Essential tremor (ET) is the most common cause of tremor in humans yet its etiology remains unclear. Environmental toxicants are likely to contribute to its etiology. Such factors are thought to play an important role in other neuro-degenerative diseases, but their role in ET has received less attention. During the last eight years (2000 - 2008), we have studied several putative toxicants. Harmane (1-methyl-9H-pyrido[3,4-b]indole) is the most promising early candidate in the search for environmental risk factors for ET. During the past three years (2005 - 2008), we studied several potential mechanisms that could underlie elevated blood harmane concentrations in our clinic-based sample of ET cases in New York. These studies suggest that dietary factors might play a role. In tandem with these studies, we have continued to collect blood harmane samples in New York. Moving forward, our goal is to now definitely establish the links between this neurotoxin and ET. This is a five-year competitive renewal in which we propose to address four inter-related questions. First, although elevated harmane concentrations have been observed in ET cases in blood, brain concentrations of this neurotoxin have not been investigated. ET is a brain disease and the brain is the presumed target organ of this neurotoxin. Are harmane concentrations elevated in the ET brain (Specific Aim 1)? Second, our finding was derived from a single study of ET cases primarily from one tertiary referral center in New York. If one were to sample a group of ET cases ascertained in a completely different manner (i.e., community-based) half-way around the world, would one find an elevated blood harmane concentration (Specific Aim 2)? Third, our finding of an elevated harmane concentration was a cross-sectional observation, sampling blood at a single time point. It is not clear whether these same ET cases would persist in demonstrating elevated blood harmane concentrations if re-assessed at a second time point several years later (Specific Aim 3)? Finally, one study found elevated blood harmane concentrations in Parkinson's disease, raising the question as to whether elevated blood harmane is specifically linked with ET or is merely a more general, global marker of neurological illness (Specific Aim 4)? Approximately 50% of ET cases are non-familial. Given its population prevalence of 4.0% in persons age >40 years, then 2.0% of the population aged >40 years has a non-familial form of ET, yet the environmental underpinnings for this tremor are just beginning to be explored. Identification and understanding of these toxicants is the first step in preventing a progressive neurological disease with few treatment options.

Public Health Relevance

We estimate that 2.0% of the population aged >40 years has sporadic (i.e., non-familial) essential tremor (ET), yet the environmental underpinnings for this tremor are just beginning to be explored. Harmane (1-methyl-9H- pyrido[3,4-b]indole) is the most promising early candidate in the search for environmental risk factors for ET. This is a five-year competitive renewal in which we propose to firmly establish the links between this neurotoxin and ET.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Project (R01)
Project #
5R01NS039422-11
Application #
8076169
Study Section
Neurological, Aging and Musculoskeletal Epidemiology (NAME)
Program Officer
Sieber, Beth-Anne
Project Start
1999-12-01
Project End
2014-04-30
Budget Start
2011-05-01
Budget End
2012-04-30
Support Year
11
Fiscal Year
2011
Total Cost
$572,742
Indirect Cost
Name
Columbia University (N.Y.)
Department
Neurology
Type
Schools of Medicine
DUNS #
621889815
City
New York
State
NY
Country
United States
Zip Code
10032
Louis, Elan D; Meyers, James H; Cristal, Ashley D et al. (2018) Unaffected first-degree relatives of essential tremor cases have more imbalance than age-matched control subjects. Parkinsonism Relat Disord 52:24-29
Alcalay, R N; Wolf, P; Levy, O A et al. (2018) Alpha galactosidase A activity in Parkinson's disease. Neurobiol Dis 112:85-90
Louis, Elan D; Kuo, Sheng-Han; Tate, William J et al. (2018) Heterotopic Purkinje Cells: a Comparative Postmortem Study of Essential Tremor and Spinocerebellar Ataxias 1, 2, 3, and 6. Cerebellum 17:104-110
Louis, Elan D (2018) Essential tremor then and now: How views of the most common tremor diathesis have changed over time. Parkinsonism Relat Disord 46 Suppl 1:S70-S74
Louis, Elan D (2018) The evolving definition of essential tremor: What are we dealing with? Parkinsonism Relat Disord 46 Suppl 1:S87-S91
Kuo, Sheng-Han; Wang, Jie; Tate, William J et al. (2017) Cerebellar Pathology in Early Onset and Late Onset Essential Tremor. Cerebellum 16:473-482
Louis, Elan D; Patel, Amar; Gerrard, Jason L (2017) What is the pathway forward for the surgical management of essential tremor? Ann Neurol 81:351-353
Louis, Elan D; Kuo, Sheng-Han; Wang, Jie et al. (2017) Cerebellar Pathology in Familial vs. Sporadic Essential Tremor. Cerebellum 16:786-791
Lenka, Abhishek; Benito-León, Julian; Louis, Elan D (2017) Is there a Premotor Phase of Essential Tremor? Tremor Other Hyperkinet Mov (N Y) 7:498
Kuo, Sheng-Han; Lin, Chi-Ying; Wang, Jie et al. (2017) Climbing fiber-Purkinje cell synaptic pathology in tremor and cerebellar degenerative diseases. Acta Neuropathol 133:121-138

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