Democrat Joe Biden, 81, is America’s oldest president. His chief rival, Republican Donald Trump, is 77. Polls consistently show voters are more worried that Mr Biden lacks “mental sharpness.” Today, why President Biden’s age matters, with our Medical Editor, Fergus Walsh, and our Special Correspondent in Washington, Katty Kay. The Global Story brings you trusted insights from BBC experts around the world, with Katya Adler. We’re keen to hear from you, wherever you are in the world. #TheGlobalStory We want your ideas, stories and experiences to help us understand and tell The Global Story. Email us at theglobalstory@bbc.com You can also message us or leave a voice note on WhatsApp on +44 330 123 9480. Today’s episode of The Global Story was made by Neal Razzell and Emilia Jansson. The technical producers were Matt Dean and Tom Brignell. The assistant editor is Sergi Forcada Freixas and the senior news editor is Jonathan Aspinwall.