My ex worked on a study that involved testing people's short-term memory. She mentioned a clear and abrupt change around the age of 45, though that wasn't what they studied and of course was not included in the study results. This issue is highly politically charged.
I heard that was related to memory strategy (i.e. the brain focusing on more important methods and information) and not ability. I'd be curious on the results - clearly they aren't published though.
