Lapses in Memory

I recently finished the novel A Slight Trick of the Mind by Mitch Cullin, which is a recently written story about an elderly Sherlock Holmes, who has retired to Sussex and is losing his mental acuity. 

I found the premise of "how does someone so sharp, someone who prides himself on his recollection and attention to detail, deal with the slow degradation of the mind due to age?"  It's a question that strikes a chord with me, blow to great proportions by the fact that it's Sherlock Holmes, and we all know that he used to function on extreme levels.

There are two really cool narrative devises that I'm taking away from this novel.

1.  Moments of confusion or gaps in memory are shuffled in with sharp details and clever deductive reasoning.  They make the lapses more surprising by how quickly they pop up, and by their very existence.  It also matches what I've experienced watching my older relatives: dementia doesn't affect memory homogeneously, but rather in little fuzzy patches, leaving other memories completely in tact.
2. The novel doesn't show the moment that is then later forgotten, it only shows when Holmes is reminded of something as if he ought to have remembered it.  So for example, early in the novel, Holmes asks where the housekeeper's son is, and his housekeeper gives him a look and says the boy has been waiting for him in the bee yard for the last hour, just as Holmes told him to.  With this device, we know only as much as Holmes does (which is weird for a Sherlock Holmes book, but interesting here) and they come as a surprise not only to the character, but to the reader.

I have a half written story on my hard drive, where the main character forgets where he put he thing the bad guys want, because he doesn't know it's valuable and he doesn't really care about it. So when the bad guys show up, and use their magic mind reading powers to go through his memories, they can't find where it is.  I think both these techniques could be used here.  Probably not with the same emotional kick as it's not a focal point of my story, but it could still be implemented.

What about y'all?  Any other examples of this in other novels or movies?