Executive function and attention in patients with stress-related exhaustion: perceived fatigue and effect of distraction

Figures & data

Table 1. Diagnostic criteria for exhaustion disorder according to the National Board of Health and Welfare.

(A) Physical and mental symptoms of exhaustion with minimum 2 weeks duration. The symptoms have developed in response to one or more identifiable stressors which have been present for at least 6 months.

(B) Markedly reduced mental energy, which is manifested by reduced initiative, lack of endurance or increase of time needed for recovery after mental efforts.

(C) At least four of the following symptoms have been present most of the day, nearly every day, during the same 2-week period:

1. Persistent complaints of impaired memory.

2. Markedly reduced capacity to tolerate demands or to work under time pressure.

3. Emotional instability or irritability.

4. Insomnia or hypersomnia.

5. Persistent complaints of physical weakness or fatigue.

6. Physical symptoms such as muscular pain, chest pain, palpitations, gastrointestinal problems, vertigo or increased sensitivity to sounds.

(D) The symptoms cause clinically significant distress or impairment in social, occupational or other areas of functioning.

(E) The symptoms are not due to the direct physiological effects of a substance (e.g. a drug abuse and a medication) or a general medical condition (e.g. hypothyroidism, diabetes and infectious disease).

(F) If criteria for major depressive disorder, dysthymic disorder, or generalized anxiety disorder are met, ED is set as co-morbid condition.

Table 2. Demographics, general cognitive level, SMBQ, and HADS for patients and controls.

	Patients (n = 25)	Controls (n = 25)	p Value^a
Sex (male/female)	(7/18)	(7/18)	1.000
Age (years)	43.6 (SD 9.4)	43.0 (SD 10.8)	.620
Education (years)	13.9 (SD 2.6)	15.2 (SD 1.9)	.061
General cognitive level
ISW test, number correct	28.2 (SD 4.7)	28.8 (SD 4.1)	.763
Prediction of full scale IQ (WAIS)^b	109.6 (SD 8.4)	111.7 (SD 7.2)	.273
SMBQ, mean score^c	5.9 (SD 0.6)		–
HADS score ≥8 on anxiety and/or depression^d	92%		–
HADS score ≥8 on anxiety^d	88%		–
HADS score ≥8 on depression^d	88%		–

^a For continuous data, Mann–Whitney’s test was used. For category data, Pearson’s Chi-Square was used; Irregularly Spelled Words (ISW).

^b Prediction of score on Wechsler Adult Intelligence Scale (WAIS) based on the ISW-score, gender, and years of education.

^c Results on the Shirom-Melamed Burnout Questionnaire (SMBQ) were available for 22 patients.

^d Results on the Hospital Anxiety and Depression Scale (HADS) were available for 24 patients.

Table 3. Ratings of fatigue and subjective cognitive functioning in patients (n = 25) and controls (n = 25).

	Controls mean (SD) 95% CIBoot	Patients mean (SD) 95% CIBoot	z Value	p^a	η^2^b
FIS	18.5 (20.0)	117.3 (26.7)	−6.043	<.001	0.75
	11.4–26.7	106.4–127.3
PRMQ	33.0 (7.4)	52.0 (12.5)	−5.060	<.001	0.52
	30.1–35.8	47.2–57.0
CFQ	33.8 (9.7)	60.6 (15.7)	−5.320	<.001	0.58
	29.8–37.2	54.9–66.9

^a Data were analyzed using Mann–Whitney’s U-test.

^b Effect sizes were given as η² based on the Chi-square from nonparametric two-sample comparisons; 95% bootstrap confidence interval (CI_Boot); Fatigue Impact Scale (FIS); Prospective and Retrospective Memory Questionnaire (PRMQ); Cognitive Failures Questionnaire (CFQ).

Table 4. Neuropsychological test results of executive function and complex attention in patients (n = 25) and controls (n = 25).

