Delirium is defined as a neurocognitive disorder characterized by sudden onset, fluctuating course, and disturbances in level of consciousness, attention, orientation, memory, thought, perception, and behavior (American Psychiatric Association, 2013). It occurs in hyperactive, hypoactive, or mixed forms in up to 50% of older hospital patients (Inouye et al., 2014) and 70% of older long-term care residents (McCusker et al., 2011), many with pre-existing dementia (Fick et al., 2002).