Sustained Attention and Working Memory Predict the Number of Days on Health-Related Benefits in the Year Following Occupational Rehabilitation

Abstract

Purpose The objective of this study was to investigate the association between cognitive and emotional functioning and the number of days on health-related benefits such as sick leave, work assessment allowance and disability pension. We investigated whether cognitive and emotional functioning at the start of rehabilitation and the change from the start to the end of rehabilitation predicted the number of days on health-related benefits in the year after occupational rehabilitation. Methods A sample of 317 individuals (age 19–67 years), mainly diagnosed with a musculoskeletal or mental and behavioural ICD-10 disorder, participated. The sample was stratified depending on the benefit status in the year before rehabilitation. Those receiving health-related benefits for the full year comprised the work assessment allowance and disability pension (WAA) group and those receiving benefits for less than a year comprised the sick leave (SL) group. The participants were administered cognitive and emotional computerised tests and work and health questionnaires at the beginning and end of rehabilitation. The cumulative number of days on health-related benefits during 12 months after rehabilitation was the primary outcome variable and age, gender, educational level, subjective health complaints, anxiety, and depression were controlled for in multiple regression analyses. Results The WAA group (n = 179) was significantly impaired at baseline compared to the SL group (n = 135) in focused attention and executive function, and they also scored worse on work and health related variables. Higher baseline scores and change scores from the start to the end of rehabilitation, for sustained attention, were associated with fewer number of health-related benefit days in the WAA group, while higher baseline scores for working memory were associated with fewer number of health-related benefit days in the SL group. Conclusions New knowledge about attention and memory and return to work in individuals with different benefit status may pave the way for more targeted programme interventions. Rehabilitation programmes could benefit from designing interventions that respectively improve sustain attention and working memory related to working life in individuals on sick leave or work assessment allowance and disability pension.

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Vol:.(1234567890)
Journal of Occupational Rehabilitation (2021) 31:592–603
https://doi.org/10.1007/s10926-020-09944-5
1 3
Sustained Attention andWorking Memory Predict theNumber
ofDays onHealth‑Related Benefits intheYear Following Occupational
Rehabilitation
ThomasJohansen1· IreneØyeaten1,2· HegeR.Eriksen3· PeterS.Lyby4· WinandH.Dittrich5· IngeHolsen6·
HanneJakobsen7· RubyDelRiscoKollerud1· ChrisJensen1
Accepted: 3 November 2020 / Published online: 20 January 2021
© The Author(s) 2021
Abstract
Purpose The objective of this study was to investigate the association between cognitive and emotional functioning and
the number of days on health-related benefits such as sick leave, work assessment allowance and disability pension. We
investigated whether cognitive and emotional functioning at the start of rehabilitation and the change from the start to the
end of rehabilitation predicted the number of days on health-related benefits in the year after occupational rehabilitation.
Methods A sample of 317 individuals (age 19–67years), mainly diagnosed with a musculoskeletal or mental and behavioural
ICD-10 disorder, participated. The sample was stratified depending on the benefit status in the year before rehabilitation.
Those receiving health-related benefits for the full year comprised the work assessment allowance and disability pension
(WAA) group and those receiving benefits for less than a year comprised the sick leave (SL) group. The participants were
administered cognitive and emotional computerised tests and work and health questionnaires at the beginning and end of
rehabilitation. The cumulative number of days on health-related benefits during 12months after rehabilitation was the primary
outcome variable and age, gender, educational level, subjective health complaints, anxiety, and depression were controlled
for in multiple regression analyses. Results The WAA group (n = 179) was significantly impaired at baseline compared to
the SL group (n = 135) in focused attention and executive function, and they also scored worse on work and healthrelated
variables. Higher baseline scores and change scores from the start to the end of rehabilitation, for sustained attention, were
associated with fewer number of health-related benefit days in the WAA group, while higher baseline scores for working
memory were associated with fewer number of health-related benefit days in the SL group. Conclusions New knowledge
about attention and memory and return to work in individuals with different benefit status may pave the way for more targeted
programme interventions. Rehabilitation programmes could benefit from designing interventions that respectively improve
sustain attention and working memory related to working life in individuals on sick leave or work assessment allowance
and disability pension.
