Date of Award

January 2020

Document Type


Degree Name

Medical Doctor (MD)



First Advisor

Elan D. Louis


Background: Essential tremor (ET) is among the most prevalent neurological disease, yet potential modifiable environmental factors contributing to its etiology are poorly understood. Harmane [1-methyl-9H-pyrido(3,4-b)indole], is a potent neurotoxin, of which elevated levels may be linked to ET. Possible etiologies for this elevation include increased dietary consumption, impaired metabolism, or increased endogenous production. Harmane is particularly abundant in meats and long cooking times can increase its concentrations. One previous study provided preliminary data of a dietary difference between male ET cases and controls. To clarify the relationship between ET and harmane we conducted a population-based, case-control study, in the Faroe Islands to examine the association between meat consumption, meat cooking practices, and blood harmane concentration levels and ET. The Faroe Islands have been the focus of epidemiological investigations of numerous neurological disorders.

Methods: 1,328 Faroese adults were screened, 27 ET cases were identified and harmane concentration, meat consumption, and meat cooking practices were compared to 197 controls. Detailed data were collected via questionnaires regarding meat consumption frequency for 15 meat types and meat doneness level for 8 meat types.

Results: Current meat consumption frequency and quantity were similar in ET cases and controls in 13 out of 15 meat types; no difference was observed when stratified by gender. ET cases had significantly more frequent and higher consumption of pork chops and bacon, however, after a Bonferroni correction due to multiple analysis this correlation was not significant. There was no statistically significant difference in harmane concentration between ET cases and controls, however, marginally elevated harmane concentrations were seen in definite and probable ET. The study did not support any correlation between harmane concentration and meat consumption in ET cases or controls.

Conclusion: This is the first population-based study of dietary factors and harmane concentration in ET. The study suggests no evidence of meat dietary difference between ET cases and controls. Nonetheless, we demonstrated marginally elevated harmane concentrations in definite and probable ET, extending the link between this neurotoxin and ET to a third population.


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