Following surgery, older patients often report being unable to think clearly, which may affect their ability to live independently. Although the vast majority will recover and return to normal, 10 to 15 per cent of older people will experience a measureable degree of cognitive impairment even 12 months after surgery, according to Associate Professor David Scott, Director of Anaesthetics at St Vincent’s.
‘The Australian Institute of Health and Wellbeing estimates that by 2050 more than 50 per cent of all anaesthetics will be administered to patients over 65 years of age, so there is a pressing need to ensure that the 10 to 15 per cent of this ageing population are not adversely affected by anaesthetics or surgery,’ the senior anaesthetist says.
Researchers believe that certain older people are pre-disposed to cognitive decline, and A/Prof Scott is working with colleague Associate Professor Lis Evered, an international expert on postoperative cognitive decline, to uncover more about this phenomenon. A/Prof Evered is the leading researcher on a number of world renowned observational and interventional studies looking at cognitive and functional decline in patients in the short and long term.
‘We followed a group of patients for seven and a half years after cardiac surgery and found that there was a prevalence of dementia that is really much greater than we would have expected in that age group of people,’ she says.
‘What this tells us is there’s something about that group of patients that means they are more susceptible to getting dementia. What this study doesn’t tell us is if the anaesthesia and surgery has contributed to that.
‘Are we just observing a decline that they were already going to experience or is something happening in the peri-operative period that is either initiated or exaggerated in vulnerable patients?’
Last year A/Prof Evered was awarded an NHMRC-ARC Dementia Research Development Fellowship, which cemented her standing among the research community and will allow her to continue working with a number of international collaborators to further the body of research in this field.
‘We are now providing samples of blood and cerebrospinal fluid to a group in Sweden who are looking at inflammatory markers to tell us what physical reaction they are having to surgery.
A/Prof Evered is also about to begin an interventional study that will look at lifestyle changes in patients who are identified as being at risk.
‘There is evidence to suggest that mild cognitive impairment symptoms can be delayed with strategies that control risk factors, in particular cardiovascular risk factors. Brain exercise and maintaining social interaction have also been found to delay the onset of cognitive impairment. So we are looking at how lifestyle changes that address these issues, together with early intervention where necessary, may prevent or reduce the incidence of cognitive decline.’
A/Prof Evered has often found that the terms used to define cognitive impairment differ across disciplines, so she is working with the Alzheimer’s Association of the United States to introduce standardised terminology this year.
‘For the last five years I have worked with an international group of neurologists, psychiatrists and geriatricians to reclassify and redefine the terms we use, so that we are talking a common language across all medical disciplines,’ she says.
A/Prof Scott says the countless hours of work A/Prof Evered puts in keeping in contact with patients and training her research team mean the department can achieve much more.
‘The boundaries have become quite blurred between clinical researchers and scientific researchers. Lis is embedded and excelling in terms of academic recognition here and around the world and she’s got as much clinical knowledge about these aspects of patients as we do.’