Mielke et al. (2018) demonstrated that plasma p-tau181 and total tau were differentially associated with neuroimaging measures of AD pathology. Both plasma tau and p-tau181 levels were elevated in patients with AD dementia compared to cognitively unimpaired patients. Plasma p-tau181 was a better predictor of elevated Aβ PET than total tau (P < 0.01), age (P < 0.05), or APOE (P < 0.05) alone (AUC = 0.7–0.85), highlighting the potential use of plasma p-tau181 as a non-invasive blood-based screener of AD pathophysiology (Mielke et al., 2018). Here, APOE is linked to dementia.