Rule induction performance in amnestic mild cognitive impairment and Alzheimer’s dementia: examining the role of simple and biconditional rule learning processes

Figures & data

Table 1. Characteristics and neuropsychological task performance of the aMCI and AD participants.

	aMCI group	% impaired	AD group	% impaired
N	26	—	39	—
Age (years)	75.2 (8.0)	—	78.0 (8.0)	—
Sex (M/F)	9/17	—	23/16	—
Education	4.0 (2.0)	—	5.0 (3.0)	—
MMSE	27.1 (2.4)	—	24.2 (2.6)	—
Memory
RAVLT-immediate recall	26.6 (6.1)	57.7% (n = 26)	19.4 (6.7)	84.6% (n = 39)
RAVLT-delayed recall	3.0 (2.6)	73.1% (n = 26)	1.2 (1.9)	89.5% (n = 38)
RAVLT-recognition	24.8 (4.5)	57.7% (n = 26)	22.6 (4.2)	86.8% (n = 38)
VAT	7.8 (3.3)	61.5% (n = 26)	7.1 (3.9)	61.5% (n = 39)
Executive function & processing speed
Animal fluency	15.3 (3.6)	34.6% (n = 26)	12.9 (5.4)	59.0% (n = 39)
Digit Span (WAIS-III)	14.0 (3.0)	0 % (n = 26)	13.2 (3.5)	10.3% (n = 39)
LDST	19.4 (6.8)	40.0% (n = 25)	19.4 (7.4)	35.1% (n = 37)
Stroop Word card (s)	67.0 (17.0)	57.7% (n = 26)	66.0 (16.3)	54.1% (n = 37)
Stroop Color card (s)	84.1 (18.2)	50.0% (n = 26)	95.6 (32.7)	55.3% (n = 38)
Stroop Color/Word card (s)	167.5 (71.7)	36.0% (n = 25)	198.5 (87.6)	56.3% (n = 32)
TMT A (s)	69.3 (31.3)	34.6% (n = 26)	87.4 (43.4)	51.4% (n = 37)
TMT B (s)	195.5 (111.6)	48.0% (n = 25)	312.8 (172.4)	71.4% (n = 35)

Means are reported for age, the MMSE, and the neuropsychological test scores, frequencies for sex distribution, and median score (interquartile range) for education. Standard deviations in parentheses. Performance on the neuropsychological tests represents the number of correct responses, with the exception of the Stroop and TMT scores, which are expressed in seconds needed to complete the test. AD: Alzheimer’s dementia; aMCI: Amnestic mild cognitive impairment; LDST: Letter Digit Substitution Test; MMSE: Mini-Mental State Examination; n: number of patients who completed the neuropsychological test; RAVLT: Rey Auditory Verbal Learning Test; TMT: Trail Making Test; VAT: Visual Association Test; WAIS-III = Wechsler Adult Intelligence Scale—3rd Edition.

Figure 1. An illustration of the rule induction task, displaying the simple two-rule condition, the four-rule second condition, and the more complex third condition, requiring biconditional learning. To view a color version of this figure, please see the online issue of the Journal.

Table 2. Characteristics and task performance of the control, aMCI, and AD participants.

	Control group	aMCI group	AD group	Statistical test
N	32	26	34
Age (years)	74.9 (9.4)	75.2 (8.0)	77.2 (8.1)	F(2, 89) = 0.72, p = .49
Sex (M/F)	11/21	9/17	20/14	χ^2(2) = 5.17, p = .08
Education	5.0 (1.0)	4.0 (2.0)	5.0 (3.0)	χ^2(2) = 2.97, p = .23
MMSE	28.5 (0.9)	27.1 (2.4)	24.6 (2.5)	F(2, 89) = 30.26, p < .001
Rule induction test
Condition 1	12.0 (11.0)	10.5 (7.25)	15.0 (18.0)	χ^2(2) = 3.26, p = .196, η^2 = .04
Condition 2	21.0 (28.75)	26.0 (53.25)	46.5 (74.0)	χ^2(2) = 10.80, p = .005, η^2 = .12
Condition 3	35.5 (74.5)	50.0 (67.5)	96.0 (60.25)	χ^2(2) = 7.76, p = .021, η^2 = .09
Condition 2–1	4.5 (32.0)	16.5 (50.5)	35.0 (41.75)	χ^2(2) = 8.53, p = .014, η^2 = .09
Condition 3–2	10.5 (44.0)	27.0 (71.5)	9.0 (79.25)	χ^2(2) = 0.85, p = .655, η^2 = .01

Means are reported for age and the MMSE score, median scores (interquartile range) for education and for the rule induction outcomes and frequencies for sex distribution. standard deviations in parentheses. AD: Alzheimer’s dementia; aMCI: Amnestic mild cognitive impairment; MMSE: Mini Mental State Examination.

Table 3. Correlations between the rule induction task conditions and the neuropsychological test scores in the aMCI and AD participants.

	Condition 1	Condition 2	Condition 3
Memory
RAVLT-immediate recall	−0.28*	−0.09	0.06
RAVLT-delayed recall	−0.06	−0.07	0.01
RAVLT-recognition	−0.20	0.05	0.18
VAT	0.02	−0.07	−0.16
Executive function
Animal fluency	−0.23	−0.33**	−0.01
Digit Span Backward (WAIS-III)	0.13	−0.07	0.26*
Stroop Color/Word card (s)	0.24	0.35**	0.15
TMT B (s)	0.14	0.19	0.08

AD: Alzheimer’s dementia; aMCI: Amnestic mild cognitive impairment; LDST: Letter Digit Substitution Test; RAVLT: Rey Auditory Verbal Learning Test; TMT: Trail Making Test; VAT: Visual Association Test; WAIS-III = Wechsler Adult Intelligence Scale—3rd Edition.

*p < .05; **p < .01.