Risk of Injurious Fall and Hip Fracture up to 26 y before the Diagnosis of Parkinson Disease: Nested Case-Control Studies in a Nationwide Cohort

Mapping morbidity 10 years prior to a diagnosis of young onset Alzheimer's disease

INTRODUCTION

Early symptoms in young onset Alzheimer's disease (YOAD) may be misinterpreted, causing delayed diagnosis. This population-based study aimed to map morbidity prior to YOAD diagnosis.

METHODS

In a register-based incidence density matched nested case-control study, we examined hospital-diagnosed morbidity for people diagnosed with YOAD in Danish memory clinics during 2016-2020 compared to controls in a 10-year period. Conditional logistic regression produced incidence rate ratios (IRRs).

RESULTS

The study included 1745 cases and 5235 controls. YOAD patients had a higher morbidity burden in the year immediately before dementia diagnosis, for certain disorders up to 10 years before. This was especially evident for psychiatric morbidity with the highest increased IRRs throughout the entire period and IRR 1.43 (95% confidence interval 1.14-1.79) in the 5-10-years before dementia diagnosis.

DISCUSSION

YOAD patients display a different pattern of morbidity up to 10 years prior to diagnosis. Awareness of specific alterations in morbidity may improve efforts toward a timely diagnosis.

HIGHLIGHTS

Retrospective, nested case-control study of young onset Alzheimer's disease (YOAD). YOAD cases had a higher morbidity burden than controls. YOAD cases had a higher psychiatric morbidity burden up to 10 years before diagnosis. Altered morbidity patterns could serve as an early warning sign of YOAD.

Time to workforce exit after a Parkinson's disease diagnosis

The impact of Parkinson's disease (PD) on workforce participation has received little attention even though demographic, lifestyle, and political changes together will result in an increased burden of PD on the working-age population. In this study, we investigate workforce survival after a PD diagnosis, as well as what demographic factors that are associated with workforce survival. As an exploratory outcome, we investigate workforce survival in persons with and without device-aided treatment (DAT). This is a nested case-cohort study based on Swedish national data from 2001-2016. Controls were matched on year of birth, sex, and municipality of residence. The used registers contain data on demographics, social insurance, in- and outpatient visits, filled drug prescriptions, and cause of death on the person-level. A total of 4781 persons with PD and 23,905 controls were included. The median survival until all-cause workforce exit was 43 months among persons that were workforce-active at the time of PD diagnosis, compared to 66 months in non-PD controls. Being female, ≥50 years old at diagnosis, or having a lower education were contributing factors to health-related workforce exit. Persons receiving DAT during follow-up exhibited shorter workforce survival than controls. However, this needs further investigation, particularly as patients have generally already left the workforce at the time for start of DAT. It is evident that PD has grave negative effects on workforce participation. Thus, supportive measures need to start at an early stage after diagnosis, and the development of new interventions is urgently needed.

Who to Enroll in Parkinson Disease Prevention Trials? The Case for Composite Prodromal Cohorts

Significant progress has been made in expanding our understanding of prodromal Parkinson disease (PD), particularly for recognition of early motor and nonmotor signs and symptoms. Although identification of these prodromal features may improve our understanding of the earliest stages of PD, they are individually insufficient for early disease detection and enrollment of participants in prevention trials in most cases because of low sensitivity, specificity, and positive predictive value. Composite cohorts, composed of individuals with multiple co-occurring prodromal features, are an important resource for conducting prodromal PD research and eventual prevention trials because they are more representative of the population at risk for PD, allow investigators to evaluate the efficacy of an intervention across individuals with varying prodromal feature patterns, are able to produce larger sample sizes, and capture individuals at different stages of prodromal PD. A key challenge in identifying individuals with prodromal disease for composite cohorts and prevention trial participation is that we know little about the natural history of prodromal PD. To move toward prevention trials, it is critical that we better understand common prodromal feature patterns and be able to predict the probability of progression and phenoconversion. Ongoing research in cohort studies and administrative databases is beginning to address these questions, but further longitudinal analyses in a large population-based sample are necessary to provide a convincing and definitive strategy for identifying individuals to be enrolled in a prevention trial.

Screening tool for identification of hip fractures in the prehospital setting

Objectives

This study aims to develop a screening tool that will help first responders identify patients with proximal femur fractures, commonly referred to as hip fractures, on site and direct these patients to hospitals with orthopaedic surgery services.

