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Parkinsonism & Related Disorders

Elsevier BV

Preprints posted in the last 7 days, ranked by how well they match Parkinsonism & Related Disorders's content profile, based on 21 papers previously published here. The average preprint has a 0.02% match score for this journal, so anything above that is already an above-average fit.

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Differential Levodopa Responsiveness and Motor Complication Trajectories in Parkinson's Disease by α-Synuclein Seed Amplification Assay Status

Azizi, H.; Fereshtehnejad, S.-M.; Moqadam, R.; Dadar, M.; Siderowf, A.; Dagher, A.; Zeighami, Y.

2026-04-22 neurology 10.64898/2026.04.21.26350973 medRxiv
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Abstract/SummaryO_ST_ABSBackgroundC_ST_ABSCerebrospinal fluid (CSF) -synuclein seed amplification assay (SAA) has emerged as a diagnostic biomarker for Parkinsons disease (PD) and has been linked to differences in disease severity and progression. However, whether SAA status predicts responsiveness to levodopa remains unknown. We investigated the longitudinal association between SAA status, levodopa responsiveness, dopaminergic denervation, and motor complications in sporadic PD. MethodsIn this longitudinal analysis, PD participants from the Parkinsons Progression Markers Initiative (PPMI) cohort with CSF SAA testing who initiated levodopa treatment were included. SAA- and SAA+ patients were matched on sex, age, and disease duration at treatment initiation. Motor severity was assessed using MDS-UPDRS Part III, with proportional and absolute responsiveness derived from ON and OFF medication states. Motor complications were assessed using MDS-UPDRS Part IV, and dopaminergic dysfunction was quantified using caudate DAT-SPECT. Linear mixed-effects models examined longitudinal differences as a function of SAA status. FindingsIn this analysis, 40 SAA- patients were compared to 183 matched SAA+ patients. SAA+ patients showed a slower rate of ON-state motor progression than SAA- patients (0.87 vs 3.47 points/year; p = 0.01). Consistently, proportional levodopa responsiveness increased over time in SAA+ patients while declining in SAA- patients (p = 0.036). These differences were accompanied by lower caudate DAT binding at treatment initiation in SAA- patients (p = 0.002) and faster dopaminergic decline over time (p = 0.008). Although SAA+ patients had fewer motor complications at treatment initiation, their progression was similar. InterpretationCSF -synuclein SAA status is associated with divergent levodopa response in PD, with SAA+ patients showing sustained and progressively greater motor benefit, while SAA- patients show declining responsiveness. Faster dopaminergic denervation in SAA- patients may underlie this difference. SAA status captures clinically relevant heterogeneity that may inform patient stratification and therapeutic decision-making.

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Linguistic Validation of the Rett Syndrome Behavior Questionnaire Spanish Translation: a Two-Stage Caregiver Study Across Latin America

Polo Sanchez, M.; Lesmes, A. C.; Muni, N.; Vigneault, F.; Novak, R.

2026-04-23 neurology 10.64898/2026.04.16.26349544 medRxiv
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Background: Rett Syndrome (RTT) is a severe neurodevelopmental disorder affecting approximately 1 in 10,000 live female births worldwide. The Rett Syndrome Behaviour Questionnaire (RSBQ), remains one of the most widely used standardized behavioral assessment tools for RTT. However, the RSBQ was originally validated only in British English, limiting its applicability for Spanish-speaking caregivers and clinical centers across Latin America and Spain. Objective: The primary aim of this study was to develop and validate the comprehension of the Spanish translation of the RSBQ to ensure cultural and linguistic equivalence, enhance data reliability, and facilitate earlier, more accurate clinical assessments among Spanish-speaking RTT populations. Methods: Surveys were administered in two phases to Spanish-speaking caregivers between November 2023 and September 2025. Phase I consisted of 12 guided survey administrations with participants being able to ask clarifying questions and offer linguistic modifications of RSBQ questions. Phase II consisted of independent online administration of the refined Spanish RSBQ and a retest at least 7 days later. Participants were recruited through direct outreach and supported virtually during questionnaire completion. Results: Following data cleaning and quality control, a total of 51 caregivers successfully completed both surveys. The Spanish RSBQ demonstrated high caregiver comprehension and strong engagement across multiple Latin American countries, including Argentina, Mexico, and Peru. Responses were highly correlated between test and retest timepoints, and no question showed biased response distributions. A slight effect of response interval on test-retest correlation was observed, potentially indicating the impact of natural disease progression confounding retest evaluation for long (>80 day) intervals; however this effect did not impact the overall linguistic validation results as analysis of only <21 day test-retest responders confirmed the findings. Conclusions: This linguistic validation study represents the first formal step toward the clinical validation of the Spanish RSBQ, enabling broader inclusion of Spanish-speaking populations in RTT research. The collaborative, bilingual data collection strategy proved both feasible and effective, paving the way for multinational trials and expanding therapeutic accessibility through localized, patient-centered innovation.

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Chlorogenic acid fails to confer neuroprotection in a chronic mouse model of Parkinsons disease

Rajan, A.; Prakash, S.; Singh, D.; Thakur, P.

