This bears out the observations I made to hospital staff and my GP after an operation on my wife for a heart valve replacement in August 2010. In the recovery room and subsequently on the ward she suffered terrible delirium and hallucinations that I told staff about and that it could have been triggered by the anaesthetic. At the time I was merely told that such delirium could occur after surgery but that it was nothing to worry about. The delirium was so bad that my wife was moved to a single bed room and I stayed by her bedside 24/7 to keep her calm.
Subsequent to discharge the delirium/hallucinations got worse and she was finally diagnosed with dementia/alzheimers in 2013 and needed constant attention until she died in 2015, suffering severe bouts of delirium and memory loss.
Perhaps doctors and nurses should listen to the patient or near relatives, who recognise such subtle changes in personality.