Table 2.

Cerebrospinal Fluid Biomarker Concentrations and Ratios in Alzheimer’s Disease Neuroimaging Initiative Study Subjects at Baseline

Characteristics	tau (pg/ml)	Aβ1–42 (pg/ml)	p-tau181p (pg/ml)	tau/Aβ1–42 Ratio	p-tau181p/Aβ1–42 Ratio
AD (n = 100)
Median	110	138	36	0.86	0.29
Mean ± SD	122 ± 58	144 ± 41	42 ± 20	0.92 ± 0.48	0.32 ± 0.19
95% CI	110–133	135–152	38–46	0.82–1.0	0.28–0.36
MCI (n = 196)
Median	86	146	32	0.62	0.23
Mean ± SD	103 ± 61	164 ± 55	36 ± 18	0.75 ± 0.62	0.26 ± 0.18
95% CI	95–112	156–171	33–38	0.66–0.84	0.24–0.29
NC (n = 114)
Median	61	217	20	0.31	0.10
Mean ± SD	70 ± 30	206 ± 55	25 ± 15	0.39 ± 0.27	0.14 ± 0.13
95% CI	64–75	195–216	22–28	0.34–0.43	0.12–0.17
MCI→AD (n = 37)a
Median	93	139	40	0.71	0.28
Mean ± SD	107 ± 54	146 ± 38	42 ± 18	0.81 ± 0.47	0.32 ± 0.17
95% CI	89–125	133–159	36–48	0.64–0.95	0.26–0.37
MCI→normal (n = 3)b
Median	73	253	21	0.29	0.08
Mean ± SD	75 ± 7	257 ± 26	22 ± 3	0.29 ± 0.02	0.09 ± 0.02
95% CI	57–93	192–322	15–29	0.24–0.34	0.03–0.14

Mann–Whitney test: p < 0.0001, for each of the five biomarker tests for Alzheimer’s disease (AD) vs cognitively normal (NC) and for mild cognitive impairment (MCI) vs NC. For AD vs MCI: p < 0.005, tau; p < 0.05, amyloid–β 1 to 42 peptide (Aβ_1–42); p < 0.01, tau phosphorylated at the threonine 181 position (p-tau_181p); p < 0.0005, tau/Aβ_1–42; p < 0.005, p-tau_181p/Aβ_1–42. p < 0.0001 for MCI converters to AD vs NC for each of the biomarkers and ratios.

^aAlzheimer’s Disease Neuroimaging Initiative (ADNI) MCI subjects who converted to a clinical diagnosis of probable AD at 1 year.

^bADNI MCI subjects who converted to cognitively normal at 1 year. SD = standard deviation; CI = confidence interval.