2026-04-22 neuroscience 10.64898/2026.04.19.719432 medRxiv
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Parkinsons disease (PD) is a progressive neurodegenerative disorder characterized by -Synuclein (-Syn) aggregation, dopaminergic neuronal loss, and chronic neuroinflammation. Chlorogenic acid (CA), a dietary polyphenol abundant in coffee, exhibits antioxidant and anti-inflammatory properties and has shown neuroprotective effects in acute toxin-based PD models. However, its efficacy in chronic, -Syn-driven PD models remains unclear. Here, we evaluated the therapeutic potential of CA using an -Syn-based in vitro system and a chronic -Syn overexpression mouse model that recapitulates key pathological features of human PD. In vitro, CA significantly improved cell viability, reduced -Syn aggregation, and attenuated H2O2-induced apoptosis in U118 and N2a cells. In contrast, chronic oral administration of CA (100 mg/kg for 16 weeks) in C57BL/6J mice (male and female) failed to improve motor behavior, attenuate -Syn pathology, preserve nigrostriatal dopaminergic neurons, or reduce oxidative stress-associated DNA double-strand breaks in vivo. Notably, CA elicited a modest reduction in microglial and astrocytic activation in female mice, highlighting a sex-dependent immunomodulatory response. Collectively, these findings reveal a clear dissociation between robust in vitro neuroprotection and limited in vivo efficacy in a chronic -Syn-driven PD mouse model, emphasizing the importance of incorporating progressive disease paradigms and sex as a biological variable in preclinical therapeutic evaluation.

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Targeted memory reactivation during sleep modulates spindle and slow wave density, but not motor memory consolidation, in Parkinson's disease

Micca, L.; Albouy, G.; King, B. R.; Nieuwboer, A.; Vandenberghe, W.; Borzee, P.; Buyse, B.; Testelman, D.; Nicolas, J.; Gilat, M.

2026-04-27 neurology 10.64898/2026.04.22.26351552 medRxiv
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Motor memory retention is impaired in Parkinson's disease (PD), affecting long-term rehabilitation outcomes. It appears that NREM sleep could be beneficial for consolidation processes in PD, and could be leveraged with non-invasive sleep interventions. This study examined the effect of auditory targeted memory reactivation (TMR) during NREM sleep on the retention of a motor sequence learning finger tapping task in 20 PD and 20 healthy older adults (HOA). TMR was applied during a 2-hour nap and its effect on motor retention was post-nap, after 24-hours and with a dual-task. The impact of TMR on sleep electrophysiology was also evaluated. Results showed no effect of TMR on motor retention or dual-tasking, with no difference between the groups. However, the TMR intervention did increase slow-wave density and decreased spindle density in both groups, and slow-wave amplitude during the presentation of the auditory cues was positively associated with performance in HOA. In conclusion, TMR applied during a 2 hour nap did not enhance motor retention, but the changes in sleep physiological features could be linked to a possible underlying effect on memory processing that warrants further investigation.

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Repurposed COMT Inhibitors Tolcapone and Entacapone Selectively Suppress Aggregation and Seeding of P301 Mutant TAU in Human Neuronal Models

Kozlov, I.; Hung, Y.-S.; Roy, S.; Goud, A. C.; Kouril, R.; Wong, Y.-H.; Das, V.

2026-04-22 neuroscience 10.64898/2026.04.20.719548 medRxiv
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Background and PurposePathogenic aggregation and propagation of seed-competent TAU assemblies drive tauopathies. MAPT P301 mutations accelerate aggregation and enhance seed competence, yet pharmacological strategies selectively targeting these pathogenic species remain limited. We investigated whether the clinically approved catechol-O-methyltransferase inhibitors tolcapone (TOL) and entacapone (ENT) preferentially modulate mutant TAU aggregation and seeding. Experimental ApproachTOL and ENT effects on TAU aggregation were evaluated via cell-free assays, surface plasmon resonance (SPR), and in silico docking. Functional consequences of compound-modified fibrils were assessed in mutant TAU-expressing SH-SY5Y cells. Translational relevance was examined in human induced pluripotent stem cell (hiPSC)-derived neurons exposed to pathogenic K18 fibrils, followed by post-seeding compound treatment. Key ResultsBoth compounds dose-dependently inhibited TAU aggregation, exhibiting greater potency, stronger SPR binding affinities, and more favorable computed interaction energies for P301S mutant versus wild-type TAU. Fibrils formed with TOL or ENT induced less downstream TAU oligomerization and phosphorylation in SH-SY5Y cells, with TOL showing superior protection. In hiPSC-derived neurons, post-seeding treatment with either compound decreased fibril-induced, sarkosyl-insoluble TAU aggregation and phosphorylation without overt cytotoxicity. Conclusion and ImplicationsTOL and ENT preferentially inhibit the aggregation and seeding of pathogenic P301 mutant TAU. This supports mutation-focused pharmacological strategies and highlights catechol scaffolds as viable starting points for the development of disease-modifying therapeutics. Future research must determine the precise interaction mechanisms with aggregation intermediates and evaluate in vivo efficacy in animal models.

