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Abstract Alzheimer ' s disease ( AD ) is a progressive neurodegenerative disorder that affects more than five million Americans and is characterized by a progressive loss of memory , loss of cholinergic neurons in the basal forebrain , formation of amyloid plaques and neurofibrillary tangles , and an increase in oxidative stress .
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Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
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