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Introduction Patients with Parkinson's disease (PD) are at increased risk for hospitalization and often experience worsening of PD when hospitalized. It is therefore important to identify strategies to prevent hospitalization. Methods Hospital encounter rates in different Parkinson's Foundation Centers of Excellence in United States, Canada, Israel and the Netherlands were analyzed as part of the Parkinson Foundation Parkinson's Outcomes Project (PF-POP). Multivariate logistic regression was used to estimate the odds ratio for hospitalization, adjusted for risk factors. Results Baseline age, disease duration, other relative than spouse/partner as care giver, cancer, arthritis, other comorbidities, falls, use of levodopa, use of dopamine agonist, use of COMT inhibitor, occupational therapy before the baseline visit, PDQ-39, MSCI total score and time between visits were significantly associated with the risk of hospital encounters. After adjustment for these factors, two centers had significantly lower odds for hospitalization admission and ER visit (minimum OR 0.3) and four centers had significantly higher odds (maximum OR 1.5) than the average center. Four centers had significantly lower hazard ratios for time to re-hospitalization compared to the average center. Reducing hospital admission rates in those centers with higher than average rates would reduce overall hospitalizations by 11%. Applied to PD patients over 65 nationwide this represents a potential for cost savings of greater than $1 billion over 48 months. Conclusion Encounter rates vary even across expert centers and suggest that practices carried out in some centers may reduce the risk of hospitalization. Further research will be necessary to identify these practices and implement them more widely to improve care for people with PD.

Object We review our experience with Parkinson's disease (PD) patients who underwent subthalamic nucleus (STN) deep brain stimulation (DBS) and then developed noninfectious, non-hemorrhagic, delayed, symptomatic brain edema associated with a DBS lead. Methods All PD patients who underwent STN DBS lead implantation from 2007 to 2015 were included. The same neurosurgeon performed all surgeries, typically in staged fashion, utilizing single pass microelectrode recordings (MER) within a stereotactic frame. A brain CT was obtained in recovery and subsequently if indicated. Results There were 189 patients who underwent 363 STN lead implantations among which 35 (9.6%) represent re-implantations of removed leads in 28 (14.8%) patients. Among the 363 STN leads implanted, there were 12 (3.3%) cases of delayed symptomatic edema associated with a DBS lead involving 10 (5.3%) of the patients studied. Of the 328 leads representing first-time operations, there were 9 (2.1%) cases of delayed symptomatic edema in 7 (3.7%) patients, one of whom (14.3%) presented with seizures. For lead re-implantations, there were 3 (8.6%) cases of the brain edema in 3 (10.7%) patients; all presenting with seizures. For the 35 re-implantations, the trajectory to target was the same or very similar via the same burr hole as prior surgery in 17 (48.6%); 3 (17.6%) of whom developed edema. There was no case of brain edema in the 18 re-operated cases using a different burr opening. Edema patients were treated with a course of anticonvulsant medication and dexamethasone. Lead-associated edema resolved over generally a 4 to 6-week course. Conclusions Noninfectious, non-hemorrhagic, delayed, symptomatic brain edema occurs in approximately 3% of implanted leads and is more common in re-implantations (9%) compared to new implantations (2%). In re-implantations, the edema is more common when the same trajectory is used (18%) compared to a new trajectory (0%). The edema generally occurs 3 to 8 days after implantation, although immediate post-op CT is normal and seizures are a common presenting feature.

Non-motor symptoms (NMS) including sleep disorders, anxiety, depression, fatigue, and cognitive decline can significantly impact quality of life in people with PD. Qigong exercise is a mind-body exercise that shows a wide range of benefits in various medical conditions. The purpose of this study was to investigate the effect of Qigong exercise on NMS with a focus on sleep quality. Seventeen participants completed a 12-week intervention of Qigong (n = 8) or sham Qigong (n = 9). Disease severity, anxiety and depression levels, fatigue, cognition, quality of life, and other NMS of the participants were evaluated prior to the intervention and at the end of the 12-week intervention. After the intervention, both Qigong and sham-Qigong group showed significant improvement in sleep quality (p < 0.05) and overall NMS (p < 0.05). No significant difference was found between groups. Qigong exercise has the potential as a rehabilitation method for people with PD, specifically alleviating NMS in PD. However, this finding needs to be carefully considered due to the small sample size and potentially low intervention fidelity of this study.