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Trans-Aqueduct Access to the Third Ventricle for Delivery of Medical Devices: A Feasibility Study

Haines, M. H.; Ronayne, S. M.; Pickles, K.; Begg, D. A.; Hurley, P. J.; Ferraccioli, M.; Desmond, P.; Opie, N. L.

2026-04-21 neurology 10.64898/2026.04.14.26348906 medRxiv
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This research demonstrates that the trans-aqueduct approach is a feasible, minimally invasive access pathway to the third ventricle, offering a potential route to the deep brain for therapeutic technologies. Further pre-clinical investigation is required to thoroughly evaluate physiological tolerance, trauma risk, and the long-term implications of intraventricular implantation. The third ventricle is a high-value site for neuromodulation due to its proximity to deep-brain targets, including the subthalamic nucleus (STN) and globus pallidus internus (GPi). This study defined the anatomical pathway; and evaluated the technical feasibility of retrograde access to the third ventricle via the cerebral aqueduct using minimally invasive interventional techniques. Evaluation was conducted in three phases using human MRI datasets (n=16; mean age 48.4 years) and cadaveric specimens (n=6; mean age 88.2 years). Phase 1 involved morphometric MRI analysis of the aqueduct and ventricles. Phase 2 tested trans-aqueduct access on cadaver specimens via fluoroscopically guided guidewires and catheters. Phase 3 utilized direct anatomical dissections on cadaver specimens (n=3) to morphometrically measure the third ventricular cavity and its relationship to deep-brain nuclei. Measurements across the sample groups showed a mean aqueduct diameter of 1.6 mm (SD=0.14). Third ventricle dimensions averaged 27.6 mm (ventral-dorsal), 19.9 mm (caudal-cranial), and 5.7 mm (lateral). Successful access to the third ventricle was achieved in 83% (5/6) of cadaveric specimens. The optimal technical configuration utilized a 0.018'' angled-tip guidewire and 5-6 Fr catheters; the aqueduct accommodated diameters up to 2.0 mm with minimal resistance. The STN and GPi were localized within 5-20 mm of the ventricular volumetric centroid. The trans-aqueduct approach is a technically feasible, minimally invasive pathway for accessing the third ventricle. This route offers a potential alternative for the delivery of therapeutic neurotechnologies. Further research is required to assess physiological tolerance, trauma risk, and the long-term safety of intraventricular implantation.

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Integrating α-Synuclein Seeding Activity (SAA) into routine practice: insights from the multicenter ALZAN Cohort

Jourdan, O.; Duchiron, M.; Torrent, J.; Turpinat, C.; Mondesert, E.; Busto, G.; Morchikh, M.; Dornadic, M.; Delaby, C.; Hirtz, C.; Thizy, L.; Barnier-Figue, G.; Perrein, F.; Jurici, S.; Gabelle, A.; Bennys, K.; Lehmann, S.

2026-04-23 neurology 10.64898/2026.04.21.26351389 medRxiv
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Objectives: To evaluate the diagnostic performance of the -synuclein seed amplification assay (SAA) and characterize the impact of -synuclein co-pathology on cognitive and biological profiles in routine clinical practice. Methods: We included 398 patients from the prospective multicenter ALZAN cohort recruited from memory clinics in Montpellier, Nimes, and Perpignan. All participants underwent CSF and blood sampling with measurement of CSF biomarkers (A{beta}42/40, tau, ptau181) and plasma biomarkers (A{beta}42/40, ptau181, ptau217, GFAP, NfL). Cognitive assessment was performed using the Mini-Mental State Examination (MMSE). Clinical diagnoses were independently confirmed by two senior neurologists. Syn status was determined by SAA (RT-QuIC). Results: Of 398 patients, 19 out of 20 patients with Lewy body dementia (LBD) (95.0%) and 32 out of 203 patients with AD (15.8%) were SAA+. SAA-positivity presented a sensitivity of 95% and a specificity of 93.5% for distinguishing LBD from patients without LBD or AD. In the entire cohort, SAA+ patients showed lower MMSE scores (p<0.01), lower CSF A{beta}42/40 ratio (p<0.01), and elevated plasma GFAP (p<0.05). Within the AD group, no significant differences in CSF or blood biomarkers were observed between SAA+ and SAA- patients. Within the AD subgroup, no significant differences in CSF or blood biomarkers were observed between SAA+ and SAA- patients, except for a lower CSF A{beta}42/40 ratio in SAA+ patients (p<0.01). Interpretation: SAA demonstrates good diagnostic capabilities for detecting LBD and confirms notable Syn co-pathology in AD. This study highlights the limitations of routine CSF and emerging blood biomarkers in capturing Syn pathology and the value of integrating SAA into routine neurodegenerative disease assessment.

