Though Reagan at the time was the oldest president to ever enter the White House — he was 69 at his inauguration in 1981 — the US didn't hold a candle to the Soviets when it came to geriatric leaders.
During the final decades of the USSR, its corrupt, aging leaders embraced policies that derailed the Soviet economy as they continued to live in opulence. They refused to embrace large-scale changes and helped set the next generation up for failure. But the changes could not repair the damage. As Gorbachev put it in his resignation address in December 1991,"the old system collapsed before the new one had time to begin working, and the crisis in the society became even more acute."
Susan Grunewald, a historian of the Soviet Union at Louisiana State University, told Insider that she'd be hesitant to directly compare the US and USSR but that"you can certainly see parallels." Brezhnev's health took a turn for the worse after a stroke in 1976, but he remained in power for years. The historian Roy Medvedevthat Brezhnev had suffered clinical death in 1976 and went on to rule in a daze for the rest of his tenure.