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. Author manuscript; available in PMC: 2015 Feb 1.
Published in final edited form as: Neurobiol Aging. 2013 Sep 27;35(2):301–308. doi: 10.1016/j.neurobiolaging.2013.08.007

Figure 2.

Figure 2

Conceptual model to explain how risk factors (age and APOE) relate to neuritic plaque and neurofibrillary tangle neuropathology. Solid boxes are observed variables in this study, and solid ovals are latent variables in this study measured by the observed neuropathology ratings. Curved dotted lines represent paths tested in this study, and values are the estimated standardized regression coefficients for these paths. Dashed ovals in the center are hypothesized processes to explain study results. Primary AD is a postulated, amyloid based, causative agent for neuritic plaques and neurofibrillary tangles. The mechanisms of Primary AD require future clarification, but correlations of plaques with tangles are hypothesized to result from their common relations with Primary AD. A non-amyloid process, or processes, is required to explain the association of age with medial temporal neurofibrillary tangles that cannot be explained by the amyloid path.