Feasibility and potential of a bedside mini-EEG for diagnosing delirium superimposed on dementia

•A brief point-of-care EEG is of promising diagnostic accuracy for recognizing delirium where superimposed on dementia (DSD).•The EEG of patients with DSD is characterized by increased slower activity compared to dementia patients without delirium.•Results indicate that EEG characteristics are associated with recovery or deterioration of delirium in DSD. Delirium superimposed on dementia (DSD) is difficult to diagnose because symptoms of delirium might be interpreted as symptoms of dementia. To improve diagnostic accuracy, we investigated the potential of a brief point-of-care EEG measurement. Thirty older patients were included, all with Major Neurocognitive Disorder (i.e. dementia) according to DSM-5 criteria. EEG was registered at right prefrontal and right temporal site, with eyes either open or closed for three minutes, simultaneously with the Discomfort Scale for Dementia of Alzheimer Type. The Confusion Assessment Method for the Intensive Care Unit was administered to determine the presence of symptoms of a delirium at the time of EEG administration. Video registrations were reviewed independently by two delirium experts. Higher activities of delta and theta1, and lower activities of theta2, alpha, and beta activity, were found in DSD when compared to dementia only. The ratio of delta and theta power during eyes-open conditions had the highest accuracy (AUC = 0.80 [0.63–0.94]; p