Charting the progression of disability in parkinson disease: study protocol for a prospective longitudinal cohort study

Journal ArticleBackground: People with Parkinson disease (PD), even in the presence of symptomatic relief from medical, surgical, and rehabilitative interventions, face a persistent worsening of disability. This disability is characterized by diminished quality of life, reduced functional mobility, declining performance in activities of daily living and worsening neurological impairments. While evidence has emerged supporting the clinically meaningful benefits of short-term exercise programs on these underlying factors, assertions regarding the effects of sustained programs of exercise and physical activity on the trajectory of disablement in PD are made in the absence of direct evidence. Indeed, the natural decline in quality of life and functional mobility in people diagnosed with PD is poorly understood. Moreover, outcome measures commonly used in clinical exercise trials typically do not capture the full spectrum of disability as defined by the World Health Organization (WHO). Methods/Design: The objective of this multicenter prospective study will be to examine the 2-year trajectory of disablement in a cohort of persons with PD. Two hundred sixty participants will be recruited to produce an expected final sample size of 150 individuals. Participants will be included if they are greater than 40 years of age, have a neurologist confirmed diagnosis of idiopathic PD, and are at Hoehn and Yahr stages 1 through 4. Data will be collected every 6 months during the study period. Primary outcome measures reflecting a broad spectrum of disablement will include, but will not be limited to, MDS-UPDRS, Timed Up and Go, Berg Balance Test, Nine Hole Peg Test, PDQ-39, and directly monitored ambulatory activity. Self-reported exercise and physical activity data also will be recorded. Statistical analyses will be used to characterize the trajectory of disablement and examine the influence of its underlying contributing factors. Discussion: Tertiary prevention is an important component of contemporary healthcare for individuals living with degenerative disease. For individuals with PD, there is growing recognition that exercise and/or physical activity efforts to slow the rate of functional mobility decline, in particular, may be critical for optimizing quality of life. By describing the natural trajectory of disablement, exercise habits, and physical activity in a cohort of persons with PD, this investigation will establish an important foundation for future intervention research. Specifically, through the evaluation of the influence of sustained exercise and physical activity on disablement, the study will serve as a preliminary step toward developing a randomized controlled trial of long-term exercise in persons with PD

Amplification of fall risk in Parkinsons disease: the influence of comorbidities

Journal ArticleLong term studies examining the progression of Parkinson's disease (PD) report the mean age of diagnosis to be in the mid sixties.' The diagnosis of PD typically .occurs after the presentation of motor deficits such as resting tremor, rigidity, hypokinesia, or postural instability. 2 Parkinson's disease in isolation results in worsening of motor deficits and progressive functional decline. While these problems are primarily the result of the degenerative process, underlying comorbidities may amplify or contribute to these deficits. In addition, given the typical age of onset, persons with PD will often present with a host of concurrent medical conditions (comorbidities). This is confirmed by research that estimated over 50% of Medicare beneficiaries had multiple comorbidities at the turn of the century.

Amplification of fall risk in Parkinson's disease: the influence of comorbidities

Journal ArticleLong term studies examining the progression of Parkinson's disease (PD) report the mean age of diagnosis to be in the mid sixties.' The diagnosis of PD typically .occurs after the presentation of motor deficits such as resting tremor, rigidity, hypokinesia, or postural instability. 2 Parkinson's disease in isolation results in worsening of motor deficits and progressive functional decline. While these problems are primarily the result of the degenerative process, underlying comorbidities may amplify or contribute to these deficits. In addition, given the typical age of onset, persons with PD will often present with a host of concurrent medical conditions (comorbidities). This is confirmed by research that estimated over 50% of Medicare beneficiaries had multiple comorbidities at the turn of the century.

