Parkinsonism & Related Disorders

Background: Problematic Internet use (PIU) has been scarcely investigated in Parkinson's disease (PD). Objectives: To estimate the prevalence of PIU symptoms in PD using a specific screening instrument and to explore the clinical characteristics of these individuals. Methods: Two-stage observational study in a Movement Disorders clinic. In Evaluation 1, participants with PD were screened by the Brazilian Portuguese Nine-Item Problematic Internet Use Questionnaire-Short Form (BR-PIUQ-SF-9). In Evaluation 2, screening-positive participants underwent an exploratory assessment of Internet use. Results: 16.7% of participants with PD were positive for the BR-PIUQ-SF-9. The median Internet use time among these positive-screened participants was 5.5 hours per day. Most of them had impulsive-compulsive behaviors, and somatic concern, anxiety, and depressive mood were common psychiatric symptoms. Conclusions: Approximately one in six participants screened positive for PIU symptoms. Impulsive-compulsive behaviors and depressive symptoms were frequent among those undergoing subsequent exploratory assessment.

Background The global burden of Parkinson's disease (PD) has increased substantially over recent decades, driven by population ageing and rising age-standardized prevalence. In Africa, accurate estimates remain limited due to a lack of recent, methodologically robust population-based studies. Objectives To determine the current age-standardized and sex-specific prevalence rates of PD in Nigeria. Methods We conducted a 2-stage, cross-sectional population-based door-to-door survey among adults aged [≥]18 years in two densely populated urban local government areas in Lagos State, Nigeria, between April 1, 2024 and January 31, 2025. The first stage involved a household census and screening for parkinsonism using a standardized screening tool. The second stage consisted of in-person clinical assessment and diagnostic confirmation by physicians using established clinical diagnostic criteria. Crude and age-standardized prevalence rates (to the World Health Organization World Standard and European Standard Populations) were calculated. Results 31,009 individuals (52.7% female) from 13,222 households were surveyed, and 70 persons were diagnosed with PD. The crude prevalence ratio was 225.7 per 100,000, with higher prevalence in males (53/14658, 361.6) than females (17/16,351, 104.0). The age-standardized prevalence rate (95% confidence interval) was 193 per 100,000 (150 -- 245) (females: 86 (50 -- 137); males: 277 (207 -- 362)), and increased with advancing age. The diagnostic gap (previously undiagnosed) was 60.0% (42/70). Treatment gap (never treated) was 44/70 (62.9%). Conclusions The age-standardized prevalence of PD is higher than previously reported in sub-Saharan Africa. These findings provide contemporary data to inform updated estimates of disease burden and support health systems planning.

Background: Levodopa is time-critical in hospitalized Parkinson disease. Whether dosing fidelity depends on care setting or documented access status is unclear. Objectives: To quantify levodopa dosing fidelity, test ICU exposure with clustering-aware methods, and test whether documented access type is associated with delayed or omitted dosing. Methods: Retrospective cohort study using MIMIC-IV (2011-2022). Adults with Parkinson disease and [&ge;]1 scheduled levodopa dose contributed 1,665 admissions and 39,322 doses. ICU exposure was tested with a patient-clustered GEE model. Among ICU-exposed doses, access type (normal, tube feeding, parenteral nutrition, NPO) was modeled in one fully adjusted model and tested for specificity, restricted to the ICU, against an active-comparator medication (statins). Results: Of 39,322 doses, 79.8% were on time by the primary 60-minute definition; a symmetric {+/-}15-minute definition classified 68.8% as mistimed. ICU exposure was not associated with delayed or omitted dosing after clustering (patient-clustered OR, 0.87; 95% CI, 0.74-1.01). Among ICU-exposed doses, NPO was associated with delayed or omitted dosing (adjusted OR, 1.89; 95% CI, 1.36-2.62) and tube feeding with lower odds (adjusted OR, 0.62; 95% CI, 0.42-0.92; P < .001). The comparator medication showed a directionally consistent but inconclusive interaction (OR, 1.27-1.28; 92 patients). A route-order association was not observed among immediate-release formulations (OR, 0.72; 4 patients). Conclusions: ICU admission alone was not associated with dosing unreliability after clustering. Among ICU-exposed doses, access type, not a single pooled category, was associated with dosing reliability; a comparator-medication check, valid only in the ICU, was directionally consistent but inconclusive.

