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Journal of Parkinson’s Disease 5 (2015) 865–879DOI 10.3233/JPD-150594IOS Press

865

Knowledge of Parkinson’s Diseasein a Multiethnic Urban Asian Setting

Ai Huey Tana, Chong Tin Tana, Connie Marrasb, Kwong Weng Loha, Niki Wai Wye Hoa,Quan Hziung Lima, Pei Wen Tana, Chee Chean Lima, Yee Weai Cheonga, Sik Thien Konga,Jie Ping Scheea, Kean Hoong Tana, Suet Ker Sooa, Cheryl Vanderschaafc, Sara Lai Heong Lewc,Ummi Affah Mahamadd, Khean Jin Goha, Hoi Sen Yonge and Shen-Yang Lima,∗aDivision of Neurology and the Mah Pooi Soo & Tan Chin Nam Centre for Parkinson’s & Related Disorders,University of Malaya, Kuala Lumpur, MalaysiabMorton and Gloria Shulman Movement Disorders Centre, Toronto Western Hospital and the Edmond J. SafraProgram in Parkinson’s Disease Research, University of Toronto, Toronto, ON, CanadacMalaysian Parkinson’s Disease Association, Kuala Lumpur, MalaysiadDepartment of Medicine, Faculty of Medicine, Universiti Sains Islam Malaysia, Kuala Lumpur, MalaysiaeInstitute of Biological Sciences, University of Malaya, Kuala Lumpur, Malaysia

Abstract.Background: Public knowledge regarding Parkinson’s disease (PD) is important to facilitate good health-seeking behavior,but the literature on this topic is scarce.Objective: We aimed to explore the level of public knowledge regarding PD in a large multiethnic urban Asian cohort, and (asa secondary aim) in a smaller cohort of PD patients and caregivers.Methods: A Knowledge of PD Questionnaire (KPDQ) was developed and administered to members of the Malaysian generalpublic, and to PD patients and caregivers. The KPDQ tests recognition of PD symptoms and general knowledge regarding PD.Results: 1,258 members of the general public completed the KPDQ. Tremor was the most widely recognized symptom (recog-nized by 79.0% of respondents); however, 83.7% incorrectly believed that all PD patients experience tremor. Memory problemwas the most widely recognized NMS. Overall, motor symptoms were better recognized than NMS. Common misperceptionswere that there is a cure for PD (49.8%) and that PD is usually familial (41.4%). Female gender, Chinese ethnicity, tertiaryeducation, healthcare-related work, and knowing someone with PD were independently associated with higher KPDQ scores.PD patients (n = 116) and caregivers (n = 135) demonstrated superior knowledge compared with the general public group, butone-third of them believed that PD is currently curable.Conclusions: This is the only study on public knowledge regarding PD in Asia. Important gaps in knowledge were evident,which could present a barrier to early diagnosis and appropriate treatment of PD. This highlights the need for targeted educationcampaigns and further research in this area.

Keywords: Parkinson’s disease, epidemiology, knowledge, awareness, education, cure, stem cells, Asia

INTRODUCTION

Health literacy is fundamental to patient engage-ment in the healthcare process, and has importantconsequences on health outcomes [1]. Previous

∗Correspondence to: Professor Dr. Shen-Yang Lim, NeurologyLaboratory, Level 6 (South block), University of Malaya MedicalCentre, 50603 Kuala Lumpur, Malaysia. Tel.: +60 16 3518009; Fax:+60 03 79494613; E-mail: limshenyang@ymail.com.

research showed that delayed treatment of Parkin-son’s disease (PD) may be associated with worsepatient outcomes, perhaps because functional declinemay be difficult to reverse once patients have becomesedentary or disabled from the accumulation of motorproblems [2, 3]. Early recognition of PD may be ham-pered by the fact that symptoms such as slownessof movements, difficulty walking and tremor can bemisattributed to other causes including “ageing” or

ISSN 1877-7171/15/$35.00 © 2015 – IOS Press and the authors. All rights reserved

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musculoskeletal disorders. The non-motor symptoms(NMS) of PD are even less well recognized [4, 5].Furthermore, a belief that little can be done for suchproblems can also discourage people from seekingassessment and treatment. Recent studies from NorthAmerica, Europe and Asia highlighted significantissues with access to reliable PD-related information[6–8]. Thus, the Global Declaration on PD by theWorld Health Organization lists efforts to “increasepublic awareness of PD as a priority health challenge”.

