Study: Prolonged general anesthesia linked to long-term cognitive decline

Editor's Note

Prolonged exposure to general anesthesia during surgery contributes to long-term cognitive decline, affecting executive functioning, selective attention, mental speed, and information processing, according to a February 18 study published in the European Journal of Anaesthesiology.

This prospective longitudinal cohort study followed 1,823 adults aged 25–84 in the Netherlands over 12 years, using standardized neuropsychological tests to assess the relationship between total exposure to general anesthesia and cognitive function over a follow-up period of 12 years while controlling for demographic and health-related factors. Participants had normal cognitive functioning at baseline and underwent three serial cognitive assessments between 1995 and 2008. Total exposure to general anesthesia was estimated from self-reported surgical histories verified by anesthesiologists, categorized by duration into four groups: less than 30 minutes, 30 minutes to 1 hour, 1 to 3 hours, and more than 3 hours. The study used the midpoint of each category to estimate total anesthesia time, which averaged 82.56 minutes at baseline.

Findings show general anesthesia negatively affected three cognitive domains:

• Executive functioning, evaluated via concept-shifting test (P < 0.05); participants showed slower task completion and reduced cognitive flexibility.
• Selective attention and mental speed, evaluated via Stroop test (P < 0.001); declines in attention control and processing speed were observed.
• Information processing speed (evaluated via letter-digit substitution test (P < 0.005); participants demonstrated slower cognitive processing and reduced efficiency.

The impact of anesthesia exposure on cognitive decline persisted even after adjusting for demographic and health-related variables. Age and education were the most significant predictors of cognitive decline, with older participants and those with lower educational attainment experiencing greater cognitive deficits. In addition to anesthesia exposure, other health factors such as hypertension, diabetes, and smoking were found to significantly contribute to cognitive decline.

Participants with a higher total time under general anesthesia displayed a steeper cognitive decline across the measured domains compared to those with less exposure.

Researchers acknowledged limitations, including reliance on self-reported surgical histories, the inability to distinguish between the effects of anesthesia and surgical stress, changes in surgical practices, and lack of data on anesthesia types. Nonetheless, they argue the findings underscore the importance of cognitive health considerations in surgical decision-making and the need for cautious perioperative planning, particularly for older adults and those with preexisting health conditions, as well as the importance of cognitive health considerations in surgical decision-making.