Anaesthesia as a risk factor for long-term cognitive decline: Results of the prospective MAAS cohort study

BACKGROUND: There are concerns whether (repeated) exposure to general anaesthesia is associated with long-term cognitive decline. OBJECTIVE: We investigated the potential, negative relationship between total exposure to surgery under general anaesthesia and its impact on long-term cognitive development. DESIGN: A prospective longitudinal cohort study. SETTING: The Netherlands. PARTICIPANTS: 1823 Adults, aged 25-84 with normal cognitive functioning on inclusion with three serial cognitive assessments between 1995 and 2008, with comprehensive documentation on demographic, lifestyle, and health factors. MAIN OUTCOME MEASURES: The primary outcomes were test scores in the cognitive domains of learning and memory, executive function, selective attention, mental speed, and information processing speed. Linear mixed models were used to analyse the effects of the estimated total time under general anaesthesia at baseline on cognitive development during a 12-year follow-up period. RESULTS: When adjusting for demographic and systemic health-related factors, prolonged exposure to surgery under general anaesthesia (measured in total baseline minutes) negatively affected three cognitive domains. These included the CST (executive functioning, P < 0.05), Stroop (selective attention and mental speed, P < 0.001) and LDST (information processing speed, P < 0.005). Age and education were the primary factors impacting lifetime cognitive decline. Hypertension, diabetes, and smoking negatively affected various cognitive domains. CONCLUSION: Increased exposure to surgery under general anaesthesia independently contributes to long-term cognitive decline. Demographic variables and health-related factors are key contributors to accelerated cognitive decline over an individual's lifetime.