Study Design

Prospective survey.

Methods

Literature and expert opinion defined parameters for the Collingwood Hip Fracture Rule (CHFR) which predict a patient's likelihood of hip fracture. The study population included adults presenting to Collingwood General and Marine Hospital with lower extremity injuries between December 1, 2019 and March 10, 2020. Excluded patients had previous hip replacement, previous hip fracture on the side of the injury, or a high energy mechanism of injury. Patients were assessed with the CHFR before receiving x-ray imaging. The parameters were scored based on their predictive powers and analyzed by a receiver operating characteristic curve.

Results

The study included 101 patients (mean age 66.3 years), and 25.7% had a hip fracture confirmed on imaging. The sensitivity, specificity, positive predictive value, and negative predictive value helped score each parameter. Factors receiving 1 point are: age 65 to 79 years, female, mechanical fall, unable to weight-bear, knee pain. Factors receiving 2 points are: bruising at greater trochanter, age >80 years. Factors receiving 3 points are: pain with hip rotation, leg shortened and externally rotated. Score is the summation of all the factors' points. The receiver operating characteristic curve (0.953; P value < .0001) demonstrated scores of 7 had sensitivity:specificity of 84.6%:94.7%.

Conclusion

The CHFR screening tool score of 7 can be used by first responders in the prehospital setting to identify patients who sustain a hip fracture and make appropriate triage decisions. This will improve patient outcomes and decrease institutional costs.

A comparison of prediction approaches for identifying prodromal Parkinson disease

Identifying people with Parkinson disease during the prodromal period, including via algorithms in administrative claims data, is an important research and clinical priority. We sought to improve upon an existing penalized logistic regression model, based on diagnosis and procedure codes, by adding prescription medication data or using machine learning. Using Medicare Part D beneficiaries age 66–90 from a population-based case-control study of incident Parkinson disease, we fit a penalized logistic regression both with and without Part D data. We also built a predictive algorithm using a random forest classifier for comparison. In a combined approach, we introduced the probability of Parkinson disease from the random forest, as a predictor in the penalized regression model. We calculated the receiver operator characteristic area under the curve (AUC) for each model. All models performed well, with AUCs ranging from 0.824 (simplest model) to 0.835 (combined approach). We conclude that medication data and random forests improve Parkinson disease prediction, but are not essential.

Current Perspectives on the Assessment and Management of Gait Disorders in Parkinson's Disease

Gait dysfunction is a key defining feature of Parkinson's disease (PD), and is associated with symptoms of freezing and an increased risk of falls. In this narrative review, we cover the putative mechanisms of gait dysfunction in PD, the assessment of gait abnormalities, and the management of symptoms caused by the inherent difficulty in walking. Our understanding of the causes of gait problems in PD has progressed in recent times, moving from neurocognitive theory to correlates of affected neuronal pathways. In particular, this can be shown to correspond with abnormalities in responses to dual-task paradigms and dysfunction in cholinergic signaling. Great progress has been made in the sophistication and precision of gait assessment; however, it has firmly remained in the research domain. There is significant momentum behind wearable technologies that can be used by patients in their own environment, acting as digital biomarkers that can not only reflect progression but also independently discriminate PD from non-PD individuals. The treatment of gait dysfunction has historically relied on physical therapies and training combined with a view to mitigating the impact of such consequences as falls. Pharmacological therapies that are the mainstay of treatment in PD have tended to address symptoms like bradykinesia; however, optimization of dopaminergic therapies likely has a positive effect on quality of gait. Other targets have been assessed with the goal of improving gait, of which medications that improve cholinergic signaling appear most promising. Neuromodulation techniques are increasingly used in the form of deep-brain stimulation; however, standard targets, such as the globus pallidus interna, have a modest effect on gait. Considerable benefit has been seen through targeting the pedunculopontine nucleus, and a dual-target approach may be warranted. Stimulation of the spinal cord and brain through direct or magnetic approaches has been assessed, but requires further evidence.

Late-life falling and depressive symptoms associated with the risk of Parkinson's disease: a nationwide cohort data analysis

BACKGROUND

This study aimed to evaluate the relationship between the history of late-life falling and the development of Parkinson's disease (PD) and investigate whether depressive symptoms interact with falling to increase PD risk.