ObjectiveIPX066 is an extended release carbidopa/levodopa formulation designed to rapidly attain and maintain therapeutic plasma concentrations for a prolonged duration, allowing dosing intervals of approximately 6 h. The objective was to assess the efficacy, safety, and impact on quality of life of IPX066 in the treatment of levodopa-naive Parkinson's disease (PD) patients.MethodsThis was a randomized, double-blind, placebo-controlled, 30-week study of 381 levodopa-naïve patients assigned to placebo or IPX066 containing 145, 245 or 390 mg of levodopa administered three times daily (TID). The primary efficacy measure was change from Baseline in Unified Parkinson's Disease Rating Scale (UPDRS) activities of daily living (Part II) + motor scores (Part III), at 30 weeks. Secondary outcome measures included UPDRS total and subscores, patient and clinician global impressions (PGI-I, CGI-I), and the Parkinson's Disease Questionnaire (PDQ-39).ResultsAll IPX066 dosages were superior to placebo throughout the study and at 30 weeks (P

The aims of this systematic review were to investigate (1) real-time brain activity during DT gait and balance, (2) whether changes in brain activity correlate with changes in behavioral outcomes in older adults and people with age-related neurodegenerative conditions. PubMed, PsycINFO, and Web of Science were searched from 2009 to 2019 using the keywords dual task, brain activity, gait, balance, aging, neurodegeneration, and other related search terms. A total of 15 articles were included in this review. Functional near-infrared spectroscopy and electroencephalogram measures demonstrated that older adults had higher brain activity, particularly in the prefrontal cortex (PFC), compared to young adults during dual task gait and balance. Similar neurophysiological results were observed in people with age-related neurodegenerative conditions. Few studies demonstrated a relationship between increased brain activity and better behavioral outcomes. This systematic review supports the notion that aging and age-related neurodegenerative conditions are associated with neuronal network changes, resulting in increased brain activity specifically in the PFC. Further studies are warranted to assess the relationship between increased PFC activation during dual task gait and balance and behavioral outcomes to better optimize the rehabilitation interventions.

Postural instability is a major unmet need in the treatment of Parkinson's disease (PD) and its progression is not well understood. This study examined compensatory stepping taken in response to a backwards waist pull in participants with moderate PD (H&Y III) compared to age-range matched healthy controls (HC). The first step in the response was quantified in terms of strategy, temporal, kinematic, and center of pressure (COP) parameters previously observed to be significantly different in mild PD (H&Y II) compared to HC. Patients with moderate PD, compared to HC, utilized more steps to regain balance, had a longer weight-shift-time, and utilized a base-width neutral step to regain balance. However, there were no differences in ankle angle or COP location at landing as observed in mild PD, possibly due to the use of the base-width neutral step. These results suggest that moderate PD significantly impairs the compensatory response to a backwards pull. Further study should examine the progression of impairment in compensatory responses across PD severity levels, and the correlation with fall risk.

Rotigotine transdermal system is a nonergot, 24-hour dopamine agonist approved for the treatment of early and advanced Parkinson's disease (PD). Recent studies have demonstrated significant improvements with rotigotine in motor function in early PD and significant improvements in daily off-time and motor function in advanced PD. In addition to motor improvements, nonmotor symptoms have been shown to be improved with rotigotine in both early and advanced PD. Rotigotine has been shown in large, controlled studies to be safe and efficacious for the treatment of motor and some nonmotor symptoms of early and advanced PD.

Defined as the transient state between standing and walking, gait initiation is negatively affected in Parkinson's disease (PD), which often results in significant disability. Although deep brain stimulation (DBS) is the most common surgical procedure for PD, the long-term effects of DBS on gait initiation are not well studied. The present study evaluated the long-term effects of subthalamic nucleus (STN) DBS on the preparation phase of gait initiation using principal component (PC) analysis. Six patients with PD who had undergone STN DBS and 24 healthy control subjects were evaluated. PD subjects were assessed 11.3 ± 10.3 (P1) and 78.9 ± 10.6 (P2) months after surgery. PD subjects were tested with STN DBS in two conditions: without medication and with medication. PC analysis was applied separately for the vertical, anterior–posterior and medial–lateral components of ground reaction force (GRF) recorded during gait initiation. Three PC scores were chosen by the scree test for each GRF component and all these PC scores were used for calculating a standard distance between healthy controls and PD subjects. The Friedman test showed a significant difference in standard distance among conditions ( P = 0.004), with the post-hoc test recognizing differences among P1 conditions and P2 medication-on condition. The eigenvector loading factors pointed to major differences between PD conditions surrounding the maximum amplitude of vertical and anterior–posterior GRF. For the studied sample, all distances increased in the follow-up evaluation (P2) with and without medications, indicating a worsening in gait initiation after seven years.

