It's a metaphor for dementia, but as a die-hard Horror fan, it's missing what I crave: unsettling atmosphere, chilling imagery, well-executed scares (if necessary to story and style), and a true sense of dread. I never felt any sense of peril and I found myself not really caring about the characters, despite how well-acted they are. If strong female performances is what you crave, go for it. But for Horror fans, I'd say skip it.