An amyloid β protein production inhibitor containing, as an active ingredient, at least one extract selected from the group consisting of extracts from rosemary, lemon, lavender and orange. A tau protein phosphorylation inhibitor containing, as an active ingredient, at least one extract selected from the group consisting of extracts from rosemary, lemon, lavender and orange. The inhibitors according to the present invention have an excellent effect to reduce amyloid β protein or phosphorylated tau protein in the brain, and therefore can be used suitably for the prevention, amelioration or treatment of diseases including Alzheimer's disease, Down syndrome, tauopathy (e.g., argyrophilic grain dementia, senile dementia of the neurofibrillary tangle type, progressive supranuclear palsy, corticobasal degeneration, Pick disease) and symptoms associated with these diseases. The inhibitors can increase BDNF, and therefore can also be used for the prevention, amelioration or treatment of diseases including dementia with Lewy bodies, frontotemporal lobar degeneration, depression, bipolar disorder, anxiety disorders, panic disorder, schizophrenia, autism, traumatic nerve injuries and ischemic brain damage and symptoms associated with these diseases.
AMYLOID β PROTEIN PRODUCTION INHIBITOR