Wasn't there also some article about how people don't get dumber as they get older, rather, their focus is less and less? Sort of strange, but if that and all

Wasn't there also some article about how people don't get dumber as they get older, rather, their focus is less and less? Sort of strange, but if that and all of this really turn out to be true, extending the human lifespan might not be as difficult as we make it out to be.