Abstract Background. Parkinson's disease (PD) is a progressive neurodegenerative disorder of increasing prevalence, with diagnostic accuracy of approximately 26% in early symptomatic patients. There is a need for accurate, non-invasive biomarkers to aid in disease diagnosis. Methods. This proof-of-concept study enrolled 90 participants (PD n = 30, other movement disorders [OM] n = 30, healthy controls [HC] n = 30) at a single institution. Participants completed two 10-minute eye-tracking sessions using the SaccadeDX 250 Hz binocular system. A two-level cascade classifier was fitted using elastic-net feature selection followed by logistic regression on the selected features, validated by 10-fold cross-validation. The cascade distinguished HC from movement disorders (Level 1) and PD from OM (Level 2), with the objective of establishing clinical validity that an eye-tracking signal correlates reliably with PD diagnosis. Results. Level 1 achieved an area under the curve (AUC) of 0.818 (95% CI: 0.71, 0.91), with a sensitivity of 83% and specificity of 63%. Level 2 achieved an AUC of 0.670 (95% CI: 0.52, 0.80), with a sensitivity of 68% and specificity of 63%. End-to-end PD detection achieved an AUC of 0.866 and an accuracy of 83.5%, meeting the prospectively specified accuracy threshold and the proof-of-concept AUC benchmark. Five adverse events were recorded (three cases of dizziness, one of nausea, and one of dry eyes); one participant withdrew from the study. Conclusions. Clinical validity is established: a reproducible eye-tracking signal for PD is detectable using a two-level cascade classifier. A multi-center confirmatory study is warranted before assessment of clinical utility.

Introduction: Parkinson's disease is a neurodegenerative disease affecting motor and cognitive function that has a major impact on society. Epidemiological evidence has suggested that the incidence of PD may be increasing; however, the underlying etiology is unclear. Here, we investigated the role of increasingly used antipsychotics in the diagnosis of PD. Methods: We harnessed Merative Marketscan insurance claims databases to conduct a case-control study of 65,275 new cases of PD and 652,364 age-, sex-, and time-matched controls. We estimated associations between exposure and duration of use for antipsychotics adjusted for important confounders using fixed effects logistic regression. We performed sensitivity analyses stratified by the level of D2 receptor inhibition to assess dose-response relationships; a lagged exposure analysis to address confounding by indication; analysis assessing exposure of other psychiatric medications without significant D2 inhibition (bupropion, trazodone, and Z-drugs); analysis assessing exposure of non-psychiatric medications with significant (metoclopramide) or no D2 inhibition (ondansetron). Results: We found cases with PD had elevated odds of antipsychotic exposure. Longer durations of exposure and greater affinity for the D2 receptor were associated with greater associations with PD. There was a dose-response relationship between D2 inhibition activity and increased odds of PD for a similar duration of exposure. There was a dose response relationship between duration of metoclopramide and the odds of PD; however, there was no such relationship between the non-D2 inhibiting control medications. The association between exposure to an antipsychotic and increased odds of PD was present even when the first exposure was 10 years prior to the PD diagnosis date. Conclusion: If these results are causal, antipsychotic use may explain up to 2.4% of all cases of PD. Given the increasing rate of use of these medications, and the concurrent increasing age-adjusted incidence of PD, there is an urgent need for further investigation into this association and greater awareness of the potential risks of these medications in older adults.

