Lewy body disease (LBD) and Alzheimer’s disease (AD) are the most common causes of cognitive decline and dementia and are associated with characteristic alterations in resting-state electroencephalographic (rsEEG) activity. This multicenter exploratory study investigated periodic and aperiodic rsEEG features in patients with cognitive decline due to Lewy body disease (LBCD) and Alzheimer’s disease (ADCD), compared with cognitively unimpaired older adults (Nold), and examined the clinical relevance of these markers in LBCD. A total of 140 LBCD, 135 ADCD, and 118 Nold datasets from the PDWAVES archive underwent spectral parameterization to decompose rsEEG power spectra (1–30 Hz) into periodic peaks and aperiodic background activity. Both clinical groups showed a significant slowing of the individual alpha frequency (IAF), more pronounced in LBCD, along with reduced periodic alpha and beta power reflected in a lower vigilance index. The aperiodic exponent was elevated in both groups, and the aperiodic offset was also higher in LBCD, suggesting steeper spectral profiles consistent with increased inhibitory cortical tone. Within the LBCD group, poorer cognition was associated with higher low-frequency alpha power, whereas better cognition was predicted by higher high-frequency alpha power. A reduced vigilance index was associated with the presence of visual hallucinations, while no associations emerged for other symptoms. These findings suggest that combined periodic and aperiodic rsEEG features may provide relevant markers of altered vigilance regulation in LBCD. Future studies should evaluate whether these EEG markers can inform targeted interventions, such as neuromodulatory or audiovisual stimulation, to stabilize quiet-vigilance states and improve clinical outcomes. Panel A shows the spectral parameterization of rsEEG activity into periodic and aperiodic components. Panel B summarizes the main group differences in key rsEEG markers across LBCD, ADCD, and Nold participants. Panel C shows the topographical associations between the vigilance index and cognition and visual hallucinations in LBCD; colors reflect the direction and strength of the associations. For the visual hallucinations map, negative log-odds indicate lower odds of hallucinations for higher vigilance index values, whereas positive log-odds indicate higher odds; values around ± 1.5 correspond approximately to odds ratios of 0.22 and 4.5, respectively. Abbreviations: rsEEG, resting-state electroencephalography; LBCD, cognitive decline due to Lewy body disease; ADCD, cognitive decline due to Alzheimer’s disease; Nold, cognitively unimpaired older adults; IAF, individual alpha frequency; MMSE, Mini-Mental State Examination; p, standardized regression coefficient; log-odds, logistic regression coefficient.

BACKGROUND:Plasma phosphorylated-tau at threonine-217 (p-tau217) and threonine-181 (p-tau181) are scalable, minimally invasive biomarkers of Alzheimer's disease (AD) pathology. In Parkinson's disease (PD), AD co-pathology may contribute to its clinical heterogeneity. However, the existing literature has predominantly focused on p-tau181, with comparatively limited investigation of p-tau217. OBJECTIVE:The aim is to evaluate plasma p-tau217 and p-tau181 as biomarkers of AD co-pathology across the PD cognitive spectrum, relative to a cohort of dementia-free older adults. METHODS:Plasma p-tau217 and p-tau181 were measured in 70 PD patients and 83 older adults. Associations with cognitive impairment, disease severity (Hoehn-and-Yahr), and neurostructural measures-including global atrophy, hippocampal volume, and a magnetic resonance imaging-based AD signature-were assessed using correlation and dominance analyses. RESULTS:Both p-tau217 and 181 were higher in PD with cognitive impairment and dementia compared with cognitively normal PD. P-tau217 showed stronger associations than p-tau181 with AD-like neurostructural changes, multidomain cognitive deficits, greater disease severity, and reduced functional independence. CONCLUSIONS:Plasma p-tau217 and p-tau181 may serve as scalable markers of AD-related processes associated with neurostructural, clinical, and cognitive outcomes in PD. © 2026 The Author(s). Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