Keywords Occupational rehabilitation· Return to work· Sick leave· Cognition· Attention· Memory
* Thomas Johansen
thomas.johansen@arbeidoghelse.no
1 Norwegian National Advisory Unit onOccupational
Rehabilitation, Haddlandsvegen 20, 3864Rauland, Norway
2 NORCE, Norwegian Research Centre, Bergen, Norway
3 Department ofSport, Food andNatural Sciences, Western
Norway University ofApplied Sciences, Bergen, Norway
4 Catosenteret Rehabilitation Center, Son, Norway
5 FOM Hochschule, KCI Competence Center forBehavioral
Economics, Frankfurt, Germany
6 Red Cross Haugland Rehabilitation Center, Flekke, Norway
7 Valnesord Health Sports Centre, Fauske, Norway
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593Journal of Occupational Rehabilitation (2021) 31:592–603
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Introduction
Participation in working life involves mental and cognitive
demands, coping with different social interactions, adjust-
ing to multiple roles, and adapting to various occupational
contexts. Therefore, it can be assumed that cognitive and
emotional abilities such as attention, memory, executive
function and emotion regulation are essential for perform-
ing well in working life [1–3]. Cognitive impairments are
prevalent in individuals on long-term sick leave [4–7]
and improving cognitive and emotional functioning will
enhance the ability to stay focused, process and remember
information, and shift focus when required because indi-
viduals have increased mental resources and capacity [7].
Emotional functioning refers to our ability to regulate and
label our emotions enabling us to influence and direct our
attention away from negative emotions and biases result-
ing in better coping [10]. The benefits of improved cogni-
tive and emotional functioning are better flexibility, better
regulation of our emotions and experiences, and increased
quality of life [8–10]. Efforts have been made to better
understand cognitive as well as emotional functioning in
long-term sick-listed individuals participating in occupa-
tional rehabilitation [4, 7, 11–13]. In Norway, the occupa-
tional rehabilitation programmes are designed to facilitate
return to work (RTW) through physical and psychological
empowerment and communication with the employer.
We have recently reported that focused and sustained
attention improved more than memory, executive function
and emotion recognition during occupational rehabilita-
tion [7]. The next step is to investigate whether baseline
scores and change scoresduring rehabilitation in cognitive
and emotional functioning, such as sustained attention and
emotion recognition, are associated with a higher probabil-
ity of RTW when the duration of sick leave before enrol-
ment in the programme is taken into account. If such asso-
ciations are present, the treatment success of occupational
rehabilitation may depend, at least partly, on improving
cognitive functioning [7] and cognitive beliefs related to
work through cognitive therapy [14].
The treatment components in occupational rehabilita-
tion programmes have a cognitive behavioural approach
and consist of an assessment of the work and health situ-
ation, physical activity, individual consultations, and
collaboration with the workplace [15, 16]. The cognitive
approach draws on principles and interventions from evi-
dence-based psychological treatments such as cognitive
therapy, acceptance and commitment therapy and motiva-
tional interviewing [17–19]. Psychological interventions
are the most common form of treatment for mental health
problems such as anxiety, depression, pain and stress [20],
which are prevalent in the patient groups being referred to
occupational rehabilitation [15, 21]. Psychological inter-
ventions have also shown to improve functional outcomes
such as physical functioning, coping with pain and fatigue
[20, 22] and RTW [18]. However, functional changes seem
to occur to a lesser extent compared to changes in cog-
nition and behaviour [20]. The effect of using a cogni-
tive approach, together with other treatment components,
has shown that work participation increased for patients
attending a long inpatient programme compared to asix
week outpatient programme with two weekly hours of
treatment [16], while a short inpatient programme, with
the same treatment components as the long, was also com-
pared to the outpatient programme but showed no superior
effects on work participation [17].
Given the documentation of cognitive impairments
in individuals on sick leave [5, 6, 23–26], the association
between cognitive functioning and RTW has not received
sufficient attention. Besides, other studies have also reported
that impaired cognitive and executive functioning have
been found to negatively affect occupational status [27–29].
