40-Year incidence of early-onset Parkinson's disease (EOPD) in Southeast Minnesota

Introduction: Parkinson's disease (PD) most commonly surfaces at middle age. Earlier onset is characterized as Early-onset Parkinson's disease (EOPD), but the exact definition has been a matter of ongoing scientific debate. We investigated 40-year EOPD incidence trends in a population-based cohort of parkinsonism in Olmsted County, MN. Methods: We used the Rochester Epidemiology Project (REP) to identify all incident EOPD cases in Olmsted County between 1976 and 2015. A movement-disorder specialist reviewed all cases to confirm the EOPD diagnosis. For EOPD definition, we used two age cut-offs: 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 than women in both groups [1.84 vs 1.03 (p = 0.04); and 0.70 vs 0.40 (p = 0.24), respectively]. EOPD incidence diagnosed before age 55 increased each decade: 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 of age cut off was used (0.28/100,000 person-years 1976–1985, to 0.59/100,000 person-year 2006–2015). Incidence was consistently higher in men than women. Median time from EOPD-symptoms 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, both in ≤55 and ≤ 50 years of age. Overall, incidence of EOPD was 1.43 (≤55) and 0.55 (≤50) cases per 100,000 person-years, and although not significant, was higher in men than in women.