精神发育迟滞（也称智能缺陷或智力低下）指一种造成不能履行社会职能的智力缺陷,这种缺陷可以从履行与年龄相称的任务中看出来,婴儿和学龄前儿童在一定年龄阶段内,可能达不到发育中的特定标志（如坐、对熟悉人物的反应、行走、讲话以及对括约肌的控制能力等）。学龄儿童会因为课堂行为、阅读、写字、算术等方面的问题达不到社会期望。成人则是在家庭内外的工作方面,交际技能上或者对金钱、运输及对地点的理解等方面显出能力不足。 比较严重的精神发育迟滞患者在出生几个月和几岁之内可诊断出来,重度的智能发育迟滞以发育延迟为特征,而诊断几乎不是 Mental retardation (also referred to as mental retardation or mental retardation) refers to a mental retardation that results in an inability to perform social functions. Such defects can be seen in the performance of tasks that are commensurate with age. Infants and preschool-age children, at certain ages, Specific signs of development (such as sitting, reactions to familiar characters, walking, talking, sphincter control, etc.) may not be reached. School-age children can not meet the social expectations because of classroom behaviors, reading, writing, arithmetic and other issues. Adults have demonstrated inadequate capacity to work, both inside and outside the home, in communicative skills or in understanding money, transport and location. Serious mental retardation in patients with a few months and years old can be diagnosed, severe intellectual retardation is characterized by delayed development, and the diagnosis is almost not