The hidden long-term risks of surgery: ‘It gives people’s brains a hard time’ |

In 2004, Mario Cibelli was preparing a 75-year-old patient for a big cardiac operation when the patient’s daughter asked for a quick word. “She explained to me how worried she was about the surgery,” says Cibelli, a consultant in anaesthesia and intensive care at the University Hospitals Birmingham. “I said: ‘Look, everybody’s worried about heart surgery, it comes with risks, but normally people benefit from it.’ And then she told me that her father had undergone a cardiac procedure two years before and he had changed dramatically.”

Cibelli listened as the woman described how her father, a former physics professor, had shown signs of significant cognitive decline after the initial operation. Once a keen chess player, he was now unable to play the game and struggled to even do basic crosswords.

For Cibelli, it was the first time he had encountered what is now termed postoperative cognitive dysfunction (POCD) – cognitive problems associated with surgery that persist well after the effects of anaesthetics have worn off. “I published some articles on the subject,” he says. “And people began finding my email address, saying their father or mother had changed a lot after a surgery in the past. So I began to realise that this wasn’t such an isolated case.”

We have known for a long time that operations can have hidden consequences for the brain. As far back as 1887, the British Medical Journal published a paper describing cases of delirium after surgery with anaesthesia. A century later, scientists in the 1980s began to look at cases of older patients who had shown a decline in memory and concentration after cardiac surgery, but it has only been more recently that this has become apparent as a risk factor for all over-65s who undergo surgery, especially when under deep sedation.

In the last 20 years, studies have shown that POCD symptoms can affect everything from memory to attention, judgment and perception, and those with pre-existing health conditions are especially vulnerable. One survey of patients who received surgery to repair hip fractures found that those who developed POCD had a poorer ability to function socially and carry out normal activities such as writing, managing money or remembering lists, with a tangible impact on their daily life.

At the moment, estimates suggest that the overall incidence of POCD in older patients can be as high as 50-80% at discharge, 20-50% at six weeks and 10-30% at six months post-surgery. Given that the NHS carries out about 5.1m operations every year, a disproportionate number of which are in the over-65s, Cibelli says that there are a considerable number of patients being left with lasting impairment.

In recent years, POCD has caught the attention of Alzheimer’s researchers, intrigued to see whether it can accelerate decline towards dementia in some cases. Jenny Barnett, chief executive of Monument Therapeutics, a Cambridge-based biotech startup developing new therapies in neurology, says that people who already have underlying impairments in memory and attention skills are particularly vulnerable to POCD and it needs to be considered as a risk factor before significant surgeries.

“Many of us have had the experience of granny breaking her hip, goes into hospital and then by the time she comes out, she isn’t the same cognitively and isn’t able to live independently any more,” says Barnett. “I think that’s something that resonates with a lot of people.”

But exactly what causes POCD remains something of a mystery. Some point the finger at anaesthetics – certain animal studies have found that inhalation anaesthetics, the most commonly used form of general anaesthesia, can cause degradation of the cholinergic system in the brain, which is involved in learning and memory – but it has proven hard to study this in humans.

Instead, many scientists are pinpointing the possibility that these symptoms arise through the body’s reaction to surgery itself. Big operations unleash a firestorm of inflammation in response to the acute tissue damage that can cross the blood-brain barrier. Because the brain contains the largest density of inflammatory receptors in the body, it is especially vulnerable to the effects of inflammation, which can damage sensitive regions. Some brain-imaging scans have found that the hippocampus – a complex and vulnerable structure that plays a key role in memory – has a reduced volume in patients with POCD.

All this emerging evidence could lead to changes in medical practice. Research is already taking place into ways of identifying at-risk patients before operations, with the idea of potentially using a regional rather than a general…