The present study sought to overcome some of the meth-
odological limitations in previous studies investigating the
relationship between cognition and RTW. These studies did
not obtain register-based sick leave [30, 31], generally had
small sample sizes when investigating RTW [31], failed to
include emotional tests [25] and interventions were not pro-
vided in a systematic manner [5, 6]. In the current study,
objective cognitive and emotional tests were administered,
health-related benefits status up to one year after rehabilita-
tion, based on register data, were obtained, and all patients
participated in occupational rehabilitation. It was expected
that attention would be associated with the number of days
on health-related benefits in the year following rehabilita-
tion as specific improvements in functioning related to atten-
tion is likely to occur during the rehabilitation programmes.
Thus, the aim of the study was to investigate the association
between cognitive and emotional functioning and RTW,
within two groups of patients characterised by different
durations of sick leave before participation in occupational
rehabilitation.
Methods
Participants
In total, 317 individuals completing either inpatient or
outpatient occupational rehabilitation were recruited from
four clinics. Those that had received health-related benefits
for the full year before rehabilitation comprised the work
assessment allowance and disability pension (WAA) group
and thosereceiving health-related benefits for less than a
year comprised the sick leave (SL) group. This split was
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594 Journal of Occupational Rehabilitation (2021) 31:592–603
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decided upon because, in the Norwegian health-related ben-
efit system, there is a natural step from sick leave benefits
after one year, where 100% of wages are compensated, to
work assessment allowance benefits, where 66% of wages
are compensated. Eight participants did not receive health-
related benefits at the time of inclusion in the study but were
on full time (inpatient) or part time (outpatient) sick leave
during rehabilitation. The majority of patients had diagnoses
in the categoriesM, diseases of the musculoskeletal sys-
tem and connective tissue (53%), F, mental and behavioural
disorders (27%), or, G, disease of the nervous system (8%)
within ICD-10 [32]. Individuals with a history of head injury
or in the process of applying for full disability pension were
excluded from the study.
Study Design
This study was a multicentre prospective cohort study
involving four rehabilitation clinics. All participants were
followed for 12months with register data on the health-
related benefit status provided by the the Norwegian Labour
and Welfare Administration. The participants completed
cognitive and emotional tests and questionnaires on the top-
ics of work and health pre and post rehabilitation. That is, on
the first, second or third day after arrival at the rehabilitation
clinic (baseline), and to enable the calculation of change
scores the participants completed a second assessment one
to three days before the end of rehabilitation (change score).
All assessments took place in a quiet room at each clinic
and completion of the tests and questionnaires took approxi-
mately 1h and 30min at each assessment. Three research
assistants, who all took online training provided by Cam-
bridge Cognition in administering the Cambridge Neuropsy-
chological Test Automated Battery (CANTAB), and the first
author (TJ), having extensive training in neuropsychological
administration, were responsible for all data collection.
Intervention
The duration of the rehabilitation programmes varied
between the four clinics from three to 12weeks. The clinics
had similar treatment components which included physical
activity adjusted according to patients’ capacity applying
endurance and resistance exercises, cognitive behaviour
treatment components based on principles from cognitive
behaviour therapy focusing on work and health issues, and
when deemed appropriate, collaboration with the workplace,
the patients’ general practitioners, and the social security
office. The majority of patients made a written plan during
rehabilitation specifying the steps needed to RTW. Patients
were followed up individually and in groups by an interdis-
ciplinary team consisting of, but not limited to, a physician,
physiotherapist, sports pedagogue, psychologist, work con-
sultant/coach and nurse/psychiatric nurse.
Health‑Related Benefits System
In Norway, medically certified sick leave is granted for a
maximum of 52weeks with 100% compensation of which
the employer is responsible for economic compensation
during the first 16days, and after that, the Norwegian
Labourand Welfare Administration. If long term benefits
are required after 52weeks it is possible to apply for work
assessment allowance of which 66% of the wage is com-
pensated. This can be granted for a maximum of 3years
and during this period or after, disability pension may be
granted. All benefits can be granted in combination with
partial work participation and are commonly named sick
leave benefits, work assessment allowance benefits and dis-
ability benefits.