	Controls mean (SD)	Patients mean (SD)	z Value	p^a	η^2^b
Fluency: Modified COWAT
No. of words	39.4 (8.7)	31.3 (9.5)	−3.147	.008	0.20
95% CIBoot	36.0–42.8	27.9–35.4
Working Memory: 2-back test
No. of errors
Without distraction^c	1.8 (3.5)	1.4 (1.8)	−0.203	.839	0.00
With distraction^d	1.5 (1.9)	1.2 (1.3)	−0.061	.951	0.00
Difference	0.3 (2.4)	0.2(1.6)	−0.45	.652	0.00
No. of omissions
Without distraction^c	1.1 (1.4)	2.9 (2.5)	−2.773	.018	0.16
With distraction^d	1.6 (2.0)	4.0 (3.4)	−2.741	.018	0.15
Difference	−0.5 (1.7)	−1.1 (2.7)	−0.890	.746	0.02
Complex attention (PVSAT)
No. correct
Without distraction	49.9 (11.0)	44.4 (10.6)	−1.828	.136	0.07
95% CIBoot	45.2–53.7	40.2–48.3
With distraction^c	51.3 (10.2)	44.8 (9.9)	−2.461	.028	0.12
95% CIBoot	47.0–54.7	41.1–48.6
Difference	1.4 (4)	0.4 (6.3)	−1.054	.876	0.02
95% CIBoot	−0.08 to 3	−1.8 to 3.2

^a Data were analyzed using Mann–Whitney’s U-test.

^b Effect sizes were given as η² based on the Chi-square from nonparametric two-sample comparisons; 95% bootstrap confidence interval (CI_Boot), no CI were given for variables with a narrow interval of scores; Difference: The difference between the scores with and without distraction (subtracting one score with the other). The difference scores were computed so that a negative score always meant an inferior performance during distraction; Holm–Bonferroni’s corrections for multiple comparisons were applied respectively for four measures without distraction, three measures with distraction, and three measures of the difference. The p values shown in the table are corrected. Controlled Word Association Test (COWAT); Paced Visual Serial Addition Test (PVSAT).

The test was found too difficult and was not completed and values one point below the lowest recorded performance was used for:

^c n = 1,

^d n = 2 individuals in the ED-group.

Table 5. Neuropsychological test results of basic and sustained attention in the CPT-II in patients (n = 25) and controls (n = 25).

	Controls mean (SD) 95% CIBoot	Patients mean (SD) 95% CIBoot	z Value	p^a	η^2^b
Basic attention
Mean reaction time	353.7 (51.4)	345.9 (46.2)	−0.243	.808	0.00
	335.1–374.6	328.4–363.4
No. of commission errors	11.6 (6.4)	14.5 (8.6)	−1.021	.614	0.02
	9.2–14.2	11.3–17.8
No. of omissions	1.4 (2.3)	2.6 (3.3)	−1.677	.282	0.06
	–	–
Sustained attention
Variability of standard error	5.3 (2.3)	7.2 (2.5)	−3.027	.006	0.18
	4.5–6.2	6.4–8.3
Hit reaction time by block	−0.0072 (0.0175)	0.0044 (0.0147)	−2.382	.034	0.12
	−0.014 to 0.000	−0.0008 to 0.0108
Standard error by block	−0.0112 (0.0540)	−0.0012 (0.0602)	−0.583	.560	0.01
	−0.034 to 0.008	−0.0252 to 0.0208

^a Data were analyzed using Mann–Whitney’s U-test.

^b Effect sizes were given as η² based on the Chi-square from nonparametric two-sample comparisons; 95% bootstrap confidence interval (CI_Boot), no CI were given for variables with a narrow interval of scores; Conners’ Continuous Performance Test II (CPT-II). Holm–Bonferroni’s corrections for multiple comparisons were applied respectively for three comparisons of basic attention, and for three comparisons of sustained attention. The p values shown in the table are corrected.

Figure 1. Mean response time (in milliseconds) with ± SEM for targets in the six consecutive blocks of the CPT-II test for the ED group (n = 25) and controls (n = 25).

Figure 2. Average number of commission errors (with ± SEM) across six test blocks of the CPT-II test for patients with stress-related exhaustion (Exhaustion Disorder (ED)) and controls (n = 25). The ED group is divided into patients with an unexpected fast response speed at the beginning of the test (UEXF; n = 9) and those with expected fast response speed in the first block (EXF; n = 16). The UEXF-group had more commission errors during the test compared to the other groups.

Figure 3. Mean mental tiredness (with ± SEM) reported by patients with stress-related exhaustion (Exhaustion disorder (ED)) (n = 25) and controls (n = 25) before, during and after the administration of the neuropsychological tests. The scale is graded as; 1 = No tiredness, 2 = Mild, 3 = Moderate, 4 = Average, 5 = Severe, and 6 = Very severe. None of the participants rated 7 = Worst thinkable tiredness.