Erratum to: The KMDS-NATION Study: Korean Movement Disorders Society Multicenter Assessment of Non-Motor Symptoms and Quality of Life in Parkinson's Disease NATION Study Group

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The KMDS-NATION Study: Korean Movement Disorders Society Multicenter Assessment of Non-Motor Symptoms and Quality of Life in Parkinson's Disease NATION Study Group

BACKGROUND AND PURPOSE: Nonmotor symptoms (NMS) in Parkinson's disease (PD) have multisystem origins with heterogeneous manifestations that develop throughout the course of PD. NMS are increasingly recognized as having a significant impact on the health-related quality of life (HrQoL). We aimed to determine the NMS presentation according to PD status, and the associations of NMS with other clinical variables and the HrQoL of Korean PD patients. METHODS: We surveyed patients in 37 movement-disorders clinics throughout Korea. In total, 323 PD patients were recruited for assessment of disease severity and duration, NMS, HrQoL, and other clinical variables including demographics, cognition, sleep scale, fatigability, and symptoms. RESULTS: In total, 98.1% of enrolled PD subjects suffered from various kinds of NMS. The prevalence of NMS and scores in each NMS domain were significantly higher in the PD group, and the NMS worsened as the disease progressed. Among clinical variables, disease duration and depressive mood showed significant correlations with all NMS domains (p<0.001). NMS status impacted HrQoL in PD (rS=0.329, p<0.01), and the association patterns differed with the disease stage. CONCLUSIONS: The results of our survey suggest that NMS in PD are not simply isolated symptoms of degenerative disease, but rather exert significant influences throughout the disease course. A novel clinical approach focused on NMS to develop tailored management strategies is warranted to improve the HrQoL in PD patients.

Translation and Validation of the Korean Version of the 39-Item Parkinson's Disease Questionnaire

BACKGROUND AND PURPOSE: The importance of health-related quality of life (HrQoL) has been increasingly emphasized when assessing and providing treatment to patients with chronic, progressive, degenerative disorders. The 39-item Parkinson's disease questionnaire (PDQ-39) is the most widely used patient-reporting scale to assess HrQoL in Parkinson's disease (PD). This study evaluated the validity and reliability of the translated Korean version of the PDQ-39 (K-PDQ-39). METHODS: One hundred and two participants with PD from 10 movement disorder clinics at university-affiliated hospitals in South Korea completed the K-PDQ-39. All of the participants were also tested using the Unified Parkinson's Disease Rating Scale (UPDRS), Korean version of the Mini-Mental State Examination (K-MMSE), Korean version of the Montgomery-Asberg Depression Scale (K-MADS), Epworth Sleepiness Scale (ESS) and non-motor symptoms scale (NMSS). Retests of the K-PDQ-39 were performed over time intervals from 10 to 14 days in order to assess test-retest reliability. RESULTS: Each K-PDQ-39 domain showed correlations with the summary index scores (rS=0.559-0.793, p or =0.70). The Guttman split-half coefficient value of the K-PDQ-39 summary index, which is an indicator of test-retest reliability, was 0.919 (p<0.001). All of the clinical variables examined except for age, comprising disease duration, levodopa equivalent dose, modified Hoehn and Yahr stage (H&Y stage), UPDRS part I, II and III, mood status (K-MADS), cognition (K-MMSE), daytime sleepiness (ESS) and (NMSS) showed strong correlations with the K-PDQ-39 summary index (p<0.01). CONCLUSIONS: The K-PDQ-39 has been validated for use in the Korean-speaking PD population. The questionnaire is a valid and reliable assessment tool for assessing the HrQoL of Korean PD patients.

