1. In a diverse population with universal access to health care, tremor and impaired memory symptoms prior to diagnosis had the strongest associations with subsequent diagnosis of Parkinson disease.

2. Several well-described prediagnostic features were replicated in this diverse population, including associations between epilepsy and hearing loss with subsequent diagnosis of Parkinson disease.

Evidence Rating Level: 3 (Average)

Study Rundown: Although early features and risk factors associated with Parkinson disease (PD) have been well-described in previous studies, they have largely been focused on White individuals from high socioeconomic backgrounds that may not be generalizable. Thus, research in this field needs and should be encouraged to be more inclusive and diverse in demographic representation. This case-control study examined the association between risk factors and prediagnostic presentations of PD in an ethnically diverse British population with high socioeconomic deprivation but universal access to health care. A matched analysis (1:10 non-PD controls matched according to age and sex) and an unmatched analysis were performed via multivariable logistic regression and analyzed separately and together between 3 time periods (<2, 2-<5, and 5-10 years before diagnosis). Among 1055 individuals who developed PD, tremor and memory symptoms observed up to 10 and 5 years respectively prior to diagnosis had the strongest associations with subsequent PD. Furthermore, several well-described prediagnostic features were replicated in this diverse population, including associations between epilepsy and hearing loss with subsequent PD. A limitation of this study was the lack of information on prescriptions for medications of interest in patients with subsequent PD including those used in the pre-diagnosis period to reduce symptoms as well as medications that may cause drug-induced Parkinsonian symptoms.

Click to read the study in JAMA Neurology

Click to read an accompanying editorial in JAMA Neurology

Relevant Reading: Prodromal symptoms and early detection of Parkinson’s disease in general practice: a nested case-control study

In-Depth [case-control study]: This study included 1055 patients with PD (mean [SD] age, 72.9 [11.3] years; 632 [59.9%] male) and 10 550 matched controls without PD or major neurological conditions from primary care in East London between 1990 to 2018. Overall, associations were observed for tremor (OR, 145.96; 95%CI, 90.55-235.28) <2 and up to 10 years before PD diagnosis and memory symptoms (OR, 8.60; 95%CI, 5.91-12.49) <2 years and up to 5 years before diagnosis. Among risk factors, hypertension (OR, 1.36; 95%CI, 1.19-1.55) and type 2 diabetes (OR, 1.39; 95%CI, 1.19-1.62) were associated with subsequent diagnosis of PD. Associations were also observed for early nonmotor features, including hypotension (OR, 6.84; 95%CI, 3.38-13.85), constipation (OR, 3.29; 95%CI, 2.32-4.66), and depression (OR, 4.69; 95%CI, 2.88-7.63), as well as previously unreported factors such as epilepsy (OR, 2.5; 95%CI, 1.63-3.83) and hearing loss (OR, 1.66; 95%CI, 1.06-2.58). There were no associations found between ethnicity or deprivation index level and future PD diagnosis.

Image: PD

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