Disease caused by brain tissue degeneration in old age; also known as [[老人痴呆症|老人痴呆症|lao3 ren2 chi1 dai1 zheng4]], [[老年痴呆症|老年痴呆症|lao3 nian2 chi1 dai1 zheng4]], or [[老人失智症|老人失智症|lao3 ren2 shi1 zhi4 zheng4]]