Visual working memory capacity in Korsakoff’s amnesia

Figures & data

Table 1. Demographic and Korskoff characteristics, individual scores and means (95% confidence intervals) per group.

ID	Sex	Age (years)	Level of education^a	MMSE^b	IQ^c	RVLT^d	TMT-A^e
1	Male	55	7	22	118	T = 28	T = 50
2	Male	51	5	25	N.A.	T = 29	T = 54
3	Female	43	5	20	92	T = 41	T = 41
4	Female	55	5	22	115	T = 34	T = 33
5	Female	54	3	28	104	T = 34	T = 64
6	Male	51	4	25	94	T = 39	T = 61
7	Male	57	4	16	N.A.	T = 32	T = 26
8	Male	55	4	23	82	T = 19	T = 17
9	Female	52	4	23	92	T = 26	T = 60
Patients (N = 9)	55.6% male	52.6 (49.4–55.7)	4.6 (3.7–5.4)
Controls (N = 30)	53.3% male	56.0 (52.3–59.8)	5.2 (4.8–5.6)

Values of patients who had a significantly lower K_max compared to the healthy control group are depicted in bold.

^aEducation level was assessed using seven categories of a Dutch classification system, according to Verhage (1964), 1 being the lowest (less than primary school) and 7 being the highest (academic degree).

^bMini Mental State Examination, developed to screen for dementia in a psychiatric setting as a cognitive screening tool (Folstein, Folstein, & McHugh, 1975). Raw scores.

^cIQ scores were estimated with the Dutch version of the National Adult Reading Test (Schmand, Bakker, Saan, & Louman, 1991).

^dRey Verbal Learning Test, for measurement of verbal memory encoding, T-value on the first five learning trials (Van Der Elst, Van Boxtel, Van Breukelen, & Jolles, 2005).

^eTrail Making Test -A, for measurement of visual attention, T-value (Tombaugh, 2004).

Figure 1. Example of a no-change display in the visual working memory task.

Figure 2. Mean accuracy (%) on set size 2, 3, 4, and 6 of the visual working memory task for Korsakoff’s syndrome (KS) patients (N = 9) and the age- and education- matched control group (N = 30). Individual tests scores are displayed as lines. Error bars indicate 1 standard error of the mean.

Figure 3. Mean K_max on set size 2, 3, 4, and 6 of the visual working memory task for Korsakoff’s syndrome (KS) patients (N = 9) and the age- and education- matched control group (N= 30). Individual tests scores are displayed as lines. Error bars indicate 1 standard error of the mean.

Table 2. Demographic characteristics and performances on the spatial working memory task, individual scores and means (95% confidence intervals) per group.

	Accuracy (%)/KMax per set size
ID	2	3	4	6	Average KMax	Point estimate	Credible limit
1	100%/2.00	96%/2.70	82%/2.67	85%/4.29	2.91	94.29%	86.29% to 98.62%
2	41%/−0.36	65%/0.92	52%/0.04	50%/0.27	0.22	2.00%*	0.22% to 6.49%
3	91%/2.00	81%/1.67	62%/1.33	57%/1.38	1.60	41.71%	28.24% to 55.97%
4	56%/0	64%/0.74	55%/0.53	33%/−2.00	−0.18	0.55%*	0.02% to 2.47%
5	100%/2.00	81%/1.73	74%/1.88	50%/−0.20	1.36	29.41%	17.40% to 43.34%
6	100%/2.00	89%/2.63	91%/3.67	76%/3.27	2.89	94.01%	85.83% to 98.50%
7	57%/0	52%/0.17	60%/0.80	65%/1.80	0.69	7.37%	2.10% to 16.34%
8	41%/−0.36	68%/1.25	50%/0	57%/1.15	0.51	4.61%*	0.95% to 11.77%
9	58%/0.23	55%/0.03	52%/0.22	50%/0.13	0.15	1.61%*	0.15% to 5.54%
Patients (N = 9)	72%/0.83	72%/1.31	64%/1.24	58%/1.12	1.13 (0.24–2.01)
Controls (N = 30)	87%/1.62	77%/1.60	75%/1.88	68%/1.90	1.75 (1.49–2.01)

*The K_Max significantly differs from the average K_Max of the healthy control group, using Bayesian Crawford statistics. Their values on other measures are depicted in bold.

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