Yazdani S, Mariosa D, Hammar N, et al. - In a prospective cohort study with 20 years of follow-up, investigators examined the interactions of several blood immune biomarkers with the future risks of amyotrophic lateral sclerosis and Parkinson disease. The study sample consisted of 812,073 candidates with repeated blood biomarker measurements between 1985 and 1996 and a follow-up until 2011. During the follow-up, a total of 585 incident cases of amyotrophic lateral sclerosis and 3,769 incident cases of Parkinson disease were reported. Findings suggested an association of lower risk of Parkinson disease with increasing concentrations of leukocytes, haptoglobin, and uric acid. Nevertheless, there was no statistically significant relationship between the biomarkers tested and amyotrophic lateral sclerosis. Patients with Parkinson disease tended to have lower levels of leukocytes and haptoglobin around 20 and 10 years prior to diagnosis and lower levels of uric acid in the 20 years prior to diagnosis relative to controls, while statistically significant differences were observed only after multivariate adjustment during parts of the respective time periods. There were no clear differences between amyotrophic lateral sclerosis patients and controls. The results may suggest a different role of systemic inflammation in the risk of Parkinson disease relative to amyotrophic lateral sclerosis when confirmed in independent population studies.