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The burden of neurogenic orthostatic hypotension in patients with multiple system atrophy: a real-world study

Kmiecik, M. J.; O'Brien, L.; Szpyhulsky, M.; Iodice, V.; Freeman, R.; Jordan, J.; Biaggioni, I.; Kaufmann, H.; Vickery, R.; Miller, A.; Saunders, E.; Rushton, E.; Valle, L.; Norcliffe-Kaufmann, L.

2026-04-22 neurology 10.64898/2026.04.20.26351214 medRxiv
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BackgroundAlthough neurogenic orthostatic hypotension (nOH) is a common and debilitating feature of multiple system atrophy (MSA), little is known about the burden of symptoms in the real world. ObjectivesTo design and conduct a cross-sectional community-based research survey targeting patients with MSA, with and without nOH. MethodsWe recruited patients with MSA to complete an anonymous online survey covering three core themes: 1) timely diagnosis, 2) nOH pharmacotherapy and refractory symptoms, and 3) confidence in physician knowledge. Responses were grouped by pre-specified diagnostic certainty levels. Relationships between symptoms, function, and pharmacotherapy were assessed using univariate and multivariate methods. ResultsWe analyzed 259 respondents with a self-reported diagnosis of MSA (age: M=64.38, SD=8.09 years; 44% female). In total, 42% also had a diagnosis nOH; 40% had symptoms highly suspicious of nOH, but no diagnosis; and 21% reported having never had their blood pressure measured in the standing position at a clinical visit. Treatment with a pressor agent was independently associated with the presence of other symptoms of autonomic failure. Each additional nOH symptom reported increased the odds of requiring pharmacotherapy by 18%. Yet, despite anti-hypotensive medication use, 97% of patients reported limitations in their ability to bathe, cook, or arise from a chair/bed with 76% needing caregiver support for refractory nOH symptoms. ConclusionsThis cross-sectional representative sample shows nOH is underrecognized and undertreated in MSA patients, leading to substantial functional limitations. It is our hope that these findings are leveraged for planning future trials and advocating for better treatments.

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Assessing ageing, cognitive ability and freezing of gait in Parkinson's disease through integrated brain-heart network dynamics

Pitti, L.; Sitti, G.; Candia-Rivera, D.

2026-04-23 neurology 10.64898/2026.04.22.26351482 medRxiv
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Parkinson's Disease (PD) is a complex neurodegenerative disorder that manifests through systemic, large-scale physiological reorganizations. While research often focuses on region-specific neural changes, there is a growing need for multidomain approaches to capture the complexity of the disease and its clinical heterogeneity. This study proposes an analytical pipeline to evaluate Brain-Heart Interplay (BHI) as a novel systemic biomarker for neurodegeneration and healthy ageing. In this study we assessed BHI across three open-source datasets (EEG and ECG signals). We compared Healthy Young, Healthy Elderly, and PD patients in resting state to investigate the effects of ageing and cognitive performance. Additionally, we studied BHI trends in PD patients in the moment of freezing of gait (FOG). Methodologically, brain network organization was quantified using coherence-based EEG connectivity and graph theory, while heart activity was analyzed through Poincare plot-derived measures of cardiac autonomic activity. The coupling between these two systems was measured using the Maximal Information Coefficient to capture linear and non-linear dependencies between global cortical organization and cardiac autonomic outflow. The results demonstrate that BHI is a sensitive biomarker for detecting early multisystem dysfunction in both neurodegeneration and ageing. Furthermore, the identification of specific BHI trends during FOG onset suggests new opportunities for understanding the physiological mechanisms driving motor complications in PD. Our proposed pipeline provides a guiding tool for large-scale physiological assessment in clinical research.

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Identifying disease-causing mechanisms and fundamental biology of neuromuscular disorder genes through genomic feature analysis

Martin, A.; Llanes-Cuesta, M. A.; Hartley, J. N.; Frosk, P.; Drogemoller, B. I.; Wright, G. E. B.

2026-04-22 genetics 10.64898/2026.04.21.719902 medRxiv
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IntroductionNeuromuscular disorders (NMDs) encompass a broad group of conditions that primarily affect the peripheral nervous system. They are often caused by genetic alterations that impair skeletal muscle function and result in debilitating symptoms. Obtaining an accurate molecular diagnosis remains a challenge, potentially because variants in genes that have yet to be identified as causal. We therefore used advanced computational methods to study the genetic architecture of NMDs and to identify key features that distinguish NMD genes from other genes in the broader genome. MethodsCurated genes implicated in NMDs (n = 639; GeneTable of NMDs) were obtained and merged with a comprehensive set of genomic features for human autosomal protein-coding genes. Machine-learning-based feature selection and ranking were performed using Boruta, along with complementary analytical approaches. These analyses were used to identify the most important genic features (n = 134, subcategories: gene complexity, genetic variation, expression patterns, and other general gene traits) for discriminating NMD genes from other genes in the genome ResultsNMD genes exhibit enriched expression in disease-relevant tissues, including skeletal muscle and heart. Additionally, compared with other protein-coding genes, these genes exhibit increased transcriptomic complexity (e.g., longer transcripts and more unique isoforms), contain more short tandem repeats, and show greater variation in conservation across model organisms. ConclusionsThis study identified several key genomic features that may distinguish NMD genes from the rest of the genome. This may enhance the identification of novel causal genes and could ultimately facilitate earlier diagnosis and medical management for affected individuals.