No correlation between COMT genotype and entacapone benefi ts in Parkinson’s disease

Catechol-O-methyltransferase (COMT) inhibitors are used to increase the bioavailability of therapeutic L-dopa. We examined the effi cacy of entacapone in Parkinson’s disease patients who had daily “off” duration of ≤2 hours, and carried different COMT polymorphisms. A total of 168 PD patients were recruited from 19 centers. Subjects were administered with 100–200 mg of entacapone in combination with each dose of L-dopa for 2 months. The clinical effi cacy was evaluated based on the activities of daily living (ADL), score on the Unifi ed Parkinson’s Disease Rating Scale (UPDRS), Hoehn and Yahr (H&Y) stage, and Clinical Global Impression (CGI). COMT polymorphisms were genotyped. 3-O-methyldopa (3-OMD) levels were measured before and after the administration of entacapone. Entacapone administration produced signifi cant improvements in the total daily “on” duration, ADL, UPDRS score, and H&Y stage. Nineteen patients (11.3%) had the low-activity COMT genotype, 68 patients (40.5%) had the intermediate-activity COMT genotype, and 81patients (48.2%) had the high-activity COMT genotype. The effi cacy, and adverse effects of entacapone therapy did not differ between the three groups. There was a signifi cant reduction in 3-OMD, but this did not differ among the three genotypes. Entacapone provided an increased “on” duration and improved motor function in all COMT genotypes.

Daily dose of dopaminergic medications in Parkinson disease: Clinical correlates and a posteriori equation

Objectives: To survey daily doses of dopaminergic medications and to draw a posteriori equation of the dose in relation to the various clinical variables in Korean patients with Parkinson disease. Methods: A multi-center cross-sectional survey was conducted over a defi ned period. Information on patient demographics and clinical features including age at Parkinson disease onset, disease duration, treatment duration and Hoehn and Yahr stage, and daily doses of anti-parkinsonian drugs was obtained from the patients’ medical records. Results: A total of 1,762 patients with Parkinson disease were recruited from 6 referral centers. The mean L-dopa equivalent daily dose (LEDD) in the whole population was 608.9 mg/day, which tended to increase linearly depending on the duration of disease and Hoehn and Yahr stage. LEDD was also signifi cantly affected by age and gender. We performed multiple linear regression analyses and devised a posteriori equation of LEDD with clinical variables. Conclusions: This survey provides systematic data for mean LEDD in Korean Parkinson disease patients. In spite of profound individual variations in LEDD, our linear regression model provides an insight about the relationship between daily doses of dopaminergic medications and various clinical features of Parkinson disease.

Is Antipsychotic Intake a Risk Factor for the Restless Legs Syndrome?

BACKGROUND: Restless-legs syndrome (RLS) is known to be caused by dopaminergic hypofunction in the brain. We investigated whether antipsychotics that act as antidopaminergics increase the risk of RLS. METHODS: We prospectively recruited 72 schizophrenic patients who had been medicated with antipsychotic drugs in a psychiatry clinic. We evaluated RLS diagnostic criteria and basic sleep habits using the Epworth Sleepiness Scale and Pittsburgh Sleep Quality Index by face-to-face interviews using a structured questionnaire. We also applied the Unified Parkinson's Disease Rating Scale to evaluate extrapyramidal symptoms. RESULTS: Three of the 72 patients (4.2%) met RLS criteria, which is similar to the previously reported RLS incidence among the general population in Korea. CONCLUSIONS: There is no evidence that antipsychotics increase the risk of RLS. We believe that the mild antidopaminergic effect of antipsychotics does not overwhelm their prominent antipsychotic effect.

Handedness and Asymmetry of Motor Skill Learning in Right-handers

BACKGROUND AND PURPOSE: The most remarkable behavioral asymmetry is handedness. The preferred hand often has better performance, motor strength, nonpreferred hand. However, whether these components are associated with skill learning is not clear. METHODS: We evaluated healthy right-handers by setting a series of motor-performance tasks including skill learning, grip strength, and speed. RESULTS: The preferred hand showed better skill performance and learning rate. However, the degree of the right-left difference in grip strength or speed difference did not correlate with the asymmetry in skill-learning rate. Therefore, although the preferred hand exhibits a better skill-learning capacity than the nonpreferred hand, asymmetry in skill learning cannot be explained by motor strength or speed. CONCLUSIONS: Our findings suggest that better skill performance of the right hand in right-handers cannot be attributed to the degree of hand preference score, strength, or motor speed.