Environmental risk factors for essential tremor.

We conducted a case-control study searching for a possible role of environment in the risk of essential tremor (ET). We interviewed 142 ET patients and 284 age- and sex-matched controls about a family history of ET, exposure to environmental products containing lead, mercury, manganese, solvents and beta-carbolines, and exposure to agricultural work, well water, pesticides, and cigarette smoking and alcohol drinking habits. In a univariate study, reported family history of ET and exposure to agricultural work, pesticides, smelting, frosted glass, paintings, wheat, corn, and barley were more frequent in the ET patient group. With a multivariate study, only reported family history of ET and exposure to agricultural work and frosted glass remained significant. Time of exposure to agricultural work, wheat and barley was significantly higher in ET patients. Age at onset of ET was significantly lower in patients with a family history of tremor and higher in patients exposed to iron-manganese alloys and alcohol. Time of exposure, but not total consumption of alcohol and cigarettes, was correlated with age at onset of ET. In conclusion, our study shows that the association between ET and reported family history of ET was robust, and that there were also associations between ET and exposure to some environmental factors (agricultural work and frosted glass).