Toward understanding ambulatory activity decline in Parkinson disease

BACKGROUND: Declining ambulatory activity represents an important facet of disablement in Parkinson disease (PD). OBJECTIVE: The primary study aim was to compare the 2-year trajectory of ambulatory activity decline with concurrently evolving facets of disability in a small cohort of people with PD. The secondary aim was to identify baseline variables associated with ambulatory activity at 1- and 2-year follow-up assessments. DESIGN: This was a prospective, longitudinal cohort study. METHODS: Seventeen people with PD (Hoehn and Yahr stages 1-3) were recruited from 2 outpatient settings. Ambulatory activity data were collected at baseline and at 1- and 2-year annual assessments. Motor, mood, balance, gait, upper extremity function, quality of life, self-efficacy, and levodopa equivalent daily dose data and data on activities of daily living also were collected. RESULTS: Participants displayed significant 1- and 2-year declines in the amount and intensity of ambulatory activity concurrently with increasing levodopa equivalent daily dose. Worsening motor symptoms and slowing of gait were apparent only after 2 years. Concurrent changes in the remaining clinical variables were not observed. Baseline ambulatory activity and physical performance variables had the strongest relationships with 1- and 2-year mean daily steps. LIMITATIONS: The sample was small and homogeneous. CONCLUSIONS: Future research that combines ambulatory activity monitoring with a broader and more balanced array of measures would further illuminate the dynamic interactions among evolving facets of disablement and help determine the extent to which sustained patterns of recommended daily physical activity might slow the rate of disablement in PD.This study was funded primarily by the Davis Phinney Foundation and the Parkinson Disease Foundation. Additional funding was provided by Boston University Building Interdisciplinary Research Careers in Women's Health (K12 HD043444), the National Institutes of Health (R01NS077959), the Utah Chapter of the American Parkinson Disease Association (APDA), the Greater St Louis Chapter of the APDA, and the APDA Center for Advanced PD Research at Washington University. (Davis Phinney Foundation; Parkinson Disease Foundation; K12 HD043444 - Boston University Building Interdisciplinary Research Careers in Women's Health; R01NS077959 - National Institutes of Health; Utah Chapter of the American Parkinson Disease Association (APDA); Greater St Louis Chapter of the APDA; APDA Center for Advanced PD Research at Washington University

Balance differences in people with Parkinson disease with and without freezing of gait

Published in final edited form as: Gait Posture. 2015 September ; 42(3): 306–309. doi:10.1016/j.gaitpost.2015.06.007.BACKGROUND: Freezing of gait (FOG) is a relatively common and remarkably disabling impairment associated with Parkinson disease (PD). Laboratory-based measures indicate that individuals with FOG (PD+FOG) have greater balance deficits than those without FOG (PD-FOG). Whether such differences also can be detected using clinical balance tests has not been investigated. We sought to determine if balance and specific aspects of balance, measured using Balance Evaluation Systems Test (BESTest), differs between PD+FOG and PD-FOG. Furthermore, we aimed to determine if time-efficient clinical balance measures (i.e. Mini-BESTest, Berg Balance Scale (BBS)) could detect balance differences between PD+FOG and PD-FOG. METHODS: Balance of 78 individuals with PD, grouped as either PD+FOG (n=32) or PD-FOG (n=46), was measured using the BESTest, Mini-BESTest, and BBS. Between-groups comparisons were conducted for these measures and for the six sections of the BESTest using analysis of covariance. A PD composite score was used as a covariate. RESULTS: Controlling for motor sign severity, PD duration, and age, PD+FOG had worse balance than PD-FOG when measured using the BESTest (p=0.008, F=7.35) and Mini-BESTest (p=0.002, F=10.37), but not the BBS (p=0.27, F=1.26). BESTest section differences were noted between PD+FOG and PD-FOG for reactive postural responses (p<0.001, F=14.42) and stability in gait (p=0.003, F=9.18). CONCLUSIONS: The BESTest and Mini-BESTest, which specifically assessed reactive postural responses and stability in gait, were more likely than the BBS to detect differences in balance between PD+FOG and PD-FOG. Because it is more time efficient to administer, the Mini-BESTest may be the preferred tool for assessing balance deficits associated with FOG.This study was conducted with funding from the Davis Phinney Foundation, Parkinson's Disease Foundation, NIH R01 NS077959, NIH UL1 TR000448, Greater St. Louis American Parkinson Disease Association (APDA), APDA Center for Advanced PD Research at Washington University in St. Louis. The funding sources had no role in the study design, in the collection, analysis and interpretation of data; in the writing of the manuscript; or in the decision to submit the manuscript for publication. (Davis Phinney Foundation; Parkinson's Disease Foundation; R01 NS077959 - NIH; UL1 TR000448 - NIH; Greater St. Louis American Parkinson Disease Association (APDA); APDA Center for Advanced PD Research at Washington University in St. Louis

