoneal injection of MPTP and intracerebroventricular injection of NPS, 0.1 nmol for seven days). The radial arm maze and pole tests were carried out, and the levels of tyrosine hydroxylase (TH) were determined using western blotting. A mass spectrometer was used to measure the levels of dopamine, glutamic acid, and glutamine. The T-turn and time to descend enhanced in MPTP group, while these parameters were decreased by NPS treatment. In the MPTP group, the number of working memory errors (WME) and reference memory errors (RME) increased, whereas NPS administration decreased both parameters. Sucrose preference decreased in the MPTP group while increasing in the NPS group. MPTP injection significantly reduced dopamine, glutamic acid, and glutamine levels. NPS treatment restored the MPTP-induced reduction in glutamine and glutamic acid levels. NPS may be involved in the future treatment of cognitive impairments and depression-like behaviors in PD.

Aberrant Salient and Corticolimbic Connectivity in Hypersexual Parkinson's Disease.

Introduction: Impulse control disorders (ICDs) represent a side effect of dopaminergic medication in Parkinson's disease (PD). Patients experience an excessive desire toward natural rewards paired with uncontrolled actions. Yet, the precise neural and behavioral mechanisms associated with ICDs and, importantly, each specific subdomain remain unclear. We aim to decipher resting-state and corticolimbic functional connectivity in PD patients with and without hypersexual ICD. Materials and Methods: Seventeen PD patients with hypersexuality (PD+HS) and 15 PD patients without hypersexuality (PD-HS) underwent two sessions (with and without medication) of resting-state functional magnetic resonance imaging and were compared with 17 healthy controls. Dual-regression independent component analyses extracted salience, sensorimotor, default-mode, and central executive networks. Seed-based functional connectivity with three striatal subdivisions (motor, associative, and limbic) was obtained and significant changes were correlated with key impulsivity and inhibitory measures. Results: Enhanced salience network (SN) activity represented by a significant rise in the right inferior frontal gyrus was found in PD+HS compared with PD-HS. Connectivity analyses revealed a functional disconnection between associative and limbic striatum with precuneus and superior parietal lobe in PD+HS, some connections explained by abnormal sexual behavior and inhibition in PD+HS. Conclusions: Hypersexual ICD is associated with enhanced SN signaling and corticolimbic disconnections, including striatal associative and limbic loops that contribute to altered control of sexually driven behavior and overall severity in PD and ICD. Impact statement We enlarge the neurobiological basis to one specific Parkinson's disease (PD) and impulse control disorder (ICD) (PD+ICD) subtype-that is, hypersexuality-and reveal its associated resting-state functional connectivity linked to altered behavior. We report enhanced salience network and right inferior frontal gyrus as part of the underlying resting-state functional networks in PD patients with hypersexuality (PD+HS). Corticolimbic changes were associated with sexual severity in PD+HS to hypoactive connectivity between associative-limbic striatum with precuneus and superior parietal lobe. The connectivity changes seen in PD+HS could explain baseline differences that engender aberrant control over sexual behavior in ICD.

Sexual Disorders and Quality of Life in Parkinson's Disease.

IntroductionSexual disorders are the most neglected nonmotor symptoms in Parkinson's disease (PD). Although doctors seek greater priority to motor manifestations, which are the basis for the diagnosis of PD, the nonmotor symptoms deserve to be highlighted as much as the motor problems because of their strong presence and discomfort in the patients, causing the important impairment in the quality of life (QoL) of the individual with PD.AimProvide the prevalence of sexual disorders among patients with PD and alert the medical profession to investigate and be familiar with problems related to QoL and sexual disorders in PD.MethodsThis is a large literature review on sexual disorders in PD and impaired QoL.Main Outcome MeasuresSexual disorders in PD and prevalence between genders have been described in epidemiological studies. Neuroanatomy, pathophysiology, risk factors, QoL, and etiologies were reviewed.ResultsThe estimate of the prevalence of sexual dysfunction in the form of compulsive sexual behavior in PD is higher in men by 5.2% than in women by 0.5%. This diagnosis is a determinant of intense and persistent suffering and is related to several health problems of a social, economic, personal, family, psychological, and occupational nature, which can even culminate in sexual abuse. It is most commonly associated with the use of drugs commonly used in PD therapy in 98.1% of cases. In addition to this serious public health problem, another common condition of sexual dysfunction occur with the decreased libido by loss of the neurotransmitter dopamine proper of the pathophysiology of PD.ConclusionThe presence of sexual disorders in PD should be tracked and monitored because of its harmful consequences, whether due to increased sexual behavior or associated psychological distress, as well as the impacts on QoL. Early recognition and adequate treatment of PD in its fullness and richness of associated symptoms are essential for improving QoL.Santa Rosa Malcher CM, Roberto da Silva Gonçalves Oliveira K, Fernandes Caldato MC, et al. Sexual Disorders and Quality of Life in Parkinson's Disease. Sex Med 2021;9:100280.

REM sleep behavior in Parkinson disease: Frequent, particularly with higher age.