INTRODUCTION:We evaluated whether the brain glymphatic drainage function estimated by the diffusion tensor imaging along the perivascular space (DTI-ALPS) index relates to white matter (WM) integrity, Alzheimer's disease (AD) neuropathology, resting-state electroencephalogram (rsEEG) alpha rhythms underpinning quiet vigilance, and cognitive decline in mild cognitive impairment (MCI). METHODS:Clinical, neuroimaging, and rsEEG data were analyzed in matched mild cognitive impairment due to AD (ADMCI) and MCI not due to AD (noADMCI) participants. DTI-ALPS index and aperiodic and periodic components of the rsEEG power spectra were calculated following standard pipelines. RESULTS:Lower DTI-ALPS index was associated with higher AD neuropathology and WM lesions, lower periodic rsEEG alpha rhythms, and worse cognition in patients with ADMCI and noADMCI as a whole population, with the ADMCI (over noADMCI) group showing lower DTI-ALPS index, greater AD neuropathology, and lower periodic rsEEG alpha rhythms. CONCLUSIONS:The DTI-ALPS index may capture glymphatic system impairment linked to AD neuropathology, vigilance dysfunction, and cognitive decline in MCI.

BACKGROUND:Motor asymmetry is a hallmark of Parkinson's disease (PD), but ~20% of patients present with symmetric motor signs, which are associated with faster disease progression and poorer dopaminergic response. The impact of motor symmetry on activities of daily living (ADL) outcomes following subthalamic deep brain stimulation (STN-DBS) remains unclear. We hypothesised that patients with symmetric PD experience less ADL improvement post-STN-DBS than asymmetric PD patients. METHODS:This was a prospective, quasi-experimental, non-randomised, controlled, international multicentre study with a 6-month follow-up. The primary outcome was the Scales for Outcomes in Parkinson's Disease-Motor ADL scale. Secondary outcomes included Unified Parkinson's Disease Rating Scale motor examination and Parkinson's Disease Questionnaire-8 (PDQ-8). We defined symmetric PD as a right-to-left hemibody motor score equalling 1. We analysed within-group longitudinal changes, between-group outcome differences, effect size and correlations between PDQ-8 and motor changes. We confirmed results in a propensity-score matched subcohort with well-balanced demographic and clinical parameters. RESULTS:We included 200 patients with asymmetric and 54 with symmetric PD. In symmetric PD, ADL remained stable, which was not associated with the observed PDQ-8 improvement. In contrast, in asymmetric PD, ADL improved with a moderate effect size, which correlated moderately with PDQ-8 improvement. In symmetric PD, the absolute risk of experiencing no clinically relevant postoperative ADL improvement was 23.8% higher. CONCLUSIONS:This study provides class IIb evidence of worse ADL outcome of STN-DBS in patients with symmetric compared with asymmetric PD. Clinicians should counsel patients with symmetric PD on their elevated risk of ADL non-response when discussing STN-DBS as a treatment option.

ObjectiveAlzheimer’s disease (AD) co-pathology may contribute to cognitive decline and faster progression in Parkinson’s disease (PD). Although blood-based biomarkers enable biological staging along the AD continuum, their contribution in the clinical-biological characterization of PD phenotypes remains unclear. We investigated associations between plasma biomarkers of AD-pathology [phosphorylated-tau-217(p-tau217), amyloid-beta-42/40 (Aβ42/40)], neurodegeneration [neurofilament light chain (NfL)], and neuroinflammation [glial fibrillary acidic protein (GFAP)] with MRI-derived neurostructural indices, cognition, functional independence, and neuropsychiatric symptoms across the PD cognitive spectrum, compared with dementia-free older adults.MethodsFifty-eight PD patients and 76 older adults underwent brain MRI, neuropsychological assessment, and plasma biomarker quantification. Multiple linear regressions examined associations between plasma biomarkers and MRI-derived measures (global atrophy, hippocampal volume, AD-specific signature) and clinical measures.ResultsAD-pathology markers (p-tau217 and Aβ42/40) showed stronger associations with neurostructural and clinical/cognitive measures than NfL and GFAP. In both cohorts, higher p-tau217 was associated with AD-like MRI alterations and worse global cognition. Further, in PD, p-tau217 reflected memory and executive dysfunctions, while lower Aβ42/40 was associated with reduced functional independence, visuospatial, and socio-cognitive deficits. In older adults, elevated p-tau217 was linked to subjective cognitive decline, language/memory deficits; lower Aβ42/40 to global atrophy, attention, visuospatial and memory deficits. Neuropsychiatric symptoms in PD (depressive mood, anxiety, apathy) were primarily associated with AD-pathology markers, whereas depressive symptoms in older adults were linked to higher NfL.ConclusionPlasma p-tau217 and Aβ42/40 were associated with neurostructural and cognitive impairment in PD and older adults, supporting the potential utility of AD-related plasma biomarkers—particularly p-tau217—for the clinical-biological characterization of cognitive decline in PD.

