We are intended to plan a project on POCD in cardiac surgical patients. Do you know any groups or are you involved in similar projects? Our center is a cardiac hospital with around 4000 patients annually most of which are coronary artery surgeries.
It would be useful in your project, to partial out the effects of Anaesthetic x Age, micro embolism, and post-operative depression (whose signs & symptoms can be similar to postpartum depression). In my experience, post cardiac-surgery depression can be due to radical decline in personal expectations.
Additionally, it is important to control for the details of 'informed consent'. Conventionally (and mistakenly) patients are not told to EXPECT cognitive decline after complex surgery. It is best to do so, first because it is highly likely, and secondly patients will make up their own stories to account for such decline if they are not given an authoritative & persuasive warning. The stories they make up are often catastrophic, such as 'I'm going crazy', or 'I'm dementing' - these contribute to post-Anaesthetic depression.