Pre-surgical memory impairment is associated with risk of postoperative cognitive dysfunction in a large geriatric cohort.

Abstract

Some patients undergoing surgical procedures display long-term post-surgery cognitive impairment (post-operative cognitive dysfunction; POCD), which may precipitate progression to dementia. We investigated whether preoperative cognitive impairment defined using specific cognitive tests (Paired-Associates Learning and Spatial-Span from the Cambridge Neuropsychological Test Automated Battery, (CANTAB) was associated with increased risk of POCD. N = 590 patients >65years and a matched control group n=114 comprised the final sample. Patients were classified as impaired if a composite memory-score derived from two tests from the CANTAB test battery (spatial working memory and paired-associate learning) scored 1 SD below norms derived from a normative database. Risk of developing POCD 3 months post-surgery was higher [odds ratio 2.048 (95% CI 1.027 - 4.087)] for those with pre-surgical cognitive impairment compared to those with no impairment. This suggests that impairment on hippocampus-based tasks spatial-span memory and paired-associates learning is associated with increased risk for POCD in older surgical patients.