This variable replaces gpath.

Global neuritic plaque-tangle burden is a quantitative summary of AD pathology derived from counts of two AD pathologies: neuritic plaques (n) and neurofibrillary tangles (nft), as determined by microscopic examination of silver-stained slides from 5 regions: midfrontal cortex (midfrontal), midtemporal cortex (midtemp), inferior parietal cortex (infparietal), entorhinal cortex (ento), and hippocampus (ca1hip). Each regional count is square root transformed, scaled within region after dividing by the corresponding standard deviation. The 5 square root transformed scaled regional measures for each type of pathology are then averaged to obtain summary measures and then averaged to obtain the measure of global neuritic plaque-tangle burden.

Notes on missing data and computation of measures: Counts may be missing for regions (e.g., due to damage from infarct). If data are present for at least 2 of 5 regions, the burden summary for a specific pathology is computed. The measure is only computed if all 2 of the pathology-specific summaries are valid (and non-missing).

Item-level variables are available upon request.