He was diagnosed as having eclipse memory.
Eclipse memory would denote a condition in which a person remembers something only vaguely or indistinctly. It is characterized by partial loss of memory and not by complete amnesia. It may be referred to as impaired or dim memory.
Dude, that guy could not completely remember what he was doing yesterday when we called at his house. As you know, he is has a problem with memory- an eclipse memory, to be precise.