Procedural learning and retention relative to explicit learning and retention in mild cognitive impairment and Alzheimer’s disease using a modification of the trail making test

Figures & data

Table 1. Participant characteristic data.

	HC	aMCI	AD
	(n = 27)	(n = 20)	(n = 30)
	n/Mean (SD)	n/Mean (SD)	n/Mean (SD)	X^2/F	p	V/ ηp^2
Gender				1.60	.439	.146
Male	16	9	13
Female	11	11	17
Age	69.48 (7.41)	70.75 (8.91)	72.43 (6.11)	1.15	.322	.030
Education (years)	15.26 (3.71)	14.609 (2.76)	14.63 (2.71)	<1	.613	.010
WRAT-WR SS	108.70 (15.20)	101.65 (16.64)	99.71 (12.56)	2.78	.069	.072
MMSE^a	29.15 (1.26)	27.5 (2.21)	23.071 (3.60)	40.70	< .001*	.524
GDS		3.05 (3.00)	3.41 (2.66)	<1	.988	.000
FAQ^a		2.41 (4.26)	12.48 (6.17)	34.68	< .001*	.452
BNT^b	56.85(3.03)	52.15(4.67)	47.85(9.1)	13.68	< .001*	.281
COWAT^a		40.25(12.96)	28.93(11.02)	10.64	.002*	.370
Animals^a		17.5(4.23)	11.97(4.52)	18.65	< .001*	.459
Similarities^a		22.53(5.55)	18.71(4.28)	5.06	.031	.349
Digit Span F^a		9.75(2.02)	8.5(1.91)	4.91	.031	.093
Digit Span B^a		8.2(1.88)	5.93(1.84)	17.93	< .001*	.272
Digit Span S^a		7.35(2.45)	4.23(2.72)	16.96	< .001*	.261
TMT-T1 ^c	29.48 (7.67	35.15 (10.40)	54.93 (32.65)	10.82	< .001*	.226
TMT-T2 ^c	22.52(6.5)	26.55(7.61)	49.2(34.03)	12.00	< .001*	.245
TMT-T3 ^c	20.78(6.54)	25.4(7.54)	45.07(27.52)	14.34	< .001*	.279
TMT-T4 ^c	17.63(4.45)	25.45(10.28)	41.67(30.28)	10.87	< .001*	.227
TMT-T5 ^c	16.93 (4.59)	23.35 (9.69)	39.50 (28.96)	10.66	< .001*	.224
TMT-D ^c	19.41(5.49)	26.10 (8.19)	47.40 (29.63)	16.26	< .001*	.305
TMT-B ^c	80.52(33.96)	114.45(71.11)	201.77(86.01)	24.13	< .001*	.395
CVLT-T1 ^c	4.96 (1.34)	4.15 (1.75)	2.93 (1.36)	13.84	< .001*	.272
CVLT-T2 ^b	6.70(1.1)	5.5(1.5)	4.03(1.3)	30.52	< .001*	.452
CVLT-T3 ^b	7.19(1.04)	6.35(1.6)	4.63(1.42)	26.69	< .001*	.419
CVLT-T4 ^b	7.70 (.95)	6.60 (1.43)	5.10 (1.73)	24.16	< .001*	.395
CVLT-LDF ^b	6.56 (1.45)	4.05 (3.12)	.90(1.49)	55.66	< .001*	.601
CVLT-Disc ^b	2.99(.46)	2.39(.87)	1.54(.91))	25.50	< .001*	.408

Note. Means and standard deviations for sample demographic and clinical characteristics. Group differences between categorical variables were tested with Pearson Chi-Square, continuous variables with one-way ANOVA. HC = healthy controls; aMCI = mild cognitive impairment-amnestic type; AD = Alzheimer’s dementia; WRAT-WR SS = Wide Range Achievement Test-4 Word Reading Subtest Standard Score; GDS = Geriatric Depression Scale; FAQ = Functional Activities Questionnaire; BNT = Boston Naming Test total correct; COWAT = Controlled Oral Word Association Test number correct in 60 seconds for letters F, A, and S; Animals = number of animals correctly named in 60 seconds; Similarities, raw score; Digit Span F = total raw score correct for the Digit Span Forward; Digit Span B = total raw score correct for Digit Span Backwards; Digit Span S = total raw score correct for Digit Span Sequencing; TMT-T1 = Trail Making Test Trial 1 in seconds; TMT-T2 = Trail Making Test Trial 2 in seconds; TMT-T3 = Trail Making Test Trial 3 in seconds; TMT-T4 = Trail Making Test Trial 4 in seconds; TMT-T5 = Trail Making Test Trial 5 in seconds; TMT-D = Trail Making Test Delay in seconds; TMT-B = Trail Making Test Trial B in seconds; CVLT-T1 = CVLT-II SF Trial 1 number recalled; CVLT-T2 = CVLT-II SF Trial 2 number recalled; CVLT-T3 = CVLT-II SF Trial 3 number recalled; CVLT-T4 = CVLT-II SF Trial 4 number recalled; CVLT-LDF = CVLT-II SF long delay free recall; CVLT-Disc = CVLT-II SF discrimination index; *p values denoting significant group differences. Superscripts characterized significant between-group differences based on Tuckey post-hoc tests resulting in p < .05:, ^a = aMCI < AD, ^b = HC > MCI > AD, ^c = HC = MCI < AD.

Figure 1. Caption: Procedural versus episodic learning and retention by group

Table 2. Cohen’s d effect sizes for aMCI vs. HC and AD vs. HC.

	CVLTL	TMTL	CVLTR	TMTR
aMCI vs. HC	−.683	−.572	−.926	.013
AD vs. HC	−1.45	−.844	−3.13	−.309

Table 3. Correlations Between Memory Measures and Neuroimaging (MCI N = 18, AD N = 25).

	CVLTL	TMTL	CVLTR	TMTR
Hippo	.053	.255*	.361*	−.041
Ento	.328*	.296*	.445**	−.095
BG	.081	.147	.256*	−.011

Note. * p < .05; ** p < .0042 corrected for multiple comparisons; CVLTL = standardized learning value for CVLT-II SF; TMTL = standardized learning value for TMT; CVLTR = percent retained for CVLT-II SF; TMTR = percent retained for TMT; Hippo = (left hippocampal volume + right hippocampal volume)/2; Ento = (left entorhinal cortex + right entorhinal cortex)/2 BG = Basal Ganglia volume (Putamen + Caudate + Globus Pallidus); all volumes are corrected for total intracranial volumes.

Table 4. Correlations between procedural learning/retention and demographic/cognitive variables.

	TMTL	TMTR
Age	−.304*	-.103
Education	−.014	.177
WRAT-WR SS	.023	.122
MMSE	.315*	−.012
GDS	.147	−.011
FAQ	−.262	−.009
CVLTL	.311*	−.152
CVLTR	.313*	.034
BNT	.103	.244*
Animals	.281	−.138
TMT-B	−.390**	.035

Note. * p < .05; ** p < .0023 corrected for multiple comparisons; WRAT-WR SS = Wide Range Achievement Test-4 Word Reading Subtest Standard Score; GDS = Geriatric Depression Scale; FAQ = Functional Activities Questionnaire; CVLTL = CVLT-II SF learning; CVLTR = CVLT-II SF retention; BNT = Boston Naming Test; TMT-B = Trail Making Test Trial B.