To identify risk factors, including beta-blocker exposure, for the development of Parkinson’s disease (PD) among patients with Essential Tremor (ET) and ET plus.

The term ET (established in 1949) describes a slowly progressive action tremor of heterogeneous etiologies again revised in the 2017 consensus criteria as ET plus. Patients with ET are at higher risk to develop PD. There is evidence that salbuterol may be protective for PD while propranolol (a common treatment option for ET) can augment pathologic expression of alpha-synuclein. There are no published reports of beta-blockers as a risk factor for PD.

This retrospective study utilized our department’s database to search for diagnoses of ET with PD or Parkinsonism (PK)—ET Plus, as defined by the most recent consensus criteria. We excluded patients using tremor-genic drugs (but allowed monoamine reuptake inhibitors). We assessed risk factors such as depression, anxiety, REM sleep behavior disorder (RBD), insomnia, constipation, anosmia, cognitive issues, family history of tremors, age of onset, utilization of DAT scan and beta-blocker exposure.

We analyzed that data in two groups: 1) ET-PD (N=35), ET later diagnosed with PD and 2) ET-PK (N=36), ET later diagnosed with PK. ET-PD patients reported an average age of ET onset of 48 (52 for ET-PK) and subsequent PD diagnosis of 69. Compared to the ET-PD, ET-PK group had a higher use of DAT scans (67% vs 30%) and incidence of insomnia (68% vs 25%) but lower incidence of constipation (29% vs 74%) and anosmia (19% vs 44%). There was no appreciable difference in RBD or beta-blocker use between groups.

Our small cohort suggests a difference in risk factors such as insomnia, anosmia and constipation between the ET-PD vs ET-PK groups. This data may help elucidate the disease course of ET and risk factors for the development PD vs PK in ET.