Zinc and Post-Operative Cognitive Dysfunction

A decline in cognitive abilities following surgery (POCD: Post-Operative Cognitive Dysfunction) affects up to 47% of patients undergoing a surgical procedure. Risk factors include age, previous depression, alcohol and drug use, smoking, cognitive impairment as well as pre-operative biochemical and haematological abnormalities. Inflammation has been proposed as a potential cause, however, there is little empirical and clinical evidence in this area to determine aetiology or reduce risk of incidence. Zinc is an important metal for brain function, with deficiency associated with poorer cognitive outcomes. In relation to POCD, biomarker studies have revealed that levels of a zinc-alpha-2-glycoprotein (AZGP1) were lower in patients with POCD. AZGP1 is a multifunctional glycoprotein implicated in cell adhesion, immune response, transmembrane transport and cellular proliferation. Microglia, the immune cells of the brain, are highly sensitive to changes in zinc which have been proposed to contribute to neurodegenerative disease as well as POCD. However, whilst animal studies looking at the effects of zinc on cognition have been promising, robust human trials are lacking. This research aims to establish the role of zinc in POCD by determining associations between zinc status, inflammation, cognitive function, and biomarkers of POCD risk and incidence. This will be achieved by gathering clinical and cognitive data from a sample of older adults undergoing surgery. Blood samples will be taken pre and post-operatively to establish zinc status and plasma concentrations of biomarkers of POCD risk and incidence. Pre and post-operative cognitive assessments will also be conducted to measure memory and executive function. Incidence of POCD will be determined via neurological assessment according to diagnostic criteria. Should associations between zinc status, POCD biomarkers, inflammation, cognitive performance and POCD incidence be established, not only would it lead to future wo