The challenging thing with delirium and dementia is that symptoms are so similar, which means one can often be misdiagnosed for the other.
The distinct difference, however, is that delirium is a temporary condition – symptoms can emerge a few hours to a few days after the surgery and at the very most will last a few weeks. However, dementia is an irreversible condition that will remain with the patient.
Delirium can be a common for older patients who have recently had surgery. Symptoms can include memory loss, reduced awareness of the environment, poor thinking skills, behaviour changes and emotional disturbances.
New research, published in British Journal of Anaesthesia, suggests that patients who experience delirium after surgery, at at three times the risk of developing dementia later in their life.
Researchers from the Mayo Clinic believe that the symptoms of delirium, such as confusion, disorientation and mood swings, may be a “warning sign” of the potential for dementia or permanent cognitive impairment.
According to the research, delirium can affect anywhere from 14 to 56 per cent of older patients who have recently had surgery requiring general anaesthetic.
This particular research was done over a ten year period, where patients over the age of 65, enrolled at the Mayo Clinic Study of Ageing in Olmsted County Minnesota and who were exposed to general anesthesia, were included in an investigation involving over two 2000 patients.
What was found was that of the 1152 patients who were deemed to be cognitively normal before surgery and returned for follow-up cognitive evaluation, 109 had developed mild cognitive impairment or dementia.
Another theory from the research suggests that postoperative delirium could itself produce brain injury, which may accelerates the trajectory of decline into dementia.
Already having dementia, or other pre-existing cognitive impairment, before undergoing surgery is widely recognised as risk factors, which increases the likelihood and severity of postoperative delirium.
However, there has previously been very little research that focuses on whether delirium itself leads to or even exacerbates the development of dementia. This research is the first of its kind to focus on the association between delirium and long-term cognitive decline in patients with normal mental capacity before surgery.
The research says risk factors for postoperative delirium includes older age, fewer years of education, and the stress of the surgery – high stress could mean procedures like orthopaedic or major heart surgery. Delirium was also more likely in men than women.
“Our research shows that delirium after surgery is not only distressing for patients and their families, but also may be a warning that patients could later develop dementia”, said lead researcher, Professor Juraj Sprung.
“We don’t yet know whether taking steps to prevent postoperative delirium could also help prevent dementia — but we need to find out.”
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