隨著全球人口老化，失智症人口快速增加。失智症並非正常老化的現象，而是一種疾病。失智症的特徵是漸進性認知功能減退，包括記憶力會受到影響，並且其症狀會使一個人正常生活的能力受損。包括台灣在內，全球在照顧失智症患者所需的成本日益增加。早期診斷失智症在失智症照護上為重要的一環，然而診斷失智症經常是困難的，尤其在失智症早期。美國精神醫學會於2013年所出版的精神疾病診斷與統計手冊第五版中，將失智症更名為重度神經認知症(major neurocognitive disorder)。在其診斷標準中，認知功能要有至少一項以上衰退，包括整體注意力、執行功能、學習能力、記憶力、語言功能、知覺動作功能或社會人際認知等。目前沒有任何藥物可以治癒已經失智症患者受損的大腦，但治療仍對患者的認知功能及行為症狀有助益。失智症的治療包括藥物治療和非藥物治療，治療的主要目標是延緩疾病的進展或改善症狀。此外，減輕照顧者的負擔及增進其生活品質亦很重要。

As populations around the world are aging rapidly, patients with dementia increase steadily. Dementia is a syndrome characterized by progressive deterioration in cognitive function, including memory, which impairs a person’s capacity to function normally. Although dementia mainly affects older people, it is not a normal part of aging. Dementia imposes huge economic burdens worldwide, including Taiwan. Diagnosing dementia is often difficult, particularly in the early stage. However, early diagnosis of dementia is a crucial element in managing dementia. In the Diagnostic and Statistical Manual of Mental Disorders, 5th Edition (DSM-5), “dementia” in the previous edition was replaced by “major neurocognitive disorder”. The criteria for major neurocognitive disorder include “significant cognitive decline from a previous level of performance in one or more cognitive domains (complex attention, executive function, learning and memory, language, perceptual-motor, or social cognition)”. Currently, there is no curable treatment for dementia. Pharmacologic and non-pharmacologic treatments may be helpful to both cognitive and behavioral symptoms of dementia. The principal goal of dementia care is to slow the disease progression and improve symptoms. It is also important to reduce the burden of caregivers and thus improve their quality of life. (J Intern Med Taiwan 2014; 25: 151-157)