 BACKGROUND: Post-operative cognitive dysfunction POCD is a potentially irreversible loss of brain functions observed in elderly patients after surgical operations under general anaesthesia. POCD at 3 post-operative months is observed in up to 15 of patients aged 70 years and more, and the only recognized risk factor for this condition is increasing age. Importantly, the incidence of POCD at 3 months has been associated to an increased disability and mortality. 