Blood Harmane (1-Methyl-9H-Pyrido[3,4-b]indole) and Mercury in Essential Tremor:A Population-Based, Environmental Epidemiology Study in the Faroe Islands

• Published in: Neuroepidemiology
• Main Authors: Louis, Elan D., Eliasen, Eina H., Ferrer, Monica, Iglesias Hernandez, Daniella, Gaini, Shahin, Jiang, Wendy, Zheng, Wei, Nielsen, Flemming, Petersen, Maria Skaalum
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2020
• Subjects: Case-control study; Environmental epidemiology; Essential tremor; Faroe Islands; Harmane; Mercury; Neurotoxin; Population based design
• Online Access: https://portal.findresearcher.sdu.dk/da/publications/0804dc04-f96d-4d8f-b2e0-ecdbc82d6ffd; https://doi.org/10.1159/000505874; https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7210050/pdf/nihms-1558051.pdf

Background: Essential tremor (ET) is among the most prevalent neurological diseases. Its environmental determinants are poorly understood. Harmane (1-methyl-9H-pyrido[3, 4-b]indole), a dietary tremor-producing neurotoxin, has been linked to ET in a few studies in New York and Madrid. Mercury, also a tremor-producing neurotoxin, has not been studied in ET. The Faroe Islands have been the focus of epidemiological investigations of numerous neurological disorders. Objective: In this population-based, case-control study, we directly measured blood harmane concentrations (HA) and blood mercury concentrations (Hg) in ET cases and controls. Methods: In total, 1,328 Faroese adults were screened; 26 ET cases were identified whose (HA) and (Hg) were compared to 197 controls. Results: Although there were no statistically significant differences between diagnostic groups, median (HA) was 2.7× higher in definite ET (4.13 g -10 /mL) and 1.5× higher in probable ET (2.28 g -10 /mL) than controls (1.53 g -10 /mL). Small sample size was a limitation. For definite ET versus controls, p = 0.126. (Hg) were similar between groups. Conclusions: We demonstrated marginally elevated (HA) in definite and probable ET. These data are similar to those previously published and possibly extend etiological links between this neurotoxin and ET to a third locale. The study did not support a link between mercury and ET.