Abstract: This invention relates to an extract composition, prepared by a process comprising the steps of a) mixing about 30 to 80 weight parts of ginseng, about 6 to 24 weight parts of Arisaematis rhizoma, about 5 to 15 weight parts of Gastrodiae rhizoma, about 5 to 15 weight parts of Acorus gramineus, about 5 to 15 weight parts of Ostericum Koreanum, about 5 to 15 weight parts of Bambusae caulis in taenium, about 5 to 15 weight parts of Bombycis corpus, about 5 to 15 weight parts of Ponciri fructus, about 5 to 15 weight parts of Hoelen, about 5 to 15 weight parts of Pinelliae tuber, about 3 to 9 weight parts of Aurantii nobilis pericarpium, and about 3 to 9 weight parts of Glycyrrhizae radix; and b) extracting the mixture with thermally-purified water or alcohol. This extract composition can be used as the active ingredient in an herbal composition for the prevention and treatment of senile dementia.