MAPT and dementia: Despite the small number, those with dementia (n = 5) had a lower mean level of Aβ42 ( 428.2 vs 718.9 ng/L, p = 0.004), lower Aβ40 level (4,781.8 vs 6,220.3 pg/mL, p = 0.02), lower Aβ42/Aβ40 ratio (0.55 vs 0.87), higher t-tau level (531.2 vs 331.1 ng/L, p = 0.001), and higher p-tau level (67.6 vs 49.4 ng/L, p = 0.021) than those without dementia (table e-2, links.lww.com/WNL/A424).