Although gaps in PD knowledge have been studiedamong medical professionals [9], to our knowledgethere are no published studies from Asia (whichaccounts for >40% of the global PD burden) on knowl-edge and attitudes towards PD among the generalpublic [10, 11]. One online survey conducted amongmore than 5,000 members of the European generalpublic by the European PD Association (EPDA) wasinterpreted by the Association as revealing a “shock-ing . . . general lack of understanding of the disease”[11]. Similarly, few studies have evaluated knowl-edge regarding PD in patients and caregivers [8, 12,13]. One small study from Singapore reported that85.3% of patients “had no knowledge” of the disease,although it is not clear how this evaluation was made[13]. Few research tools have also been developed inthis area, and the questionnaires that have been usedto gauge PD knowledge have significant limitations,including ambiguous wording of questions and theinclusion of content that is contentious even amongPD experts [10, 11].

Improved understanding of these issues will facil-itate the development of more informed educationalprograms about the nature of PD and its treatments. Wetherefore aimed to explore the level of public knowl-edge regarding PD in a large multiethnic urban Asiancohort. A secondary aim was to assess the level ofknowledge in a smaller cohort of PD patients and care-givers. To do this, we devised and administered a novelKnowledge of PD Questionnaire (KPDQ).

MATERIALS AND METHODS

The Knowledge of Parkinson’s DiseaseQuestionnaire (KPDQ)

The KPDQ was developed by neurologists withexpertise in PD, epidemiology and questionnairedesign (Supplementary Materials, Appendix e-1).Chinese and Malay-language versions were translatedby multilingual clinicians familiar with PD (Supple-

mentary Materials, Appendices e-2 and e-3). Part 1of the KPDQ tests recognition of PD symptoms (4motor, 10 NMS), and respondents are instructed totick a box for “problems experienced by people withPD”. For Part 2, respondents are asked to provide aTrue or False answer for ten statements testing gen-eral knowledge regarding PD. Only issues consideredto be of practical significance are tested and variousaspects of PD are covered including diagnosis (Part1; and Part 2 Statements 1 and 4), etiology (State-ments 2 and 3), epidemiology (5–7), treatment (8 and9), and psychosocial impact (10). Other sources forquestion selection included recent reviews on PD [4,5, 14] and a PD information booklet published by theMalaysian PD Association (MPDA) [15]. User reviewwas sought from patients, caregivers, members of theMalaysian PD Association, and lay members of thepublic. Items deemed unsuitable were amended ordropped; the questionnaire went through five revisions.

Subjects

The KPDQ was administered to adults attending ahealth fair in Kuala Lumpur, Malaysia, in April 2013.Participants had to be ≥18 years old and able to com-plete the survey reliably as judged by trained researchassistants. As a secondary objective, the questionnairewas also administered to a smaller convenience sampleof non-demented PD patients and caregivers attendingthe University of Malaya Medical Centre (UMMC)Neurology Clinic during this period. Demographicdata of the respondents were collected. Questionnaireforms were returned anonymously. The study wasapproved by the UMMC Ethics Committee and verbalconsent was obtained from all participants, as stipu-lated by the Ethics Committee (verbal consent wasdeemed sufficient, as the questionnaire was very brief,was intended to be completed anonymously to pro-tect participant privacy, and posed no other potentialdownside or harm to the participants).

Statistical analyses

Group differences in demographics and question-naire responses were analyzed using the Chi Squaretest and analysis of variance (ANOVA). Multivariateanalysis of variance (MANOVA) was used to examinebetween-group demographic differences in the generalpublic cohort with regards to questionnaire perfor-mance, followed by ANOVA and post hoc Tukey toidentify where the significant differences lay within thedifferent variables. Preliminary assumption testing was

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Table 1Demographic characteristics of respondents

Clinical General Public Caregivers PD Patients P ValueCharacteristics (n = 1,258) (n = 135) (n = 116)

Age (years)a 37.6 ± 15.2 47.0 ± 16.2 64.7 ± 9.0 <0.001∗Gender (% male)b 47.2 37.8 55.2 0.021∗Raceb

% Chinese 60.6 65.2 66.4 <0.001∗% Malay 23.7 11.9 9.5% Indian 11.4 20.7 22.4% others 4.3 2.2 1.7

Education levelb

% tertiary 75.2 54.8 27.6 <0.001∗% secondary 23.1 38.5 54.3% primary 1.2 6.7 16.4% none 0.5 0.0 1.7

Occupation (% healthcare related)b 28.3 16.3 6.9 <0.001∗

∗Denotes significant between-group differences (P < 0.05); aDenotes statistical testing with analysis of variances (ANOVA); bDenotes statisticaltesting with Chi Square test.

conducted to check for normality, linearity, univariateand multivariate outliers, homogeneity of variance-covariance matrices, and multicollinearity, with noserious violations noted. P < 0.05 was the cut-off forsignificance, unless otherwise specified.