Materials
More details about the cognitive and emotional tests and the
work and healthrelated questionnaires are available from
Johansen etal. [7].
Tests onCognitive andEmotional Functions
A battery of eight cognitive and emotional tests from the
CANTAB was administered to cover a broad range of func-
tions. The following tests were administered: Simple Reac-
tion Time, Choice Reaction Time, Rapid Visual Information
Processing, Spatial Working Memory, Spatial Recognition
Memory, Stockings of Cambridge (a version of the Tower
of London task measuring executive planning), Intra-Extra
Dimensional Set Shift, Emotion Recognition Task. All tests
were administered on a touch-sensitive computer screen. The
administration of the tests was counterbalanced in two orders
so that each participant experienced each order once. This
was carried out to avoid the effects of order which could
potentially influence the performance.
Work andHealth Questionnaires
The following questionnaires and single-item questions were
administered: Work ability measured by one item compar-
ing current work ability with lifetime best [33]; Expectation
to RTW based on one item asking about when the partici-
pant expected to RTW [34]; Return to Work Self-Efficacy
(RTWSE–19) [35, 36]; Subjective Health Complaints (SHC)
inventory [37]; Theoretically Originated Measure of the
Cognitive Activation Theory of Stress (TOMCATS) [38];
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595Journal of Occupational Rehabilitation (2021) 31:592–603
1 3
Fear Avoidance Beliefs Questionnaire (FABQ) [39]; Hospi-
tal Anxiety and Depression Scale (HADS) [40].
Statistical Analysis
SPSS version 25 was used to analyse the data (SPSS Inc.,
2019). As described under participants, the sample was split
into two groups based on the individuals’ health-related ben-
efit status in the year before rehabilitation. The cognitive
and emotional distribution of baseline and change scores
were both graphically and descriptively examined in terms
of skewness and outliers. It was decided to remove extreme
latencies and error rates, which were considered subtle and
clearly distinguishable from the rest [41]. In total, six outli-
ers were removed. Between-group differences at baseline
were examined for demographic, work and health character-
istics and baseline performance in cognitive and emotional
functioning using independent samples t-tests. Gender,
education and expectation to RTW were subjected to chi-
square analysis. The two groups were separately subjected to
multiple linear regression analysis. The predictor variables
were the tests within thecognitive domains attention, mem-
ory, executive function, and emotion. The outcome variable
was measured using register data on health-related benefits
one year from the second assessment and was the accumu-
lated number of days on either sick leave, work assessment
allowance or disability pension. The number of days was
counted from the second assessment to take into account
the difference in duration of the rehabilitation programmes
between the four clinics. Graded benefits were converted to
full days. This ensured that all health-related benefit days
were counted from the same time point for all participants.
The analyses were split in two, first using baseline cogni-
tive and emotional scores as predictors and secondly using
the change scores in cognitive and emotional performance
as predictors. Prior to the multiple regression analysis, the
association between each of the cognitive and emotional pre-
dictors (baseline scores and change scores) and the depend-
ent variable was separately examined in the two groups by
bivariate linear regression analyses. Three multiple regres-
sion models were subsequently created.
Model 1: Predictors associated with the dependent
variable at a statistically significant level of p < 0.20 in
thebivariate analyses were further analysed in multiple
regression analyses controlling for age, gender and educa-
tion, separately for each cognitive and emotional domain
(see Tables3–6). Model 2: Same as model 1 but adding
the variables SHC pseudoneurology and SHC musculoskel-
etal pain. Model 3: Same as model 1 but adding the vari-
ables HADS anxiety and HADS depression. The independ-
ent variables included in the three models were separately
checked for multicollinearity in the WAA and SL group by
the variance inflation factor (VIF), where values > 5 indicate
multicollinearity [42]. Statistical significance was accepted
with a two-tailed p-value of ≤ 0.05.
