21350
Alzheimer ' s disease ( AD ) is a complex neurodegenerative disorder , typified by the pathological accumulation of beta - amyloid peptides ( A beta ) and neurofibrillary tangles within the brain , culminating to cognitive impairment .
 None
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
 None