Summary Background The effects of constant-current deep brain stimulation (DBS) have not been studied in controlled trials in patients with Parkinson's disease. We aimed to assess the safety and efficacy of bilateral constant-current DBS of the subthalamic nucleus. Methods This prospective, randomised, multicentre controlled trial was done between Sept 26, 2005, and Aug 13, 2010, at 15 clinical sites specialising in movement disorders in the USA. Patients were eligible if they were aged 18–80 years, had Parkinson's disease for 5 years or more, and had either 6 h or more daily off time reported in a patient diary of moderate to severe dyskinesia during waking hours. The patients received bilateral implantation in the subthalamic nucleus of a constant-current DBS device. After implantation, computer-generated randomisation was done with a block size of four, and patients were randomly assigned to the stimulation or control group (stimulation:control ratio 3:1). The control group received implantation without activation for 3 months. No blinding occurred during this study, and both patients and investigators were aware of the treatment group. The primary outcome variable was the change in on time without bothersome dyskinesia (ie, good quality on time) at 3 months as recorded in patients' diaries. Patients were followed up for 1 year. This trial is registered with ClinicalTrials.gov, number NCT00552474. Findings Of 168 patients assessed for eligibility, 136 had implantation of the constant-current device and were randomly assigned to receive immediate (101 patients) or delayed (35 patients) stimulation. Both study groups reported a mean increase of good quality on time after 3 months, and the increase was greater in the stimulation group (4·27 h vs 1·77 h, difference 2·51 [95% CI 0·87–4·16]; p=0·003). Unified Parkinson's disease rating scale motor scores in the off-medication, on-stimulation condition improved by 39% from baseline (24·8 vs 40·8). Some serious adverse events occurred after DBS implantation, including infections in five (4%) of 136 patients and intracranial haemorrhage in four (3%) patients. Stimulation of the subthalamic nucleus was associated with dysarthria, fatigue, paraesthesias, and oedema, whereas gait problems, disequilibrium, dyskinesia, and falls were reported in both groups. Interpretation Constant-current DBS of the subthalamic nucleus produced significant improvements in good quality on time when compared with a control group without stimulation. Future trials should compare the effects of constant-current DBS with those of voltage-controlled stimulation. Funding St Jude Medical Neuromodulation Division.

Purpose The primary purpose was to demonstrate the feasibility of executing treatment tasks focused on increasing loudness in a group format for individuals with Parkinson's disease (PD). A second purpose was to report preliminary pre-to-post treatment outcomes for individuals with PD immediately after they complete the group program. Methods The group intervention is described. Fifteen adults with PD who participated in the group and three clinicians leading the group provided feedback about the execution of the intervention. The participants also provided voice samples and self-ratings of voice handicap once before completing the 8-week voice group and once immediately after completing the voice group. Outcome measures included voice intensity, fundamental frequency (F0) mean, standard deviation and range, maximum phonation time, and listener judgment of loudness. Results Feedback from the clinicians suggested that many, but not all, of the voice activities could be executed within a group setting. Participants with PD indicated they understood the focus of the group and that subjectively they felt the group was helpful for increasing loudness. Statistically significant increases occurred for voice intensity, F0 maximum, and F0 range. Voice handicap scores decreased significantly and 80% of the participants were judged louder post intervention. Conclusions Clinician and participant feedback indicated that it was feasible to execute most LSVT ® tasks in a group format with some modifications. The preliminary outcome data indicate that the targeted behavior (voice dB and loudness) did change in the predicted direction as did several other measures. Future studies comparing outcomes of group intervention to the gold standard LSVT ® , and exploring retention of treatment gains over time, are needed. Learning outcomes: After reading the manuscript, readers will be able to: (1) Describe previous attempts at group intervention to improve voice for individuals with Parkinson's disease. (2) List three ways that the group intervention tried in this study differed from LSVT ® . (3) Identify three limitations to this study that must be addressed before advocating implementation of the group approach in clinical situations.