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Evaluating High-Frequency Automated Cognitive Tasks Across Immune-Mediated Inflammatory Disease and Neurodegenerative Disease Patients.

Kaula, A. J.; Taptiklis, N.; Cormack, F.; Kuijper, L. M. C.; Avey, S.; Chatterjee, M.; Rehman, R. Z. U.; de Bot, S.; Pilotto, A.; van der Woude, C. J.; Lamb, C.; Reilmann, R.; Manyakov, N. V.; Maetzler, W.; Ng, W.-F.

2026-04-27 health systems and quality improvement 10.64898/2026.04.26.26351685 medRxiv
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This analysis evaluates the feasibility and psychometric properties of daily digital cognitive assessments (DCAs) delivered on smartphones using data from the large, international Identifying Digital Endpoints to Assess FAtigue, Sleep and acTivities of daily living in Neurodegenerative disorders and Immune-mediated inflammatory diseases (IDEA-FAST) study. The data we analyse were collected from patients with neurodegenerative diseases (NDDs) and immune-mediated inflammatory diseases (IMIDs), and healthy controls (a subset who participated in all phases of the study, total N=977) in their own homes. These data were obtained alongside data from other devices that monitored physiology, kinematics, and sleep quality. Following a baseline visit, participants were remotely monitored via three scheduled daily sessions for 6-7 days in each of 4 active assessment phases (APs). APs were separated by 6-week intervals. Daily schedules comprised a morning psychomotor vigilance task (PVT) with eDiary, afternoon session (eDiary only), and an evening digit symbol substitution task (DSST) with eDiary. We evaluated session coverage using logistic mixed effects, test-retest reliability using ICCs, disease impacts on performance using linear mixed effect ANCOVA, and familiarisation using linear mixed effects. Overall coverage was 67.5% for the PVT and 77.0% for the DSST, with no significant differences between the healthy volunteers and disease cohorts. Coverage varied significantly by time-of-day (Evening > Morning > Afternoon), and improved with age, with an interaction revealing session time-of-day affected older participants less, all p < .001. Coverage was highest in AP 1 and reduced in subsequent APs. AP-day effects on coverage interacted significantly with AP, with a modest decline over AP 1, and the pattern reversed in APs 2-4. Baseline reliability was good (> .70) for both PVT mean reaction time and DSST total correct across all cohorts, and the movement-based measure from the DSST ranged [.55, .75], with lower values in the Parkinson's Disease and Primary Sjogren's Syndrome cohorts. Both tasks showed significant cohort effects, with performance in IMID cohorts intermediate between healthy controls and NDD. Longitudinal analysis revealed significant familiarisation effects in DSST. This was greatest in healthy controls, with significant attenuation of these effects in disease cohorts. No effect of familiarisation was seen in the PVT. Collectively, these results support the usefulness of at-home cognitive assessment on smartphones. Brief measures of cognition can be captured remotely in disease as well as controls with good adherence and sensitivity to distinguish known patient groups from healthy controls.

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Effects of transcranial direct current stimulation (tDCS) combined with cognitive therapy in individuals with cognitive impairment: a systematic review and meta-analysis.

Soto-Ferndandez, P.; Toledo-Rodriguez, L.; Figueroa-Vargas, A.; Figueroa-Taiba, P.; Billeke, P.

2026-04-27 neurology 10.64898/2026.04.26.26351755 medRxiv
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Background: Cognitive impairment poses a significant challenge to healthcare systems worldwide, impacting patient autonomy, social participation, and quality of life, while placing a considerable burden on caregivers. Non pharmacological interventions, particularly cognitive training and non invasive brain stimulation, have emerged as promising therapeutic strategies. Objective: This study aims to quantify the synergistic effects of transcranial direct current stimulation (tDCS) with cognitive training on cognitive function across a spectrum of pathologies that induce cognitive impairment. Methods: We conducted a systematic review and metaanalysis following PRISMA guidelines. We searched PubMed for randomized controlled trials that investigated the effect of combined tDCS and cognitive training compared with cognitive training alone. The analysis was based on the GRADE framework for systematic reviews and metaanalyses. Results: Across 27 studies including 1,012 participants, tDCS combined with cognitive training showed a small effect compared with cognitive training alone (SMD = 0.36, 95% CI: 0.15 0.56). The effect was found only immediately after the intervention and declined during follow-up. Conclusion: tDCS combined with cognitive training may provide a small, short term benefit for cognitive function, but high heterogeneity across studies and loss of effect at follow up underscore the need for larger, better standardized trials to clarify its clinical value.

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Psychomotor retardation and risk of Parkinson's disease in unipolar depression: a retrospective cohort study

Morrin, H.; Badenoch, J. B.; Burchill, E.; Fayosse, A.; Singh-Manoux, A.; Shotbolt, P.; Zandi, M. S.; David, A. S.; Lewis, G.; Rogers, J. P.