We report here, based on Parkinson's Progression Markers Initiative (PPMI) data, on the Cerebrospinal Fluid (CSF) profile of a group of 12 Parkinson's Disease (PD) subjects with the prototypical p.A53T SNCA mutation, comparing them to 36 matched Healthy Controls (HCs) and 36 idiopathic PD (iPD) cases. We furthermore assessed the CSF profile of 7 asymptomatic carriers of this mutation. There was no significant difference between the 3 groups of A53T-PD, HC and iPD in total alpha synuclein (a-syn) levels, beta-amyloid 1-42, total-Tau and p-Tau, although A53T-PD subjects tended to have slightly lower beta-amyloid 1-42, total-Tau and especially total a-syn levels. All A53T-PD cases had a positive CSF a-syn Seeding Amplification Assay (SAA). Four out of 7 asymptomatic carriers also had a positive SAA, in 3 without motor symptoms or signs and absence of clear prodromal manifestations. Conversion to motoric manifestations has occurred in one out of these 3 subjects, 8 years after SAA positivity, while one other subject only has hyposmia 8 years later. Overall, these results indicate that at least in early stages of PD, CSF Alzheimer's Disease profiles are not significantly different in A53T-PD compared to HCs or iPD, while the CSF a-syn SAA is universally positive in this group. Furthermore, the assay may be positive in asymptomatic carriers at a time with no prodromal manifestations and many years before motor disease onset, opening a window into very early stages of disease pathobiology and opportunities for early therapeutic intervention.

Background: Deep brain stimulation (DBS) of the subthalamic nucleus (STN) is an effective treatment for Parkinson's Disease (PD), but identifying optimal stimulation contacts is time-intensive. Beta-band activity (13-35 Hz) from local field potentials (LFP) correlates with motor symptoms and attenuation by dopaminergic therapy and DBS supports its role as a programming biomarker. The recently introduced Electrode Identifier (EI) feature of Medtronic PerceptTM neurostimulators may facilitate beta-guided contact selection. Objective: To evaluate whether pseudo-monopolar STN beta power obtained using EI predicts optimal stimulation contacts and compare its performance with reconstructed bipolar recordings and MPR. Methods: LFPs were recorded in 69 patients using EI and Electrode Survey (ES). Prediction accuracy was assessed using predefined ranking rules and compared with clinically selected contacts. Agreement between EI, ES, and MPR was evaluated. Motor outcome was assessed using MDS-UPDRS-III. Results: EI predicted clinically selected contacts above chance (TOP1: 45%, p = 0.010; TOP2-80: 57%, p = <0.001), whereas ES exceeded chance only under more inclusive selection criteria (TOP1: 38%, p = 0.073; TOP2-80: 55%, p = 0.0021). Accuracy did not differ between methods (TOP1: p = 0.720; TOP2-80: p = 1.000). EI showed highest agreement with MPR and tended to select ventral contacts. Neither method predicted motor outcome, although EI-matched contacts showed a trend toward greater improvement. Due to technical constraints, one-third of EI recordings were excluded. Conclusions: Pseudo-monopolar STN beta power provides clinically relevant information for DBS contact selection with performance comparable to bipolar approaches. Further improvements are needed before clinical implementation.

Transcranial alternating current stimulation (tACS) is a promising noninvasive intervention for modulating pathological brain oscillations in Parkinson's disease (PD). To evaluate its clinical and neurophysiological efficacy, we searched five databases (Web of Science, PubMed, Scopus, Google Scholar and APA PsycInfo) up to August 31, 2025, for trials employing tACS in patients with idiopathic PD. Risk of bias was assessed using the RoB 2 and ROBINS-I tools. Random-effects meta-analyses were used to calculate standardized (SMD) and unstandardized mean differences (MD) with 95% confidence intervals (CIs). We included 10 studies (184 patients with PD, mean age: 64.9, mean disease duration: 5.2 years) in the qualitative review and seven trials (146 patients with PD, mean age: 65.6, mean disease duration: 5 years) in the meta-analysis. No statistically significant differences favoring active tACS over control were found in overall motor severity (UPDRS: SMD = 0.21, 95% CI [-0.10, 0.52], p = 0.097), tremor (SMD = -0.40, 95% CI [-1.97, 1.17], p = 0.478), or a neurophysiological marker of inhibitory response, represented by short intracortical inhibition (MD = 0.00, 95% CI [-0.40, 0.41], p = 0.971). The prediction intervals indicated substantial uncertainty, and significant between-study heterogeneity was observed, particularly for tremor outcomes (I2 = 86.1%). This variability and limitation in evidence quality is largely driven by small sample sizes, highly heterogeneous stimulation protocols, and varying outcome assessments. Systematically, tACS was generally well-tolerated, with no serious adverse events reported across the included studies; however, formal safety assessment was beyond the scope of this review. Current exploratory evidence shows a lack of consistent improvements in motor symptoms or functions in PD largely due to protocol-level heterogeneity. Future studies should consistently assess the MDS-UPDRS III post-tACS and report its specific subscores alongside neurophysiological measures to enable robust meta-analyses.

