Dementia, a syndrome of deterioration of cognition in alert persons that results in their impaired performance of activities of daily living, is difficult to recognize, especially in the early stages, and should be distinguished from delirium. Dementia is an acquired loss of multiple cognitive functions and is usually, but not always, progressive, resulting in the deterioration of social, occupational, and functional abilities. The three major categories of dementias are cortical, subcortical, and mixed. Dementia is identified in patients with Parkinson’s disease. Delirium, also known as acute confusional state, is a primary disorder of attention characterized by fluctuating features of abrupt onset of inattention, variable psychomotor activity, disorganized sleep-wake cycles, and global cognitive impairment. Caring for the caregiver of a patient experiencing delirium is similar to the care and concerns identified with dementia.