Delirium is a common neurological complication after cardiac surgery and associated with negative clinical outcomes, such as higher rates of mortality. Since the pathophysiology of delirium is still not well understood, the identification of risk factors for improving the prediction of delirium is critical. Cognitive impairment and dementia have been found to be predisposing factors for delirium. However, research shows that higher rates of cognitive reserve – defined as the ability of the brain to effectively cope with brain pathology – is not only thought to reduce the risk of dementia but also to lower the incidence and severity of delirium. To improve the prediction of delirium, the presence of cognitive impairment is assessed preoperatively. In addition, a semi-structured interview with the patient is conducted and recorded, which collects information about the entire adult life. The linguistic material obtained in this way is then analysed using text mining approaches and could thus be used for risk prediction.