2026-04-27 psychiatry and clinical psychology 10.64898/2026.04.26.26351763 medRxiv
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Background: Depression is associated with an increased risk of subsequent Parkinson's disease. Neuroimaging studies suggest a neurobiological overlap in mechanisms underlying Parkinson's disease and psychomotor retardation in depression. Our aim was to investigate whether, among individuals with depression, the presence of psychomotor retardation was associated with the development of subsequent Parkinson's disease. Methods: In a retrospective cohort study, electronic healthcare records from individuals diagnosed with depression at age 40 or over in a large mental health service in London, UK were examined for the presence of psychomotor retardation. Linkage to general hospital records was used to ascertain diagnoses of Parkinson's disease between 2007 and 2023. Cox regression was used to compare the hazard of Parkinson's disease in individuals with depression with and without psychomotor retardation. Results: Among 6327 patients with depression, 2402 (38.0%) had psychomotor retardation. The adjusted hazard ratio for development of Parkinson's in those with psychomotor retardation was 1.43 (95% CI 1.02 - 2.01, p = 0.04). Secondary analyses demonstrated a significant difference in psychomotor retardation incidence at least 10 years before Parkinson's diagnosis. Conclusions: Psychomotor retardation in later-life depression is associated with increased risk of subsequent Parkinson's diagnosis over an extended period of time, suggesting that the relationship cannot solely be explained by misdiagnosis. Psychomotor retardation may therefore serve as a marker of prodromal Parkinson's disease.

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Variation at COMT, ADH1B-ADH1C and HTR2A loci is associated with genetic predisposition to substance use disorders in Ukrainians

Bashynska, V.; Zahorodnia, O.; Borysovych, Y.; Zaplatnikov, Y.; Vasilyeva, V.; Arefiev, I.; Darvishov, N.; Osychanska, D.; Karapetov, A.; Melnychuk, O.; Boiko, O.; Zil'berblat, G.; Turos, O.; Prokopenko, I.; Kaakinen, M.

2026-04-24 genetic and genomic medicine 10.64898/2026.04.23.26351594 medRxiv
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Background: Substance use disorders (SUDs), including alcohol and drug dependence, and smoking, pose a public health threat with their high prevalence and comorbidity with other diseases, and contribution to mortality. SUDs are highly correlated, and their genetic background is shared to some degree. Objectives: We aimed to investigate the genetic associations of previously reported loci for a wide range of SUDs in an unstudied Ukrainian population. Methods: We collected data from 595 individuals (339 women, 253 men), including 321 participants from two rehab centres. Based on clinical review and questionnaire data we defined drug dependence, alcohol dependence, alcohol abuse, binge drinking, smoking, opiate, amphetamine, cannabis, and hallucinogen use, along with several intermediary alcohol use and smoking variables considering the amount of use and the level of dependence. We genotyped COMT-rs4680, ADH1B-ADH1C-rs1789891, and HTR2A-rs6313, and applied logistic and ordered logistic regression assuming an additive inheritance model, controlling for the recruitment group, other substance uses, age, and sex, in the association analyses. Results: We replicate (P<0.05) the associations at COMT-rs4680 with smoking status (OR[95% CI]=1.56[1.01-2.41], P=0.047) and heaviness (1.37[1.04-1.80], P=0.026), and at ADH1B-ADH1C-rs1789891 and HTR2A-rs6313 with alcohol dependence (1.69[1.03-2.76], P=0.038 and 0.66[0.47-0.92, P=0.016], respectively). Furthermore, we provide evidence for an association at HTR2A-rs6313 with hallucinogen use (0.58[0.35-0.98], P=0.040). Conclusion: In this study on multiple SUDs we shed light on the genetic background of SUDs in Ukrainians and provide further evidence that variation at COMT is mainly associated with smoking, at ADH1B-ADH1C with alcohol-related variables, whereas HTR2A is a more general SUD-associated locus.

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Multimodal MRI and Machine Learning Uncovers Distinct Progression Patterns in Friedreich Ataxia

Saha, S.; Georgiou-Karistianis, N.; Teo, V.; Szmulewicz, D. J.; Strike, L. T.; Franca, M. C.; Rezende, T. J.; Harding, I. H.

2026-04-22 neurology 10.64898/2026.04.21.26351375 medRxiv
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Background Friedreich ataxia (FRDA) is a rare neurodegenerative disorder with substantial heterogeneity in clinical presentation and progression, complicating prognosis and trial design. Neuroimaging offers objective biomarkers to track disease evolution, yet variability in progression patterns remains poorly understood. Objective To identify biologically meaningful FRDA progression subtypes using longitudinal multimodal MRI and assess their associations with demographic, genetic, and clinical factors. Methods Longitudinal structural and diffusion MRI data from 54 FRDA and 57 controls were analysed. Annualised progression rates of macrostructural (volumetric) and microstructural (diffusion) features across cerebellum, brainstem, and spinal cord regions were clustered using Gaussian Mixture Models. Cluster robustness was assessed using per-cluster Jaccard similarity and other validation metrics. Random Forest classification examined predictors of cluster membership. Results Three reproducible clusters/subtypes emerged: micro-dominant/dual progression, characterised by widespread microstructural deterioration with modest volumetric decline; macro-dominant, marked by pronounced volumetric decline with minimal microstructural change; and minimal/no progression, showing negligible change in all measures. FRDA participants predominated in the first two clusters. Random Forest prediction of cluster membership using clinical and demographic variables identified length of the trinucleotide repeat expansion in the FXN gene as key predictor. Conclusions Data-driven clustering of longitudinal MRI identified distinct FRDA subtypes with unique co-progression patterns, underscoring genetic burden as a key driver. Recognising such heterogeneity can improve patient stratification, enable personalised monitoring, and guide targeted therapeutic strategies. Future studies should validate these subtypes in larger, more diverse cohorts and integrate additional biomarkers for enhanced precision.

