Jun 06, 2018

When operations subtly cause our powers of thinking to deteriorate: Postoperative Cognitive Dysfunction

Have you known of someone who had an operation, and family and friends say afterwards, “They haven’t been quite the same since”?

Sometimes surgery can subtly impact mental abilities. In particular, after surgery some patients report problems with memory, attention, multitasking, and concentration.

This condition has been dubbed ‘postoperative cognitive dysfunction’ (POCD), and it can last months – even years.

The other bad news is it can be a sign of even worse to come.

Developing postoperative delirium and postoperative cognitive dysfunction have long-term consequences, such as higher mortality and morbidity along with increased hospital stay. Which if left untreated or resolved can result in higher dependency and risk of being institutionalised.

Patients with delirium are 2.6 times more likely to die than those without delirium.

POCD: the unanswered questions

There remain many unanswered questions about POCD.

The mysteries remain in part because of the problems of studying the condition – it wouldn’t be ethical to prevent some people from having operations simply to study POCD.

Some anesthesiologists even deny the condition exists, saying that operations do not cause mental decline.

Research has been conclusive on both sides. Many studies have shown operations cause mental impairment, while other studies fail to show any impact.

A study by Duke University Medical Center found 53% of adults who had heart-bypass surgery showed significant evidence of cognitive decline when discharged from hospital – 36% were still affected six weeks later, and 42% were still affected five years after their operation.

But Charles Hugh Brown IV, assistant professor of anesthesiology at Johns Hopkins Medicine, told The Herald Tribune that cognitive decline will occur in people who are already on a declining mental-ability trajectory.

What causes POCD: the theories

While doctors don’t know what might cause a deterioration in some people’s mental abilities after an operation, theories include:

  • Slower blood flow to the brain during surgery
  • Anesthetics kill or harm brain cells
  • The illnesses that gave rise to the operation may in fact be causing the cognitive slowdown
  • Inflammation caused by the operation could send harmful chemicals to the brain

Some operations seem to cause POCD more often – heart surgery in particular.

In contrast, after some operations, patients report feeling mentally sharper. For example, after bariatric surgery for obesity, clinical neuropsychologist John Gunstad of Kent State University in Ohio, says patients perform better on cognitive tests after 12 weeks, and the boost remains intact for up to four years.

Should patients be warned of the risks?

Many patients are not told of the risk of POCD when they are preparing for an operation. It’s not surprising when so much uncertainty surrounds the condition.

But some say patients should be warned of the condition.

“Each patient must determine if the proposed benefits of a procedure outweigh the foreseeable and material risks of cognitive decline after surgery,” Kirk Hogan, professor of anesthesiology at the University of Wisconsin told The Herald Tribune.

If you were preparing for an operation, would you want to know what the possible, yet real risks are were to your cognition? How much would this impact your decision?

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  1. this phenomenon does occur July last year I had an operation and I did an experiment, before surgery I completed a task one that I would usually finish in 10-15 mins, after the operation it took me 30mins or more. this confirmed that there was a neurological reaction to anaesthesia, I was 70 at the time. I suffered mild to medium depression/anxiety until May of this year, hopefully, I can now return to normal mental function. I was not ill as such before the theatre it was a Gallbladder removal operation. so this article is correct and scary to think what you think is normal can be changed so quickly.


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