Equal access, unequal impact: Parkinson's minorities in the UK are tougher

Equal access, unequal impact: Parkinson's minorities in the UK are tougher

A landmark UK study shows that South Asian and black patients with Parkinson's suffer worse symptoms, even with equal access to care, highlighting urgent gaps in diagnosis and support for diverse communities.

In a recent studypublished in the journalNPJ Parkinson's diseaseResearchers used data from the East London Parkinson's Disease Project to compare clinical outcomes of Parkinson's disease (PD).the diverse ethnic backgrounds of Britain. Study results showed that South Asian and Black PD patients performed significantly worse on motor score ratings than their white counterparts.

Cognitive impairment was similarly more common in minority patients (75% black, 73% South Asian) compared to whites (45%). While there was weak evidence that South Asian patients had a slightly earlier age of symptom onset, the time from symptoms to diagnosis was found to be similar across groups. These results highlight the urgent need for policy reforms for more inclusive neuroscience and suggest that factors beyond diagnostic access may be driving these disparities in underrepresented populations.

background

Parkinson's disease (PD) is a neurodegenerative disorder, but PD is also associated with a variety of non-motor complications such as cognitive impairment.

Decades of clinical and genetic studies have contributed greatly to the scientific understanding of PD outcomes and genetic predisposition. Recent technological advances, including next-generation multiomic tools and artificial intelligence (AI) statistical models, have advanced our understanding of PD pathophysiology by leaps and bounds.

Unfortunately, most of what we know about the disease comes from studies involving predominantly white, Western European populations. These populations are genetically diverse and are typically wealthier and more educated than South Asian, black and other ethnic minorities.

The lack of ethnically diverse cohorts has left crucial questions unanswered: Does PD manifest differently in underrepresented groups? Are patients from racial minorities more affected or simply diagnosed and therefore treated later? As modern medicine enables the world's population to understand how Parkinson's disease unfolds in different racial and cultural contexts, it is critical to the rigor of research and to building a healthcare system that equitably serves all patients.

About the study

The present study uses data from the East London Parkinson's Disease Project, one of the UK's most ethnically diverse urban population cohorts, to elucidate differences in age at diagnosis and clinical PD outcomes between White, South Asian and Black ethnic groups. The study used a case-control design and collected data across multiple health services and NHS clinics between 2019 and 2024.

Participants included in the study were classified as “cases” (MDS 2015 confirmed, PD diagnosis) or “controls” (age-matched volunteers with no medical history of neurological diseases). Data collected included demographic information (age, gender, ethnicity, and educational status), medical history (including PD diagnoses and treatments), and economic variables.

Clinical assessments were performed using previously validated and standardized diagnostic tools such as the Unified Parkinson's Disease Rating Scale (UPDRS) to assess motor function. Cognitive performance was assessed by memory, attention and executive function tests, primarily using the Montreal Cognitive Assessment (MOCA).

Comparisons between groups were performed using t tests, χ2 tests, Mann-Whitney U tests, and Fisher exact tests. Logistic regression models were used to identify strengths of clinical PD findings. All models were adjusted for confounding demographic, medical, and socioeconomic variables, particularly age, gender, and disease duration.

Study results

​​​​​​​APercentage of patients from White (blue), South Asian (red) and Black ethnicities (yellow).bDetailed bar chart of cognitive status for each ethnic group. Classification based on MOCA: darker shade – cognitive impairment (≤ 25), lighter shade – normal cognition (> 25).

After excluding patients with 'secondary parkinsonism', alternative neurological or movement disorder diagnoses, and patients offering incomplete baseline data, the final study cohort included 218 PD patients and 90 healthy controls (total N = 318; 37% female), a majority of whom (64% controls, 50% patients) belonged to minority ethnic groups. Bangladeshis (49%) and Black Africans (71%) were the dominant ethnicities in South Asian and Black subcohorts, respectively.

Age in symptom symptom analyzes showed weak evidence that South Asian patients developed symptoms slightly earlier (59.2 years) than their white (62.6 years) or black (64.4 years) or black (64.4 years) counterparts. Crucially, the time from symptoms to diagnosis was similar across all three ethnic groups, which the authors noted was a positive finding suggesting equivalent access to primary care and awareness of PD symptoms in East London.

Patients of South Asian and Black descent had significantly worse Society Movement Disorders-Uniform Parkinson's Disease Rating Scale (MDS-UPDRS) motor scores than their white counterparts (42.2, 47.0, and 35.2, respectively). Objective motor assessments such as the brain test also showed poorer performance in South Asian patients, although the authors noted that factors such as low computer literacy could influence these specific results.

Cognitive impairment showed an equally striking gap between white and minority groups: 75% of black patients and 73% of South Asian patients showed cognitive dysfunction compared to only 45% of white patients. This included problems with memory, planning and visual reasoning, significantly affecting quality of life (QoL). Additionally, burden of specific non-motor symptoms differed, with South Asian patients reporting worse depression and sleep quality, and black patients showing a more significant odor identification deficit compared to white patients. However, the study authors added an important caveat: However, the cognitive test used has language, literacy and cultural biases, and they emphasized that such screening tools developed in white, English-speaking countries may not be the most appropriate for diverse populations without cultural adaptation.

Conclusions

This study provides clear evidence that PD affects racial groups differently, with the authors suggesting that black and South Asian patients may experience more severe motor and cognitive outcomes compared to white patients. In doing so, it challenges the longstanding assumption that Parkinson's presents uniformly across racial groups and limits the global generalizability of PD knowledge to a white focus.

These differences appear to exist despite fair time to diagnosis, and the work suggests that they may be driven by various factors such as unmeasured genetic or environmental influences or a higher prevalence of comorbidities such as type 2 diabetes in South Asian patients. While further research is needed to determine underlying causes, the results highlight the need for ethnically tailored screening and care protocols that take these differences into account.

Sources: