This study finds those who developed postoperative delirium were three times more likely to suffer permanent cognitive impairment or dementia | ScienceDaily
Over a ten year period, patients over the age of 65 enrolled at the Mayo Clinic Study of Ageing in Olmsted County Minnesota who were exposed to general anesthesia were included in an investigation involving over two 2000 patients. Their cognitive status was evaluated in regular 15 month periods before and after surgery by neuropsychologic testing and clinical assessment. Out of 2014 patients, 1667 were deemed to be cognitively normal before surgery. Of the 1152 patients who returned for follow-up cognitive evaluation, 109 (9.5%) had developed mild cognitive impairment (pre-dementia) or dementia, and those who had suffered postoperative delirium were three times more likely to be subsequently diagnosed with permanent cognitive decline or dementia. This research is the first to focus on the association between delirium and long-term cognitive decline in patients with normal mental capacity before surgery.
While previous studies have highlighted cognitive decline in the elderly following postoperative delirium, no others have involved such a detailed neuro-cognitive assessment identifying those with normal pre-operative cognitive abilities who go on to develop dementia. In conclusion, researchers believe that postoperative delirium could be a warning sign of future permanent cognitive impairment (dementia) in patients who at the time of surgery were still just above the threshold for registering cognitive decline. Alternatively, postoperative delirium could itself produce injury, which per se accelerates the trajectory of decline into dementia.