In Japan, some people say "Japan has been becoming aging society. That's why most of the political leaders in Japan are elderly people."
But, this article denies that hypothesis. In some African countries with high fertility rate, there are political leaders over 80 years old.
According to the recent study, brain in 70s has the best ability among all generations in terms of thinking something, though memory is not the best.
So, we cannot always say "The younger the politician is, the better politics will be."