Dementia is a major risk factor for delirium, and delirium is often superimposed on dementia in both hospital and community settings, can persist for days to weeks after discharge from an acute hospital, and is a risk factor for functional decline and mortality.

Misdiagnosis, overdiagnosis, or underdiagnosis and resulting inappropriate management of conditions associated with cognitive impairment in geriatric patients can cause substantial morbidity among the patients, hardship for their families and caregivers, and excessive health-care expenditures. This chapter provides a practical framework for diagnosing and managing geriatric patients who demonstrate “confusion” or signs of cognitive impairment. We focus on the most common causes of confusion in the geriatric population—delirium and dementia—although a variety of other disorders can cause the same or similar signs.

Imprecise definition of the abnormalities of cognitive function in older patients labeled as “confused” has led to problems in diagnosis and management. Descriptions such as impairment of cognitive function or cognitive impairment coupled with careful documentation of the timing and nature of specific abnormalities provide more precise and clinically useful information. Screening for dementia is controversial and is not recommended by the U.S. Preventive Services Task Force (Moyer, 2014). The best method of evaluating a patient suspected of cognitive impairment or dementia is a thorough mental status examination.