Table 1. Demographics and clinical measures of N-MCI and P-MCI subjects at baseline.

Item	N-MCI	P-MCI	t value (χ2)	p value
	n=34	n=12
ADNI data
Age (years)	70.24 (7.20)	73.90(5.41)	-1.605	0.116
Gender (male/female)	17/17	6/6	0.000	1.000
Education level (years)	15.76(2.73)	15.75(2.45)	0.016	0.987
MMSE	27.71(1.77)	27.42(1.38)	0.513	0.610
ADAS-Cog	8.62(3.23)	13.08(4.21)	-3.800	0.000*
AVLT	37.47(10.20)	29.25(5.85)	3.382	0.002*
Item	N-MCI	P-MCI	t value (χ2)	p value
	n=40	n=16
NADS data
Age (years)	66.73(7.05)	72.93(5.79)	-3.123	0.003*
Gender (male/female)	23/17	9/7	0.007	0.932
Education level (years)	11.93(3.48)	11.38(2.94)	0.557	0.580
MMSE	27.53(1.60)	24.56(2.63)	5.154	0.000*
Composite Z scores of each cognitive domain
Episodic memory	0.33(0.57)	-0.82(0.73)	6.338	0.000*
Information processing speed	0.17(0.73)	-0.42(0.71)	2.780	0.007*
Executive function	0.22(0.52)	-0.56(0.49)	5.132	0.000*
Visuospatial function	0.05(0.52)	-0.13(0.52)	1.148	0.255

Notes: Values are expressed as the mean (standard deviation, SD). * Significant differences are found between P-MCI and N-MCI subjects. P values are obtained by t test except for gender (chi-square test). The performances of MMSE are presented as raw scores. The level of each cognitive domain is denoted by the composite Z scores.

Abbreviations: MCI, mild cognitive impairment; MMSE, Mini-Mental State Examination; ADNI, Alzheimer’s Disease Neuroimaging Initiative; NADS, Nanjing Aging and Dementia Study; P-MCI, progressive MCI, including MCI subjects who have progressed to AD-type dementia at the three-year follow-up; N-MCI, nonprogressive MCI, including MCI subjects who have not progressed to dementia at the three-year follow-up. ADAS-Cog, Alzheimer’s Disease Assessment Scale-Cognitive Subscale; AVLT, Rey Auditory Verbal Learning Test