Long-term postoperative cognitive dysfunction in the elderly: ISPOCD1 study by J T Moller, et al. The Lancet.  1998

This is the largest POCD study ever done, involving 13 hospitals in Europe and the US.  The primary focus was on elderly patients.  They included tests for “the activity of daily living” and determined that those with long-term POCD did have a measurable decrease in the activity of daily living.  I also appreciated their candor in admitting to not understanding the causal mechanisms for POCD.  Surprisingly, they did not find a relationship between POCD and depression.  Also, they dismissed patients’ reports of cognitive impairment because those reports were not supported by the neuropsychological test results.

Postoperative cognitive dysfunction in middle-aged patients.  ISPOCD 2. by Tim Johnson F.R.C.A., et al.  Anesthesiology.  2002

This second phase of the ISPOCD involved 7 hospitals in 5 countries and focused on middle-aged (40-59 yrs.) patients.  They did a great job of trying to include the subjective experiences of patients and their relatives.  They did highlight the discrepancy between a lack of objective evidence of POCD in the formal testing and the subjective complaints of cognitive impairment that are commonly expressed.  Also, they did find a relationship between POCD and depression.

Postoperative Cognitive Dysfunction after Noncardiac Surgery; A Systematic Review by Stanton Newman, et al.  Anesthesiology.  2007

This is the mother lode of research!  They did a massive search of medical databases to find all the articles that have ever been published on POCD (excluding research around cardiac surgery) and found 46 articles.  Wow!  If you like statistics and want a lot of data and research on this topic, it’s all here.  One interesting note from the conclusion, “None of the studies have elucidated the possible mechanisms for any cognitive changes.”

Cognition after major surgery in the elderly: test performance and complaintsby J. B. Dijkstra, et al.  British Journal of Anaesthesia.  1999

A fine article.  Unfortunately it is encrypted so I couldn’t highlight it.  This study explored “the correlation between objective cognitive performance and self-reported cognitive dysfunction in the long term.”  The authors worked hard not to invalidate the subjective experiences of the patients, even when it did not manifest in the testing.  They also acknowledged the role of depression and anxiety.  This was a great blend of science with an acknowledgement of subjective human conditions.  “Although most patients recover from surgery under general anaesthesia, a subgroup of patients suffer long-term self-reported cognitive complaints.”

Postoperative cognitive dysfunction by C. D. Hanning.  British Journal of Anaesthesia.  2005

Another thoughtful, interesting, and open-minded article.  The author defines cognition (as opposed to intelligence), clearly presents the challenges to understanding the connection between anesthesia and POCD, and gives an excellent anecdotal story of a professional man who “passed” his testing and was forced to retire because of his cognitive dysfunction.  Thoughtful and articulate.

Long-term Consequences of Postoperative Cognitive Dysfunction by Jacob Steinmetz, M.D., et al.  Anesthesiology.  2009

This study concluded that, “cognitive dysfunction after noncardiac surgery was associated with increased mortality, risk of leaving the labor market prematurely, and dependency on social transfer payments (i.e. unemployment payments).”  They do mention the patient’s perspective on cognitive decline and seem to respect the “anecdotal reports.”  They also focus on the long-term consequences of impairment.  “…patients with POCD at 3 months may have been more severely cognitively injured during surgery, initiating a different life trajectory.”  Finally, this is the only study that expresses the view that patients may test better during the first testing phase because they have the ability to compensate.  As the compensation breaks down over time, patients can test more poorly.

Does anaesthesia cause postoperative cognitive dysfunction?  A randomized study of regional versus general anaesthesia in 438 elderly patients by L. S. Rasmussen, et al. Acta Anaeshesiologica Scandinaavica.  2003

This study explored the effect of regional versus general anesthesia on POCD.  The findings were that there was no significant difference between the two in terms of cognitive impairment.

Cognitive and functional competence after anaesthesia in patients aged over 60: controlled trial of general and regional anaesthesia for elective hip or knee replacement by M J T Jones, et al.  British Medical Journal.  1990

On the surface this is another exploration of the difference between regional and general anesthesia.  However, it does include some fascinating admissions and perspectives.  “An impairment that is not resolved by the time the patient is discharged from the hospital could have long lasting social and economic consequences.”   “Our tests may not be sensitive enough to detect a small change in function that can be noticed by patients with a high degree of self awareness and insight.  This subjective feeling of “things not being quite right”has been reported previously and may last for up to 30 days after general anaesthesia in young volunteers.  Conversely, there is evidence that patients may report themselves as fully recovered and back to normal and still have a measurable decrease in function.”  After saying that, they calmly conclude, “we found that modern anaesthesia, either general or regional seemed to have no significant long term effects on mental function in elderly patients.”  Wow!

Long-term Cognitive Decline:  Is There a Link to Surgery and Anesthesia? by Leung and Sands.  Editorial Views, Anesthesiology.  2009

This short editorial shows the conflict that is generated within the field of anesthesiology over this issue.  There is data.  But it is unclear.  And controversial.  And nobody really knows if it is real or what to do about it.

Long term cognitive dysfunction in older people after non-cardiac surgery by Selwood and Orrell.  Editorial British Medical Journal.  2004

This is another editorial that shows the present state of medical opinion on this subject.  It is unclear.  Does it even exist?  And from the article’s subtitle, “no definite conclusion is possible.”

Can postoperative Cognitive Dysfunction Be Prevented? By Neubauer and Golden.  Journal of American Physicians and Surgeons.  2005

Short and interesting on two fronts.  First is the follow up by Dr. Monk on the Duke University study.  The numbers testing for POCD are very high and include patients under 40 years of age.  The second is that the authors float the totally theoretical idea of using hyperbaric oxygenation therapy (HBOT) pre- and postoperatively as a way to prevent POCD.  And still not one single word about treatment!