Item does not contain fulltext OBJECTIVES: To explore current practices and opinions regarding hospital management of Parkinson disease (PD) patients in specialized PD Centers. METHODS: Fifty-one out of 54 National Parkinson Foundation (NPF) Centers worldwide completed an online survey regarding hospitalization of PD patients. RESULTS: Many Centers were concerned about the quality of PD-specific care provided to their patients when hospitalized. Primary concerns were adherence to the outpatient medication schedule and poor understanding by hospital staff of medications that worsen PD. Few Centers had a policy with their primary hospital that notified them when their patients were admitted. Rather, notification of hospitalization came often from the patient or a family member. Several Centers (29%) reported not finding out about a hospitalization until a routine clinic visit after discharge. Quick access to outpatient PD care following discharge was a problem in many Centers. Elective surgery, fall/fracture, infection, and mental status changes, were identified as common reasons for hospitalization. CONCLUSIONS: There is a perceived need for PD specialists to be involved during hospitalization of their patients. Improvement in communication between hospitals and PD Centers is necessary so that hospital clinicians can take advantage of PD specialists' expertise. Education of hospital staff and clinicians regarding management of PD, complications of PD, and medications to avoid in PD is critical. Most importantly, outpatient access to PD specialists needs to be improved, which may prevent unnecessary hospitalizations in these patients.

Purpose Adequate velopharyngeal control is essential for speech, but may be impaired in Parkinson's disease (PD). Bilateral subthalamic nucleus deep brain stimulation (STN DBS) improves limb function in PD, but the effects on velopharyngeal control remain unknown. We tested whether STN DBS would change aerodynamic measures of velopharyngeal control, and whether these changes were correlated with limb function and stimulation settings. Methods Seventeen PD participants with bilateral STN DBS were tested within a morning session after a minimum of 12 h since their most recent dose of anti-PD medication. Testing occurred when STN DBS was on, and again 1 h after STN DBS was turned off, and included aerodynamic measures during syllable production, and standard neurological ratings of limb function. Results We found that PD participants exhibited changes with STN DBS, primarily consistent with increased intraoral pressure ( n = 7) and increased velopharyngeal closure ( n = 5). These changes were modestly correlated with measures of limb function, and were correlated with stimulation frequency. Conclusion Our findings suggest that STN DBS may change velopharyngeal control during syllable production in PD, with greater benefit associated with low frequency stimulation. However, DBS demonstrates a more subtle influence on speech-related velopharyngeal control than limb motor control. This distinction and its underlying mechanisms are important to consider when assessing the impact of STN DBS on PD. Learning outcomes: As a result of this activity, the participant will be able to (1) describe the effects of deep brain stimulation on limb and speech function; (2) describe the effects of deep brain stimulation on velopharyngeal control; and (3) discuss the possible reasons for differences in limb outcomes compared with speech function with deep brain stimulation of the subthalamic nucleus.

Deep brain stimulation of the subthalamic nucleus (DBS-STN) is an approved treatment for advanced Parkinson disease (PD) patients; however, there is a need to further evaluate its effect on gait. This study compares logistic regression (LR), probabilistic neural network (PNN) and support vector machine (SVM) classifiers for discriminating between normal and PD subjects in assessing the effects of DBS-STN on ground reaction force (GRF) with and without medication. Gait analysis of 45 subjects (30 normal and 15 PD subjects who underwent bilateral DBS-STN) was performed. PD subjects were assessed under four test conditions: without treatment (mof-sof), with stimulation alone (mof-son), with medication alone (mon-sof), and with medication and stimulation (mon-son). Principal component (PC) analysis was applied to the three components of GRF separately, where six PC scores from vertical, one from anterior-posterior and one from medial-lateral were chosen by the broken stick test. Stepwise LR analysis employed the first two and fifth vertical PC scores as input variables. Using the bootstrap approach to compare model performances for classifying GRF patterns from normal and untreated PD subjects, the first three and the fifth vertical PCs were attained as SVM input variables, while the same ones plus the first anterior-posterior were selected as PNN input variables. PNN performed better than LR and SVM according to area under the receiver operating characteristic curve and the negative likelihood ratio. When evaluating treatment effects, the classifiers indicated that DBS-STN alone was more effective than medication alone, but the greatest improvements occurred with both treatments together.

