Rehabilitation for improved cognition in patients with stress-related exhaustion disorder: RECO – a randomized clinical trial

Figures & data

Table 1. Sample characteristics at baseline.

Variable	Control group (n = 41)	Cognitive training (n = 44)	Aerobic training (n = 47)
Sex, n
Female/male	38/3	34/10	39/8
Age
Mean (SD)	41.88 (7.41)	43.89 (9.21)	44.15 (8.60)
Range	22–58	25–58	25–60
Education, n (%)
University	26 (63%)	25 (57%)	29 (62%)
Marital status, n (%)
Married/co-habited	30 (73%)	32 (73%)	35 (75%)
Family situation, n (%)
Living with children at home	33 (81%)	28 (64%)	34 (72%)
Sick leave before MMR, n (%)
No sick leave	10 (24%)	4 (9%)	6 (13%)
≤6 month	20 (49%)	25 (57%)	30 (64%)
7–12 months	5 (12%)	6 (14%)	6 (13%)
12–24 months	3 (7%)	3 (7%)	2 (4%)
>24 months	3 (7%)	6 (13%)	3 (6%)
Problems with memory and concentration, n (%)^a
None/negligible	0 (0%)	0 (0%)	0 (0%)
Small	1 (2.5%)	1 (3%)	1 (2%)
Moderate	10 (25%)	15 (43%)	9 (20%)
Severe/pronounced	29 (72.5%)	19 (54%)	36 (78%)
Problems with sleep, n (%)^a
None/negligible	1 (2.5%)	3 (8%)	0 (0%)
Small	3 (7.5%)	2 (6%)	5 (11%)
Moderate	15 (37.5%)	11 (31%)	12 (27%)
Severe/pronounced	21 (52.5%)	20 (56%)	28 (62%)
BMI kg/m^2, mean (SD)	26.37 (4.65)	25.10 (4.33)	26.65 (5.50)
Physical activity in everyday life, n (%)
<30 min/day	18 (45%)	11 (31%)	15 (33%)
≥30 min/day	22 (55%)	25 (69%)	31 (67%)
Physical exercise, n (%)
≤2 hours/week	34 (85%)	29 (83%)	37 (80%)
>2 hours/week	6 (15%)	6 (17%)	9 (20%)
Verbal ability, mean (SD)^b	22.83 (4.78)	21.46 (4.73)	22.87 (3.97)

Number of respondents varies for different variables; control group: n = 40–41; cognitive training group: n = 35–44; aerobic training group: n = 45–47.

^a Based on the question “For the past three months, have you experienced any of the following problems: (1) Problems with sleep; (2) Problems with memory or concentration. If so, rate how severe these problems have been: negligible; small; moderate; severe; pronounced.”

^b SRB:1 (Dureman, Kebbon, & Österberg, 1971).

Figure 1. CONSORT flow diagram. ITT: intention-to-treat.

Table 2. Means and standard deviations on the cognitive variables for each group and time-point.

