The poor old man is in his second childhood and doesn't know what he's saying.这可怜的老人年老昏聩，自己也不知道在胡说些什么。Her grandfather's in his second childhood and talks nonsense most of the time.她祖父年老昏聩，大多数时候总是不知所云。Grandpa seems to be in his second childhood.祖父好像有些老年痴呆。