This variable has been replaced by amylsqrt_est_8reg.

Amyloid beta protein identified by molecularly-specific immunohistochemistry and quantified by image analysis. Value is percent area of cortex occupied by amyloid beta. Mean of amyloid beta score in 8 regions (4 or more regions are needed to calculate).

8 regions used : amyloid_hip - hippocampus : amyloid_ec - entorhinal cortex : amyloid_mf - midfrontal cortex : amyloid_it - inferior temporal : amyloid_ag - angular gyrus : amyloid_calc - calcarine cortex : amyloid_cg - anterior cingulate cortex : amyloid_sf - superior frontal cortex

RADC recommendation: use AMYLSQRT when using as outcome variable in models. (mean of the square-root; has better statistical properties)

Item level variables are available upon request.