The association between physical activity and delayed neurocognitive recovery in elderly patients: a mediation analysis of pro-inflammatory cytokines

Abstract Background Delayed neurocognitive recovery (dNCR) can result in unfavorable outcomes in elderly surgical patients. Physical activity (PA) has been shown to improve cognitive function, potentially by reducing systemic inflammatory responses. However, there is a lack of supportive data indicating whether PA has a protective effect against dNCR. Aims To examine the correlation between dNCR and PA, and to further analyze if pro-inflammatory cytokines mediate this relationship. Methods This study is a prospective nested case-control investigation of elderly patients who had knee replacement surgery. dNCR was defined as a decline in cognitive function compared with baseline by using a battery of neuropsychological tests. PA was assessed with the Physical Activity Scale for the Elderly (PASE). Enzyme-linked immunosorbent assay (ELISA) was used to measure the serum concentrations of IL-6, IL-1β, and TNF-α. Multivariable logistic regression analysis was conducted to assess the association between PA and dNCR. Mediation analysis was employed to evaluate whether pro-inflammatory cytokines mediate the relationship between them. Results A cohort of 152 patients was included, resulting in an incidence rate of dNCR of 23.68%. PA was associated with dNCR after full adjustment [OR = 0.199, (95% CI, 0.061; 0.649), P = 0.007]. Mediation analysis showed that the IL-6 mediated the statistical association between PA and dNCR, with mediation proportions (%) of 77.68 (postoperative concentration of IL-6) or 27.58 (the absolute change in IL-6 before and after surgery). Conclusions PA serves as a protective factor against dNCR, possibly through the reduction of pro-inflammatory cytokine concentrations. The Chinese Clinical Trail Registry : www.http://chictr.org.cn , Registration No. ChiCTR2300070834, Registration date: April 24, 2023.