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Background and Objectives: Racial and ethnic minorities have been underrepresented in Parkinson disease (PD) research, limiting our understanding of treatments and outcomes across all non-White groups. The goal of this research is to investigate variability in health-related quality of life (HRQoL) and other outcomes in patients with PD across different races and ethnicities., Methods: This was a retrospective, cross-sectional and longitudinal, cohort study of individuals evaluated at PD Centers of Excellence. A multivariable regression analysis adjusted for sex, age, disease duration, Hoehn and Yahr (H&Y) stage, comorbidities, and cognitive score was used to investigate differences between racial and ethnic groups. A multivariable regression with skewed-t errors was performed to assess the individual contribution of each variable to the association of 39-item PD Questionnaire (PDQ-39) with race and ethnicity., Results: A total of 8,514 participants had at least 1 recorded visit. Most of them (90.2%) self-identified as White (n = 7,687), followed by 5.81% Hispanic (n = 495), 2% Asians (n = 170), and 1.9% African American (n = 162). After adjustment, total PDQ-39 scores were significantly higher (worse) in African Americans (28.56), Hispanics (26.62), and Asians (25.43) when compared with those in White patients (22.73, p < 0.001). This difference was also significant in most PDQ-39 subscales. In the longitudinal analysis, the inclusion of cognitive scores significantly decreased the strength of association of the PDQ-39 and race/ethnicity for minority groups. A mediation analysis demonstrated that cognition partially mediated the association between race/ethnicity and PDQ-39 scores (proportion mediated 0.251, p < 0.001)., Discussion: There were differences in PD outcomes across racial and ethnic groups, even after adjustment for sex, disease duration, HY stage, age, and some comorbid conditions. Most notably, there was worse HRQoL among non-White patients when compared with White patients, which was partially explained by cognitive scores. The underlying reason for these differences needs to be a focus of future research., (© 2023 American Academy of Neurology.)

Objective: To delineate the natural history, diagnosis, and treatment response of Parkinson disease (PD) in individuals with 22q11.2 deletion syndrome (22q11.2DS), and to determine if these patients differ from those with idiopathic PD., Methods: In this international observational study, we characterized the clinical and neuroimaging features of 45 individuals with 22q11.2DS and PD (mean follow-up 7.5 ± 4.1 years)., Results: 22q11.2DS PD had a typical male excess (32 male, 71.1%), presentation and progression of hallmark motor symptoms, reduced striatal dopamine transporter binding with molecular imaging, and initial positive response to levodopa (93.3%). Mean age at motor symptom onset was relatively young (39.5 ± 8.5 years); 71.4% of cases had early-onset PD (<45 years). Despite having a similar age at onset, the diagnosis of PD was delayed in patients with a history of antipsychotic treatment compared with antipsychotic-naive patients (median 5 vs 1 year, p = 0.001). Preexisting psychotic disorders (24.5%) and mood or anxiety disorders (31.1%) were common, as were early dystonia (19.4%) and a history of seizures (33.3%)., Conclusions: Major clinical characteristics and response to standard treatments appear comparable in 22q11.2DS-associated PD to those in idiopathic PD, although the average age at onset is earlier. Importantly, treatment of preexisting psychotic illness may delay diagnosis of PD in 22q11.DS patients. An index of suspicion and vigilance for complex comorbidity may assist in identifying patients to prioritize for genetic testing., (Copyright © 2018 The Author(s). Published by Wolters Kluwer Health, Inc. on behalf of the American Academy of Neurology.)

Objective: To determine the utility of detecting a-synuclein (aSyn) in colonic mucosal biopsy tissue as a potential diagnostic biomarker for Parkinson disease (PD)., Methods: We used the paraffin-embedded tissue (PET) blot, which degrades physiologic nonaggregated aSyn using proteinase K and enhances antigen retrieval allowing sensitive and selective detection of remaining protein aggregates, to detect aSyn in colonic mucosal biopsies from 15 patients with early PD (,3 years), 7 patients with later PD (.5 years), and 11 individuals without PD. aSyn and serine 129–phosphorylated aSyn (Ser129p-aSyn) were assessed by PET blot and conventional immunohistochemistry., Results: PET blot–resistant aggregated aSyn and Ser129p-aSyn was present in 12 of 15 individuals with early PD, 7 of 7 individuals with later PD, and 11 of 11 control subjects. The number of biopsies positive by PET blot relative to conventional immunohistochemistry was significantly lower in both PD groups compared with the control group for both aSyn and Ser129p-aSyn,whereas routine immunohistochemistry was positive more often in PD, but was positive in as many as 9 of 11 control individuals., Conclusion: Strong evidence of the presence of aggregated hyperphosphorylated aSyn in individuals with and without PD, using such a sensitive and specific method as the PET blot, suggests that colonic deposition of aSyn is not a useful diagnostic test for PD. The utility of detecting aSynin the colon as a biomarker in combination with other assessments remains to be determined.

Recent years have seen major changes in our understanding of Parkinson disease (PD), challenging conventional wisdom, much of which was established during the Decade of the Brain. In this article, we highlight important changes in our understanding of PD in six general categories: definition, etiology, pathology, pathogenesis, clinical features, and therapeutics.