Structural integrity of the anterior mid‐cingulate cortex contributes to resilience to delirium in SuperAging

Abstract Background Identifying factors that confer resilience to developing delirium is critical given the negative impact of delirium on clinical care and risk for mortality. Here, we investigated a cohort of cognitively normal older adults undergoing elective surgery and examined the role of pre‐operative memory function and cortical thickness in the incidence and severity of post‐operative delirium (POD). We hypothesized that 1) those older adults with episodic memory function comparable to that of young adults (“SuperAgers" or SA) would show reduced incidence of POD compared with typically‐aging older adults (TOA) and 2) cortical thickness in the anterior mid‐cingulate cortex (aMCC), the integrity of which has been consistently associated with SuperAging, would predict reduced incidence and severity of POD. Method 19 SA and 74 TOA (mean age 75.8 +/‐ 4.1; 57F/36M) completed neuropsychological testing and underwent structural brain MRI pre‐operatively as part of the Successful AGing after Elective Surgery (SAGES) Study. SA were identified based on neuropsychological criteria defined in previous studies. Delirium incidence and severity were assessed using the Confusion Assessment Method (CAM) daily throughout hospitalization. A general linear model analysis was performed to identify regions of the cerebral cortex whose thickness was associated with CAM scores. Results No differences were found in age or education between SA and TOA. Remarkably, no SA developed POD; POD occurred only in the TOA group (D‐TOA = 15). Severity of POD was negatively associated with cortical thickness of bilateral aMCC. A one‐way ANOVA comparing mean aMCC thickness across subgroups revealed a significant effect (F(2,89) = 3.09, p ≤ .05), with thickness greatest in SA compared with D‐TOA (t(31) = 2.47, p ≤ .019, Cohen’s d = 0.89), but comparable compared to thickness seen in non‐delirious (ND) TOA (t(76) = 0.72, p ≤ .72, d = 0.10). Greater aMCC thickness was also observed for ND‐TOAs compared with D‐TOAs (t(71) = 2.26, p ≤ .03 d = 0.72). Conclusion These findings suggest that superior memory function and greater structural integrity of the aMCC may be important indices of resilience to delirium in older adults that can serve as a target of preventive or therapeutic interventions.