Results
There were no group differences at baseline in age and edu-
cation, while the number of female participants was higher
in the WAA compared to the SL group (Table1). Partici-
pants in the SL group had expectations about faster RTW
compared to the WAA group. For the work variables, the SL
group compared to the WAA group reported higher work
ability and higher RTW self-efficacy for the factors “meeting
job demands” and “modifying job tasks”. For the health var-
iables, the SL group showed better coping and lower scores
on the SHC pseudoneurology, TOMCATS hopelessness,
FABQ for work and physical activity, and HADS depression.
Overall, the SL participants performed better on most
of the cognitive and emotional tests compared to the WAA
group, where significant group differences were found in
focused attention on the simple and choice reaction time
tests and in executive function on the stockings of Cam-
bridge task (Table2).
Sustained attention and executive function were associ-
ated with the number of days on health-related benefits in
the year after rehabilitation for the WAA group (Table3) and
working memory and executive function for the SL group
(Table4). Thus, these variables were separately included for
each group, as baseline predictors and change score predic-
tors, in the multiple regression analysis.
Cognitive Baseline andChange Score Predictors
andNumber ofDays onHealth‑Related Benefits
intheWork Assessment Allowance andDisability
Pension Group
Regression model 1 indicated that latency on the rapid
visual information processing test was significant both at
baseline (t (163) = − 2.574, p = 0.011) and as change score
(t (150) = − 2.527, p = 0.013) (Table5). Latency on therapid
visual information processing testremained significant in
models 2 and 3 after controlling for SHC pseudoneuroloy
and musculoskeletal pain and HADS anxiety and depression
respectively. In model 3, the change score for HADS depres-
sion was also significant (p = 0.019). For the domain execu-
tive function, the change score for HADS depression was
significant in model 3 (p = 0.044) (Table5). These results
did not change when the same analyses were run including
the outliers.
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596 Journal of Occupational Rehabilitation (2021) 31:592–603
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Cognitive Baseline andChange Score Predictors
andtheNumber ofDays onHealth‑Related Benefits
intheSick Leave Group
Errors on the spatial working memory test was signifi-
cant at baseline in regression model 1 (t (131) = 2.067,
p = 0.041) and 2 (t (122) = 2.533, p = 0.013) (Table6).
For the domain executive function, choice duration on the
stockings of Cambridge test at baseline was significant in
model 3 (t (121) = -2.051, p = 0.043). The results did not
change when the same analyses were run including the
outliers.
The VIF of the independent variables in the three mod-
els for the WAA and SL group were all below 2.0, indicat-
ing no multicollinearity.
Table 1 Demographic, work and health characteristics at baseline
SD standard deviation, Χ2 chi-square statistic, RTWSE-19 return-to-work self-efficacy, SHC subjective health complaints inventory, TOMCATS
theoretically originated measure of the cognitive activation theory of stress, FABQ fear avoidance beliefs questionnaire, HADS hospital anxiety
and depression scale
# Not all participants responded
Work assessment
allowance and disability
pension (n = 181)
Sick leave (n = 136) Statistics
Variable Mean SD Mean SD t (df)#p-value
Age 45.3 9.8 44.3 9.7 0.936 (315) 0.350
Number of days on health-related benefits one year after
rehabilitation 263.2 90.1 15.5 14.5 Not applicable
Work ability (0–10; 10 = best work ability) 3.0 2.1 4.8 2.2 − 6.997 (291) 0.000
