ABSTRACT
Alzheimer's disease (AD) is the most common cause of dementia in the elderly. Transgenic mice engineered to have copies of mutant amyloid precursor protein (APP) genes are proving useful animal models of AD since they express aspects of the abnormal pathology. β-amyloid is derived from APP by the action of proteases. APP is processed by two pathways, only one of which gives rise to the two βA peptides, with 40 and 42 amino acids, that are deposited in plaques. The mutations of the APP gene in familial early onset AD enhance the cleavage of APP by β-secretase or γ-secretase, but are also likely to increase the tendency for the mutant peptides to aggregate. Tau, a cytoplasmic protein required for the proper formation of microtubules, and which forms the paired helical filaments in tangles, is crucial to the neurodegeneration that leads to dementia. The only drugs licensed specifically for the treatment of AD are acetylcholinesterase inhibitors.