METHODS

We identified 1,223,726 subjects without PD who underwent the National Screening Program for Transitional Age at 66 years between 2009 and 2013 using the National Health Cohort database. In this program, every participant was assessed whether they experienced falling for the past six months. Depressive symptoms were evaluated with a three-item questionnaire extracted from the Geriatric Depression Scale. Incident PD was traced for a mean 4.23 ± 1.50 years. Cox proportional hazard regression models were used to assess the risk of PD by falling history with and without depressive symptoms after adjusting for other confounding variables.

RESULTS

In this cohort, the PD incidence rate was 1.30 and 1.03 cases per 1000 person-years in groups with and without falling and 1.34 and 1.00 cases per 1000 person-years in groups with and without depressive symptoms. The predictive risk of PD was increased by either a history of falling (HR = 1.24; 95% CI 1.11-1.40) or the presence of depressive symptoms (HR = 1.31; 95% CI 1.21-1.42) after adjusting for possible confounding variables. For individuals with both falling and depressive symptoms, PD risk increased further (HR = 1.66; 95% CI 1.40-1.97), but with sex-differences. The two factors increased PD risk in a sub-additive manner in men, whereas synergistically in women.

CONCLUSIONS

This national cohort database shows that late-life depressive symptoms accompanied by a falling event pose an increase in the risk of PD in older adults.

Fractures in the prodromal period of Parkinson disease

OBJECTIVE

To examine the association between fractures and Parkinson disease (PD) during the 5-year prodromal phase as compared to controls.

METHODS

We performed a population-based case-control study of Medicare beneficiaries in the United States from 2004 to 2009. We identified 89,632 incident PD cases and 117,760 comparable controls 66-90 years of age in 2009. PD case status was the outcome, and noncranial fracture the independent variable. We used logistic regression models to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for association between fracture and PD in yearly time intervals prior to PD diagnosis/control reference date, after adjusting for covariates.

RESULTS

There were 39,606 total fractures (25.4% cases, 14.3% controls) over the 5 years prior to the PD diagnosis/control reference date. PD was positively associated with fractures even after adjusting for age, sex, race/ethnicity, Charlson comorbidity index, alcohol use, tobacco use, and osteoporosis. The association between PD and fracture was evident at yearly time windows prior to PD diagnosis/control reference date. The association between PD and each type of fracture strengthened as the PD diagnosis/control reference date approached (all time interaction p values ≤0.02). Among beneficiaries with a mechanism of injury, the majority were attributed to falls (74.6% cases, 72.8% controls).

CONCLUSION

Fractures occur more commonly during the prodromal period of PD compared to controls, especially as diagnosis date approached, suggesting that patients with PD may experience unrecognized motor and nonmotor symptoms.

Validation of a Parkinson Disease Predictive Model in a Population-Based Study

Parkinson disease (PD) has a relatively long prodromal period that may permit early identification to reduce diagnostic testing for other conditions when patients are simply presenting with early PD symptoms, as well as to reduce morbidity from fall-related trauma. Earlier identification also could prove critical to the development of neuroprotective therapies. We previously developed a PD predictive model using demographic and Medicare claims data in a population-based case-control study. The area under the receiver-operating characteristic curve (AUC) indicated good performance. We sought to further validate this PD predictive model. In a randomly selected, population-based cohort of 115,492 Medicare beneficiaries aged 66-90 and without PD in 2009, we applied the predictive model to claims data from the prior five years to estimate the probability of future PD diagnosis. During five years of follow-up, we used 2010-2014 Medicare data to determine PD and vital status and then Cox regression to investigate whether PD probability at baseline was associated with time to PD diagnosis. Within a nested case-control sample, we calculated the AUC, sensitivity, and specificity. A total of 2,326 beneficiaries developed PD. Probability of PD was associated with time to PD diagnosis (p < 0.001, hazard ratio = 13.5, 95% confidence interval (CI) 10.6-17.3 for the highest vs. lowest decile of probability). The AUC was 83.3% (95% CI 82.5%-84.1%). At the cut point that balanced sensitivity and specificity, sensitivity was 76.7% and specificity was 76.2%. In an independent sample of additional Medicare beneficiaries, we again applied the model and observed good performance (AUC = 82.2%, 95% CI 81.1%-83.3%). Administrative claims data can facilitate PD identification within Medicare and Medicare-aged samples.

