‘We started work a number of years ago looking at the way that older people’s minds become impaired after surgery.

This affects the independence of older people. At the moment, about one-third of all anaesthetics given in Australia are given to people aged 65 or greater. It’s expected to be 50 per cent by 2050.

With dementia being as prevalent as it is and leading to people not being able to live independently, it’s important for us to make sure that we are doing the best that we can for their health outcomes.

One of the things that hadn’t been covered in previous research is functional change. We wanted to look at if the cognitive decline we see after surgery actually affects the functionality of older people.

My thesis looked at patients undergoing surgery. We looked at the number of people who had cognitive decline at three months and 12 months post-operatively.

Of those people, we looked out for how many ended up progressing to what we would classify as dementia. We followed the cardiac surgery patients on an average of 7.5 years and looked at how many of those patients would have been clinically classified with dementia. They did not have a pre-operative assessment for dementia.

What I found was that one-third of patients who had heart surgery developed dementia. In the population of that age group only about 10 per cent had dementia so, compared to the population, it was much, much higher than what we expected.

The patients having non-cardiac surgery and sedation did have a baseline assessment for dementia. What we found was that patients who underwent hip joint replacement surgery with insignificant coronary abnormalities had a progression to dementia in a year that was pretty much what we expected in the general population.

Those who had some sort of cognitive impairment before the hip joint replacement surgery progressed more rapidly but no more than what we would have expected in a normal person not undergoing surgery who had an impairment.

‘The group of people undergoing heart surgery progressed to an incidence of dementia in a year at a greater rate than what we would have expected in the general population regardless of their cognitive stage.’

The people who didn’t have any impairment in their cognitive abilities progressed at a lower rate similar to someone not undergoing surgery.

But the group of people undergoing heart surgery progressed to an incidence of dementia in a year at a greater rate than what we would have expected in the general population regardless of their cognitive stage.

We have yet to find out in further studies whether that’s associated with something already existing within the patients with heart disease or whether it has something more to do with the state of the patients, perhaps as part of the disease or as part of the consequences of the surgery.

In both of these groups, patients who had some sort of subtle impairment of their cognition deteriorated much more rapidly than what we would have expected if they hadn’t undergone surgery.

At the moment, the main information that has come out of my thesis is that there is a cognitive decline following surgery in older individuals that impacts their standard of living. This hasn’t been previously identified.

If we’re going to be giving a whole lot of older people procedures to improve their quality of life, we need to make sure that we’re actually improving their quality of life.’

Lis Evered’sthesis was titled: “Cognitive change that matters: the impact of cognitive change as a result of anaesthesia and surgery on functional outcomes and dementia.”  Her research provides new insights into those at risk of cognitive decline that has implications for healthier cognition and ageing.

* My PhD is an irregular series in which The Citizen speaks with recent Melbourne University PhD graduates.