He explained: “Delirium is a sudden loss in mental function, sometimes described as ‘acute confusion’, that occurs in many older people. It’s often caused by an infection or surgery and is common in hospitals, where it affects one in five patients. This is very distressing for patients, their carers and their loved ones, but is often not recognised or even named by doctors. This is a very important condition to recognise though, as risk of death is doubled and delirium causes a higher risk of developing dementia and worsens the condition where it already exists.”