Hello, I have a few related questions about the MSBB array neuropathological variables whose definitions are given below: **PLQ_Mn**: plaque density mean (average of NP counts in 5 cardinal cortical regions) **NPrSum**: sum of neuritic plaque density estimates (sum of CERAD semi-quantitative rating scores for all cortical regions examined neuropathologically) **NTrSum**: sum of neurofibrillary tangles density estimates  (sum of semi-quantitative NFT density ratings for all cortical regions examined) **CERAD**: 1=Normal, 2=Definite AD, 3=probable AD, 4=possible AD Here are my questions: 1) Given there are values as big as 35 for NPrSum and the maximum possible CERAD score is 4, I think there are at least 9 regions examined for NPrSum. Is that correct? If so, which regions are included in NPrSum calculation in addition to the 5 regions included for PLQ_Mn, which are I believe middle frontal gyrus, orbital frontal cortex, superior temporal gyrus, inferior parietal cortex and calcarine cortex? 2) For the CERAD score, given the adjective "probable" corresponds to a higher likelihood than the adjective "possible", the numbers in the middle of the range (2 and 3) correspond to a worse patient outcome, which looks counter-intuitive, because then neither a high nor a low NPrSum value would necessarily mean a worse patient outcome. Am I missing something? 3) For NTrSum, what exactly "sum of semi-quantitative NFT density rating" means? What are the possible different ratings? Is it the same as the Braak score? I would really appreciate a quick response. Thanks!