Background: Freezing of gait (FOG) is a disabling and often underrecognized feature of Parkinsons disease (PD). Objective gait analysis may improve characterization of this motor symptom. Objective: To compare quantitative 3D gait parameters in PD with FOG (PDF) and PD without FOG (PDNF) in a routine clinical cohort. Methods: We retrospectively analyzed a sequential sample of 180 patients with PD referred for motion analysis between 2020 and 2024. All patients underwent 3D motion capture in the off-medication state. Eighteen gait outcomes spanning pace, rhythm, postural control, variability, and asymmetry domains were derived from steady-state walking tasks. FOG status was determined using physician documentation and Movement Disorder Society Unified Parkinsons Disease Rating Scale (MDS-UPDRS) items. Group differences between PDF (n=99) and PDNF (n=81) were evaluated using independent samples t-tests, with outcomes adjusted for disease duration and corrected for multiple comparisons. A secondary analysis among PDF compared those in Hoehn and Yahr (H&Y) stage [&ge;]III to those in H&Y [&le;]II. Results: PDF had longer disease duration, higher OFF MDS-UPDRS III scores, and higher Hoehn and Yahr stage than PDNF but were similar in age and sex. After adjusting for disease duration and multiplicity, PDF demonstrated reduced step length, stride length, and forward velocity, and greater cadence variability, while most postural control, and asymmetry measures were comparable between groups. Among PDF, advanced H&Y stage was associated with impaired pace and rhythm, similar to previous reports among PD in general. Conclusion: In this large, sequential, clinically referred cohort, FOG was associated with more advanced PD and specific impairments in pace and gait variability. These findings support comprehensive 3D gait analysis as an objective tool to better delineate FOG-related gait abnormalities and identify features that may predict FOG, informing targeted interventions.

As genetic testing becomes increasingly integrated into Parkinson disease (PD) research, including targeted testing for variants in LRRK2 and GBA1, the return of individual research results is becoming more common. However, limited qualitative data exists regarding how research participants experience genetic results disclosure and post-test genetic counseling in PD research settings. We conducted semi-structured qualitative interviews with participants (n=13) enrolled in the Parkinson Precision Medicine Initiative (formerly Parkinson Progression Markers Initiative; PPMI) who had received PD-related genetic test results and post-test genetic counseling. Interviews were conducted 1 to 3 weeks following result disclosure and analyzed using thematic analysis with a primarily deductive coding approach informed by study aims and inductive identification of emergent themes. Four primary themes were identified: (1) personal connection and motivations for participation, (2) centrality of result disclosure and information preferences, (3) emotional experiences and support needs, and (4) communication quality and alignment with participant needs. Overall, our findings underscore the importance of person-centered genetic counseling within PD research. As return of genetic and biomarker results in research and clinical trial contexts expand, thoughtful integration of relational, informational, and communication-focused practices will be essential to support participant engagement and trust.

Introduction: GCH1 has been implicated in Parkinson's disease (PD), but its risks variants and associations are not well defined. Objectives: To investigate the clinical relevance and PD risk associated with the GCH1 p.Ser80Asn variant. Methods: We first identified a segregating GCH1 p.Ser80Asn variant in a Malaysian Chinese PD family via whole genome sequencing (WGS). We assessed its risk association using multi-ancestry WGS data from the Global Parkinson's Genetics Program (GP2) (n=22,372PD vs n=8,826Controls) and meta-analysis of East Asian (EAS) cohorts (n=4,712PD vs 38,733Controls). Clinico-demographic details of affected variant carriers were collated. Results: The GCH1 p.Ser80Asn variant was enriched in GP2 EAS PD populations (n=9/2,757; 0.33%) but not detected in other ancestries. Meta-analysis revealed increased PD risk in EAS populations (odds ratio:5.1; 95%CI:2.3-10.7; p=2.89x10-5). Affected carriers (mean age at onset:56.3+-12.5 years) had additional occurrence of dystonia, while dementia was rare. Conclusions: The GCH1 p.Ser80Asn variant is a rare, EAS-enriched risk variant for PD.