Choreographing life-experiences of balance control in people with Parkinson's disease

BACKGROUND

Parkinson's disease (PD) is a devastating neurodegenerative disorder. Reduced balance is one of the cardinal symptoms of PD, predisposing people living with PD to experience difficulties with the execution of tasks and activities, as well as hindering their involvement in meaningful life areas. The overarching aim of this study was to explore how deficits in balance control manifest in everyday life and how it is managed by people with PD (PwPD).

METHODS

Qualitative description was used as methodology, and in-depth interviews were conducted with 18 participants, between the ages of 46 to 83 years, with mild to severe PD. Interview transcripts were analyzed using qualitative content analysis, following an inductive approach.

RESULTS

One theme emerged from the analysis: Increased planning-choreographing life. Within this overarching theme, two categories were identified, namely Limitations in mobility and New restricted functioning in everyday life, each with 3-4 sub-categories. The categories described how PwPD handled decreased balance control in their everyday life by using motor and cognitive strategies as a consequence of not trusting their body's capacity to control balance. Activities in everyday life, as well as the ability to partake in leisure and social activities were profoundly affected.

CONCLUSION

People with mild to severe PD used strategies to handle decreased balance and they choreographed their lives around their individual current state of mobility and balance. The knowledge gained from this study can be used to develop targeted interventions addressing the nuances of balance deficits in everyday life.

Falls in Synucleinopathies

Parkinson's disease (PD) and other synucleinopathies, namely dementia with Lewy bodies (DLB) and multiple system atrophy (MSA), are common degenerative neurological disorders that share synuclein pathology. Although certain cardinal features of parkinsonism, including bradykinesia and rigidity, respond well to levodopa, axial features, such as gait and balance impairment, are less reliably responsive to dopaminergic therapy and surgical interventions. Consequently, falls are common in PD and other synucleinopathies and are a major contributor toward injury and loss of independence. This underscores the need for appropriate fall risk assessment and implementation of preventative measures in all patients with parkinsonism. The aim of this review is therefore to explore modifiable and non-modifiable risk factors for falls in synucleinopathies. We next review and evaluate the evidence for pharmacological, nonpharmacological, and surgical approaches for fall prevention, and emphasize individualized and multifaceted approaches.

Pre-Existing Disability and Its Risk of Fragility Hip Fracture in Older Adults

Background: Hip fracture is one of the significant public concerns in terms of long-term care in aging society. We aimed to investigate the risk for the incidence of hip fracture focusing on disability among older adults. Methods: This was a population-based retrospective cohort study, focusing on adults aged 65 years or over who were included in the Korean National Health Insurance Service⁻National Sample from 2004 to 2013 (N = 90,802). Hazard ratios with 95% confidence interval (CIs) were calculated using the Cox proportional hazards model according to disability adjusted for age, household income, underlying chronic diseases, and comorbidity index. Results: The incidence of hip fracture was higher among older adults with brain disability (6.3%) and mental disability (7.5%) than among those with other types of disability, as observed during the follow-up period. Risk of hip fracture was higher among those who were mildly to severely disabled (hazard ratio for severe disability = 1.59; 95% CI, 1.33⁻1.89; mild = 1.68; 95% CI, 1.49⁻1.88) compared to those who were not disabled. Older men with mental disabilities experienced an incidence of hip fracture that was almost five times higher (hazard ratio, 4.98; 95% CI, 1.86⁻13.31) versus those that were not disabled. Conclusions: Older adults with mental disabilities and brain disability should be closely monitored and assessed for risk of hip fracture.

Reduced workforce participation 5 years prior to first Parkinson's disease sick-leave

The importance of understanding the prodromal phase of Parkinson’s disease (PD) by systematic recording of prediagnostic symptoms and reductions in body functions has been highlighted. The aim of this study was to investigate whether persons later diagnosed with PD exhibit increased physician-certified sickness absence 1, 2, and 5 years prior to a first sick-leave episode attributed to PD. A case-control study was performed to analyze data from all nontrivial (exceeding 14 days) sick-leave episodes in Sweden between 2008 and 2014. The 537 incident PD sick-leave episodes were identified as PD sick-leave cases and compared to 537 sick-leave controls identified by matching age, sex, and date of the first day of the sick-leave episode. The total sickness absence and sickness absence due to musculoskeletal diagnoses were found to be increased among the PD sick-leave cases from 5 years prior to the first sick-leave episode ascribed to PD when compared to the controls. No differences between PD sick-leave cases and sick-leave controls were found with regard to mental and behavioral diagnoses. We conclude that the capacity to participate in working life is reduced already at the early prediagnostic stages of PD. This finding can be used as a basis for further research into the process of identifying individuals at risk for developing PD, particularly in combination with further investigation into biochemical, genetic, and imaging biomarkers.

