MAPT and Alzheimer disease: This is in line with other studies reporting that in addition to tau tangles, CSF tau levels may also reflect other (patho)physiological processes that are disrupted in AD.9,14,41 For example, up to 70% of individuals with Ad dementia and CSF A+T– had high AD neuropathologic changes at post-mortem examination;31,42 and of those with repeated CSF measurements, most remained T– over time.