RESULTS

The KPDQ was administered to 1,285 membersof the general public, of which 1,258 questionnaires(97.9%) were included in the analysis (the common-est reason for exclusion was respondent age <18 yearsand incomplete forms). One hundred and sixteen PDpatients and 135 caregivers were approached and allconsented and completed the KPDQ. Subject demo-graphics are summarized in Table 1. The KPDQ tookabout 10 minutes to complete and was easily under-stood and well accepted. The rates of PD symptomrecognition are shown in Fig. 1

General public cohort

Among the general public, tremor was the mostwidely recognized symptom (79.0%) while mem-ory problem was the most widely recognized NMS(51.8%) (Fig. 1). Overall, motor symptoms weresignificantly better recognized (range 47.0–79.0%,mean 2.5 of 4 symptoms) compared to NMS (range9.4–51.8%, mean 2.2 of 10 symptoms, P < 0.001)(Table 2). The results for Part 2 of the KPDQ are shownin Table 3. The three most common misperceptionsconcerned Statements 4 (all patients with PD experi-ence tremor; 83.7%), 8 (there is a cure for PD; 49.8%)and 7 (PD is usually familial; 41.4%).

In multivariate analysis (MANOVA, SupplementaryTable), being in healthcare-related work and know-ing someone with PD were significantly associatedwith higher mean scores in all knowledge assess-ments (recognition of motor symptoms, NMS, andtotal symptoms, and the number of Part 2 questionsanswered correctly, P values ranging from <0.001to 0.011). Females demonstrated superior knowledgecompared to males in all the categories, with sig-nificant differences for motor symptoms (P < 0.004)and total symptoms recognition (P < 0.013). Signifi-cant between-group differences were also found forage group with respect to motor symptoms recognition(P = 0.014); for race with respect to NMS (P = 0.001)and total symptoms (P = 0.005) recognition, as wellas the number of Part 2 questions answered correctly(P < 0.001); and for level of education with respect tomotor symptoms recognition (P = 0.001) and Part 2(P < 0.001).

These results were further analyzed using uni-variate analysis (ANOVA) and post hoc Tukey toidentify where the significant differences lay within thedemographic variables (age, race, etc.). On univariateanalysis, although age group 51–65 had the highestmean score in motor symptoms recognition, compar-ison with each of the other age groups separately didnot reveal significant differences. With regards to race,there were significant differences between the Chineseand Malay groups with respect to recognition of NMS(2.37 vs. 1.79, P < 0.001); total symptoms (4.91 vs.4.29, P < 0.01) and Part 2 (7.01 vs. 6.36, P < 0.001);and between the Chinese and Indian groups withrespect to Part 2 (7.01 vs. 6.59, P < 0.009). Compar-ing the education-level groups separately, significantdifferences were seen between tertiary-educated and

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Fig. 1. Part 1 of the KPDQ – recognition of PD symptoms. Motor symptoms are listed first, followed by non-motor symptoms, in descendingorder of frequency in the General Public group. Chi Square analysis was performed. ∗Denotes significant between-group differences, using aBonferroni-adjusted alpha level of P < 0.003 for multiple tests.

secondary-educated respondents for motor symptomsrecognition (2.60 vs. 2.30, P = 0.001) and Part 2 (6.89vs. 6.53, P < 0.001).

