An approach to the patient with cognitive impairment: delirium and dementia

Patients with cognitive impairment can be divided into 2 broad groups: those with chronic cognitive decline (most likely diagnosable with a dementia) and those with acute cognitive changes (most likely experiencing a delirium). However, diagnosis in clinical practice is far more complicated than it is in textbooks. Perhaps the greatest hurdle in evaluating the cognitively impaired patient is the clarification of a cohesive history. Unfortunately, the cognitively impaired patient is most often unable to provide such a history, and in the absence of a reliable family member, friend, or caregiver to fill in the gaps, diagnostic clarity can be difficult to achieve. This article outlines the broad diagnostic spectra of delirium and dementia, reviews current understanding of their pathogenesis, and discusses useful diagnostic and therapeutic techniques.