Table 1.

Demographic data and relevant parameters.

References	Subject	N	Age	Sex (M/F)	Olfactory test	MMSE	Correlation r		Side(s)
Devanand et al., 2010	MCI	571	–	–	UPSIT	–	MCI + NC	0.16	Double
	NC
Hagemeier et al., 2016	aMCI	19	73.6 ± 11	9/10	22.9 ± 8.6	–	AD	0.394	Right
	AD	42	76 ± 9	18/24	21.1 ± 7.9		aMCI	0.675
	NC	19	69.4 ± 2.9	6/13	30.0 ± 6.7		NC	−0.185
					UPSIT		AD	0.364	Left
							aMCI	0.438
							NC	−0.132
Vasavada et al., 2015	MCI	21	73.2 ± 9.0	10/11	24.2 ± 8.6	26.5 ± 1.9	AD + MCI + N	0.55	Double
	AD	16	71.9 ± 11.9	5/10	15.5 ± 8.4	18.9 ± 5.4	AD + MCI	0.33
	NC	27	69.5 ± 10.4	12/15	34.0 ± 4.2	28.5 ± 1.5
					UPSIT
Wu et al., 2019	MCI	27	68.04 ± 7.58	13/14	CSIT	26 (25, 28)	AD	0.242	Right
	AD	37	66.86 ± 10.27	17/20		16.03 ± 4.04	MCI	0.231
	NC	30	67.23 ± 6.71	11/19		29 (28, 30)	NC	0.167
							TOTAL	0.512
							AD	0.323	Left
							MCI	0.088
							NC	0.326
							TOTAL	0.512
Yu et al., 2019	MCI	31	65.9 ± 7.9	14/17	UPSIT	–	MCI + NC	0.42	Right
	NC	9	66.44 ± 7.05	3/6			MCI + NC	0.55	Left
Marigliano et al., 2014	aMCI	18	68.05 ± 3.5	9/9	SSET	–		0.508	Double
Murphy et al., 2003	AD	13	73.08 ± 2.19	8/5	SDOIT	22.85 ± 1.04	AD	0.54	Right
	NC	22	72.45 ± 1.78	10/12		29.68 ± 0.12	NC	0.23
							AD	0.85	Left
							NC	0.17

M/F, Male/Female; MMSE, Mini-Mental State Examination; UPSIT, University of Pennsylvania Smell Identification Test; CSIT, Chinese smell identification test; SSET, Sniffin Sticks Extended Test; SDOIT, San Diego Odor Identification Test; MCI, mild cognitive impairment; NC, normal control; AD, Alzheimer's disease.