Parkinson's Disease in African Americans: A Review of the Current Literature

Differences in [123I]Ioflupane Striatal Binding Between African American and White Patients

Ethnic differences exist among patients with Parkinson disease (PD). PD is more common in the White than the African American population. This study aimed to explore whether differences exist in [123I]ioflupane binding, which reflects dopamine transporter binding, between African American and White individuals. Methods: Medical charts were reviewed for patients who underwent [123I]ioflupane SPECT imaging as part of routine practice in a single academic medical center. All images were visually graded as showing normal or abnormal presynaptic dopaminergic function (normal or abnormal scan status). Quantitative [123I]ioflupane uptake as measured by the specific binding ratios in the right and left striata and their subregions (caudate nucleus and anterior and posterior putamen) and by bilateral putamen-to-caudate ratios were compared between African American and White patients using multiple linear regression adjusted for age, sex, and abnormal scan status. Additional models included an ethnicity-by-abnormal-scan-status interaction term to determine whether abnormal scan status was modulated by ethnicity effect. Results: The percentage of patients with abnormal scan status was comparable between African American and White patients. Compared with White patients (n = 173), African American patients (n = 82) had statistically significantly higher uptake as measured by specific binding ratios in the right and left striata and some of their subregions (right and left caudate nuclei and right posterior putamen). Ethnicity-by-abnormal-scan-status interactions were not statistically supported for any models. Conclusion: We observed differences in [123I]ioflupane binding between African American and White patients independent of presynaptic dopaminergic dysfunction status. Future studies are needed to examine whether and how ethnicity affects dopamine transporter binding activities and its clinical relevance.

Epidemiology of Parkinson's Disease: An Update

PURPOSE OF REVIEW

In recent decades, epidemiological understanding of Parkinson disease (PD) has evolved significantly. Major discoveries in genetics and large epidemiological investigations have provided a better understanding of the genetic, behavioral, and environmental factors that play a role in the pathogenesis and progression of PD. In this review, we provide an epidemiological update of PD with a particular focus on advances in the last five years of published literature.

RECENT FINDINGS

We include an overview of PD pathophysiology, followed by a detailed discussion of the known distribution of disease and varied determinants of disease. We describe investigations of risk factors for PD, and provide a critical summary of current knowledge, knowledge gaps, and both clinical and research implications. We emphasize the need to characterize the epidemiology of the disease in diverse populations. Despite increasing understanding of PD epidemiology, recent paradigm shifts in the conceptualization of PD as a biological entity will also impact epidemiological research moving forward and guide further work in this field.

Disparities in Access to Deep Brain Stimulation for Parkinson's Disease and Proposed Interventions: A Literature Review

BACKGROUND

Deep brain stimulation (DBS) is an effective therapy for Parkinson's disease (PD), but disparities exist in access to DBS along gender, racial, and socioeconomic lines.

SUMMARY

Women are underrepresented in clinical trials and less likely to undergo DBS compared to their male counterparts. Racial and ethnic minorities are also less likely to undergo DBS procedures, even when controlling for disease severity and other demographic factors. These disparities can have significant impacts on patients' access to care, quality of life, and ability to manage their debilitating movement disorders.

KEY MESSAGES

Addressing these disparities requires increasing patient awareness and education, minimizing barriers to equitable access, and implementing diversity and inclusion initiatives within the healthcare system. In this systematic review, we first review literature discussing gender, racial, and socioeconomic disparities in DBS access and then propose several patient, provider, community, and national-level interventions to improve DBS access for all populations.

Parkinson Disease Genetics Extended to African and Hispanic Ancestries in the VA Million Veteran Program

Background and Objectives

Nearly all genetic analyses of Parkinson disease (PD) have been in populations of European ancestry. We sought to test the ability of a machine learning method to extract accurate PD diagnoses from an electronic medical record (EMR) system, to see whether genetic variants identified in European populations generalize to individuals of African and Hispanic ancestries, and to compare the rates of PD across ancestries.

Methods

A machine learning method using natural language processing was applied to EMRs of US veterans participating in the VA Million Veteran Program (MVP) to identify individuals with PD. These putative cases were vetted via blind chart review by a movement disorder specialist. A polygenic risk score (PRS) of 90 established genetic variants whose genotypes were imputed from a customized Axiom Biobank Array was evaluated in different case groups.