BackgroundParkinson’s disease (PD) entails widespread neurodegenerative changes extending beyond motor symptoms to cognitive and large-scale network alterations that compromise functional autonomy. Financial abilities (FAs) are complex, ecologically relevant skills crucial for independent living, yet their neurocognitive and neurofunctional substrates in PD remain largely unexplored. This study investigates the cognitive, structural, and neurofunctional correlates of basic and advanced FAs in PD with mild cognitive impairment (PD-MCI), using voxel-based morphometry to identify structural brain changes associated with FAs and resting-state network analyses to elucidate how brain connectivity supports preserved financial functioning.MethodsThirty three individuals with PD-MCI completed a comprehensive neuropsychological assessment, including the Numerical Activities of Daily Living-Financial Short battery, to evaluate basic and advanced FAs. A subset of patients (n = 24) underwent acquisition of 3T structural and resting-state functional neuroimaging data. To identify cognitive and neural predictors of basic and advanced FAs, multiple regression models incorporating demographic covariates, cognitive and neuroimaging predictors were employed via stepwise Akaike Information Criterion and LASSO procedures.ResultsBasic FAs were associated with general cognition and formal numerical competence (i.e., arithmetic knowledge), alongside negative functional correlations between somatomotor and subcortical networks. Advanced FAs were associated with different cognitive functions, such as executive ones, informal numerical competencies (i.e., use of numbers in everyday life), social cognition, language, and memory, and were linked to cerebellar network dynamics, specifically, increased anti-correlation with salience and limbic systems and enhanced synchronization with frontoparietal and subcortical circuits.DiscussionFAs in PD-MCI rely on a dynamic balance between network specialization and compensatory integration, reflecting adaptive reorganization of cortico-subcortical and cerebellar systems that may sustain complex cognitive functioning and functional independence.

BackgroundCognitive impairment is a clinically significant, non-motor symptom of Parkinson’s disease (PD) commonly associated with reduced quality of life, increased caregiver burden, and higher risk of progression to dementia. Mild cognitive impairment in PD (PD-MCI) is expressed heterogeneously, with likely prognostic implications. This pilot study evaluated the feasibility and preliminary diagnostic performance of a Machine Learning/Augmented Reality (ML/AR)-based digital assessment for identifying PD-MCI to compare with clinician-led classification.MethodsThe Altoida NeuroMarker (hereafter, “NeuroMarker”) is a 10 min, self-administered digital cognitive and functional assessment performed by tablet, comprised of thirteen task challenges. The NeuroMarker was administered to 21 patients with PD. NeuroMarker-based MCI classification was compared to clinician-led classification using a confusion matrix to compute sensitivity, specificity, PPV, NPV, accuracy, and Cohen’s κ. Clinical assessments included the MMSE, ACE-III, Hoehn and Yahr stage, and BDI.ResultsThe NeuroMarker identified all six clinician-classified PD-MCI cases and classified an additional 11 patients with likely MCI. Sensitivity was 100% (95% CI: 54.1–100), specificity was 26.7% (95% CI: 7.8–55.1), PPV was 35.3% (95% CI: 14.2–61.7), NPV was 100% (95% CI: 39.8–100), accuracy was 47.6% (95% CI: 25.7–70.2), and κ = 0.17. Group differences were observed for age, ACE-III, sex, and education.ConclusionThese preliminary findings suggest that the NeuroMarker may identify clinician-recognized PD-MCI cases, with the potential to also flag patients with early or subthreshold cognitive impairment. However, the study’s wide confidence intervals, low agreement, smaller sample size, and absence of longitudinal confirmation limit interpretation. Larger studies utilizing comprehensive neuropsychological assessment and longitudinal follow-up are required.

