dementia
noun [ U ] medical specialized uk/dɪˈmen.ʃə/ us/dɪˈmen.ʃə/
（尤指老年性）痴呆
a medical condition that affects especially old people, causing the memory and other mental abilities to gradually become worse, and leading to confused behaviour
The most common form of dementia is Alzheimer's disease. 最常见的痴呆病是阿尔茨海默氏症。