Patient and caregiver cohort

PD patients were significantly older than caregivers,who in turn were significantly older than the general

public sample, on post hoc analysis (correspondingto lower rates of higher education). Nevertheless,the proportions of patients and caregivers who wereable to correctly identify PD symptoms were highercompared to the general public, with significantbetween-group differences seen for nearly all PDsymptoms except for tremor, memory problem andreduced sense of smell (Fig. 1). For example, 52.6% of

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Table 2Part 1 of the KPDQ – recognition of PD symptoms (mean scores)

Symptoms Mean number of symptoms correctly recognized P ValueGeneral Public Caregivers PD Patients

(n = 1,258) (n = 135) (n = 116)

Motor symptoms (maximum = 4) 2.52 ± 1.22a,b (63%) 3.24 ± 1.02a (81%) 3.15 ± 0.99b (78.8%) <0.001∗Non-motor symptoms (maximum = 10) 2.20 ± 2.27a,b (22%) 3.86 ± 2.40a (38.6%) 4.26 ± 2.73b (42.6%) <0.001∗Total symptoms (maximum = 14) 4.72 ± 2.96a,b (33.7%) 7.10 ± 3.10a (50.7%) 7.41 ± 3.33b (52.9%) <0.001∗

Analysis of variance (ANOVA) and post hoc testing with Tukey were performed. ∗Denotes significant between-group differences (P < 0.05);aDenotes significant differences between the General Public and Caregiver groups; bDenotes significant differences between the General Publicand PD Patient groups. Differences between the PD Patient and Caregiver groups were not significant. ± Denotes standard deviation.

Table 3Part 2 of the KPDQ – rates of true-false statements answered correctly

Statement Correct Answer Percentage answered correctly (%) P ValueGeneral Public Care-givers PD Patients

(n = 1,258) (n = 135) (n = 116)

1. Parkinson’s disease andAlzheimer’s disease aredifferent names for the samedisease

False 70.1 80.7 78.4 0.008

2. Parkinson’s disease is adegenerative disease of thebrain (associated with loss ofbrain cells)

True 80.5 79.3 81.9 0.871

3. In Parkinson’s disease, thelevel of a chemical(neurotransmitter) in the braincalled dopamine is reduced

True 82.0 86.7 87.1 0.176

4. All patients withParkinson’s diseaseexperience tremor(involuntary shakingmovements)

False 16.3 26.7 37.1 <0.001∗

5. Parkinson’s disease is morecommon in older persons

True 73.7 72.6 80.0 0.312

6. Parkinson’s disease canalso affect young adults

True 77.1 84.4 79.3 0.139

7. Parkinson’s disease usuallyaffects multiple members ofthe same family

False 58.6 79.3 80.2 <0.001∗

8. There are new treatmentsthat can cure Parkinson’sdisease

False 50.2 63.7 67.2 <0.001∗

9. There are treatments thatcan improve the symptoms ofParkinson’s disease

True 91.8 93.3 95.7 0.284

10. Patients with Parkinson’sdisease often feel sociallyisolated

True 78.3 69.6 54.3 <0.001∗

Chi Square analyses were performed. ∗Denotes significant between-group differences, using a Bonferroni-adjusted alpha level of P < 0.005 formultiple tests.

patients and 48.1% of caregivers were able to identifyconstipation as a PD symptom compared to only 9.4%of the general public. Compared with the generalpublic, both patients and caregivers had higher meanscores for motor symptoms, non-motor symptoms andtotal symptoms recognition, with highly significantP values on both ANOVA and post hoc testing(Table 2).

Compared with the general public, both PD patientsand caregivers were also found to have higher ratesof correct responses for all Part 2 questions, exceptfor Statements 2 and 5, for which the correct responserate was slightly (but non-significantly) higher in thegeneral public group compared with the caregivergroup (Table 3). These differences were significant forStatements 4, 7, 8 and 10.

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DISCUSSION

To the best of our knowledge, there are no pub-lished studies from Asia on the level of knowledgeregarding PD in the general population. The liter-ature on this topic is limited to only two studiesfrom Europe and Australia [10, 11]. In the presentstudy, we administered a novel questionnaire to a large(n = 1,258) multiethnic general public cohort in urbanMalaysia and found that, overall, subjects were rea-sonably well-informed (for example, three-quartersof respondents recognized tremor and slowness ofmovement as PD symptoms). However, mispercep-tions were common, particularly with regard to tremoras a “universal” feature of PD (83.7% of respon-dents). Furthermore, 49.8% of subjects responded thatPD is curable with current treatments, and 41.4%believed that PD is usually familial. Understandably,motor symptoms, which remain the defining featuresof PD, were better recognized than NMS. In com-parison to motor symptoms, the connection betweenNMS and PD was also less frequently recognizedby PD patients and caregivers. As expected (and inspite of having lower levels of education attainment,corresponding to their older age), patients and care-givers demonstrated superior knowledge comparedwith the public group. Surprisingly, however, one-thirdof patients and caregivers believed that PD is currentlycurable.