Social experience does not abolish cultural diversity in eye movements.

Adults from Eastern (e.g., China) and Western (e.g., USA) cultural groups display pronounced differences in a range of visual processing tasks. For example, the eye movement strategies used for information extraction during a variety of face processing tasks (e.g., identification and facial expressions of emotion categorization) differs across cultural groups. Currently, many of the differences reported in previous studies have asserted that culture itself is responsible for shaping the way we process visual information, yet this has never been directly investigated. In the current study, we assessed the relative contribution of genetic and cultural factors by testing face processing in a population of British Born Chinese adults using face recognition and expression classification tasks. Contrary to predictions made by the cultural differences framework, the majority of British Born Chinese adults deployed "Eastern" eye movement strategies, while approximately 25% of participants displayed "Western" strategies. Furthermore, the cultural eye movement strategies used by individuals were consistent across recognition and expression tasks. These findings suggest that "culture" alone cannot straightforwardly account for diversity in eye movement patterns. Instead a more complex understanding of how the environment and individual experiences can influence the mechanisms that govern visual processing is required

Two-year trajectory of fall risk in people with Parkinson disease: a latent class analysis

Published in final edited form as: Arch Phys Med Rehabil. 2016 March ; 97(3): 372–379.e1. doi:10.1016/j.apmr.2015.10.105.OBJECTIVE: To examine fall risk trajectories occurring naturally in a sample of individuals with early to middle stage Parkinson disease (PD). DESIGN: Latent class analysis, specifically growth mixture modeling (GMM), of longitudinal fall risk trajectories. SETTING: Assessments were conducted at 1 of 4 universities. PARTICIPANTS: Community-dwelling participants with PD of a longitudinal cohort study who attended at least 2 of 5 assessments over a 2-year follow-up period (N=230). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Fall risk trajectory (low, medium, or high risk) and stability of fall risk trajectory (stable or fluctuating). Fall risk was determined at 6 monthly intervals using a simple clinical tool based on fall history, freezing of gait, and gait speed. RESULTS: The GMM optimally grouped participants into 3 fall risk trajectories that closely mirrored baseline fall risk status (P=.001). The high fall risk trajectory was most common (42.6%) and included participants with longer and more severe disease and with higher postural instability and gait disability (PIGD) scores than the low and medium fall risk trajectories (P<.001). Fluctuating fall risk (posterior probability <0.8 of belonging to any trajectory) was found in only 22.6% of the sample, most commonly among individuals who were transitioning to PIGD predominance. CONCLUSIONS: Regardless of their baseline characteristics, most participants had clear and stable fall risk trajectories over 2 years. Further investigation is required to determine whether interventions to improve gait and balance may improve fall risk trajectories in people with PD.Supported by the Davis Phinney Foundation, the Parkinson's Disease Foundation, National Institutes of Health (NIH) (grant nos. NIH R01 NS077959 and NIH UL1 TR000448), the Massachusetts and Utah Chapters of the American Parkinson Disease Association (APDA), the Greater St Louis Chapter of the APDA, and the APDA Center for Advanced Research at Washington University. (Davis Phinney Foundation; Parkinson's Disease Foundation; NIH R01 NS077959 - National Institutes of Health (NIH); NIH UL1 TR000448 - National Institutes of Health (NIH); Utah Chapter of the American Parkinson Disease Association (APDA); Greater St Louis Chapter of the APDA; APDA Center for Advanced Research at Washington University; Massachusetts Chapter of the American Parkinson Disease Association (APDA)