	Control group			Cognitive training			Aerobic training
Variable	T1	T2	T3	T1	T2	T3	T1	T2	T3
Global cognitive score	0.12 (0.66) n = 36	0.33 (0.53) n = 30	0.38 (0.55) n = 26	−0.06 (0.63) n = 39	0.25 (0.68) n = 27	0.40 (0.81) n = 21	−0.08 (0.53) n = 43	0.18 (0.55) n = 23	0.29 (0.59) n = 20
Executive function
3-back	22.50 (6.97) n = 38	25.56 (5.59) n = 32	25.46 (6.19) n = 26	20.33 (6.22) n = 39	24.54 (7.65) n = 28	25.43 (8.58) n = 21	19.70 (8.30) n = 43	23.61 (8.03) n = 23	25.95 (6.52) n = 21
Shift cost	44.60 (25.36) n = 40	38.22 (20.75) n = 32	43.35 (14.11) n = 26	53.29 (27.63) n = 42	48.64 (33.01) n = 28	41.39 (17.92) n = 23	48.07 (19.81) n = 46	42.54 (20.94) n = 24	42.57 (25.05) n = 21
Inhibition cost	29.00 (14.41) n = 40	23.47 (7.98) n = 32	23.15 (8.26) n = 26	29.93 (9.02) n = 42	25.46 (8.33) n = 28	31.04 (16.54) n = 23	29.87 (11.56) n = 46	28.67 (10.95) n = 24	26.29 (10.16) n = 21
Working memory
Digit span forwards	7.23 (2.11) n = 40	7.19 (1.69) n = 32	6.96 (1.66) n = 26	6.83 (2.00) n = 42	7.36 (2.13) n = 28	7.70 (2.16) n = 23	6.70 (1.95) n = 46	6.71 (2.33) n = 24	6.48 (2.29) n = 21
Digit span backwards	6.20 (1.76) n = 40	6.65 (1.70) n = 31	6.88 (1.95) n = 26	6.74 (2.30) n = 42	7.07 (2.11) n = 28	7.52 (2.84) n = 23	6.46 (1.93) n = 46	6.42 (2.10) n = 24	6.43 (2.66) n = 21
Letter-number-sequencing	10.31 (2.02) n = 39	10.38 (2.43) n = 32	10.42 (2.39) n = 26	9.88 (2.93) n = 40	10.22 (2.75) n = 27	10.90 (2.79) n = 21	9.22 (2.25) n = 45	10.29 (2.69) n = 24	10.30 (2.75) n = 20
Episodic memory
Recall of concrete nouns	52.46 (9.83) n = 37	53.58 (11.19) n = 31	55.92 (12.03) n = 26	50.50 (11.34) n = 40	54.71 (13.37) n = 28	56.57 (11.57) n = 21	50.11 (8.21) n = 44	55.67 (6.91) n = 24	55.30 (7.37) n = 20
Perceptual speed
Digit symbol	54.83 (11.88) n = 40	59.63 (13.42) n = 32	60.27 (12.66) n = 26	50.93 (9.07) n = 42	57.39 (12.08) n = 28	59.91 (14.21) n = 23	51.72 (9.63) n = 46	56.21 (9.98) n = 24	57.33 (9.37) n = 21
Reasoning ability
Raven’s matrices	6.90 (2.70) n = 39	6.28 (2.73) n = 32	7.65 (3.14) n = 26	6.60 (3.01) n = 40	7.29 (2.81) n = 28	7.71 (3.72) n = 21	7.48 (2.81) n = 44	6.71 (2.76) n = 24	7.50 (3.07) n = 20
Cognitive training criterion task
Letter memory running span	2.40 (1.79) n = 40	2.66 (1.62) n = 32	2.62 (1.55) n = 26	2.07 (1.59) n = 41	4.36 (2.26) n = 28	4.09 (1.78) n = 23	2.34 (1.64) n = 44	1.96 (1.65) n = 24	2.95 (1.72) n = 21

T1: pre intervention; T2: post intervention; T3: one-year follow-up.

Table 3. Long-term training-related effects on the cognitive variables.

		T1 to T3
Variable	Group (ref. control group)	β (95% CI)	p Value	d
Global cognitive score	Cognitive training	0.21 (0.03, 0.39)	.02	0.35
	Aerobic training	0.06 (−0.11, 0.24)	.48	0.11
Executive function	Cognitive training	0.04 (−0.26, 0.35)	.78	0.06
	Aerobic training	0.10 (−0.21, 0.40)	.52	0.14
Working memory	Cognitive training	0.25 (−0.06, 0.55)	.11	0.30
	Aerobic training	−0.05 (−0.36, 0.26)	.76	0.06
Episodic memory	Cognitive training	0.32 (−0.12, 0.76)	.15	0.31
	Aerobic training	0.33 (−0.11, 0.77)	.14	0.32
Perceptual speed	Cognitive training	0.18 (−0.15, 0.51)	.27	0.18
	Aerobic training	0.11 (−0.23, 0.44)	.54	0.10
Reasoning ability	Cognitive training	0.28 (−0.23, 0.78)	.29	0.27
	Aerobic training	−0.12 (−0.63, 0.39)	.65	0.12
Cognitive training criterion task	Cognitive training	0.88 (0.29, 1.47)	.004	0.87
	Aerobic training	0.12 (−0.49, 0.72)	.71	0.11

Estimates represent the average difference in change across time between intervention group and control group based on the z-transformed test scores. For all variables, a positive value indicates improved performance. Cohen’s d is calculated as the difference in mean change across time between intervention group and control group, divided by the baseline standard deviation. T1: preintervention; T3: one-year follow-up.

Figure 2. Changes across time for each group based on the estimated means from the model in (A) performance on the global cognitive score, based on the mean z-score of nine cognitive tests covering the domains executive function, working memory, episodic memory, processing speed, and reasoning ability; (B) performance in episodic memory; (C) performance on the cognitive training criterion updating task and; (D) aerobic capacity. Error bars indicate SEM. T1: pre intervention; T2: post intervention; T3: one-year follow-up; VO_2max: maximal oxygen uptake.

Table 4. Means and standard deviations on psychological variables, work ability, and aerobic capacity for each group and time-point.

