精神发育不全(mental retardation)(也有称“智力发育不全”或“智力障碍”),是最常见的影响人类十分严重的慢性神经系统疾患。它包括智力明显低下这一特征的不同情况的类型,而并不是指一个定义清晰的实体。美国精神缺陷学会最近提出,精神发育不全是指“在发育期间,一般智力功能严重低于平均水平,并伴有适应行为缺陷者”。有资料说,平均30个 Mental retardation (also called “mental retardation” or “mental retardation”) is the most common chronic neurological disorder that affects humans very much. It includes the different types of intelligence with a markedly lower intelligence, not a well-defined entity. The American Society of Mental Defects recently proposed that mental underdevelopment refers to “a person who has under-average mental function during development, who is accompanied by a defect in his or her adaptive behavior.” According to statistics, an average of 30