Anemia in men and increased Parkinson's disease risk: A population-based large scale cohort study

Objective: To evaluate the association between anemia and Parkinson's disease risk (PD) in men and women. Methods: A population-based cohort of 474,129 individuals (aged 40–79 years at date of first Hb test, 47.4% men) with repeated Hb levels was derived from a large Healthcare Maintenance Organization that serves 2 million citizens in Israel (study-period 1.1.1999–31.12.2012). An annual anemia indicator [Hb levels (g/dL) for men <13; for women <12.0] was assessed for each individual and they were followed from first Hb test until the date of PD incidence, death or end of the study. Cox-proportional hazards models, stratified by sex and age, with time-dependent anemia covariate were used to estimate adjusted Hazard Ratio with 95% of confidence intervals (HR, 95%CI) for PD. Results: During a mean follow up of 8.8 ± 3.9 years (7.0 ± 3.6 for men and 7.9 ± 4.1 for women), 2427 incident PD cases were detected. Cumulative PD incidence at ages over 65 years was 3.3%. The mean levels of Hb at baseline was 14.8 ± 1.1 g/dL among men; 12.8 ± 1.1 g/dL among women. Anemia was associated with significant PD risk among men, age-pooled HR = 1.19 (95%CI: 1.04–1.37), with the highest risk between ages 60–64 years [HR = 1.41 (95%CI: 1.03–1.93)]. Anemia was not associated with PD risk among women across all age-groups. The age-pooled HR for women was 1.02 (95%CI 0.95–1.09). Conclusions: The finding that anemia was associated with PD risk in men, especially in middle age, warrants further investigations on common pathophysiologic processes between Hb abnormalities and brain dysfunction.