This retrospective single-center polysomnography-based study was designed to assess the frequency of REM sleep behavior disorder (RBD) in consecutive patients with Parkinsonism, including Parkinson disease, dementia with Lewy bodies, multiple system atrophy, progressive supranuclear palsy, and corticobasal degeneration. We observed RBD in 77% of 540 Parkinson patients, with rising frequency at higher age and regardless of sex, in >89% of 89 patients with dementia with Lewy bodies or multiple system atrophy, and in <15% of 42 patients with progressive supranuclear palsy or corticobasal degeneration. Thus, the prevalence of RBD in sporadic Parkinson disease might be higher than previously assumed, particularly in elderly patients.

Impaired Hand Dexterity Function in a Non-human Primate Model with Chronic Parkinson's Disease.

Symptoms of Parkinson’s disease (PD) caused by loss of dopaminergic neurons are accompanied by movement disorders, including tremors, rigidity, bradykinesia, and akinesia. Non-human primate (NHP) models with PD play an essential role in the analysis of PD pathophysiology and behavior symptoms. As impairments of hand dexterity function can affect activities of daily living in patients with PD, research on hand dexterity function in NHP models with chronic PD is essential. Traditional rating scales previously used in the evaluation of animal spontaneous behavior were insufficient due to factors related to subjectivity and passivity. Thus, experimentally designed applications for an appropriate apparatus are necessary. In this study, we aimed to longitudinally assess hand dexterity function using hand dexterity task (HDT) in NHP-PD models. To validate this assessment, we analyzed the alteration in Parkinsonian tremor signs and the functionality of presynaptic dopaminergic neuron using positron emission tomography imaging of dopamine transporters in these models. In addition, a significant inverse correlation between HDT and DAT level was identified, but no local bias was found. The correlation with intention tremor signs was lower than the resting tremor. In conclusion, the evaluation of HDT may reflect behavioral symptoms of NHP-PD models. Furthermore, HDT was effectively used to experimentally distinguish intention tremors from other tremors.

Neuroprotective effects associated with immune modulation by selected lactic acid bacteria in a Parkinson's disease model.

Parkinson's disease (PD) is a neurodegenerative process that affects the motor function and involves an inflammatory response and B vitamin deficiencies. The aim of this study was to evaluate the effect of B-group vitamin-producing and immunomodulatory lactic acid bacteria (LAB) in a murine model of PD. The effect of Lactobacillus plantarum CRL 2130 (a riboflavin producer), Streptococcus thermophilus CRL 807 (an immunomodulatory strain), and Streptococcus thermophilus CRL 808 (a folate producer) were evaluated individually and as a mixture in mice injected with 1-methyl-4-fenil-1,2,3,6-tetrahidropiridina. Motor capacity, tyrosine hydrolase in the brain, and cytokine concentrations in serum and brain tissues were evaluated in 1-methyl-4-fenil-1,2,3,6-tetrahidropiridina-treated mice after bacterial supplementation. The mice receiving the selected LAB showed significantly improved motor skills compared with those that did not receive bacterial supplementation. When given the mixture of all 3 strains together, the animals had higher brain tyrosine hydrolase-positive cell counts, decreased inflammatory cytokines interleukin 6 and tumor necrosis factor alpha in serum, and increased antiinflammatory cytokine interleukin 10 in serum and brain tissues compared with animals that did not receive LAB supplementation. The results showed the potential of a selected LAB mixture to improve motor behavior and neuroinflammation in PD. This probiotic mixture could be used as an adjunct treatment in the control of PD.

Genetic, Structural, and Functional Evidence Link TMEM175 to Synucleinopathies.

The TMEM175/GAK/DGKQ locus is the 3rd strongest risk locus in genome-wide association studies of Parkinson disease (PD). We aimed to identify the specific disease-associated variants in this locus, and their potential implications. Full sequencing of TMEM175/GAK/DGKQ followed by genotyping of specific associated variants was performed in PD (n = 1,575) and rapid eye movement sleep behavior disorder (RBD) patients (n = 533) and in controls (n = 1,583). Adjusted regression models and a meta-analysis were performed. Association between variants and glucocerebrosidase (GCase) activity was analyzed in 715 individuals with available data. Homology modeling, molecular dynamics simulations, and lysosomal localization experiments were performed on TMEM175 variants to determine their potential effects on structure and function. Two coding variants, TMEM175 p.M393T (odds ratio [OR] = 1.37, p = 0.0003) and p.Q65P (OR = 0.72, p = 0.005), were associated with PD, and p.M393T was also associated with RBD (OR = 1.59, p = 0.001). TMEM175 p.M393T was associated with reduced GCase activity. Homology modeling and normal mode analysis demonstrated that TMEM175 p.M393T creates a polar side-chain in the hydrophobic core of the transmembrane, which could destabilize the domain and thus impair either its assembly, maturation, or trafficking. Molecular dynamics simulations demonstrated that the p.Q65P variant may increase stability and ion conductance of the transmembrane protein, and lysosomal localization was not affected by these variants. Coding variants in TMEM175 are likely to be responsible for the association in the TMEM175/GAK/DGKQ locus, which could be mediated by affecting GCase activity. ANN NEUROL 2020;87:139-153.