RTWSE-19
Meeting job demands (1–70; 70 = highest SE) 28.4 17.3 40.7 17.8 − 5.670 (266) 0.000
Modifying job tasks (1–60; 60 = highest SE) 26.4 12.9 31.3 13.7 − 2.975 (263) 0.003
Communicating needs (1–60; 60 = highest SE) 34.9 14.8 38.2 14.2 − 1.826 (269) 0.069
SHC
Pseudoneurology (0–21; 21 = most complaints) 7.6 4.1 6.7 4.2 1.977 (289) 0.049
Musculoskeletal pain (0–24; 24 = most complaints) 10.3 4.9 9.6 5.2 1.103 (286) 0.271
TOMCATS
Coping (1–4; 1 = best coping)) 2.1 0.6 1.9 0.6 2.443 (285) 0.015
Hopelessness (1–12; 1 = most hopelessness) 8.8 1.9 9.4 1.9 − 2.737 (286) 0.007
Helplessness (1–12; 1 = most helplessness) 9.5 2.1 9.7 1.9 − 1.148 (284) 0.252
FABQ
Work (0–42; 0 = no fear avoidance) 21.9 11.4 18.8 11.2 2.258 (266) 0.025
Physical activity (0–24; 0 = no fear avoidance) 9.7 6.1 8.2 5.9 2.078 (270) 0.039
HADS
Anxiety (0–21; 0 = no anxiety) 8.6 4.1 7.9 4.6 1.265 (280) 0.207
Depression (0–21; 0 = no depression) 6.8 3.9 5.7 3.8 2.232 (280) 0.026
Variable n % n % Χ2 (df)#
Gender
Female 131 72 78 57 7.802 (1) 0.005
Male 50 28 58 43
Education
Elementary 23 13 16 12 0.426 (2) 0.808
Secondary 73 43 62 46
Higher 75 44 56 42
Expectation to return to work
Within 3 months 58 37 99 79 49.039 (1) 0.000
More than 3 months 97 63 26 21
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597Journal of Occupational Rehabilitation (2021) 31:592–603
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Discussion
The association between cognitive and emotional func-
tioning and RTW in employees on health-related ben-
efits is under-studied. We investigated this relationship in
work assessment allowance, disability pension and sick
leave groups participating in occupational rehabilitation.
Individuals in the WAA group had been on health-related
benefits for the whole year before entering the rehabilita-
tion programme, while the SL group had been on benefits
for less than a year. Our results indicated that baseline and
change scores from the start to the end of rehabilitation for
sustained attention in the WAA group and baseline scores
for working memory in the SL group were associated with
fewer number of health-related benefit days in the year after
rehabilitation. That is, better functional status in sustained
attention and working memory at baseline, and the greater
the improvement in sustained attention during rehabilitation,
the fewer days on health-related benefits are expected. The
association seemed strongest in the WAA group, as the effect
of sustained attention remained even after controlling sepa-
rately for SHC pseudoneuroloy and musculoskeletal pain
and HADS anxiety and depression. In the SL group, the
working memory baseline association remained when con-
trolling for SHC pseudoneuroloy and musculoskeletal pain.
In the WAA group, change scores for depression showed an
association with days on health-related benefits, and in the
SL group, baseline scores for executive function also showed
an association, albeit difficult to interpret. Therefore, in the
following, we focus on the most robust results and discuss
the cognitive aspects related to work for sustained attention
and working memory. The WAA and SL group differed in
cognitive performance at baseline, with the former scoring
worse in focused attention and executive function. On the
work variables, the WAA group reported lower work abil-
ity and RTW self-efficacy compared to the SL group. They
also had lower expectations about RTW, where the majority
reported that it would take more than three months to RTW.
The WAA group reported lower health status compared to
the SL group as they scored higher in SHC pseudoneurology
symptoms, hopelessness, fear avoidance for work and physi-
cal activity, depression and worse on coping.
