Cognitive test norms and comparison between healthy ageing, mild cognitive impairment, and dementia: A population‐based study of older Aboriginal Australians

Figures & data

short-legendFigure 1.

Table 1. Demographic and screening data according to each diagnostic group

	Sex	Age		Education		MMSE		mKICA		RUDAS
	Male	Mean (SD)	Range	Mean (SD)	Range	Mean (SD)	Range	Mean (SD)	Range	Mean (SD)	Range
Control (n = 31)	15 (48%)	64.90 (4.26)	60–74	9.71 (2.43)	6–15	28.74 (1.00)	27–30	37.84 (1.16)	34–39	26.58 (2.54)	20–30
MCI (n = 38)	13 (34%)	67.74 (6.36)	60–80	8.76 (2.93)	4–15	26.29^2 (2.49)	19–30	37.11^2 (1.54)	32–39	23.93^2 (3.14)	15–30
Dementia (n = 35)	22 (63%)	69.57 (6.78)	60–88	8.40 (3.31)	0–15	21.31^3 (5.57)	7–29	32.77^4 (3.97)	20–38	20.84^4 (4.88)	8–28

Note: MMSE, mKICA, and RUDAS scores were prorated for participants with sensory/physical impairment or poor literacy for a subset of items (for an overview of the total KGOWS sample, see Radford et al., 2015b).

n = 37 for cognitive screening (n = 1 not screened due to speech difficulties resulting from stroke).

n = 32 (n = 3 not screened due to cognitive impairment).

n = 30 (n = 4 not screened due to cognitive impairment and n = 1 not screened due to cognitive and motor impairment).

Table 2. Descriptive statistics for major study variables according to the diagnostic group

	Control (n = 31)			MCI (n = 38)			Dementia (n = 35)
	Mean (SD)	Range	Median (IQR)	Mean (SD)	Range	Median (IQR)	Mean (SD)	Range	Median (IQR)
ACE‐R
Attention/orientation	17.71 (0.78)	14–18	18 (0)	17.03 (1.12)^6	14–18	17 (1)	12.85 (4.31)^8	2–18	13.5 (5)
Memory	22.32 (2.50)	19–26	22 (4)	17.41 (3.48)^6	11–25	17 (5)	10.71 (5.78)^8	0–20	11 (10)
Fluency	10.23 (2.55)	5–14	10 (4)	8.05 (2.35)^6	3–14	8 (3)	4.21 (3.92)^8	0–11	3 (8)
Language	24.13 (1.78)	18–26	24 (3)	22.68 (2.57)^6	14–26	23 (4)	17.65 (5.82)^8	3–25	20 (8)
Visuospatial	15.06 (0.96)	13–16	15 (2)	13.86 (1.72)^6	9–16	14 (2)	10.38 (4.77)^8	0–16	11 (5)
ACE‐R total	89.45 (5.38)	76–98	89 (7)	79.03 (5.84)^6	67–93	78 (8)	55.79 (20.80)^8	13–84	55 (30)
Digit span forward
Longest span	6.16 (1.46)	4–9	6 (2)	5.81 (1.33)^6	4–8	6 (2)	4.94 (1.05)^9	3–8	5 (1)
Total correct	9.26 (2.49)	5–15	9 (4)	8.70 (2.07)^6	6–13	8 (3)	7.06 (1.92)^9	4–12	7 (3)
Digit span backward
Longest span	4.13 (0.92)	3–6	4 (2)	3.22 (0.75)^6	2–5	3 (1)	2.77 (1.09)^10	0–5	3 (1)
Total correct	5.61 (1.60)	3–9	5 (3)	3.84 (1.19)^6	2–6	4 (2)	3.03 (1.73)^9	0–6	3 (2)
Logical memory
Immediate recall total	12.26 (3.73)	4–19	12 (5)	7.87 (3.93)	0–16	7.5 (4)	4.13 (3.37)^10	0–12	4 (5)
Delayed recall total	9.26 (3.66)	2–18	9 (4)	4.89 (3.48)	0–13	5 (5)	1.97 (2.75)^10	0–10	0 (3)
Percent recall	74.45 (17.43)	42.86–100	75 (30.36)	53.95 (30.63)	0–100	58.57 (46.98)	28.82 (37.24)^10	0–100	0 (60)
Recognition total	11.61 (2.01)	6–15	12 (3)	9.87 (2.53)	4–14	10 (4)	8.94 (1.93)^10	5–14	9 (2)
Oral trail making A
Total time	9.26 (2.56)	4–16	9 (3)	9.72 (2.48)^7	6–14	9.5 (5)	16.09 (16.34)^9	6–99	12 (7)
Oral trail making B
Total time	46.68 (22.32)	22–99	40 (26)	79.70 (22.76)^6	34–99	90 (40)	89.04 (17.68)^11	45–99	99 (19)

IQR: interquartile range.

n = 37.

n = 36.

n = 34.

n = 32.

n = 31.

n = 27.

