Displaying publications 21 - 40 of 93 in total

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  1. Liong CC, Rahmat K, Mah JS, Lim SY, Tan AH
    Can J Neurol Sci, 2016 Sep;43(5):719-20.
    PMID: 27670213 DOI: 10.1017/cjn.2016.269
  2. Lim SY, Tan AH, Fox SH, Evans AH, Low SC
    Curr Neurol Neurosci Rep, 2017 01;17(1):3.
    PMID: 28102483 DOI: 10.1007/s11910-017-0717-2
    Parkinson's disease (PD) is a complex motor and non-motor disorder and management is often challenging. In this review, we explore emerging approaches to improve the care of patients, drawing from the literature regarding patient-centred care, patient and caregiver perspectives and priorities, gaps in knowledge among patients and caregivers and the need for accurate information, individual variability in disease manifestations, prognostication of disease course, new developments in health technologies and personalized medicine, specialty care, pharmacological and non-pharmacological management, financial burden, lifestyle and work-related issues, support groups and palliative care.
  3. Tan AH, Low SC, Tan CY, Lim KS, Tan CT, Lim SY
    Parkinsonism Relat Disord, 2016 11;32:137-139.
    PMID: 27688197 DOI: 10.1016/j.parkreldis.2016.09.019
  4. Tan AH, Chuah KH, Beh YY, Schee JP, Mahadeva S, Lim SY
    J Mov Disord, 2023 May;16(2):138-151.
    PMID: 37258277 DOI: 10.14802/jmd.22220
    Patients with Parkinson's disease (PD) face a multitude of gastrointestinal (GI) symptoms, including nausea, bloating, reduced bowel movements, and difficulties with defecation. These symptoms are common and may accumulate during the course of PD but are often under-recognized and challenging to manage. Objective testing can be burdensome to patients and does not correlate well with symptoms. Effective treatment options are limited. Evidence is often based on studies in the general population, and specific evidence in PD is scarce. Upper GI dysfunction may also interfere with the pharmacological treatment of PD motor symptoms, which poses significant management challenges. Several new less invasive assessment tools and novel treatment options have emerged in recent years. The current review provides an overview and a practical approach to recognizing and diagnosing common upper and lower GI problems in PD, e.g., dyspepsia, gastroparesis, small bowel dysfunction, chronic constipation, and defecatory dysfunction. Management aspects are discussed based on the latest evidence from the PD and general populations, with insights for future research pertaining to GI dysfunction in PD.
  5. Taufik SA, Ramli N, Tan AH, Lim SY, Ghani MTA, Shahrizaila N
    J Clin Neurol, 2024 May;20(3):285-292.
    PMID: 38627230 DOI: 10.3988/jcn.2023.0353
    BACKGROUND AND PURPOSE: There is increasing evidence that the anterior visual pathways are involved in neurodegenerative diseases including amyotrophic lateral sclerosis (ALS) and Parkinson's disease (PD). This study investigated longitudinal changes in retinal nerve fiber layer (RNFL) thickness in patients with ALS and PD with the aim of better understanding their roles as biomarkers of disease progression.

    METHODS: This study recruited 21 ALS patients, 19 age-matched PD patients, and 21 agematched healthy controls. Patient demographics and clinical scores relating to the respective diseases were documented. The RNFL thickness was measured using optical coherence tomography at baseline and after 6 months.

    RESULTS: At baseline, the RNFL in the superior quadrant was significantly thinner in the patients with ALS than in healthy controls (109.90±22.41 µm vs. 127.81±17.05 µm [mean±standard deviation], p=0.008). The RNFL thickness did not differ significantly between the ALS and PD patients or between the PD patients and healthy controls. At 6 months, there was further significant RNFL thinning in patients with ALS, for both the overall thickness (baseline: median=94.5 µm, range=83.0-106.0 µm; follow-up: median=93.5 µm, range=82.5-104.5 µm, p=0.043) and the thickness in the inferior quadrant (median=126 µm, range=109.5-142.5 µm; and median=117.5 µm, range=98.5-136.5 µm; respectively, p=0.032). However, these changes were not correlated with the ALS functional scores. In contrast, the patients with PD did not demonstrate a significant change in RNFL thickness between the two time points.