The misperception surrounding “cures” contrastswith findings from Australia, where only 15% ofrespondents thought that there was a cure for PD[10]. This may be due, for example, to the widespreaduse of “stem cell” procedures which are performedwithout proper regulatory controls and which oftenclaim to produce dramatic results [16]. It could alsoarise from a belief in complementary treatments [17],which are widely practiced in Asia and other devel-oping countries [18–20]. This misperception wouldbe an important one to target from a public educa-tion perspective, since it could lead to inappropriatehealthcare-seeking behaviors. An erroneous belief thatPD is familial may possibly also result in stigmati-zation of patients and family members [21], but thisissue has not been investigated specifically in PD.On the other hand, “young persons’ diseases” oftenreceive more public sympathy and research dollars[10], hence, the recognition by almost 80% of ourgeneral public respondents that PD can also affectyoung adults (exemplified by high-profile cases suchas Michael J. Fox) could perhaps be construed in apositive light.

Our observation that tremor was the best recog-nized symptom of PD (as also found in the studycommissioned by the EPDA) is unsurprising, sincetremor is present in about 80% of PD patients [14,22] and is often a highly visible manifestation of thedisease. In line with this, one recent study reportedthat presentation with tremor (vs. gait disturbance)was associated with a shorter time to PD diagnosis[23]. However, it is important to recognize that othermotor features of PD (particularly bradykinesia andaxial motor impairments) progress more rapidly andare typically the main cause of motor disability inpatients with PD [24, 25]. The NMS of PD have beenunder-recognized and patients presenting with NMStake longer to be diagnosed [26], in part because NMSmay be non-specific and misattributed to normal age-ing or comorbidities such as depression, osteoarthritis,diabetes, and prostatic hypertrophy. Indeed, studiesshow that many NMS occur with a fairly high fre-quency in non-PD elderly controls; even so, NMSoccur significantly more commonly and with greaterseverity in PD patients compared to controls [27,28].

In our study, female gender, Chinese ethnicity,tertiary education, healthcare-related work, and know-ing someone with PD were independently associatedwith higher scores on the KPDQ. One study inves-tigating the determinants of delayed diagnosis inPD showed that male gender was associated withdelayed presentation, which the authors postulatedcould be due to poor knowledge about health-related matters [23]. One possible explanation forthe lower level of PD awareness in our Malaysubgroup could be that PD may be less preva-lent in this racial group [29], although this findinghas not been confirmed by other investigators [30].There are very few studies concerning health literacyamong the Malaysian general public; previous stud-ies including one conducted among students attendinga Malaysian university found relatively high levelsof awareness and knowledge of epilepsy [31, 32].Importantly, the observed socio-demographic differ-ences may be due to varying levels of health literacyand access to PD-related information, and to dif-ferences in values and attitudes. The observation ofethnic and international differences suggests that fur-ther population-specific research is needed to informeducational efforts.

We devised a novel self-completed questionnaireto assess knowledge levels regarding PD, since wecould find no suitable instruments for this purpose inthe literature. The high rate of completion indicates

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that the KPDQ was acceptable to respondents across abroad demographic. From the results obtained in thislarge sample, the KPDQ appears to have face validity,with (1) PD patients having the highest scores, fol-lowed by caregivers and the general public, and (2) theobserved pattern of predictors of correct responses inthe general public cohort. Of the questionnaires thathave been used previously, the wording was some-times ambiguous; for example, the question on whetherPD causes an “inability to move” (regarded as trueby the study authors) [11], since the actual problemis usually one of slowness or difficulty in initiation,rather than a true paralysis. Issues of contention werealso tested, for example the statement that PD “signif-icantly shortens the lifespan” (regarded as false by thestudy authors) [10] is supported by a number of stud-ies, including a recently published systematic reviewby Macleod et al. that found a pooled mortality ratioof 1.4 in PD patients [33]. To make reliable compar-isons between different cultural groups and countries,consistent data collection procedures are needed, andthe KPDQ, which is simple to administer and easilytranslated into non-English languages, can be usefulfor this purpose.

