As the US presidential race heats up, former President Donald Trump is facing increased scrutiny over his age and cognitive abilities ahead of his first debate with Vice President Kamala Harris on September 11. Concerns about Trump's mental fitness have been amplified by his recent incoherent remarks at the Economic Club of New York, leading critics to question his capacity to serve another term. At 78, Trump would be the oldest president in US history if elected, a stark contrast to the 59-year-old Harris. Previously, age-related criticisms were more focused on President Joe Biden, who has since exited the race. Trump's campaign has been highlighting his energy and stamina, but the upcoming debate will be a significant test of his ability to convince voters of his mental acuity. Analysts predict that the debate could be a defining moment for Trump's campaign.