Choosing a basis that eliminates spurious solutions in k.p theory

A small change of basis in k.p theory yields a Kane-like Hamiltonian for the conduction and valence bands of narrow-gap semiconductors that has no spurious solutions, yet provides an accurate fit to all effective masses. The theory is shown to work in superlattices by direct comparison with first-principles density-functional calculations of the valence subband structure. A reinterpretation of the standard data-fitting procedures used in k.p theory is also proposed.Comment: 15 pages, 2 figures; v3: expanded with much new materia

Are the average gait speeds during the 10 meter and 6 minute walk tests redundant in Parkinson disease?

Published in final edited form as: Gait Posture. 2017 February ; 52: 178–182. doi:10.1016/j.gaitpost.2016.11.033.We investigated the relationships between average gait speed collected with the 10Meter Walk Test (Comfortable and Fast) and 6Minute Walk Test (6MWT) in 346 people with Parkinson disease (PD) and how the relationships change with increasing disease severity. Pearson correlation and linear regression analyses determined relationships between 10Meter Walk Test and 6MWT gait speed values for the entire sample and for sub-samples stratified by Hoehn & Yahr (H&Y) stage I (n=53), II (n=141), III (n=135) and IV (n=17). We hypothesized that redundant tests would be highly and significantly correlated (i.e. r>0.70, p<0.05) and would have a linear regression model slope of 1 and intercept of 0. For the entire sample, 6MWT gait speed was significantly (p<0.001) related to the Comfortable 10 Meter Walk Test (r=0.75) and Fast 10Meter Walk Test (r=0.79) gait speed, with 56% and 62% of the variance in 6MWT gait speed explained, respectively. The regression model of 6MWT gait speed predicted by Comfortable 10 Meter Walk gait speed produced slope and intercept values near 1 and 0, respectively, especially for participants in H&Y stages II-IV. In contrast, slope and intercept values were further from 1 and 0, respectively, for the Fast 10Meter Walk Test. Comfortable 10 Meter Walk Test and 6MWT gait speeds appeared to be redundant in people with moderate to severe PD, suggesting the Comfortable 10 Meter Walk Test can be used to estimate 6MWT distance in this population.This study was funded by the Davis Phinney Foundation, the Parkinson's Disease Foundation, and the National Institutes of Health (R01 NS077959, K12 HD055931, UL1 TR000448). The funding sources had no input related to study design, data collection, or decision to submit for publication. (Davis Phinney Foundation; Parkinson's Disease Foundation; R01 NS077959 - National Institutes of Health; K12 HD055931 - National Institutes of Health; UL1 TR000448 - National Institutes of Health

Long-distance remote comparison of ultrastable optical frequencies with 1e-15 instability in fractions of a second

We demonstrate a fully optical, long-distance remote comparison of independent ultrastable optical frequencies reaching a short term stability that is superior to any reported remote comparison of optical frequencies. We use two ultrastable lasers, which are separated by a geographical distance of more than 50 km, and compare them via a 73 km long phase-stabilized fiber in a commercial telecommunication network. The remote characterization spans more than one optical octave and reaches a fractional frequency instability between the independent ultrastable laser systems of 3e-15 in 0.1 s. The achieved performance at 100 ms represents an improvement by one order of magnitude to any previously reported remote comparison of optical frequencies and enables future remote dissemination of the stability of 100 mHz linewidth lasers within seconds.Comment: 7 pages, 4 figure