Results

The EMR prediction scores had a distinct trimodal distribution, with 97% of the high group and only 30% of the middle group having a credible diagnosis of PD. Using the 3,542 cases from the high group matched 4:1 to controls, the PRS was highly predictive in individuals of European ancestry (n = 3,137 cases; OR = 1.82; p = 8.01E-48), and nearly identical effect sizes were seen in individuals of African (n = 184; OR = 2.07; p = 3.4E-4) and Hispanic ancestries (n = 221; OR = 2.13; p = 3.9E-6). The PRS was much less predictive for the 2,757 European ancestry cases who had an ICD code for PD but for whom the machine learning method had a lower confidence in their diagnosis. No novel ancestry-specific genetic variants were identified. Individuals with African ancestry had one-quarter the rate of PD compared with European or Hispanic ancestries aged 60-70 years and one half the rate in the 70-80 years age range. African American cases had a higher proportion of their DNA originating in Europe compared with African American controls.

Discussion

Machine learning can reliably classify PD using data from a large EMR. Larger studies of non-European populations are required to confirm the generalizability of PD risk variants identified in populations of European ancestry and the increased risk coming from a higher proportion of European DNA in African Americans.

Explainable machine learning for predicting conversion to neurological disease: Results from 52,939 medical records

Objective

This study assesses the application of interpretable machine learning modeling using electronic medical record data for the prediction of conversion to neurological disease.

Methods

A retrospective dataset of Cleveland Clinic patients diagnosed with Alzheimer's disease, amyotrophic lateral sclerosis, multiple sclerosis, or Parkinson's disease, and matched controls based on age, sex, race, and ethnicity was compiled. Individualized risk prediction models were created using eXtreme Gradient Boosting for each neurological disease at four timepoints in patient history. The prediction models were assessed for transparency and fairness.

Results

At timepoints 0-months, 12-months, 24-months, and 60-months prior to diagnosis, Alzheimer's disease models achieved the area under the receiver operating characteristic curve on a holdout test dataset of 0.794, 0.742, 0.709, and 0.645; amyotrophic lateral sclerosis of 0.883, 0.710, 0.658, and 0.620; multiple sclerosis of 0.922, 0.877, 0.849, and 0.781; and Parkinson's disease of 0.809, 0.738, 0.700, and 0.651, respectively.

Conclusions

The results demonstrate that electronic medical records contain latent information that can be used for risk stratification for neurological disorders. In particular, patient-reported outcomes, sleep assessments, falls data, additional disease diagnoses, and longitudinal changes in patient health, such as weight change, are important predictors.

Under-Diagnosis of Dementia with Lewy Bodies in Individuals Racialized as Black: Hypotheses Regarding Potential Contributors

Dementia with Lewy bodies (DLB) is one of the most common degenerative dementias after Alzheimer's disease (AD) dementia. DLB is under-diagnosed across populations but may be particularly missed in older Black adults. The object of this review was to examine key features of DLB and potential associations with race in order to hypothesize why DLB may be under-diagnosed in Black adults in the U.S. In terms of dementia, symptoms associated with high rates of co-pathology (e.g., AD, vascular disease) in older Black adults may obscure the clinical picture that might suggest Lewy body pathology. Research also suggests that clinicians may be predisposed to give AD dementia diagnoses to Black adults, potentially missing contributions of Lewy body pathology. Hallucinations in Black adults may be misattributed to AD or primary psychiatric disease rather than Lewy body pathology. Research on the prevalence of REM sleep behavior in diverse populations is lacking, but REM sleep behavior disorder could be under-diagnosed in Black adults due to sleep patterns or reporting by caregivers who are not bed partners. Recognition of parkinsonism could be reduced in Black adults due to clinician biases, cultural effects on self-report, and potentially underlying differences in the frequency of parkinsonism. These considerations are superimposed on structural and systemic contributions to health (e.g., socioeconomic status, education, structural racism) and individual-level social exposures (e.g., social interactions, discrimination). Improving DLB recognition in Black adults will require research to investigate reasons for diagnostic disparities and education to increase identification of core symptoms in this population.

Black and hispanic patients with movement disorders less likely to undergo deep brain stimulation

BACKGROUND

DBS is an effective surgical treatment for ET, PD, and dystonia. Racial disparities in DBS utilization in PD have been documented demonstrating that Black patients receive DBS at lower rates than White patients. To our knowledge, no studies have investigated if this pattern of non-use persists in other movement disorders with FDA-approval.

OBJECTIVE

To identify racial and ethnic disparities in DBS utilization in those hospitalized for ET, PD, and dystonia.

METHODS

The NIS database was queried for US hospitalizations from 2012 to 2018 with a primary diagnosis of ET, PD, or dystonia, and a total of 3,363, 21,963, and 1,835 discharges were recorded, respectively. Within that sample, treatment with DBS was identified. Sex, race, age, payment method, income quartile, year, mortality risk, hospital size, urban/rural setting, teaching status, and geographic region were extracted. A multivariate logistic regression was performed to identify predictors for use and non-use of DBS.