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Decision-making in patients with ALS: experiences and implications for decision support

Nagase, M.; Hino, K.; Sakamoto, A.; Seo, M.

2026-04-24 nursing 10.64898/2026.04.22.26351518 medRxiv
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Patients with amyotrophic lateral sclerosis (ALS) face critical decisions regarding life-sustaining treatments, such as invasive mechanical ventilation and percutaneous endoscopic gastrostomy. Advance care planning and shared decision-making are standard supportive frameworks but they often fail to account for structural pressures like progressive decline, shifting patient values, and fear of becoming a burden that may influence decision-making. This study explores how patients with ALS interpret ventilator and care options amid progressive physical decline, thereby reconsidering approaches to decision support. Using a qualitative descriptive design, the researcher (a nurse/sociologist) conducted 2-3 hour home interviews with five purposively sampled patients with ALS. Data, including eye-tracking-aided responses, were analysed via Sandelowskis framework. Rigour was ensured through team-based triangulation, independent coding by two researchers, and a reflexive audit trail. Subjective narratives were prioritised without medical record cross-referencing to capture patients experiences. Four categories emerged: (1) Rewriting clinical prognosis into a narrative of exploration via peer models, where meeting active ventilator users transformed future perceptions; (2) The conflict between securing care infrastructure and the burden on family, which greatly influenced the will to survive; (3) Existential fluctuation, where patients intentions shifted with daily fulfilment and family events; and (4) Governance of the body via pre-emptive technology use and training carers as physical extensions. Findings showed decision-making was a multi-layered process redefining lifes meaning within social resources. This necessitate shifting from independent to relational autonomy, where agency relies on care infrastructure, not physical ability. Treatment choice is a dynamic exploration requiring narrative companions to support existential fluctuations. Professionals must coordinate environments to reduce patient indebtedness. Limitations include the small, resource-advantaged sample (N = 5) and reliance on subjective narratives without medical record verification. Living with ALS means governing a new self through relational support and continuous dialogue.

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Leronlimab a humanized anti-CCR5 monoclonal antibody ameliorates hepatic fibrosis in two preclinical fibrosis mouse models

Palmer, M.; Hashiguchi, T.; Arman, A. C.; Shirakata, Y.; Buss, N. E.; Lalezari, J. P.

2026-04-21 pharmacology and toxicology 10.64898/2026.04.17.719186 medRxiv
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BackgroundChemokine receptor type 5 (CCR5) is expressed on hepatic stellate cells (HSCs), which, together with fibroblasts, are major producers of extracellular matrix during liver fibrosis. Leronlimab is a humanized IgG4{kappa} monoclonal antibody that binds to CCR5. The objective of the present study was to evaluate the antifibrotic effects of leronlimab in three independent preclinical studies using two mouse models of liver fibrosis. MethodsIn STAM (Stelic Animal Model) model 1, leronlimab was administered at doses of 5 or 10 mg/kg/week for 3 weeks. STAM model 2 was conducted as a confirmatory study to validate the antifibrotic effect observed with the 10 mg/kg/week dose in STAM model 1. In a third study, a carbon tetrachloride (CCl)-induced liver fibrosis mouse model was used to evaluate leronlimab administered at 10 mg/kg/week for 3 weeks. An isotype-matched control antibody was included in all studies for comparison. Evaluations included liver enzymes and histological assessment of liver fibrosis. ResultsIn STAM model 1, leronlimab at 10 mg/kg/week significantly reduced fibrosis area compared with the isotype control (p = 0.0005). These findings were confirmed in STAM model 2 (p < 0.0001). Consistent antifibrotic effects were also observed in the CCl-induced liver fibrosis model (p = 0.0006). ConclusionsCollectively, these preclinical results demonstrate that CCR5 blockade by leronlimab is associated with a significant reduction of established liver fibrosis in multiple mouse models and support further evaluation of leronlimab as a potential therapeutic option, either as monotherapy or in combination regimens, for chronic liver diseases with fibrosis.