OBJECTIVES:This exploratory study tested the hypothesis that Huntington's disease (HD) is characterized by distinct abnormalities in resting-state electroencephalographic (rsEEG) rhythms compared to Alzheimer's disease (AD). METHODS:Clinical and rsEEG data were collected from 35 patients with HD, 81 patients with AD, and 102 healthy controls (HC). The rsEEG cortical source activations from 30 electrodes were estimated using eLORETA and were harmonized across clinical sites. RESULTS:Compared to the HC group, both the HD and AD groups showed widespread increases in rsEEG delta source activation and decreases in alpha source activation, with the HD patients exhibiting the most pronounced frontal effects. In patients with HD, those abnormal rsEEG source activations were associated with cognitive, motor, and functional deficits. CONCLUSIONS:Patients with HD were characterized by a particular slowing of frontal rsEEG rhythms associated with clinically relevant variables. SIGNIFICANCE:A topographically widespread slowing of cortical oscillatory activity was observed in both HD and AD groups, with a particularly pronounced frontal effect in HD, which may predict a greater impact on the sleep-wake cycle. These observations should be considered exploratory and need validation in future studies with enhanced vigilance monitoring during longer rsEEG recordings.

Sedentary behavior is a recognized and modifiable risk factor for cognitive decline and dementia across neurodegenerative conditions. This study used a smartwatch-based telemonitoring procedure combined with ecological cognitive assessment to examine whether step counts can capture sedentary behavior and its association with cognitive functioning in patients with mild cognitive impairment (ADMCI) and dementia (ADD) due to Alzheimer’s disease. Then, 19 ADD, 28 ADMCI, and 23 cognitively unimpaired older adults (Nold) were consecutively recruited. Participants underwent clinical assessment, resting-state electroencephalography (rsEEG), and neuropsychological testing. They were then monitored at home for approximately one week using Samsung Galaxy Watch 4–6 devices recording step counts (total, purposeful, and incidental) and activity intensity (peak 30-min cadence), together with the unsupervised SmartMe You-TELEMAIA serious videogame battery administered on a commercial tablet for cognitive assessment. The ADD group showed reduced step counts and lower peak cadence than both ADMCI and Nold participants, whereas rsEEG markers and cognitive measures discriminated the three groups with a graded pattern. Within the AD sample, smartwatch-derived activity metrics were associated with cognitive functioning as assessed by conventional neuropsychological testing and ecological serious videogame performance, but showed limited associations with rsEEG rhythms. EEG delta and alpha rhythms were also more abnormal in the ADD group than in the ADMCI group. Home-based daytime activity monitoring with commercial smartwatches indicated that step volume and intensity are associated with cognitive status in patients with ADMCI and ADD. These findings suggest that smartwatch-derived activity metrics may provide feasible and cost-effective markers of everyday functioning in Alzheimer’s disease. a Schematic overview of the study design, including resting-state EEG, one-week smartwatch-based activity monitoring, and unsupervised ecological cognitive assessment with the SmartMe You-TELEMAIA Platform. b Group differences in daily activity metrics across participants with Alzheimer’s disease with dementia (ADD; N = 19), Alzheimer’s disease with mild cognitive impairment (ADMCI; N = 28), and cognitively unimpaired older adults (Nold; N = 23), indicating reduced daily step volume and peak cadence mainly in ADD. c Representative significant associations within the AD clinical sample (ADD + ADMCI; up to N = 47), showing that step metrics were more closely related to cognition (MMSE) and depressive symptom severity (BDI-II) than to resting-state EEG activity, for which only limited associations emerged.

Alzheimer's disease (AD) dementia is associated with marked disruptions in resting-state eyes-closed electroencephalographic (rsEEG) rhythms, particularly in the periodic alpha band (8-12 Hz), suggesting impaired vigilance regulation. In contrast, the aperiodic rsEEG component, reflecting global cortical arousal, has been reported to remain unchanged. This exploratory study examined periodic and aperiodic EEG activity in patients with mild cognitive impairment due to AD (ADMCI) during transitions from quiet wakefulness to light sleep. EEG datasets (∼30 min) from 19 ADMCI patients and 18 matched cognitively unimpaired older adults (control) were analyzed. Vigilance stages were scored using a reduced version of Hori's system, distinguishing the alpha-dominant wakefulness stage and the theta-dominant light sleep (ripples) stage. EEG spectra were parameterized using the specparam algorithm. ADMCI participants showed reduced reactivity of individual alpha power between the wakefulness and ripples stages compared to the control group. Conversely, both groups exhibited comparable increases in fronto-central theta power and steepening of the aperiodic slope and offset. No group differences emerged in aperiodic exponent and offset, although statistical power was limited by modest sample size. Overall, EEG alpha rhythms reflecting vigilance regulation are disrupted in prodromal AD, while periodic and aperiodic signatures of sleep onset are relatively preserved, suggesting selective vulnerability of attentional thalamocortical systems.

