I have a life-long yearly battle w/ seasonal depression in which the meaning drains from everything in my experience during the darkest winter months. Among other awful effects, objects lose their familiarity and 'mine-ness'. Everything is foreign and artificial looking and this is most pronounced with the people in my life. I know that I know a particular person intimately yet the experience is one where they are suddenly just skin and hair and noise. I can see how someone with the same or similar boichemical malady might subconsciously impose the narrative of 'imposters' familiar to Capgrass Syndrome in order to continue some semblance of purposeful functioning in a devasatingly meaning-drained world. It's odd ill-logic makes perfect sense to me.

My own method of coping has often included aping the forms and feelings of meaning that are no longer present in the winter-- just to get through it. In that sense, in those situations, I am the imposter, pretending to be the same engaged meaningful friend I am at other times in the year.