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Serotonergic Polypharmacology of 2-Halogenated Tryptamines

Yacoub, J.; Bray, E.; Bayyat, J.; Glatfelter, G. C.; Leake, A.; Buitrago, E. M.; Maitland, A. D.; Partilla, J.; Cavalco, N. G.; Schalk, S. S.; Lammers, J. C.; Baumann, M. H.; McCorvy, J.; Leahy, J. W.; Gulick, D.; Witowski, C. G.; von Salm, J. L.

2026-04-21 pharmacology and toxicology 10.64898/2026.04.16.718915 medRxiv
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Serotonergic psychedelics such as N,N-dimethyltryptamine (DMT) and 4-phosphoryloxy-N,N-dimethyltryptamine (psilocybin) show therapeutic promise for psychiatric and neurodegenerative disorders but may be limited by liabilities from serotonin (5-HT)-2A mediated psychoactive effects and potential cardiotoxicity via 5-HT2B activation. To address these limitations, we designed and synthesized 2-halogenated derivatives of DMT and psilacetin to reduce 5-HT2A/5-HT2B activity while retaining engagement of therapeutically relevant targets, particularly 5-HT6, 5-HT2C, and 5-HT1B. This study demonstrated that 2-position halogenation decreased affinities, potencies, and efficacies at 5-HT2A and 5-HT1A receptors while preserving potent 5-HT6 agonism, especially for 2-Br-psilocin. The analogues exhibited reduced affinities at 5-HT2B and hERG ion channels, suggesting safer cardiac valve and cardiotoxic profiles. In C57BL/6J mice, 2-Br-psilacetin did not induce the head-twitch response and attenuated 2,5 dimethoxy-4-iodoamphetamine (DOI)-induced head-twitch behavior, suggesting a reduced potential for inducing psychedelic effects. Behavioral assays further revealed improvements in stress-induced affective measures and hippocampus-independent cued learning at intermediate doses. These findings identify 2-halogenated tryptamines as polypharmacological serotonergic ligands with reduced psychoactivity and cardiac valve and toxic liabilities, supporting their potential as next-generation psychedelic-inspired therapeutics. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=86 SRC="FIGDIR/small/718915v1_ufig1.gif" ALT="Figure 1"> View larger version (16K): org.highwire.dtl.DTLVardef@16aa5b2org.highwire.dtl.DTLVardef@a4813corg.highwire.dtl.DTLVardef@20c5f7org.highwire.dtl.DTLVardef@1a50a61_HPS_FORMAT_FIGEXP M_FIG C_FIG

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Zebrafish Functional Screening of FDA-Approved Drugs for Autosomal Dominant Retinitis Pigmentosa Caused by RHODOPSIN Q344X Mutation

Wang, B.; Ganzen, L.; Coskun, E.; James, R.; Kha, T.; Zhu, X.; New, J. A.; Tsujikawa, M.; Leung, Y. F.

2026-04-21 neuroscience 10.64898/2026.04.18.719270 medRxiv
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Retinitis Pigmentosa (RP) is a group of inherited retinal degenerations for which most subtypes lack effective drug treatments. This challenge is particularly critical for autosomal dominant (ad) RP, which is often unsuitable for gene replacement therapy. To address this challenge, we screened an FDA-approved compound library using a zebrafish adRP model expressing a human RHODOPSIN transgene with the Q344X mutation. The screen evaluated drug effects on larval visual behavior by assessing the visual-motor response (VMR). Four compounds significantly improved VMR in Q344X zebrafish: amitriptyline, difluprednate, maprotiline, and prednisolone. Further characterization revealed that these hits act through distinct mechanisms, including reducing rod death, promoting rod neogenesis, and enhancing the function of extraocular photoreceptors. Together, these findings demonstrate the potential to repurpose these drugs for adRP caused by the RHO Q344X mutation, providing preclinical candidates and revealing potential targets for future drug development.

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Non-invasive glucose monitoring vs iCGM: a systematic review and meta-analysis of accuracy and methodological challenges

Zhang, H.; Dromard, E.; Tsang, K. C. H.; Guemes, A.; Guo, Z.; Baldeweg, S. E.; Li, K.

2026-04-27 endocrinology 10.64898/2026.04.24.26351680 medRxiv
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Non-invasive glucose monitoring (NIGM) has been pursued for decades, yet no device has achieved regulatory approval despite numerous studies reporting high accuracy. This systematic review and meta-analysis of 32 studies (38 cohorts: 20 NIGM, 18 iCGM; N = 1,693) investigated methodological factors underlying this accuracy-regulatory gap. The pooled Mean Absolute Relative Difference (MARD) for NIGM (10.21%; 95% CI: 8.73-11.69%) showed no significant difference from iCGM (11.82%; 95% CI: 10.36-13.29%; p = 0.13), with extreme heterogeneity (I^2 = 95.2%). Meta-regression revealed that study duration was the strongest predictor of NIGM accuracy ({beta} = 3.94, p < 0.001), with MARD degrading from 8.7% in short-term to 15.2% in long-term studies, while iCGM accuracy remained stable. Only 15% of NIGM cohorts validated in the hypoglycemia range, compared to 89% of iCGM studies (p < 0.001). These findings suggest that reported NIGM accuracy is substantially influenced by methodological asymmetries.