(-)Clausenamide is an active alkaloid isolated from the leaves of Clausena lansium (Lour.) Skeels,and improves cognitive function in both normal physiological and pathological conditions.(-)Clausenamide inhibits β-amyloid (Aβ) toxicity, blocking neurofibrillary tangle formation by inhibiting the phosphorylation of tau protein. (-)Clausenamide exerts a significant neuroprotective activity against Aβ 25-35. (-)Clausenamide can be used for researching Alzheimer's disease (AD).