Deep brain stimulation (DBS) of the subthalamic nucleus (STN) is effective for the treatment of advanced Parkinson's disease. Most studies have evaluated the effectiveness of DBS of the STN using clinical motor scores or simple timed tests of motor function. There have been few studies that quantitatively assessed the outcome of STN DBS using multiple testing paradigms. In the current study, 11 patients who had bilateral STN DBS were quantitatively evaluated under four conditions using gait, postural control, and gait initiation. The four conditions included the medication on/stimulation on (M_on/S_on), medication on/stimulation off (M_on/S_off), medication off/stimulation on (M_off/S_on), and medication off/stimulation off (M_off/S_off) conditions. DBS of the STN significantly increased walking speed with and without levodopa, but had no influence on the cadence. The addition of levodopa had a minimal additional effect on walking speed. The effect of STN DBS on gait initiation approached the significant level. The mean values of lateral body sway during quiet standing increased moderately with medication and/or DBS, but the changes were not statistically significant. Future studies need to determine whether or not there is a potential negative effect of STN DBS on the postural control.

Background/Objective Essential tremor (ET) can diminish functioning and quality of life (QOL) but generic QOL measures may be relatively insensitive to ET and its therapies. We sought to develop an ET-specific measure that might be more sensitive, acceptable to patients, relatively brief, and easily used. Design/Methods A sample of 200 patients (average age 70 years, range 30–91; average disease duration 15 years) rated the extent to which tremor impacts a function or state, tremor severity in various body parts, perceived health, and overall QOL. Responses to this initial questionnaire were subjected to principal components analysis (PCA). Inspection of factor coordinates, Eigenvalues, variance accounted for, and correlation matrices were used to select items for confirmatory PCA. Final scale reliability was assessed using Cronbach's α. Validity was evaluated by correlations between QOL scales and self-rated tremor severity. Results PCA of 65 initial items yielded 11 factors accounting for 71% of variance. Six factors were discarded. Two items were eliminated for not loading on a factor and 33 for perceived redundancy. Confirmatory PCA of the retained 30 items yielded an almost identical factor structure (six factors, 70% of variance accounted for, and similar item loadings). Because two factors had very few items loading on them, these two factors were combined into one scale. The final measure has five scales: Physical, Psychosocial, Communication, Hobbies/Leisure, and Work/Finance. Reliability was excellent for the whole instrument and four scales (≥0.89), and good for the Work/Finance scale (0.79). Severity of voice and head tremor were the best correlates of Communication (0.70 and 0.35), while the Physical scale was related to right and left upper extremity tremor (0.59 and 0.56). Scales correlated more highly with patients' rating of their overall QOL than their health perception. Conclusions A brief, 30-item, ET-specific QOL scale with excellent reliability was developed. Preliminary validity data are encouraging. The Quality of Life in Essential Tremor Questionnaire (QUEST) promises to facilitate QOL measurement in ET.

Parkinson’s disease (PD) is a progressive neurodegenerative disorder in which dopaminergic neurons are lost from the substantia nigra, causing basal ganglia dysfunction [1]. Resting tremor, bradykinesia, rigidity, and postural instability are the cardinal symptoms [2]. Levodopa is the most efficacious medication for PD [3]. Early in the course of PD, levodopa controls the primary motor symptoms and provides relief for nearly all patients. Initially, the effects of a single dose of levodopa last more than 4 hours. Over time, however, the drug eventually ceases to provide these relatively long and predictable symptom-free periods [4–6]. In addition, patients develop periods of involuntary choreic (twisting or turning) movements known as levodopainduced dyskinesias. Motor fluctuations and dyskinesias can become more disabling than the original PD symptoms. In moderate to advanced disease, patients may be afflicted by tremor, loss of mobility, dystonias, choreiform dyskinesias, episodes of ‘‘freezing,’’ and other motor symptoms [7]. Managing motor fluctuations and dyskinesias represents one of the major challenges of the long-term treatment of PD [7]. Recent research has led to many treatment innovations and strategies that provide patients with more

