Fertility in essential tremor: Data from population-based and clinical sources

Background: The view of essential tremor (ET) as a degenerative disorder, which is now gaining support from postmortem studies, is at odds with traditional views of ET as a 'super-healthy' condition characterized by increased longevity and fertility. Longevity has recently been re-examined in ET, yet fertility, measured by number of offspring, has never been critically assessed in this disease. The objective was to determine whether ET cases and controls differ in terms of number of children. Methods: Family history data were collected on ET cases and controls from 2 distinct sources, a population and a clinical (referred) sample. Results: In the population, the number of children was similar in 59 cases vs. 72 controls [mean ± SD (median) = 2.3 ± 2.9 (1) vs. 2.2 ± 1.8 (2); p = 0.26]. In the referred sample, number of children was similar in 184 cases vs. 241 controls [2.0 ± 1.5 (2) vs. 1.9 ± 1.7 (2); p = 0.33]. In adjusted analyses, results were similar. Conclusions: Fertility, measured by number of children, was similar in cases and controls. With a newer understanding of the biological substrate of ET emerging from postmortem studies, it is important to critically reassess this and other fundamental biological questions about the disease.