Essential Tremor Genes (IMAGE) McGill University Caption Essential tremor affects nearly 1 percent of the world's population, increasing to 4 percent of those over 40. Credit Simon Girard Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.