Questions exist regarding the validity of patient-reporting of psychiatric symptoms in Parkinson’s disease (PD). We assessed observer variability and validity in reporting of impulse control disorder (ICD) symptoms in PD by using the Questionnaire for Impulsive-Compulsive Disorders in Parkinson’s Disease (QUIP). PD patients and their informants (71 pairs) completed the QUIP to assess four ICDs (compulsive gambling, buying, sexual behavior, and eating) in patients. Trained raters then administered a diagnostic interview. Sensitivity of the QUIP for a diagnosed ICD was 100% for both patient- and informant-completed instruments, and specificity was 75% for both raters. Approximately 40% of patients without an ICD diagnosis had a positive QUIP, suggesting that many PD patients experience subsyndromal ICD symptoms that require ongoing monitoring. Agreement between patient- and informant-reporting of any ICD behaviors on the QUIP was moderate (kappa = 0.408), and for individual ICDs was highest for gambling (kappa = 0.550). Overall, a negative QUIP from either the patient or informant rules out the possibility of an ICD, while a positive QUIP requires a follow-up diagnostic interview and ongoing monitoring to determine if symptoms currently are, or in the future become, clinically significant.

Clinicogenetic and pathological studies have shown that mutations of the glucocerebrosidase gene (GBA) are a risk factor for Parkinson’s disease and Lewy body disorders. In the present study, we have identified GBA mutations in 6.8% (4/59) of cases with a pathological diagnosis of diffuse Lewy body disease. Taken with previous studies, it appears that GBA mutations are associated with a more diffuse pattern of Lewy body distribution involving the cerebral cortex than the brainstem/limbic distribution observed in typical Parkinson’s disease.

Sentence processing in Alzheimer's disease (AD) has been found to be influenced by several grammatical and extragrammatical factors, including phrase structure and verb–argument relations, number of propositions/verbs, and processing resource capacity. This study examines the effects of these variables on sentence production in AD. Normal control and AD subjects were asked to repeat six types of sentences varying along the above dimensions of complexity. Subjects' processing resource capacity was measured using several verbal working memory tests. AD subjects' sentence-repetition performance was impaired compared to the normal control group. Significant effects were observed for branching direction of phrase struc- ture, canonicity of verb–argument relations, and serial position of errors. Sentence-repetition performance significantly correlated with working memory scores. The findings are interpreted within a resource capacity theory of sentence processing.

Parkinson's disease (PD) is associated with an array of signs and symptoms and motor fluctuations. In addition, treatments such as levodopa and dopamine agonists are associated with side-effects that impact the same health domains as disease symptomatology. To comprehensively and sensitively assess drug therapies in respect of disease symptoms and side-effects, we designed the Parkinson's disease symptom inventory (PDSI). The PDSI consists of 51 symptoms items identified through expert opinion, patient interviews, and the medical literature. Items represent a detailed array of motor, postural, muscular, gastro-intestinal, emotional, and cognitive domains. Subjects are asked to report the frequency with which each symptom is experienced, as well as the associated subjective distress. After initial elimination of 8 items that did not meet retention criteria, psychometric analysis showed excellent internal consistency (alpha=0.92-0.95) and acceptable reproducibility (ICC=0.72-0.79) of items. Comparison of results with the Unified Parkinson's disease rating scale (UPDRS) and the Parkinson's impact scale (PIMS) revealed correlation with the PDSI, with Pearson's r values of roughly 0.5 and 0.7, respectively. The PDSI demonstrated power to discriminate mean scores of patients comprising the highest and lowest tertiles of the UPDRS and PIMS instruments. In summary, the PDSI demonstrated good psychometric performance characteristics, and may yield valuable data regarding the comparative effectiveness of PD therapies.

This study examined the grammatical content of written sentences elicited from 96 Parkinson's patients, 30 Parkinson's with dementia patients and 167 control subjects. Parkinson's patients without dementia or with mild dementia presented no impairments in sentence length, syntactic complexity or amount of information content. Moderately demented Parkinson's patients showed reduced sentence length and information content but normal syntactic complexity. This pattern of results provides evidence that lexical-semantic content is more susceptible to decline than syntactic structure with the progression of dementia in Parkinson's disease.

This study was designed to determine if the presence of tremor, rigidity, bradykinesia and postural instability and gait abnormalities differentially influence Parkinson's disease patients' ratings of quality of life as measured by the Parkinson's Disease Questionnaire (PDQ-39). A regression analysis indicated that the presence of postural instability and gait abnormalities and bradykinesia were strongly predictive of PDQ-39 quality of life scores. The presence of tremor and rigidity had little effect on patients' ratings of quality of life.