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. 2020;54(3):272-280.
doi: 10.1159/000505874. Epub 2020 Jan 31.

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

Elan D Louis  1   2   3 , Eina H Eliasen  4 , Monica Ferrer  5 , Daniella Iglesias Hernandez  5 , Shahin Gaini  6   7   8 , Wendy Jiang  9 , Wei Zheng  9 , Flemming Nielsen  10 , Maria Skaalum Petersen  4   6
Affiliations

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

Elan D Louis et al. Neuroepidemiology. 2020.

Abstract

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.

Keywords: Case-control study; Environmental epidemiology; Essential tremor; Faroe Islands; Harmane; Mercury; Neurotoxin; Population-based design.

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Figures

Figure 1:
Figure 1:
Median blood harmane concentrations in g−10/ml
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