Dementia impacting U.S. officials poses a threat to national security, according to a first-of-its-kind study by a Pentagon-funded think tank. The report came as several prominent U.S. officials trusted with some of the nation’s most highly classified intelligence experienced public lapses, stoking calls for resignations. Sen. Mitch McConnell, R-Ky., who had a second freezing episode last month, enjoys the most privileged access to classified information of anyone in Congress as a member of the so-called Gang of Eight congressional leadership. Ninety-year-old Sen. Dianne Feinstein, D-Calif., whose decline has seen her confused about how to vote and experiencing memory lapses — forgetting conversations and not recalling a monthslong absence — was for years a member of the Gang of Eight and remains a member of the Senate Intelligence Committee, on which she has served since 2001.