title: Blood harmane (1-methyl-9H-pyrido[3,4-b]indole) concentrations in essential tremor: repeat observation in cases and controls in New York.
abstract: Essential tremor (ET) is a widespread late-life neurological disease. Genetic and environmental factors are likely to play important etiological roles. Harmane (1-methyl-9H-pyrido[3,4-b]indole) is a potent tremor-producing neurotoxin. Previously, elevated blood harmane concentrations were demonstrated in ET cases compared to controls, but these observations have all been cross-sectional, assessing each subject at only one time point. Thus, no one has ever repeat-assayed blood harmane in the same subjects twice. Whether the observed case-control difference persists at a second time point, years later, is unknown. The current goal was to reassess a sample of our ET cases and controls to determine whether blood harmane concentration remained elevated in ET at a second time point. Blood harmane concentrations were quantified by a well-established high-performance liquid chromatography method in 63 ET cases and 70 controls. A mean of approximately 6 yr elapsed between the initial and this subsequent blood harmane determination. The mean log blood harmane concentration was significantly higher in cases than controls (0.30 ± 0.61 g(-10)/ml versus 0.08 ± 0.55 g(-10)/ml), and the median value in cases was double that of controls: 0.22 g(-10)/ml versus 0.11 g(-10)/ml. The log blood harmane concentration was highest in cases with a family history of ET. Blood harmane concentration was elevated in ET cases compared to controls when reassessed at a second time point several years later, indicating what seems to be a stable association between this environmental toxin and ET.
authors: Department of Neurology, College of Physicians and Surgeons, Columbia University, New York, New York 10032, USA. EDL2@columbia.edu
authors: Elan D
authors: ED
authors: Louis
authors: Wendy
authors: W
authors: Jiang
authors: Marina
authors: M
authors: Gerbin
authors: Amanda S
authors: AS
authors: Viner
authors: Pam
authors: P
authors: Factor-Litvak
authors: Wei
authors: W
authors: Zheng
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D016022:Case-Control Studies; D002851:Chromatography, High Pressure Liquid; D020329:Essential Tremor / Q000097:blood* / Q000139:chemically induced / Q000453:epidemiology; D006247:Harmine / Q000031:analogs & derivatives* / Q000097:blood; D006801:Humans; D008875:Middle Aged; D009498:Neurotoxins / Q000097:blood*; D009518:New York / Q000453:epidemiology
chemical_list: D009498:Neurotoxins; D006247:Harmine; C005010:harman