Pharmaceutical compositions containing an extract of Houttuynia cordata (THUNB) as an active ingredient for preventing and treating dementia, Parkinson's disease, or epilepsy and methods for using the same. Since the extract of Houttuynia cordata or the mixture of the extract of Houttuynia cordata and the extract of Ampelopsis japonica Makino has a cell protection effect and/or a cognition function improved effect in various models including an Amyloid-β induced dementia model, a scopolamine induced dementia model, a 6-hydroxydopamine (6-OHDA) induced Parkinson's disease model, and a Kainic acid induced epilepsy model, the extract of Houttuynia cordata or the mixture of the extract of Houttuynia cordata and the extract of Ampelopsis japonica Makino may be used as the pharmaceutical composition for preventing and treating dementia, Parkinson's disease, or epilepsy and in health foods for preventing and treating dementia, Parkinson's disease, or epilepsy.