I have noticed Reddington plays a lot of games in the fifth season. Puzzles, strategy games, word games. There are also a couple of references to his death for several minutes in Marrakech.
This mirrors Samar's situation after drowning and being revived in the sixth season. Due to her temporary death, parts of her brain died causing vascular dementia.
Progressive memory loss might explain Reddington's determination to tick the people off his blacklist. He wants to protect Lizzy before he forgets those who threaten her. Of course, being able to spend time with her before he no longer recognises her is a bonus.