RESULTS

Between 2012 and 2018, Black patients with PD, ET, and dystonia were less likely to receive DBS than White patients. Black patients with PD were 7 times less likely to receive DBS (OR = 0.145, CI = 0.111-0.189), and Black patients with ET and dystonia were 5 times less likely to receive DBS than White patients (OR = 0.188, CI = 0.124-0.285; OR = 0.186, CI = 0.084-0.414). Compared to White patients, Hispanic patients with PD (OR = 0.631, OR = 0.539-0.740) and ET (OR = 0.438, CI = 0.277-0.695) were less likely to undergo DBS. When controlling for patient and hospital level characteristics, racial and ethnic disparities remained.

CONCLUSIONS

Our data suggest that Black patients with a diagnosis of ET, PD, or dystonia and Hispanic patients with a diagnosis of ET or PD were less likely to be treated with DBS than White patients between 2012 and 2018.

Racial disparities in access to DBS: results of a real-world U.S. claims data analysis

Introduction

Deep brain stimulation (DBS) is an effective and standard-of-care therapy for Parkinson's Disease and other movement disorders when symptoms are inadequately controlled with conventional medications. It requires expert care for patient selection, surgical targeting, and therapy titration. Despite the known benefits, racial/ethnic disparities in access have been reported. Technological advancements with smartphone-enabled devices may influence racial disparities. Real-world evidence investigations can shed further light on barriers to access and demographic disparities for DBS patients.

Methods

A retrospective cross-sectional study was performed using Medicare claims linked with manufacturer patient data tracking to analyze 3,869 patients who received DBS. Patients were divided into two categories: traditional omnidirectional DBS systems with dedicated proprietary controllers ("traditional"; n = 3,256) and directional DBS systems with smart controllers ("smartphone-enabled"; n = 613). Demographics including age, sex, and self-identified race/ethnicity were compared. Categorical demographics, including race/ethnicity and distance from implanting facility, were analyzed for the entire population.

Results

A significant disparity in DBS utilization was evident. White individuals comprised 91.4 and 89.9% of traditional and smartphone-enabled DBS groups, respectively. Non-White patients were significantly more likely to live closer to implanting facilities compared with White patients.

Conclusion

There is great racial disparity in utilization of DBS therapy. Smartphone-enabled systems did not significantly impact racial disparities in receiving DBS. Minoritized patients were more likely to live closer to their implanting facility than White patients. Further research is warranted to identify barriers to access for minoritized patients to receive DBS. Technological advancements should consider the racial discrepancy of DBS utilization in future developments.

Does Black vs. White race affect practitioners' appraisal of Parkinson's disease?

Black patients are diagnosed with Parkinson's disease (PD) at half the rate as White patients. The reasons for this large disparity are unknown. Here, we review evidence that practitioner bias may contribute. A key sign of PD is hypomimia or decreased facial expressivity. However, practitioner bias surrounding facial expressivity in Black people versus White people may lead practitioners to appraise Black patients with hypomimia as having higher levels of facial expressivity. Furthermore, practitioner bias may cause them to characterize reduced facial expressivity as being due to negative personality traits, as opposed to a medical sign, in Black patients with hypomimia. This racial bias in the evaluation of hypomimia in Black versus White patients could profoundly impact subsequent referral decisions and rates of diagnosis of PD. Therefore, exploring these differences is expected to facilitate addressing health care disparities through earlier and more accurate detection of PD in Black patients.

Racial and Ethnic Disparities in Parkinson Disease: A Call to Action

Health disparities are pervasive in the United States. In the field of Parkinson disease (PD), profound racial and ethnic disparities exist in diagnosis, treatment, and research participation, leading to differential health outcomes and lack of generalizable research data. Racial and ethnic disparities not only limit our understanding of this complex heterogeneous disorder but also hamper our ability to provide new evidence-based care for America's most vulnerable populations. In this report, we summarize findings from our comprehensive white paper for the Michael J. Fox Foundation that reviews the current state of knowledge on racial and ethnic disparities in PD care in the following areas: epidemiology, etiology, phenotype and diagnosis, treatment, and research. We also identify knowledge gaps and necessary policy changes to ensure equitable, high-value care for all persons with PD. These strategies are designed to help identify and reduce health disparities among persons with PD and may serve as a model for other neurologic diseases.

