在临床实践中，对影响工作、生活和社交能力的严重认知障碍英文称为dementia ，中文称为痴呆。英文是这样解释dementia的：是一种广泛的脑疾病引起的长期的、逐渐思维和记忆能力下降而影响了个人日常功能的疾病（ Dementia， is a broad category of brain diseases that cause a long term and often gradual decrease in the ability to think and remember that is great enough to affect a person′s daily functioning ）［1］。然而，痴呆在中文中有白痴和呆傻的意思，显然有贬义，有失患者尊严，使患者和家人难以接受。