What can be done to improve awareness andknowledge regarding PD? The findings of this studysuggest that educational programs should include thefollowing information: (1) rest tremor is typical, but itspresence is neither sufficient nor necessary to diagnosePD; (2) various NMS are common in PD (and theseshould be elucidated); (3) effective treatments exist formotor and NMS, but there is currently no cure for PD;and (4) PD is usually sporadic rather than familial. Inthis respect, trusted and influential professional bodiesand lay/advocacy organizations such as the Interna-tional Parkinson and Movement Disorder Society(MDS), the National Parkinson Foundation and theMichael J. Fox Foundation, can play an important role,for example by providing a clearly-worded factsheeton PD via their websites that is updated (and seen to beupdated) regularly. PD-related health messages needto be disseminated across different languages and cul-tures, and tailored according to the different interests,values, and health literacy levels of specific groups.Since knowing someone with PD independentlypredicted better knowledge of the condition in ourstudy, it is possible that “personalized” messages, e.g.,in the form of videotaped testimonials from patientsmay be an effective means of conveying some ofthis information.

The main limitation of this study is that the higher-than-average level of education in our general public

cohort is likely to overestimate PD knowledge in thegeneral population. Moreover, recruitment of partici-pants from a health fair may also tend to capture a groupmore knowledgeable than average about health issues.The general public, caregiver and patient groups werenot well-matched in terms of age, gender, ethnicity,education and occupation; although the possibility ofbias exists, the results obtained would argue againstthis, since despite having higher levels of education, thegeneral public group scored more poorly compared tothe PD patients and caregivers. The use of close-endedquestions with fixed response options (as opposedto open-ended questions) may have also resulted inhigher estimates of PD knowledge. It is possible thatsome respondents may have over-responded if theyreached the conclusion that all symptoms in Part 1(symptom checklist) were probably correct. However,only 28 out of a total of 1,509 (1.86%) respondentsanswered in the affirmative to all 14 symptoms;and only 24 (1.59%) respondents identified 13symptoms and 21 (1.39%) respondents identified 12symptoms; thus, it would not appear that respondentsover-responded. We did not include an item on speechand communication difficulties, which we wouldrecommend adding to Part 1 of the KPDQ. Finally,the questionnaires were completed anonymously andwe were thus unable to correlate disease features ofpatients with their questionnaire responses. In futurestudies, the KPDQ should be tested in other cohorts(e.g., general public subjects with lower educationalattainment or from rural communities; and PD patientsfrom the general community as opposed to thoseattending a University neurology clinic, where patienteducation may be more effective), and should includemore evidence for the validity of different translatedversions.

In conclusion, there need to be further efforts aimedat raising awareness and providing accurate informa-tion regarding PD, especially targeting groups withpoorer knowledge. This may facilitate earlier diagno-sis and treatment, reduce stigma, provide an increasedsense of self-empowerment to people living with PD,and help to protect them from seeking ineffective oreven potentially hazardous, and costly, treatments.

ACKNOWLEDGMENTS

The authors are grateful to members of theMalaysian public, and patients with Parkinson’sdisease at UMMC and their caregivers, for their par-ticipation in this research. The study was supported by

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the Malaysian Ministry of Higher Education grant forHigh-Impact Research (HIR) UM.0000017/HIR.C3.

CONFLICT OF INTEREST STATEMENT

There are no conflicts of interest.

STUDY FUNDING

Malaysian Ministry of Higher Education grant forHigh-Impact Research (HIR) UM.0000017/HIR.C3.

SUPPLEMENTARY MATERIAL

The supplementary table is available in the elec-tronic version of this article: http://dx.doi.org/10.3233/JPD-150594.

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among Chinese in Malaysia. Neurol J Southeast Asia, 4,31-36.

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Appendix 1 – Knowledge of Parkinson’s Disease Questionnaire (KPDQ), English-Language Version.

Urinary urgency Weight loss

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876 A.H. Tan et al. / Knowledge of Parkinson’s Disease

Appendix 2 – Knowledge of Parkinson’s Disease Questionnaire (KPDQ), Chinese-Language Version.

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A.H. Tan et al. / Knowledge of Parkinson’s Disease 877

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878 A.H. Tan et al. / Knowledge of Parkinson’s Disease

Appendix 3 – Knowledge of Parkinson’s Disease Questionnaire (KPDQ), Malay-Language Version.

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A.H. Tan et al. / Knowledge of Parkinson’s Disease 879