Table 3. Control group percentile scores for main test variables, stratified by education

	Low education (0–9 years) (n = 18)				High education (10+ years) (n = 13)				Total (n = 31)
Percentiles	10	25	50	75	10	25	50	75	10	25	50	75
ACE‐R
Attention/orientation	17.00	17.00	18.00	18.00	15.60	18.00	18.00	18.00	17.00	18.00	18.00	18.00
Memory	19.00	20.00	21.00	24.00	19.00	20.50	24.00	25.50	19.00	20.00	22.00	24.00
Fluency	5.00	6.75	10.00	11.25	9.00	10.00	12.00	13.00	6.00	9.00	10.00	13.00
Language	21.60	22.75	24.00	24.25	22.40	25.00	26.00	26.00	22.00	23.00	24.00	26.00
Visuospatial	13.00	14.00	15.00	16.00	14.00	15.00	16.00	16.00	14.00	14.00	15.00	16.00
ACE‐R total	79.60	84.75	87.00	89.25	85.60	89.50	93.00	97.00	83.20	86.00	89.00	93.00
Digit span forward
Longest span	4.00	5.00	5.50	7.25	4.40	5.00	7.00	7.00	4.20	5.00	6.00	7.00
Total correct	5.90	7.00	8.50	10.50	6.40	7.00	10.00	11.50	6.20	7.00	9.00	11.00
Digit span backward
Longest span	3.00	4.00	4.00	5.00	3.00	3.00	4.00	4.00	3.00	3.00	4.00	5.00
Total correct	4.00	4.75	6.00	8.00	3.00	4.00	5.00	6.00	4.00	4.00	5.00	7.00
Logical memory
Immediate recall total	5.80	8.75	10.50	14.00	7.80	12.00	14.00	16.00	7.20	10.00	12.00	15.00
Delayed recall total	3.80	5.75	8.50	10.25	5.40	7.00	10.00	13.50	5.00	7.00	9.00	11.00
Percent recall	50.00	57.14	74.47	93.18	46.89	56.10	75.00	85.42	50.59	57.14	75.00	87.50
Recognition total	8.70	10.00	11.50	13.00	8.40	11.50	12.00	13.00	9.00	11.00	12.00	13.00
Oral trail making A
Total time	13.30	12.25	9.50	7.75	11.60	9.50	9.00	7.50	13.00	11.00	9.00	8.00
Oral trail making B
Total time	83.70	59.50	46.00	35.50	95.40	47.50	31.00	26.00	88.40	55.00	40.00	29.00

Table 4. Results from parametric (t‐tests) and non‐parametric (Mann–Whitney U) analyses comparing diagnostic groups on performance for test variables of interest

	Control vs dementia		Control vs MCI		MCI vs dementia
	t/U	p	t/U	p	t/U	p
ACE‐R
Attention/orientation	78.50	<0.001	333.50	0.001	192.50	<0.001
Memory^12	10.68	<0.001	6.58	<0.001	−5.86	<0.001
Fluency	119.50	<0.001	297.50	0.001	292.00	<0.001
Language	109.50	<0.001	363.50	0.009	261.50	<0.001
Visuospatial	165.50	<0.001	335.00	0.003	332.00	0.001
ACE‐R total	15.00	<0.001	108.00	<0.001	176.50	<0.001
Digit span forward
Total correct^12	3.91	<0.001	1.01	0.318	−3.40	0.001
Digit span backward
Total correct	142.50	<0.001	228.00	<0.001	423.50	0.038
Logical memory
Percent recall^12	6.18	<0.001	3.489	0.001	−3.02	0.004
Recognition total	158.50	<0.001	350.00	0.004	451.00	0.093
Oral trail making A
Total time	265.50	0.001	498.50	0.450	317.00	0.001
Oral trail making B
Total time	74.50	<0.001	180.00	<0.001	360.00	0.041

t‐statistics reported; all others Mann–Whitney U. All statistically significant values (p < 0.05) remained significant after FDR correction for multiple comparisons.

Radford, K., Mack, H. A., Draper, B., Chalkley, S., Delbaere, K., Daylight, G., … Broe, G. A. (2015b). Comparison of three cognitive screening tools in older urban and regional Aboriginal Australians. Dementia and Geriatric Cognitive Disorders, 40, 22–32. https://doi.org/10.1159/000377673

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