RT Book, Section A1 Seeley, William W. A1 Miller, Bruce L. A2 Hauser, Stephen L. A2 Josephson, S. Andrew SR Print(0) ID 1145768171 T1 DEMENTIA T2 Harrison's Neurology in Clinical Medicine, 4e YR 2018 FD 2018 PB McGraw-Hill Education PP New York, NY SN 9781259835865 LK neurology.mhmedical.com/content.aspx?aid=1145768171 RD 2024/10/09 AB Dementia, a syndrome with many causes, affects >5 million people in the United States and results in a total annual health care cost between $157 and $215 billion. Dementia is defined as an acquired deterioration in cognitive abilities that impairs the successful performance of activities of daily living. Episodic memory, the ability to recall events specific in time and place, is the cognitive function most commonly lost; 10% of persons age >70 years and 20–40% of individuals age >85 years have clinically identifiable memory loss. In addition to memory, dementia may erode other mental faculties, including language, visuospatial, praxis, calculation, judgment, and problem-solving abilities. Neuropsychiatric and social deficits also arise in many dementia syndromes, manifesting as depression, apathy, anxiety, hallucinations, delusions, agitation, insomnia, sleep disturbances, compulsions, or disinhibition. The clinical course may be slowly progressive, as in Alzheimer’s disease (AD); static, as in anoxic encephalopathy; or may fluctuate from day to day or minute to minute, as in dementia with Lewy bodies. Most patients with AD, the most prevalent form of dementia, begin with episodic memory impairment, although in other dementias, such as frontotemporal dementia, memory loss is not typically a presenting feature. Focal cerebral disorders are discussed in Chap. 22 and illustrated in a video library in Chap. 23; the pathogenesis of AD and related disorders is discussed in Chap. 35.