The impact of surgery and anesthesia on post-operative cognitive decline and Alzheimer's disease development: biomarkers and preventive strategies.
Alzheimer's disease (AD) is a major social and clinical burden in the elderly, affecting 5% of people aged over 65 and 20% aged over 80. Despite improved management, a cure has not been found and hence analysis of predisposing factors to identify preventive strategies has become increasingly important. Surgery and anesthesia have been proposed to increase the incidence of post-operative cognitive decline (POCD) and AD. This is hypothesized to be the result of a malignant neuroinflammatory response and subsequent synaptic impairment in the elderly and susceptible individuals. As a result, strategies are being explored to prevent surgery and anesthesia induced cognitive impairment. Whereas previously the diagnosis of AD was primarily dependent on clinical examination, biomarkers such as inflammatory cytokines, amyloid-β, and tau deposition in the cerebrospinal fluid have received increased attention. Nonetheless, AD is currently still treated symptomatically with acetylcholinesterase inhibitors and NMDA antagonists to improve cholinergic transmission and prevent glutamatergic excitotoxicity. Therapeutic success is, however, often not achieved, since these treatment methods do not address the ongoing neuroinflammatory processes and hence novel therapeutic and protective strategies are urgently needed. This review provides an insight into the current understanding of age-related cognitive impairment post-surgery and reflects on novel markers of AD pathogeneses exploring their use as targets for treatment. It gives a summary of recent efforts in preventing and treating POCD or AD with regards to the choice and depth of anesthesia, surgical strategy, and peri-operative medication, and discusses the mechanism of action and therapeutic prospects of novel agents.