Table 1.

Sample characteristics

Variables	Healthy control subjects and MCI-Aβ−	MCI-Aβ+ and AD	P value
N	20	24
Age (y)	70 ± 8.8	74.0 ± 8.0	.1∗
Male:female	12:8	14:10	.9†
MMSE	28.8 ± 2.1	26.1 ± 1.9	<.001‡
Education (y)	14.4 ± 2.8	13 ± 3.2	.1‡
Scan interval (d)	72.1 ± 81.5	204.8 ± 169.6	.002‡

Abbreviations: Aβ, amyloid β; AD, Alzheimer's disease; MCI, mild cognitive impairment; MMSE, Mini-Mental State Examination, MRI, magnetic resonance imaging.

^∗t Test.

^†χ² Test.

^‡Mann-Whitney rank sum.