Background: Mutations in leucine-rich repeat kinase 2 (LRRK2) are the most common genetic risk factor for Parkinson's disease (PD). G2019S, the most common pathogenic variant, has been linked to milder motor symptoms, but the effects of other LRRK2 variants on disease trajectory remain incompletely characterized. R1441G, the second most common pathogenic variant, co-occurs with the PD risk variant M1646T on a shared haplotype. Whether this haplotype confers a distinct rate of motor progression has not been established. Methods: We analyzed up to 12 years of longitudinal data from 603 participants in the Parkinson's Progression Markers Initiative (PPMI) with PD and available whole-genome sequencing data: 394 sporadic PD, 169 G2019S carriers, 20 R1441G+M1646T carriers, and 20 M1646T carriers. Motor symptom progression (MDS-UPDRS III) was assessed using linear mixed-effects models with genotype-by-time interactions, adjusted for age at onset, disease duration at baseline, sex, race, baseline score, and levodopa equivalent daily dose. Results: R1441G+M1646T carriers exhibited 76% slower progression in OFF-state MDS-UPDRS III than sporadic PD (0.50 vs. 2.04 points/year; {beta}=-1.54 [95% CI: -2.48, -0.60]; p=0.001). G2019S carriers exhibited 26% slower progression (1.52 points/year; {beta}=-0.52 [-0.99, -0.06]; p=0.03). M1646T carriers did not differ from sporadic PD (p=0.60). Slower progression in R1441G+M1646T carriers was characterized by attenuated bradykinesia (64% slower; p=0.008), axial decline (76% slower; p=0.002), and a lack of orofacial symptom progression (p<0.001). R1441G+M1646T carriers also exhibited 55% slower self-reported motor decline (MDS-UPDRS II; p=0.04) Conclusions: R1441G+M1646T carriers exhibit substantially slower motor progression than sporadic PD while M1646T carriers do not.

The genetics of Parkinsons disease (PD) in underrepresented populations remain poorly characterized, potentially overlooking population-specific contributions. We analyzed 461 Chilean PD cases from a movement disorders center. Pathogenic, likely pathogenic, or GBA1 risk variants were identified in 58 individuals (12.6%), mainly in LRRK2 (50%) and GBA1 (44.8%), while PRKN, SNCA, and SQSTM1 collectively represented 5.2%. All LRRK2 variants were p.G2019S, with an overall frequency of 6.3%, the highest reported in South America, and enrichment of Ashkenazi Jewish ancestry at this locus. These findings characterize the genetic landscape of PD in Chile and support its relevance for LRRK2-targeted studies.

Background: Motor complications, such as motor fluctuations and Levodopa-induced dyskinesias (LID), significantly impair quality of life in persons with Parkinson's disease (PD) on long-term Levodopa treatment. Predicting their onset is crucial for tailored patient care. Objectives: To develop and evaluate machine learning (ML) models to forecast the onset of new motor fluctuations and LID in PD patients within three years from baseline assessment, and to assess how training cohort composition influences performance. Methods: A comprehensive ML workflow with repeated Nested Grid Search Cross-Validation was applied to real-world clinical data from a multicentric cohort of 247 PD patients. ML models were rigorously evaluated on the clinically relevant subgroup free of motor complications at baseline. SHAP analysis provided model explainability. Results: Models achieved moderate predictive power for both LID (SVC: MCC 0.28 {+/-} 0.14) and motor fluctuations (Voting MCC = 0.32 {+/-} 0.18). For LID prediction, the strongest predictors were the Levodopa Equivalent Daily Dose (LEDD), baseline motor fluctuations, and duration of Levodopa therapy, with risk increasing significantly above a LEDD threshold of 300-400 mg. A critical ablation study revealed that excluding patients with pre-existing complications caused a collapse in model sensitivity, highlighting their essential role in defining the upper bound of predicted risk. Conclusions: The model-based risk assessment is consistent with established clinical factors. Inclusion of the full spectrum of disease severity, including patients with pre-existing motor complications, in the training set is essential for achieving a robust probabilistic risk scale and reliable model calibration for new-onset prediction.