Patients with mild cognitive impairment due to Alzheimer’s disease (ADMCI) typically show abnormally high delta (<4 Hz) and low alpha (8–12 Hz) rhythms measured from resting-state eyes-closed electroencephalographic (rsEEG) activity. Here, we hypothesized that the abnormalities in rsEEG activity may be greater in ADMCI patients than in those with MCI not due to AD (noADMCI). Furthermore, they may be associated with the diagnostic cerebrospinal fluid (CSF) amyloid–tau biomarkers in ADMCI patients. An international database provided clinical–demographic–rsEEG datasets for cognitively unimpaired older (Healthy; N = 45), ADMCI (N = 70), and noADMCI (N = 45) participants. The rsEEG rhythms spanned individual delta, theta, and alpha frequency bands. The eLORETA freeware estimated cortical rsEEG sources. Posterior rsEEG alpha source activities were reduced in the ADMCI group compared not only to the Healthy group but also to the noADMCI group (p < 0.001). Negative associations between the CSF phospho-tau and total tau levels and posterior rsEEG alpha source activities were observed in the ADMCI group (p < 0.001), whereas those with CSF amyloid beta 42 levels were marginal. These results suggest that neurophysiological brain neural oscillatory synchronization mechanisms regulating cortical arousal and vigilance through rsEEG alpha rhythms are mainly affected by brain tauopathy in ADMCI patients.

Here, we investigated whether educational attainment influences the neurophysiological mechanisms underlying vigilance regulation, as reflected in resting-state eyes-closed electroencephalographic (rsEEG) rhythms, in patients with dementia due to Parkinson's (PDD) and Lewy body disease (DLB). Clinical, demographic, and rsEEG data were obtained from an international database, including PDD patients (N = 75), DLB patients (N = 50), and cognitively unimpaired older controls (Healthy; N = 54). Each group was partitioned into low (Edu-) and high (Edu+) educational attainment subgroups, matched for age, sex, and cognitive-motor status. We analyzed rsEEG rhythms across the individual delta, theta, and alpha frequency bands. Cortical rsEEG source topography was estimated using eLORETA freeware. In the Healthy group, Edu+ participants exhibited significantly greater widespread rsEEG alpha source activities compared to Edu- participants, possibly reflecting neuroprotective neurophysiological mechanisms. Conversely, in the PDD group, Edu+ patients showed lower widespread rsEEG alpha source activities than Edu- patients, possibly indicating compensatory mechanisms. No significant differences in rsEEG source activities were observed between DLB-Edu+ and DLB-Edu- patients. Educational attainment may be associated with compensatory mechanisms that counteract the abnormal neurophysiological processes underlying rsEEG alpha rhythms and vigilance regulation in PDD patients, but not in DLB patients. Future studies combining rsEEG and neuroimaging techniques should investigate the metabolic and functional connectivity correlates of these putative compensatory mechanisms in the PDD brain. Early education may be a key investment for national governments, especially in low-income countries, to prevent the cognitive deficits of Parkinson's disease along aging, thereby reducing the unbearable social and economic burden.

Introduction:Plasma phospho-tau 217 (pTau217) is a biomarker for Alzheimer's disease (AD) pathology, reflecting amyloid (Aβ) and tau burden, but its role in Parkinson disease (PD) and 4-repeat(4R)-tauopathies remains incompletely understood. We measured plasma pTau217 across the cognitive spectrum of Lewy body diseases (PD, Dementia with Lewy bodies [DLB]) and in 4R-tauopathies, comparing these groups to cognitively unimpaired (CU) and mild cognitive impairment (MCI) individuals. Methods:Participants included 18 cognitively normal PD (PD-NC), 32 PD with MCI, and 7 PD with dementia (PDD), alongside 4 DLB patients, grouped as PDD/DLB. The 4R-tauopathy group included 28 Progressive Supranuclear Palsy (PSP) and 4 corticobasal syndrome (CBS) patients, compared to 51 CU and 26 MCI individuals. Ptau217 was measured using the fully automated Lumipulse platform, with values adjusted for creatinine levels. Further, the presence of AD-pathology was defined using a validated cut-off based on Aβ-PET. Results:PTau217 levels were significantly lower in PD-NC and CU individuals compared to those with greater cognitive impairment (PD-MCI, PDD/DLB, and PSP/CBS), and MCI individuals. AD co-pathology was identified in 28% of PDD/DLB and PSP/CBS patients, 16% of PD-MCI, and none of PD-NC. MCI showed the highest pTau217 positivity (35%), while 8% of CU individuals were positive despite normal cognition. In PD, pTau217 negatively correlated with cognitive performance, as assessed by Montreal Cognitive Assessment (MoCA: rs = -0.38, p = 0.004) and Mini-Mental State Examination (MMSE: rs = -0.37, p = 0.006). Discussion:Plasma pTau217 levels serve as a scalable, non-invasive marker of AD-pathology across Lewy body diseases, PSP/CBS, and MCI/CU populations. AD co-pathology independently contributes to cognitive deficits in PD, but not in PSP/CBS.

