A. i.e. Delirium In Delirium, there is disturbance of immediate and recent memory. Remote memory is normal. Immediate & Recent memory are responsible for registration & retention of new memories. And memory loss means the memories that are already registered will be lost (i.e. Remote memory will be lost). So in delirium there is only defect in registration & retention of new memories and there is no memory loss. In delirium, the EEG characteristically shows a generalized slowing of activityQ, which is useful in differenciating it from depression or psychosis. Delirium Definition & Epidemiology - It is characterized by global impairment of consciousness (clouding of consciousness), resulting in reduced levels of aleness, attention & perception of environment along with acute onset of fluctuating cognitive impairment. - It is the commonest organic mental disorderQ. It is a syndrome not a disease, as it has many causes, all of which resulting in a similar clinical picture. Clinical Features & Diagnosis Acute rapid onset (usually hours-days), brief duration (usually days - week), often marked unpredictable fluctuations in severity and manifestations during the course of the day, sometimes worse at night (sundowning), and rapid improvement when the causative factor is eliminated.