The music center is very alive in their brains. They still can sing the first stanza of a familiar hymn and participate in praying the Lord's Prayer and confessing the Apostle's Creed. They still love to receive Holy Communion, especially if it was a regular event in their lives. Sometimes they paraphrase out loud words spoken in a sermon. Some persons may even be able to learn new words or parts of the service.
Repetition is helpful.
However, in her home congregation, they were using the red hymnal that used the Victorian English for the Benediction. She had remembered the new words from repetition. It is important for pastors to make monthly visits to the confused person, which will probably be the only contact the person has with the congregation. The person may not remember the visit or even the pastor's name. He or she will, however, remember the pastor's presence and get to know a friendly voice.