A Swedish study shows that Parkinson’s disease (PD) patients had more sick-leave episodes in the years before diagnosis than matched controls not diagnosed with PD. There is growing evidence that prior PD diagnosis, patients experience a variety of nonmotor symptoms and subtle motor signs. Further understanding these symptoms could prompt earlier therapeutic intervention and increase the likelihood of slowing down or even halting disease progression. A study led by Jonathan Timpka at Lund University examined the sickness leave history of 537 workers 1, 2 and 5 years before a first sick-leave episode due to PD. These workers took more sick-leave due to musculoskeletal symptoms, but not due to mental or behavioral issues, than the control group. These findings highlight a potential effect of preclinical PD on patients’ ability to work.

β2-adrenoreceptor medications and risk of Parkinson disease

OBJECTIVE

A recent study observed a 2-fold greater risk of Parkinson disease (PD) in relation to the β2-adrenoreceptor antagonist propranolol and a markedly lower risk of PD for the β2-adrenoreceptor agonist salbutamol. We examined whether confounding by clinical indication for these medications, that is, tremor and smoking-related pulmonary conditions, explained these associations.

METHODS

In a large, population-based case-control study of United States Medicare beneficiaries in 2009 with diagnosis codes, procedure codes, and prescription data (48,295 incident PD cases, 52,324 controls), we examined the risk of PD in relation to use of selected β antagonists (propranolol, carvedilol, metoprolol), the β2 agonist salbutamol, and other medications used for the same clinical indications (primidone, inhaled corticosteroids). We adjusted for demographics, smoking, and overall use of medical care. We then examined the effect of also adjusting for clinical indication and applying medication exposure lagging.

RESULTS

Propranolol appeared to increase PD risk (odds ratio [OR] = 3.62, 95% confidence interval [CI] = 3.31-3.96). When we adjusted for tremor or abnormal involuntary movement prior to the PD diagnosis/reference date and lagged propranolol exposure, the association was 0.97 (95% CI = 0.80-1.18). Primidone, also used for tremor, was similarly sensitive to this adjustment and lagging. β Antagonists not indicated for tremor appeared to reduce PD risk (carvedilol: OR = 0.77, 95% CI = 0.73-0.81; metoprolol: OR = 0.94, 95% CI = 0.91-0.97) and were insensitive to adjustment for indications and lagging. Neither salbutamol nor inhaled corticosteroids were consistently associated with PD risk.

INTERPRETATION

β2-adrenoreceptor agonists and antagonists do not appear to alter PD risk. Ann Neurol 2018;84:691-701.

Parkinson's disease and risk of hip fracture: systematic review and meta-analysis

The relationship between Parkinson's disease (PD) and risk of hip fracture yielded inconsistent results. Therefore, we conducted the present systematic review and meta-analysis of published observational studies to assess the association between PD and risk of hip fracture. PubMed, ISI, EMBASE, and Cochrane databases were searched systematically to identify studies assessing the relationship between PD and the risk of hip fracture up to July 01, 2017. In addition, to find related articles, the reference section of retrieved articles was checked. Random-effects model was used for calculation of pooled hazard ratio (HR) and 95% confidence intervals (CI). Thirteen independent studies containing 564,947 participants were included in the meta-analysis. The overall results of included studies showed PD to be associated with the risk of hip fracture (HR_overall = 3.13, 95% CI 2.53-3.87) in women 3.11 (2.51-3.86) and men 2.60 (2.19-3.09). Our meta-analysis showed the direct association between PD and the risk of hip fracture in both men and women. However, due to the limitations of this study, further well-designed studies are required to confirm our findings.

Use of medical care biases associations between Parkinson disease and other medical conditions

OBJECTIVE

To examine how use of medical care biases the well-established associations between Parkinson disease (PD) and smoking, smoking-related cancers, and selected positively associated comorbidities.