    CONCLUSIONS: The RNFL thickness is a promising biomarker of disease progression in patients with ALS but not in those with PD, which has a slower disease progression.

  6. Bhidayasiri R, Phuenpathom W, Tan AH, Leta V, Phumphid S, Chaudhuri KR, et al.
    Front Aging Neurosci, 2022;14:979826.
    PMID: 36034128 DOI: 10.3389/fnagi.2022.979826
    Gastrointestinal (GI) issues are commonly experienced by patients with Parkinson's disease (PD). Those that affect the lower GI tract, such as constipation, are the most frequently reported GI problems among patients with PD. Upper GI issues, such as swallowing dysfunction (dysphagia) and delayed gastric emptying (gastroparesis), are also common in PD but are less well recognized by both patients and clinicians and, therefore, often overlooked. These GI issues may also be perceived by the healthcare team as less of a priority than management of PD motor symptoms. However, if left untreated, both dysphagia and gastroparesis can have a significant impact on the quality of life of patients with PD and on the effectiveness on oral PD medications, with negative consequences for motor control. Holistic management of PD should therefore include timely and effective management of upper GI issues by utilizing both non-pharmacological and pharmacological approaches. This dual approach is key as many pharmacological strategies have limited efficacy in this setting, so non-pharmacological approaches are often the best option. Although a multidisciplinary approach to the management of GI issues in PD is ideal, resource constraints may mean this is not always feasible. In 'real-world' practice, neurologists and PD care teams often need to make initial assessments and treatment or referral recommendations for their patients with PD who are experiencing these problems. To provide guidance in these cases, this article reviews the published evidence for diagnostic and therapeutic management of dysphagia and gastroparesis, including recommendations for timely and appropriate referral to GI specialists when needed and guidance on the development of an effective management plan.
  7. Majeed ABA, Ramasamy K, Tan MP, LIm SM, Hui KM, Tan AH, et al.
    Alzheimers Dement, 2024 Dec;20 Suppl 6(Suppl 6):e093563.
    PMID: 39782435 DOI: 10.1002/alz.093563
    BACKGROUND: Gut microbiota modulation of the brain function may present an opportunity to devise preventive or treatment strategies to manage impairments such as cognitive frailty (CF). This study aims to uncover the relationship between CF, gut microbiota, intestinal permeability and proteome.

    METHOD: A total of 137 fecal samples of the elderly were collected, and subjected to DNA analysis, and enzyme-linked immunosorbent assays (ELISA). Plasma samples were subjected to mass spectrometry proteomic analysis. The parameters of the subjects measured include functional reach test (FRT), handgrip strength (HGS), Visual Cognitive Assessment Test (VCAT), Montreal Cognitive Assessment (MoCA), timed up and go (TUG) and UCLA three-item loneliness scale (UCLA-3).

    RESULT: At the genus level, Alistipes which are potential drivers of dysbiosis, are significantly increased in CF subjects. Proteobacteria are also negatively linked to FRT, HGS, VCAT, and MoCA, but positively correlated to TUG and UCLA-3. Lactoferrin was upregulated in pre-frail subjects. The plasma apolipoprotein AI (Apo-AI) was upregulated 5 times in the CF subjects.

    CONCLUSION: These findings provide evidence for dietary intervention to alter gut microbiota that may modulate cognitive status.