BACKGROUND:The burden of non-motor symptoms in Parkinson's disease (PD) can be measured with the Non-Motor Symptoms Scale (NMSS) and the International Parkinson and Movement Disorder Society Non-Motor Rating Scale (MDS-NMS), for which scoring systems, structure and clinical coverage differ. OBJECTIVES:The goal was to develop conversion formulas between the NMSS and the MDS-NMS scores. METHODS:Data from 402 patients with PD participating in the primary MDS-NMS validation study were used. The association between domain and total scores of both scales was assessed by the Spearman rank correlation coefficient and Kendall's W concordance coefficient. Equations for between-scale transformation of total score were constructed from weighted linear regression models. RESULTS:Spearman rank correlations showed that MDS-NMS domains correlated 0.39 to 0.88 with the corresponding NMSS domains. The equation for transforming the NMSS total score to MDS-NMS total score is: MDS-NMS = 11.629 + 1.624 × NMSS (P < 0.001, R2 = 0.748). For converting the MDS-NMS total score to NMSS total score, the formula is NMSS = 2.475 + 0.495 × MDS-NMS (P < 0.001, R2 = 0.771). CONCLUSIONS:Our conversion equations enable direct comparison of the NMSS and MDS-NMS instruments, facilitating data comparability across studies. © 2025 International Parkinson and Movement Disorder Society.

BACKGROUND:Cognitive impairment in Parkinson's disease (PD) is a well-established non-motor complication that significantly affects the quality of life and well-being of both patients and care partners. To optimally detect mild cognitive impairment or dementia, extensive neuropsychological assessment is essential. A wide range of cognitive tests and clinical outcome assessments have been used in clinical settings, often without regard to their clinimetric quality. METHODS:We performed a literature review of tests assessing attention/working memory and executive domains in PD (tests on other domains are included in an accompanying review). The selected tests were evaluated for their clinimetric properties and categorized by a panel of experts as "recommended," "recommended with caveats," "suggested," or "listed" according to the International Parkinson and Movement Disorder Society Clinical Outcome Assessment Scientific Evaluation Committee guidelines. RESULTS:A total of 30 tests were reviewed. Eight tests were "recommended," including four tests assessing attention/working memory abilities (WAIS-IV Digit Span, Coding and Symbol Search subtests, and Trail Making Test) and four tests assessing executive abilities (WAIS-IV Similarities, Wisconsin Card Sorting Test, Fluency Tests, and Stroop Color-Word Test). These tests demonstrated good to excellent levels of reliability and validity, have normative datasets, and are sensitive to change. Eight other tests were "recommended with caveats", eleven were "suggested," and three were "listed." CONCLUSIONS:The recommended tests for attention/working memory and executive functioning in PD can guide PD cognitive assessment. Other tests were identified as potentially useful; however, caution is advised due to their clinimetric limitations. Further validation studies are required for these tests. © 2025 The Author(s). Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

