U.S. guidelines for assessing Alzheimer's disease (AD) neuropathology are getting a much-needed facelift. The existing ones, in place since 1997, had fallen out of step with the current understanding of AD as a disease with a long preclinical stage. The new ones, developed by a committee set up by the National Institute on Aging (NIA) and the Alzheimer's Association (AA), recommend a full evaluation of the neuropathologic changes in the brains of deceased patients regardless of whether or not they had clinical symptoms of dementia. This means someone who died cognitively intact can afterwards be found to have had Alzheimer's pathology.

The new guidelines are viewed as a welcome change in the community, although they stirred up quite a bit of discussion, particularly about the technical aspects of how to measure brain lesions. This two-part series summarizes what's new and what was debated at this year's Alzheimer's Association International Conference in Paris, where a draft document of the guidelines was first presented. Read also a comment from 25 researchers of the BrainNet Europe Consortium calling for harmonization between U.S. and European approaches.