  8. Teixeira-Dos-Santos D, Tan AH, Okubadejo N, Kalia LV, Schuh AFS
    Nat Rev Neurol, 2026 Apr;22(4):239-250.
    PMID: 41667846 DOI: 10.1038/s41582-026-01183-1
    The global burden of Parkinson disease (PD) is rapidly shifting towards low-income and middle-income countries (LMICs), which already account for 44% of all individuals with PD. Despite this trend, the populations of LMICs and other under-represented populations defined by ethnicity, sex, geography and minority groups within high-income countries remain largely excluded from PD research. The continuation of these disparities limits our knowledge of disease biology and restricts the applicability of advances in prevention, diagnosis and treatment, increasing inequity in global health. Substantial disparities persist across the PD research continuum, extending beyond resource limitations and encompassing epidemiology, environment, genetics, deep phenotyping and biomarkers, data integration and diversity-aware analytics, clinical trials and basic science. To repair structural diversity gaps that compromise validity and equity in PD research, we propose an ethically grounded, coordinated agenda that prioritizes increased funding and local capacity building in under-represented regions, the development and adoption of harmonized and context-adapted methods, sustained community engagement with cultural competence, the creation of collaborative research networks, and more inclusive editorial and regulatory policies. Moreover, because inequities in care and research commonly co-occur and are mutually reinforcing, PD research should advance alongside a worldwide commitment to minimum standards of care and access to treatment. This Perspective details diversity gaps across PD research, outlines priority actions to address them, and illustrates, through recent examples, how interventions along these axes can advance equity and representation in PD studies.
  9. Lim SY, Tan AH, Ahmad-Annuar A, Schneider SA, Bee PC, Lim JL, et al.
    J Mov Disord, 2018 May;11(2):89-92.
    PMID: 29860786 DOI: 10.14802/jmd.17082
    We present a case of beta-propeller protein-associated neurodegeneration, a form of neurodegeneration with brain iron accumulation. The patient harbored a novel mutation in the WDR45 gene. A detailed video and description of her clinical condition are provided. Her movement disorder phenomenology was characterized primarily by limb stereotypies and gait dyspraxia. The patient's disability was advanced by the time iron-chelating therapy with deferiprone was initiated, and no clinical response in terms of cognitive function, behavior, speech, or movements were observed after one year of treatment.
  10. Tan AH, Toh TH, Low SC, Fong SL, Chong KK, Lee KW, et al.
    J Mov Disord, 2018 Sep;11(3):149-151.
    PMID: 30086616 DOI: 10.14802/jmd.18017
  11. Lim SY, Ishiura H, Ramli N, Shibata S, Almansour MA, Tan AH, et al.
    Parkinsonism Relat Disord, 2020 05;74:25-27.
    PMID: 32289521 DOI: 10.1016/j.parkreldis.2020.03.025
    Two ethnic Chinese men with clinico-radiologic features of Fragile X-associated tremor-ataxia syndrome (FXTAS) were found on genetic testing to have neuronal intranuclear inclusion disease (NIID), highlighting that NIID should be considered in the differential diagnosis of FXTAS. NIID may also be much more common than FXTAS in certain Asian populations.
  12. Suwarnalata G, Tan AH, Isa H, Gudimella R, Anwar A, Loke MF, et al.
    PLoS One, 2016;11(4):e0153725.
    PMID: 27100827 DOI: 10.1371/journal.pone.0153725
    Parkinson's disease (PD) is the second most common chronic and progressive neurodegenerative disorder. Its etiology remains elusive and at present only symptomatic treatments exists. Helicobacter pylori chronically colonizes the gastric mucosa of more than half of the global human population. Interestingly, H. pylori positivity has been found to be associated with greater of PD motor severity. In order to investigate the underlying cause of this association, the Sengenics Immunome protein array, which enables simultaneous screening for autoantibodies against 1636 human proteins, was used to screen the serum of 30 H. pylori-seropositive PD patients (case) and 30 age- and gender-matched H. pylori-seronegative PD patients (control) in this study. In total, 13 significant autoantibodies were identified and ranked, with 8 up-regulated and 5 down-regulated in the case group. Among autoantibodies found to be elevated in H. pylori-seropositive PD were included antibodies that recognize Nuclear factor I subtype A (NFIA), Platelet-derived growth factor B (PDGFB) and Eukaryotic translation initiation factor 4A3 (eIFA3). The presence of elevated autoantibodies against proteins essential for normal neurological functions suggest that immunomodulatory properties of H. pylori may explain the association between H. pylori positivity and greater PD motor severity.
  13. Rashidah NH, Lim SM, Neoh CF, Majeed ABA, Tan MP, Khor HM, et al.
    Ageing Res Rev, 2022 Dec;82:101744.
    PMID: 36202312 DOI: 10.1016/j.arr.2022.101744
    This systematic review appraised previous findings on differential gut microbiota composition and intestinal permeability markers between frail and healthy older adults. A literature search was performed using PubMed, Scopus, ScienceDirect and the Cochrane Library. Relevant studies were shortlisted based on inclusion and exclusion criteria as well as assessed for risk of bias. The primary outcome was the differential composition of gut microbiota and/ or intestinal permeability markers between frail and healthy older adults. A total of 10 case-control studies and one cohort study were shortlisted. Based on consistent findings reported by more than one shortlisted study, the microbiota of frail older adults was characterised by decreased phylum Firmicutes, with Dialister, Lactobacillus and Ruminococcus being the prominent genera. Healthy controls, on the other hand, exhibited higher Eubacterium at the genera level. In terms of intestinal permeability, frail older adults were presented with increased serum zonulin, pro-inflammatory cytokines (TNF-α, HMGB-1, IL-6, IL1-ra, MIP-1β) and amino acids (aspartic acid and phosphoethanolamine) when compared to healthy controls. Altogether, frail elderlies had lower gut microbiota diversity and lower abundance of SCFA producers, which may have led to leaky guts, upregulated pro-inflammatory cytokines, frailty and sarcopenia.
  14. Fong SL, Dy Closas AMF, Lim TT, Lean PL, Loh EC, Lim SY, et al.
    Parkinsonism Relat Disord, 2023 Apr;109:105332.
    PMID: 36948111 DOI: 10.1016/j.parkreldis.2023.105332
    The diagnostic approach to sleep-related movements disorders is seldom discussed. We report a case of fatal familial insomnia who initially presented with persistent limb movements in sleep, which later progressed to a state of agrypnia excitata. Here, the evaluation of abnormal movements in sleep is discussed using a step-by-step diagnostic approach. Although no cure is available for fatal familial insomnia, prompt recognition of this condition is important to facilitate proper management, including the involvement of interdisciplinary neuropalliative care.
  15. Lim KB, Lim SY, Hor JW, Krishnan H, Mortadza F, Lim JL, et al.
    Parkinsonism Relat Disord, 2024 Apr 22;123:106980.
    PMID: 38657381 DOI: 10.1016/j.parkreldis.2024.106980
    BACKGROUND: Screening for orthostatic hypotension (OH) is integral in Parkinson's disease (PD) management, yet evidence-based guidelines on best practice methods for diagnosing OH in PD are lacking.

