psychosis after aneurysm clipping

My father recently had a ICH stroke and then underwent clipping of a brain aneurym 4 weeks later.  Physically he is doing wonderful, but mentally he goes through phases of paranoia, anger, confusion, disorientation etc. They are telling me that this may be a psychosis due to surgery?  Almost 85% of the time any conversation makes absolutely no sense and he also can't focus on tasks but will become obsessed with other things such as finding flashlights or the cat?

[Nassim Abi Chahine, MD]

A related discussion, no worries was started.

[Jana94]

A related discussion, Brain surgery was started.