Background. Cognitive impairment in Parkinson's disease (PD) is highly prevalent and heterogeneous. Assessing multiple cognitive domains is challenging and risks redundancy. This study evaluated whether a discriminant analysis approach could optimize the selection of specific tasks and measures for identifying attention and memory deficits in PD. Methods. Thirty PD patients and 25 cognitively unimpaired (CU) controls completed four experimental tasks: two assessing attention (flanker and spatial Stroop), one for recognition memory, one for working memory (n-back). Following group-level difference analyses, a discriminant analysis was performed to identify which tasks, and performance metrics possessed the highest sensitivity for distinguishing PD patients from CU individuals. Results. At the group level, PD patients exhibited significantly worse conflict costs in both attention tasks and lower sensitivity scores (d') in the recognition memory task compared to CU controls. The discriminant analysis revealed that time-based measures from the spatial Stroop task and the sensitivity score from the recognition memory task provided the highest discriminating power to differentiate between the two groups. Conclusion. These findings suggest that cognitive deficits in PD can be identified with high diagnostic accuracy using a targeted subset of metrics, eliminating the need for extensive and redundant neuropsychological testing batteries for attention and memory, without needing an extensive number of cognitive tasks for attention and memory.

Background: Motor disturbances are common in neurologic and neurodegenerative syndromes. A standard motor speed and dexterity measure is the finger tapping test (FTT). The FTT has traditionally been administered in clinic using a mechanical FTT, limiting accessibility and early motor change quantification. This study assessed the validity of a smartphone app-based FTT, which may expand access and enable more frequent testing. Methods: The cohort was diagnostically diverse, including participants with frontotemporal dementia (FTD), progressive supranuclear palsy (PSP), corticobasal syndrome, primary progressive aphasia, multiple sclerosis, and clinically unimpaired controls. Participants completed a 20-second ALLFTD Mobile App (mApp)-FTT with each hand. Tapping speed metrics were extracted. Participants completed the gold-standard mechanical FTT, a neurologist-administered finger tapping exam, the PSP Rating Scale (PSPRS) and the Unified Parkinson`s Disease Rating Scale (UPDRS). Correlations assessed mApp-FTT and mechanical FTT relationships; regressions evaluated associations with neurologist-rated finger tapping impairment, PSPRS and UPDRS, adjusting for age and sex. Results: The mApp-FTT showed moderate-to-strong correlations with the mechanical FTT (dominant: r=0.63, p<0.001; non-dominant: r=0.55, p<0.001). Taps per second were associated with PSPRS motor severity (dominant hand: std. {beta}=-0.59, 95% CI [-0.91, -0.27], p<0.001) and the UPDRS (dominant hand: std. {beta}=-0.41, 95% CI [-0.82, 0.00], p=0.049). Flight time was modestly associated with neurologist-rated finger tapping impairment (dominant hand: std. {beta}=0.15, 95% CI [0.00, 0.29], p=0.044). Conclusion: These findings support mApp-FTT validity as a measure of motor function across neurodegenerative conditions. Validation in longitudinal and unsupervised remote settings is warranted to understand scalability and evaluate change over time.

Background An X-linked levodopa-responsive parkinsonism-epilepsy syndrome has been associated with PGK1, and the gene lies within the previously suspected PD locus PARK12. Objective To examine the association of common and rare PGK1 variants with PD. Methods We analyzed common and rare variants from Accelerated Medicines Partnership - Parkinsons Disease (AMP-PD) and UK Biobank (UKBB, total N=4,523 PD cases, 19,736 proxy cases, and 390,532 controls). To account for the X-linked location of PGK1, we used sex-stratified, combined regression models and optimized sequence Kernel association (SKAT-O) tests, followed by meta-analysis using MetaSKAT. Results We found no association between common or rare PGK1 variants and PD in sex-stratified or combined analyses, including after cross-cohort meta-analysis. Conclusion Although we did not find evidence supporting an association between PGK1 and PD, very rare pathogenic PGK1 variants may still contribute to syndromic parkinsonism. Future research could explore larger datasets to further examine this potential association.

