早老性痴呆

zǎo lǎo xìng chī dāi

(coll.) Alzheimer's disease

zǎo

early

lǎo

prefix used before the surname of a person or a numeral indicating the order of birth of the children in a family or to indicate affection or familiarity

xìng

nature

chī

variant of 痴[chi1]

dāi

foolish; stupid (variant of 呆[dai1])