    METHODS: We investigated the frequency and correlates of OH, symptomatic OH, and neurogenic OH, in a large consecutively recruited PD cohort (n = 318), and compared the diagnostic performance of the sit-to-stand vs. the supine-to-stand blood pressure (BP) test. We evaluated the utility of continuous BP monitoring and tilt table testing in patients with postural symptoms or falls who were undetected to have OH with clinic-based BP measurements. Disease severity, fluid intake, orthostatic and overactive bladder symptoms, falls, comorbidities and medication history were evaluated.

    RESULTS: Patients' mean age was 66.1 ± 9.5years, with mean disease duration 7.8 ± 5.5years. OH frequency was 35.8 % based on the supine-to-stand test. OH in PD was significantly associated with older age, lower body mass index, longer disease duration, worse motor, cognitive and overactive bladder symptoms and functional disabilities, falls, and lower fluid intake. A similar profile was seen with asymptomatic OH. Three quarters of OH were neurogenic, with the majority also having supine hypertension. The sit-to-stand test had a sensitivity of only 0.39. One quarter of patients were additionally diagnosed with OH during continuous BP monitoring.

    CONCLUSIONS: The sit-to-stand test substantially underdiagnoses OH in PD, with the important practice implication that supine-to-stand measurements may be preferred. Screening for OH is warranted even in asymptomatic patients. Adequate fluid intake, treatment of urinary dysfunction and falls prevention are important strategies in managing PD patients with OH.

  16. Lim SY, Pajo AT, Dy Closas AMF, Hor JW, Toh TS, Ngim SJ, et al.
    Parkinsonism Relat Disord, 2025 Jan;130:107162.
    PMID: 39406616 DOI: 10.1016/j.parkreldis.2024.107162
    Recent studies highlight an over-representation of progressive supranuclear palsy, with atypical features, in South Asians. We offer additional insights, including an over-representation of PSP among Malaysian patients of Indian compared to other Asian ancestries. However, RBD symptoms, hallucinations, and early onset were not more frequent in Indians vs. Chinese.
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