Background: People with Parkinsons disease (PD) experience substantial psychosocial burden, but the extent of their concern about the future is not well characterized. Objective: The objective of the present study is to characterize concerns about the future among people with PD (PwP), with an emphasis on the clinical and demographic correlates of future-oriented concerns. Methods: A survey in the online Fox Insight study platform asked PwP to rate their degree of concern about the future across seven domains: quality of life, disease progression, healthcare needs, social relationships, financial responsibilities, stigma, and specific symptoms. Relationships among uncertainty and demographic and clinical features, such as age of onset, gender, and disease severity, were examined. Latent class analysis was conducted to identify patterns of fear/uncertainty. Results: Among 3372 respondents, concerns about the future were common and spanned cognitive, functional, social, and symptom-related domains. Concerns about future cognitive impairment, independence, mobility, and disease progression were most prominent. Women and individuals with young-onset PD reported higher levels of concern than other groups. Latent class analysis revealed two clear patterns, including a high-concern subgroup with elevated worry across nearly all domains. Fewer than half of respondents had discussed these concerns with a healthcare professional. Conclusion: Future-related concerns are common among people with PD but is not routinely explored in clinical care. Greater attention to these concerns, especially for young-onset individuals and women, may help clinicians offer more timely and supportive guidance.

Introduction: Variants in the polymerase gamma (POLG) gene are associated with a wide range of mitochondrial disorders. Emerging evidence suggests a potential link between POLG variants and Parkinson's disease (PD); yet, results remain inconclusive. Objectives: To investigate the genetic spectrum and prevalence of POLG variants in PD across diverse ancestries. Methods: We leveraged multi-ancestry genetic data from the Global Parkinson's Genetics Program (GP2), including genotyping data from 98,589 and short-read sequencing data from 36,022 individuals. We performed a POLG rare variant screen, case-control association, and gene-level burden analyses. Results: Five PD cases carried potentially biallelic rare pathogenic/likely pathogenic POLG variants. Additionally, 228 individuals (<1%; 161 PD cases, 28 individuals with other neurological disorders, and 39 controls) carried 34 distinct rare pathogenic/likely pathogenic heterozygous variants, with no significant frequency differences between cases and controls, except for the p.Ala467Thr variant in the European population. The co-inherited pathogenic variants p.Thr251Ile and p.Pro587Leu were present in <1% of both cases and controls, with no significant group differences. Burden and variant-level association analyses showed no association between rare POLG variant burden or common POLG variant enrichment and PD. Conclusions: POLG variants are overall rare in PD. The identification of rare pathogenic variants among PD cases suggests that POLG-related mitochondrial dysfunction may contribute to PD in isolated instances, particularly under recessive inheritance. Our findings support a role for POLG variants in select cases and underscore the need for larger-scale sequencing and functional studies.

BackgroundThe relationship between essential tremor (ET) and Parkinsons disease (PD) remains controversial. Beyond viewing ET as a discrete risk factor for PD, recent frameworks propose that an ET phenotype may represent a clinical presentation of prodromal PD (pPD), consistent with the current reconceptualization of ET as a syndrome. Whether co-occurring subtle motor signs alter pPD probability in ET remains unknown. MethodsUsing the MDS research criteria, we calculated pPD probability in a large cohort of ET patients with and without subtle motor signs (rest tremor, hypomimia, isolated rigidity, reduced arm swing, altered repetitive movements, global slowing). Multivariable regression was used to identify independent predictors of pPD probability. ResultsAmong 599 ET patients (median disease duration: 12 years), only 6 (1.0%) met criteria for probable pPD. Although ET patients with subtle motor signs exhibited higher continuous pPD probability scores than those without, the frequency of possible or probable pPD did not differ significantly between groups. In multivariable regression, neither ET nor individual subtle motor signs, but hypomimia, were independent predictors of pPD probability, which was primarily driven by older age and male sex. ConclusionsLong-standing ET, whether isolated or accompanied by subtle motor signs, is not associated with pPD, with the possible exception of co-occurring hypomimia.