Table 2. Comparison of questionnaire scores by group.

Variables			Normal (A) (n = 200)	MCI (B) (n = 50)	Dementia (C) (n = 170)	P for A vs. B	P for A vs. C
Participant
	MMSE-DS					< 0.001	< 0.001
		Mean ± SD	27.3 ± 1.9	24.3 ± 3.2	18.5 ± 5.4
		Median (IQR)	28.0 (26.0–29.0)	25.0 (23.0–27.0)	19.0 (15.0–23.0)
		Range	21–30	10–29	3–30
	p-KDSQ-C					< 0.001	< 0.001
		Mean ± SD	3.9 ± 3.5	6.4 ± 5.0	9.3 ± 7.4
		Median (IQR)	3.0 (1.0–5.0)	5.5 (3.0–9.0)	7.0 (4.0–12.0)
		Range	0–19	0–29	0–30
	p-AD8					< 0.001	< 0.001
		Mean ± SD	1.0 ± 1.5	2.5 ± 2.0	3.7 ± 2.6
		Median (IQR)	0.0 (0.0–1.5)	2.0 (1.0–4.0)	4.0 (1.0–6.0)
		Range	0–7	0–8	0–8
	p-SMCQ					< 0.001	< 0.001
		Mean ± SD	2.9 ± 2.6	5.2 ± 3.0	5.9 ± 4.0
		Median (IQR)	2.0 (1.0–4.0)	5.0 (3.0–7.0)	5.0 (2.0–9.0)
		Range	0–14	0–12	0–14
Informants
	i-KDSQ-C					< 0.001	< 0.001
		Mean ± SD	3.2 ± 3.5	8.6 ± 5.4	16.1 ± 8.5
		Median (IQR)	2.0 (1.0–5.0)	7.0 (5.0–12.0)	15.5 (9.0–24.0)
		Range	0–20	1–30	0–30
	i-AD8					< 0.001	< 0.001
		Mean ± SD	0.8 ± 1.4	3.1 ± 2.1	5.3 ± 2.4
		Median (IQR)	0.0 (0.0–1.0)	3.0 (1.0–5.0)	6.0 (3.0–7.0)
		Range	0–7	0–8	0–8
	i-SMCQ					< 0.001	< 0.001
		Mean ± SD	2.4 ± 2.6	6.9 ± 3.3	9.6 ± 3.8
		Median (IQR)	2.0 (0.0–3.0)	7.0 (4.0–9.0)	11.0 (7.0–13.0)
		Range	0–13	1–14	0–14

P for differences were determined by using the Wilcoxon rank sum test.

MCI = mild cognitive impairment, SD = standard deviation, IQR = interquartile range, MMSE-DS = Mini-Mental State Examination-Dementia Screening, p-KDSQ-C = participant-completed Korean Dementia Screening Questionnaire-Cognition, p-AD8 = participant-completed Alzheimer Disease 8, p-SMCQ = participant-completed Subjective Memory Complaints Questionnaire, i-KDSQ-C = informant-completed Korean Dementia Screening Questionnaire-Cognition, i-AD8 = informant-completed Alzheimer Disease 8, i-SMCQ = informant-completed Subjective Memory Complaints Questionnaire.