METHODS

We conducted a population-based, case-control study of 89,790 incident PD cases and 118,095 randomly selected controls, all Medicare beneficiaries aged 66 to 90 years. We ascertained PD and other medical conditions using ICD-9-CM codes from comprehensive claims data for the 5 years before PD diagnosis/reference. We used logistic regression to estimate age-, sex-, and race-adjusted odds ratios (ORs) between PD and each other medical condition of interest. We then examined the effect of also adjusting for selected geographic- or individual-level indicators of use of care.

RESULTS

Models without adjustment for use of care and those that adjusted for geographic-level indicators produced similar ORs. However, adjustment for individual-level indicators consistently decreased ORs: Relative to ORs without adjustment for use of care, all ORs were between 8% and 58% lower, depending on the medical condition and the individual-level indicator of use of care added to the model. ORs decreased regardless of whether the established association is known to be positive or inverse. Most notably, smoking and smoking-related cancers were positively associated with PD without adjustment for use of care, but appropriately became inversely associated with PD with adjustment for use of care.

CONCLUSION

Use of care should be considered when evaluating associations between PD and other medical conditions to ensure that positive associations are not attributable to bias and that inverse associations are not masked.

Perceptions of balance and falls following a supervised training intervention - a qualitative study of people with Parkinson's disease

PURPOSE

To explore perceptions of balance and falls among people with mild to moderate Parkinson's disease 3 - 12 months following participation in supervised balance training.

MATERIALS AND METHODS

This qualitative study used in-depth individual interviews for data collection among 13 people with Parkinson's disease. Interviews were systematically analyzed using qualitative content analysis with an inductive approach.

RESULTS

Three main themes arose: Falls - avoided and intended highlights the wide spectrum of fall perceptions, ranging from worse-case scenario to undramatized events; Balance identity incorporates how gradual deterioration in balance served as a reminder of disease progression and how identifying themselves as "aware not afraid" helped certain participants to maintain balance confidence despite everyday activity restriction; Training as treatment recounts how participants used exercise as disease self-management with the aim to maintain independence in daily life. Interpretation of the underlying patterns of these main themes resulted in the overarching theme Training as treatment when battling problems with balance and falls.

CONCLUSIONS

Whereas certain participants expressed a fear of falling which they managed by activity restriction, others described being confident in their balance despite avoidance of balance-challenging activities. Training was used as treatment to self-manage disease-related balance impairments in order to maintain independence in daily life. Implication for Rehabilitation People with Parkinson's disease require early advice about the positive effects of physical activity as well as strategies for self-management in order to ease the psychological and physical burden of progressive balance impairment. Fear of falling should be investigated alongside activity avoidance in this group in order to provide a more accurate insight into the scope of psychological concerns regarding balance and falls in everyday life. Certain people with Parkinson's disease define their balance according to activities they continue to participate in, while others who express fear-related activity avoidance require help to adapt balance-challenging activities in order to maintain balance confidence and avoid physical inactivity.

Traumatic brain injury in the prodromal period of Parkinson's disease: A large epidemiological study using medicare data

OBJECTIVE

Studies suggest a greater risk of Parkinson's disease (PD) after traumatic brain injury (TBI), but it is possible that the risk of TBI is greater in the prodromal period of PD. We aimed to examine the time-to-TBI in PD patients in their prodromal period compared to population-based controls.

METHODS

We identified 89,790 incident PD cases and 118,095 comparable controls aged > 65 years in 2009 using Medicare claims data. Using data from the preceding 5 years, we compared time-to-TBI in PD patients in their prodromal period to controls. We estimated hazard ratios (HRs) and 95% confidence intervals (CIs) for TBI in a Cox regression, while adjusting for age, sex, race/ethnicity, modified Charlson comorbidity index, smoking, and alcohol use.

RESULTS

Risk of TBI was greater in PD patients in their prodromal period across all age and sex groups, with HRs consistently increasing with proximity to PD diagnosis. HRs ranged from 1.64 (95% CI, 1.52, 1.77) 5 years preceding diagnosis to 3.93 (95% CI, 3.74, 4.13) in the year before. The interaction between PD, TBI, and time was primarily observed for TBI attributed to falls. Motor dysfunction and cognitive impairment, suggested by corresponding International Classification of Diseases, Ninth Revision codes, partially mediated the PD-TBI association.