Opportunities and challenges of alpha-synuclein as a potential biomarker for Parkinson's disease and other synucleinopathies

Parkinson’s disease (PD), the second most common progressive neurodegenerative disease, develops and progresses for 10–15 years before the clinical diagnostic symptoms of the disease are manifested. Furthermore, several aspects of PD pathology overlap with other neurodegenerative diseases (NDDs) linked to alpha-synuclein (aSyn) aggregation, also called synucleinopathies. Therefore, there is an urgent need to discover and validate early diagnostic and prognostic markers that reflect disease pathophysiology, progression, severity, and potential differences in disease mechanisms between PD and other NDDs. The close association between aSyn and the development of pathology in synucleinopathies, along with the identification of aSyn species in biological fluids, has led to increasing interest in aSyn species as potential biomarkers for early diagnosis of PD and differentiate it from other synucleinopathies. In this review, we (1) provide an overview of the progress toward mapping the distribution of aSyn species in the brain, peripheral tissues, and biological fluids; (2) present comparative and critical analysis of previous studies that measured total aSyn as well as other species such as modified and aggregated forms of aSyn in different biological fluids; and (3) highlight conceptual and technical gaps and challenges that could hinder the development and validation of reliable aSyn biomarkers; and (4) outline a series of recommendations to address these challenges. Finally, we propose a combined biomarker approach based on integrating biochemical, aggregation and structure features of aSyn, in addition to other biomarkers of neurodegeneration. We believe that capturing the diversity of aSyn species is essential to develop robust assays and diagnostics for early detection, patient stratification, monitoring of disease progression, and differentiation between synucleinopathies. This could transform clinical trial design and implementation, accelerate the development of new therapies, and improve clinical decisions and treatment strategies.

Persistent Racial Disparities in Deep Brain Stimulation for Parkinson's Disease

We sought to determine whether racial and socioeconomic disparities in the utilization of deep brain stimulation (DBS) for Parkinson's disease (PD) have improved over time. We examined DBS utilization and analyzed factors associated with placement of DBS. The odds of DBS placement increased across the study period, whereas White patients with PD were 5 times more likely than Black patients to undergo DBS. Individuals, regardless of racial background, with 2 or more comorbidities were 14 times less likely to undergo DBS. Privately insured patients were 1.6 times more likely to undergo DBS. Despite increasing DBS utilization, significant disparities persist in access to DBS. ANN NEUROL 2022;92:246–254

A Call to Action: Promoting Diversity, Equity, and Inclusion in Parkinson's Research and Care

The current base of knowledge around Parkinson's disease has been assembled in partnership with a cohort of participants that does not resemble the diversity of people with the disease. This poor representation in research results in an incomplete picture of the disease and disparities in care. The Michael J. Fox Foundation has defined four major areas of action: 1) identifying barriers and solutions to research participation; 2) funding inclusive research with greater participant diversity; 3) building a clinician/researcher workforce committed to health equity; and 4) supporting a more holistic understanding of PD. While factors driving disparities, including broader societal challenges, are complex, it is imperative that the PD research, care, and patient communities move in a decisive and coordinated fashion to identify and implement strategies that advance treatments for everyone with PD and eliminate care inequities.

Exploring the experiences of people and family carers from under-represented groups in self-managing Parkinson's disease and their use of digital health to do this

Introduction

Digital health is thought to enable people to better manage chronic conditions, such as Parkinson's. However, little is known about how people from under-represented groups with chronic conditions use digital health to self-manage.

Objective

The objective of our study was to explore the experiences of people and family carers from under-represented groups in self-managing Parkinson's, including their use of digital health to do this.

Methods

Semi-structured interviews (n = 18, including four dyadic) were conducted remotely, with 16 people with Parkinson's and six family carers in 2020–2021. Participants were purposively sampled from under-represented groups: belong to an ethnic minority, or having significant physical or sensory impairment. Interviews were audio-recorded, transcribed and analysed using thematic analysis.

Results

Three main themes of importance were developed: ‘self-management support’, ‘digital health use to support self-management’ and ‘identity, attitudes and characteristics’. Participants received medical, psychological, social and practical self-management support. Some participants used digital health resources, e.g., Parkinson's UK website. Digital literacy was the biggest barrier to using digital health, regardless of background, often dependant on previous occupation and confidence. Few ethnic minority participants thought race or culture alters self-management ability and most believed there was no need for digital health interventions to be tailored to an individual's race or culture. Some felt inclusivity was important in terms of diverse images of people. A range of considerations were identified to optimise digital health, such as assistive equipment for people with sensory impairment.

Conclusions

Barriers to using digital health for self-management were primarily dependent on personal factors including digital literacy and attitudes but rarely race or culture. We recommend the optimisation of digital health interventions by providing assistive technology at low cost, and visual inclusiveness should be promoted by including images of people from diverse backgrounds.