Variable	Control group			Cognitive training			Aerobic training
	T1	T2	T3	T1	T2	T3	T1	T2	T3
SMBQ	4.78 (1.03) n = 38	4.34 (1.07) n = 40	3.94 (1.25) n = 40	4.98 (0.88) n = 38	4.20 (1.06) n = 44	3.95 (1.02) n = 40	4.87 (0.95) n = 43	4.05 (1.22) n = 46	4.05 (1.28) n = 45
HAD
Depression	7.26 (3.48) n = 38	6.05 (4.14) n = 40	5.25 (4.12) n = 40	6.76 (2.70) n = 38	4.73 (2.82) n = 44	4.58 (2.68) n = 40	6.81 (3.79) n = 43	4.93 (3.84) n = 46	4.82 (3.55) n = 45
Anxiety	9.41 (3.82) n = 38	8.40 (3.67) n = 40	7.18 (4.30) n = 40	10.47 (3.03) n = 38	7.75 (3.15) n = 44	7.70 (4.03) n = 40	9.19 (3.83) n = 43	6.87 (3.40) n = 46	7.67 (4.73) n = 45
CIS	96.02 (19.64) n = 38	86.93 (22.58) n = 40	79.70 (24.43) n = 40	95.83 (17.87) n = 38	85.01 (21.06) n = 43	79.88 (20.31) n = 40	94.24 (19.45) n = 43	79.54 (21.90) n = 46	82.11 (26.60) n = 45
WAI	27.41 (6.94) n = 38	30.08 (6.79) n = 33	33.40 (6.09) n = 28	26.29 (6.91) n = 38	29.68 (6.77) n = 28	34.02 (7.27) n = 23	26.71 (6.29) n = 43	31.77 (5.34) n = 24	31.83 (9.25) n = 19
VO2max	35.96 (9.15) n = 40	36.83 (10.55) n = 32	37.24 (10.74) n = 27	35.58 (7.00) n = 43	34.31 (8.55) n = 26	33.91 (8.22) n = 23	34.66 (8.12) n = 45	40.48 (9.79) n = 23	35.88 (8.32) n = 17

CIS: Checklist Individual Strength; HAD: Hospital Anxiety and Depression Scale; SMBQ: Shirom-Melamed Burnout Questionnaire; T1: pre intervention; T2: post intervention; T3: one-year follow-up; VO_2max: maximal oxygen uptake; WAI: Work Ability Index.

Table 5. Long-term training-related effects on psychological variables, work ability, and aerobic capacity.

Variable	Group (ref. control group)	T1 to T3
		β (95% CI)	p value	d
SMBQ	Cognitive training	−0.20 (−0.64, 0.24)	.37	0.19
	Aerobic training	−0.07 (−0.36, 0.49)	.76	0.06
HAD
Depression	Cognitive training	−0.02 (−1.36, 1.33)	.98	0.01
	Aerobic training	0.49 (−0.81, 1.79)	.46	0.14
Anxiety	Cognitive training	−0.30 (−1.93, 1.34)	.72	0.08
	Aerobic training	0.93 (−0.65, 2.51)	.25	0.25
CIS	Cognitive training	0.51 (−8.82, 9.85)	.91	0.02
	Aerobic training	5.96 (−3.06, 14.98)	.19	0.28
WAI	Cognitive training	1.91 (−1.28, 5.09)	.24	0.28
	Aerobic training	−1.32 (−4.64, 2.00)	.43	0.20
VO2max	Cognitive training	−1.91 (−4.94, 1.12)	.22	0.22
	Aerobic training	0.06 (−3.23, 3.36)	.97	0.01

Estimates represent the average difference in change across time between intervention group and control group. For the psychological variables, a negative value indicates a decrease in symptoms. For work ability and aerobic capacity, a positive value represents an improvement. Cohen’s d is calculated as the difference in mean change across time between intervention group and control group, divided by the baseline standard deviation. CIS: Checklist Individual Strength; HAD: Hospital Anxiety and Depression Scale; SMBQ: Shirom-Melamed Burnout Questionnaire; T1: preintervention; T3: one-year follow-up; VO_2max = maximal oxygen uptake: WAI: Work Ability Index.

Figure 3. The distribution of sick leave levels for each group at the different time-points. Total number of observations: T1: n = 132; T2: n = 85; T3: n = 82. T1: pre intervention; T2: post intervention; T3: one-year follow-up.

Dureman, I., Kebbon, L., & Österberg, E. (1971). Manual till DS-batteriet [Manual for the DS-battery]. Stockholm: Psykologiförlaget.

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