second childhood vs dotage

second childhood and dotage both are nouns.

Word	Noun	Adjective	Verb	Adverb
second childhood	Yes	No	No	No
dotage	Yes	No	No	No

As nouns, second childhood and dotage are synonyms defined as:

second childhood and dotage: mental infirmity as a consequence of old age; sometimes shown by foolish infatuations

Other synonyms of second childhood include senility.

second childhood (noun)	dotage (noun)
mental infirmity as a consequence of old age; sometimes shown by foolish infatuations	mental infirmity as a consequence of old age; sometimes shown by foolish infatuations