METHODS: This study included PD patients along with their caregivers and was undertaken at the Malaysian Parkinson's Disease Association from June 2016 to November 2016. Clinical features of PD patients were assessed using the Movement Disorder Society revised Unified Parkinson Disease Rating Scale; the Hoehn and Yahr stage and the Schwab and England Activities of Daily Living Scale were used to assess the severity and the ability of PD patients respectively. QoL of PD patients was measured using the Parkinson's Disease Questionnaire-39 (PDQ-39). The revised version of the Zarit Burden Interview assessed caregiver burden.
RESULTS: At least one of the clinical features affected PD patients' QoL, and at least one of the QoL domains affected the caregivers' burden. Clinical features "saliva and drooling" and "dyskinesia" explained 29% of variance in QoL of PD patients. The QoL domains "stigma," along with "emotional well-being" explained 48.6% of variance in caregivers' burden.
CONCLUSIONS: The clinical features "saliva and drooling" and "dyskinesia" impacted the QoL of PD patients, and the QoL domains "stigma" and "emotional well-being" of PD patients impacted their caregivers' burden.
METHODS: A multi-ethnic cohort of PD patients from Malaysia (n = 499, including 185 Malays) were tested using a next-generation sequencing-based PD gene panel. The prevalence and clinico-radiological features of patients with the PINK1 p. Leu347Pro mutation are described. This mutation has previously only been reported in people of Filipino or Chamorro (native Guamanian) ancestry.
RESULTS: Homozygous p. Leu347Pro mutations were found in five unrelated Malay patients, yielding a prevalence of 6.9% among Malays with PD onset ≤50 years (2.7% of the Malay group overall). This variant was not detected in the homozygous state in 300 Malay controls, but two were heterozygous carriers (0.67%) indicating a relatively high population frequency in keeping with the high frequency of PARK-PINK1 among Malay patients. Interesting clinical features were observed, e.g., differences in the age at PD onset and clinical progression, despite having the same point mutations. Previously unreported brain MRI abnormalities involving the corticospinal tract and hypothalamus, and "loss of the swallow tail" sign, were documented.
CONCLUSIONS: This report contributes to the very limited literature on PD genetics in the Malay population, and more broadly to the epidemiological, phenotypic and neuroimaging characterization of PARK-PINK1. It also further supports the pathogenicity of the p. Leu347Pro variant.
METHODS: A total of 715 incident PD cases were ascertained in a cohort of 220 494 individuals from NeuroEPIC4PD, a prospective European population-based cohort study including 13 centres in eight countries. Smoking habits were recorded at recruitment. We analysed smoking status, duration, and intensity and exposure to passive smoking in relation to PD onset.
RESULTS: Former smokers had a 20% decreased risk and current smokers a halved risk of developing PD compared with never smokers. Strong dose-response relationships with smoking intensity and duration were found. Hazard ratios (HRs) for smoking <20 years were 0.84 [95% confidence interval (CI) 0.67-1.07], 20-29 years 0.73 (95% CI 0.56-0.96) and >30 years 0.54 (95% CI 0.43-0.36) compared with never smokers. The proportional hazard assumption was verified, showing no change of risk over time, arguing against a delaying effect. Reverse causality was disproved by the consistency of dose-response relationships among former and current smokers. The inverse association between passive smoking and PD, HR 0.70 (95% CI 0.49-0.99) ruled out the effect of unmeasured confounding.
CONCLUSIONS: These results are highly suggestive of a true causal link between smoking and PD, although it is not clear which is the chemical compound in cigarette smoking responsible for the biological effect.
METHODS: A three-phase community-based survey among a disproportionate random sample of 15,000 individuals (9,000 Chinese, 3,000 Malays, 3,000 Indians) aged 50 years and above who live in central Singapore was conducted. In phase 1, trained interviewers conducted a door-to-door survey using a validated 10-question questionnaire. In phase 2, medical specialists examined participants who screened positive to any of the questions. Participants suspected to have PD had their diagnosis confirmed in phase 3 by a movement disorders specialist.
RESULTS: The participation rate was 67% among 22,279 eligible individuals. Forty-six participants with PD were identified of which 16 were newly diagnosed cases. The prevalence rate of PD for those aged 50 and above in Singapore was 0.30% (95% CI: 0.22 to 0.41), age-adjusted to US 1970 census. The prevalence rates increased significantly with age. The age-adjusted prevalence rates among Chinese (0.33%, 95% CI: 0.22 to 0.48), Malays (0.29%, 95% CI: 0.13 to 0.67), and Indians (0.28%, 95% CI: 0.12 to 0.67) were the same (p = 1.0).
CONCLUSIONS: The prevalence of PD in Singapore was comparable to that of Western countries. Race-specific rates were also similar to previously reported rates and similar among the three races. Environmental factors may be more important than racially determined genetic factors in the development of PD.
METHODS: Cases (523) which conformed to the United Kingdom PD Brain Bank Criteria for PD were recruited through trained neurologists and age- and ethnically matched controls (491) were individuals free of any neurological disorder. The N551K and R1398H mutations were genotyped using the Taqman SNP genotyping assay.
RESULTS: A significant protective association for N551K was found in those of Malay ancestry, with a protective trend seen for R1398H. A meta-analysis of Chinese individuals in this cohort with other published cohorts of Chinese ancestry indicated a significant protective role for N551K and R1398H.
CONCLUSION: This study reports that the N551K-R1398H haplotype is also relevant to the Malaysian population, with a significant protective effect found in those of Malay and Chinese ancestries.