The present invention relates to a composition for treating or preventing amyloid-related diseases, said composition containing 4-O-methylhonokiol as an active ingredient. More particularly, the present invention relates to a pharmaceutical composition which contains as an active ingredient and which is useful in treating or preventing amyloid-related diseases such as Alzheimer’s disease, cognitive disorders, memory impairment, amyloidosis, etc. The inventors of the present invention first found that 4-O-methylhonokiol of the present invention inhibits the formation of beta-amyloid, and it is evidenced that 4-O-methylhonokiol can be used in the treatment and prevention of amyloid-related diseases. The inventors of the present invention have performed animal tests such as a water maze test, a passive avoidance test, and the like using experimental rats to find that 4-O-methylhonokiol is effective in the treatment or prevention of amyloid-related diseases such as Alzheimer’s disease, cognitive disorders, memory impairment, amyloidosis, etc. The inventors of the prevent invention further have performed an acetylcholinesterase activity inhibition test using the cortex and hippocampus of the brain of a rat to find that 4-O-methylhonokiol is significantly effective in the treatment or prevention of Alzheimer’s disease specifically from among the amyloid-related diseases.