INTERPRETATION

There is a strong association between PD and a recent TBI in the prodromal period of PD. This association strengthens as PD diagnosis approaches and may be a result of undetected nonmotor and motor symptoms, but confirmation will be required. Ann Neurol 2017;82:744-754.

Falls in Parkinson's disease: A complex and evolving picture

Falls are a major determinant of poor quality of life, immobilization, and reduced life expectancy in people affected by Parkinson's disease (PD) and in older adults more generally. Although many questions remain, recent research has advanced the understanding of this complex problem. The goal of this review is to condense new knowledge of falls in PD from prodromal to advanced disease, taking into account risk factors, assessment, and classification as well as treatment. The fundamental steps of clinical and research-based approaches to falls are described, namely, the identification of fall risk factors, clinical and instrumental methods to evaluate and classify fall risk, and the latest evidence to reduce or delay falls in PD. We summarize recent developments, the direction in which the field should be heading, and what can be recommended at this stage. We also provide a practical algorithm for clinicians.© 2017 International Parkinson and Movement Disorder Society.

A predictive model to identify Parkinson disease from administrative claims data

OBJECTIVE

To use administrative medical claims data to identify patients with incident Parkinson disease (PD) prior to diagnosis.

METHODS

Using a population-based case-control study of incident PD in 2009 among Medicare beneficiaries aged 66-90 years (89,790 cases, 118,095 controls) and the elastic net algorithm, we developed a cross-validated model for predicting PD using only demographic data and 2004-2009 Medicare claims data. We then compared this model to more basic models containing only demographic data and diagnosis codes for constipation, taste/smell disturbance, and REM sleep behavior disorder, using each model's receiver operator characteristic area under the curve (AUC).

RESULTS

We observed all established associations between PD and age, sex, race/ethnicity, tobacco smoking, and the above medical conditions. A model with those predictors had an AUC of only 0.670 (95% confidence interval [CI] 0.668-0.673). In contrast, the AUC for a predictive model with 536 diagnosis and procedure codes was 0.857 (95% CI 0.855-0.859). At the optimal cut point, sensitivity was 73.5% and specificity was 83.2%.

CONCLUSIONS

Using only demographic data and selected diagnosis and procedure codes readily available in administrative claims data, it is possible to identify individuals with a high probability of eventually being diagnosed with PD.

Shared molecular and cellular mechanisms of premature ageing and ageing-associated diseases

Ageing is the predominant risk factor for many common diseases. Human premature ageing diseases are powerful model systems to identify and characterize cellular mechanisms that underpin physiological ageing. Their study also leads to a better understanding of the causes, drivers and potential therapeutic strategies of common diseases associated with ageing, including neurological disorders, diabetes, cardiovascular diseases and cancer. Using the rare premature ageing disorder Hutchinson-Gilford progeria syndrome as a paradigm, we discuss here the shared mechanisms between premature ageing and ageing-associated diseases, including defects in genetic, epigenetic and metabolic pathways; mitochondrial and protein homeostasis; cell cycle; and stem cell-regenerative capacity.

Prodromal symptoms of Parkinson's disease: Implications for epidemiological studies of disease etiology

In recent years, there has been a major shift in our understanding of the course of Parkinson's disease (PD) from a disease of the brain to a disease of long latency, characterized by the progressive emergence of multiple non-motor symptoms, including hyposmia, constipation, depression, anxiety, rapid eye movement (REM) sleep behavior disorder and excessive daytime sleepiness, as well as subtle motor signs, before the typical motor signs appear. Epidemiological studies have made major contributions by allowing better characterization of subsequent PD risk in relation to non-motor symptoms. Such findings have profound implications for the conduct of epidemiological studies examining risk and protective factors in PD, and the interpretation of their findings. Given the length of the prodromal period, reverse causation in particular is a major concern with many reported associations. One striking feature of PD etiology, compared with other diseases, is the presence of numerous inverse associations. If these associations are truly causal, they would have major implications for disease prevention and for slowing disease progression. However, whether these associations are truly causal remains to be demonstrated in future studies. Experimental studies play an important role by offering a better understanding of the underlying mechanisms. Well-designed epidemiological studies using innovative approaches will also be key in elucidating whether these intriguing associations are causal or a consequence of reverse causation.