Ahlskog, J. Eric

Background: Parkinson’s disease (PD) most commonly surfaces at middle age. An earlier onset is named early-onset Parkinson’s disease (EOPD), but the exact definition is a matter of ongoing scientific debate. Objective: To investigate 40-year EOPD incidence trends in a population-based cohort of parkinsonism in Olmsted County, Minnesota. Methods: We used the Rochester Epidemiology Project (REP) to identify all incident EOPD cases in Olmsted County, 1976–2015. A movement-disorder specialist reviewed all cases to confirm the EOPD diagnosis. For EOPD definition, we used two age cut-offs: motor-symptom onset at or before 50 and 55 years. Results: EOPD incidence was 1.43/100,000 person-years for ≤55 and 0.55/100,000 for ≤50 years. Men had a higher incidence in both groups [1.84 vs. 1.03 ( p = 0.04); and 0.70 vs. 0.40 ( p = 0.24), respectively]. EOPD incidence of patients with motor-symptom onset before age 55 increased from 1.02/100.000 person-year 1976–1985, to 1.32/100.000 person-year 2006–2015. A similar trend was observed when ≤50 years cut-off was used (0.28/100,000 person-years 1976–1985, to 0.59/100,000 person-year 2006–2015). However, negative binomial regression found no significant change in incidence per 10 years (RR = 1.04 and 1.24 in the two groups). Incidence was consistently higher in men than women. Median time from EOPD-symptom onset to death was shorter in the EOPD ≤55 group (21.9 years) compared to the EOPD ≤50 group (25.6 years). Conclusion: We observed an increased trend in the incidence of EOPD with both cut-off ages. Overall, incidence of EOPD was 1.43 (≤55) and 0.55 (≤50) cases per 100,000 person-years, higher in men.

Autoimmune movement disorders are increasingly recognized, but isolated tremor is extremely rare. We describe a 70‐year‐old male with rapidly progressive, severe postural and intention tremor and weight loss. His cerebrospinal fluid was inflammatory and harbored a neural tissue‐restricted antibody. The autoantigen was identified by immunoprecipitation and mass spectrometry and confirmed by antigen‐specific assays to be specific for tenascin‐R. He was investigated for cancer and diagnosed with follicular lymphoma that expressed tenascin‐R suggesting a paraneoplastic origin; cancer treatment and immunotherapy led to complete recovery. With this individualized patient approach and antibody discovery, we expand the spectrum of antibodies accompanying autoimmune hyperkinetic movement disorders. ANN NEUROL 2023;94:502–507