BACKGROUND:Cognitive impairment in Parkinson's disease (PD) is a key non-motor complication during the disease course. OBJECTIVES:A review of detailed cognitive instruments to detect mild cognitive impairment (PD-MCI) or dementia (PDD) is needed to establish optimal tests that facilitate diagnostic accuracy. METHODS:We performed a systematic literature review of tests that assess memory, language including premorbid intelligence, and visuospatial domains (for tests of attention and executive functions see accompanying review) to determine suitability to assess cognition in PD. Based on in-depth scrutiny of psychometric and other relevant clinimetric properties, tests were rated as "recommended," "recommended with caveats," "suggested," or "listed" by the International Parkinson and Movement Disorder Society (IPMDS) panel of experts according to the IPMDS Clinical Outcome Assessment Scientific Evaluation Committee guidelines. RESULTS:We included 39 tests encompassing 48 outcome measures. Seven tests (different versions or subtests of the test counted once) were recommended, including four for memory, one for visuospatial domains, one for language (including three measures), and one for estimated premorbid intelligence. Furthermore, 10 tests (12 measures) were "recommended with caveats," 11 were "suggested," and 11 (15 measures) were "listed." CONCLUSIONS:Recommended neuropsychological tests in memory, visuospatial functions, and language are proposed to guide the assessment of cognitive impairment and its progression in PD-MCI and PDD, and for use in clinical trials to stratify participants or as outcome measures. Novel measures being developed will need extensive validation research to be "recommended." © 2025 The Author(s). Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Background/Objectives: Depression, anxiety and apathy are often associated with subjective cognitive complaints (SCCs) in people with Parkinson’s disease (PwPD) without cognitive impairment. Cognitive reserve (CR) enhances emotional resilience, allowing people to better cope with stress and emotional challenges, factors affecting quality of life. We aimed to explore the relationship between CR and mood/anxiety in cognitively intact PwPD with and without SCCs. Methods: In this cross-sectional study we enrolled 133 PwPD and normal cognitive function (age 59.8 ± 6.7 years; disease duration 9.0 ± 5.5 years; male/female 84/49). We assessed cognitive reserve (CR scale), subjective cognitive complaints (with PD-CFRS), QoL (PDQ8), mood, anxiety and apathy (BDI-II; STAI, PAS, Apathy scales). We used a t-test to compare groups (with/without SCC; M/F); correlations and moderation analysis to evaluate the relation between CR and behavioral features and the interplay between CR, behavioral discomfort and QoL. Results: The group with SCCs had significantly (p < 0.05) higher scores in PDQ8, Apathy, STAI, PAS-C and BDI-II scales than those with no SCCs. Males with SCCs had higher scores in PDQ8, Apathy scale and BDI-II while females differed in PDQ8 and Apathy scale scores. In the SCC group, late-life CR was negatively correlated with PAS-C (avoidance behavior) and BDI-II; correlations were confirmed in the male group where CR also correlated with PDQ-8 and PAS persistent anxiety. Conclusions: PwPD and SCCs are more depressed and anxious compared to people without SCCs. Furthermore, we found a relationship between depressive symptoms, anxiety and CR: PwPD with SCCs may rely on cognitive reserve to better cope with the feeling of anxiety and depression, especially in male gender.

Biomarkers of impulsive compulsive behaviours (ICBs) in Parkinson's disease (PD) are lacking. We combined behavioural and electrophysiological markers of sensitivity to negative feedback to address this lack of knowledge. Eighteen PD patients (ICB+, N = 8; ICB-, N = 10) underwent electroencephalography during the Balloon Analogue Risk Task (BART), a measure of risky behaviour, and the feedback-related negativity (FRN), a measure of negative feedback processing, was recorded. Participants also completed the Questionnaire for Impulsive-Compulsive Disorders in Parkinson's Disease Rating Scale (QUIP-rs), and underwent cognitive, affective and motivation measures. Behaviour on the BART and FRN measures did not differ between the ICB + and ICB- groups. However, a significant positive correlation was observed between the amplitude of the FRN at the Cz electrode and the BART discrepancy score when the two groups were combined into one PD group (rs(18) = 0.52, p = 0.03; 95% CI = 0.07, 0.80). No additional correlations were found between FRN amplitudes and the QUIP-rs score, nor with cognitive, affective, or motivational measures. Our findings indicate that, regardless of ICB status, PD patients may be able to process negative feedback to mitigate risky behaviour during reward-related decision-making. We observed that a higher feedback-related negativity (FRN) is linked to a decrease in risky behaviour following a balloon burst. However, due to the small sample size, these findings should be interpreted with caution. Future studies should explore both positive and negative feedback processing using a task that maintains the dynamics of the ongoing decision-making process while increasing risk.