By: 27 July 2018
Anaesthesia and surgery linked to decline in memory and thinking

In adults over 70, exposure to general anaesthesia and surgery is associated with a subtle decline in memory and thinking skills, according to new Mayo Clinic research.

The study analysed nearly 2,000 participants in the Mayo Clinic Study of Aging and found that exposure to anaesthesia after age 70 was linked to long-term changes in brain function. The results appear in the British Journal of Anaesthesia.

Although the decline in brain function was small, it could be meaningful for individuals with already low cognitive function or pre-existing mild cognitive impairment who are considering surgery with general anaesthesia, the researchers note. In older adults with borderline cognitive reserve that is not yet clinically obvious, exposure to anaesthesia and surgery may unmask underlying problems with memory and thinking.

“We need to be sure that patients considering surgery, and their families, are properly informed that the risk of cognitive dysfunction is possible,” says Juraj Sprung, a Mayo Clinic anaesthetist, who is the study’s senior author.

“In addition, alternative strategies should be discussed with patients before surgery is undertaken for those deemed to be at high risk. This study provides further reasons for clinicians to start performing routine preoperative cognitive evaluations of the elderly to further clarify an individual’s risk of exposure to surgery and anaesthesia. This initiative has been endorsed by the American Geriatrics Society but was not widely put into clinical practice.”

The link between exposure to anaesthesia and surgery, and cognitive decline in older adults has been debated for many years. Animal studies have suggested that exposure to inhaled anaesthetics may be related to brain changes linked to Alzheimer’s disease; however, most previous studies in humans have not consistently shown association between anaesthesia and impaired brain function.

In this study, researchers used resources from the Mayo Clinic Study of Aging, a long-term epidemiologic and population-based prospective study about cognitive changes related to aging. Participants in Olmsted County, Minnesota, undergo cognitive assessments at roughly 15-month intervals. The group included 1,819 participants, ages 70 to 89 at the time of study enrollment. The researchers analysed whether exposure to surgery and anaesthesia during the period 20 years before enrollment was associated with cognitive decline and whether exposure to anaesthesia after study enrollment as an older adult was associated with a cognitive change. While older adults often experience cognitive decline associated as part of the normal aging process, decline following exposure to anaesthesia and surgery was found to be slightly accelerated beyond that associated with normative aging.

The authors emphasised that it is not possible to determine whether anaesthesia, surgery or the underlying conditions necessitating surgery caused the decline.

Source: Mayo Clinic

Reference: PJ Schulte, RO Roberts, DS Knopman, RC Petersen, AC Hanson, DR Schroeder, TN Weingarten, DP Martin, DO Warner, J Sprung. Association between exposure to anaesthesia and surgery and long-term cognitive trajectories in older adults: report from the Mayo Clinic Study of AgingBritish Journal of Anaesthesia, 2018; DOI: 10.1016/j.bja.2018.05.060