In line with the present findings, a recent study reported
an association between subjective cognitive complaints
Table 2 Cognitive and
emotional performance at
baseline
Variables Work assessment
allowance and
disability pension
(n = 179)
Sick leave
(n = 135) Statistics
Mean SD Mean SD t (df) p-value
Attention
Simple reaction time
Reaction time (milliseconds) 264.8 73.1 248.5 39.8 2.334 (312) 0.020
Choice reaction time
Reaction time (milliseconds) 329.6 74.0 313.2 49.8 2.214 (310) 0.028
Rapid visual information processing
Latency (milliseconds) 411.9 89.2 406.1 84.7 0.574 (305) 0.567
Probability of hit 0.60 0.20 0.62 0.15 − 0.990 (306) 0.323
Memory
Spatial working memory
Total between errors 13.7 10.0 11.9 9.8 1.573 (313) 0.117
Spatial recognition memory
Response time (milliseconds) 2729.4 1032.7 2716.5 767.3 0.121 (311) 0.904
Total correct (%) 79.5 10.2 81.4 9.9 − 1.669 (313) 0.096
Executive function
Stockings of Cambridge
Choice duration (milliseconds) 4007.4 1752.5 4279.0 2210.7 − 1.208 (309) 0.228
Total correct 8.6 2.1 9.1 2.0 − 2.128 (313) 0.034
Intra-extra dimensional set shift
Trials extradimensional shift stage 10.1 9.3 8.5 8.8 1.502 (312) 0.134
Emotion recognition
Emotion recognition task
Total correct (%) 59.0 10.1 58.2 10.5 0.646 (312) 0.519
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598 Journal of Occupational Rehabilitation (2021) 31:592–603
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Table 3 Bivariate linear regression analysis for the work assessment allowance and disability pension group using baseline and change scores
from cognitive and emotional tests to examine the association with number of days on health-related benefits up to oneyear after rehabilitation
Bold values denote statistical significance at the p<0.20 level
SRT simple reaction time, CRT choice reaction time, RVP rapid visual information processing, SWM spatial working memory, SRM spatial rec-
ognition memory, SOC stockings of Cambridge, EDS intra-extra dimensional set shift, ERT emotion recognition task
Work assessment allowance and disability pension (n = 165)
Baseline predictors Change score predictors
β, Beta 95% CI p β, Beta 95% CI p
Attention
SRT reaction time (s) 69.737 − 112.896/252.370 0.452 − 100.287 − 419.546/218.973 0.536
CRT reaction time (s − 15.602 − 197.519/166.615 0.866 99.511 − 123.504/322.526 0.379
RVP latency (s) − 170.972 − 321.472/− 20.471 0.026 − 195.375 − 357.519/− 33.231 0.019
RVP probability of hits − 13.038 − 82.052/55.976 0.710 − 8.523 − 112.246/95.201 0.871
Memory
SWM total errors − 0.804 − 2.127/.518 0.232 − 0.450 − 2.211/1.311 0.614
SRM latency (s) − 8.311 − 21.119/.4.496 0.202 6.629 − 9.582/22.839 0.421
SRM total correct (%) 0.357 − .943/1.658 0.589 0.149 − 1.067/1.366 0.809
Executive function
SOC choice duration (s) 3.969 − 3.644/11.581 0.305 7.970 − 0.664/16.605 0.070
SOC total correct 1.080 − 5.259/7.419 0.737 − 2.976 − 10.360/4.408 0.427
EDS trials − 0.454 − 1.881/.973 0.531 − 0.082 − 1.835/1.672 0.927
Emotion recognition
ERT total correct (%) − 0.483 − 1.792/0.827 0.468 − 0.545 − 2.593/1.503 0.600
Table 4 Bivariate linear
regression analysis for the sick
leave group using baseline and
change scores from cognitive
and emotional tests to examine
the association with number
of days on health-related
benefits up to oneyear after
rehabilitation
Bold values denote statistical significance at the p<0.20 level
SRT simple reaction time, CRT choice reaction time, RVP rapid visual information processing, SWM spatial
working memory, SRM spatial recognition memory, SOC stockings of Cambridge, EDS intra-extra dimen-
sional set shift, ERT emotion recognition task
Sick leave (n = 132)
Baseline predictors Change score predictors
β, Beta 95% CI p β, Beta 95% CI p
Attention
SRT reaction time (s) − 24.431 − 86.837/37.975 0.440 − 26.692 − 96.540/43.155 0.451
CRT reaction time (s) − 1.482 − 51.372/48.408 0.953 − 20.815 − 89.295/47.665 0.548
RVP latency (s) − 6.972 − 36.792/22.848 0.644 − 14.310 − 45.089/16.470 0.359
RVP probability of hits − 5.042 − 21.879/11.075 0.518 6.479 − 12.030/25.527 0.478
Memory
SWM total errors 0.290 0.040/0.540 0.023 0.234 − 0.125/0.593 0.200
SRM latency (s) − 0.560 − 3.849/2.729 0.737 0.777 − 2.962/4.517 0.681
SRM total correct (%) − 0.133 − 0.385/0.118 0.296 0.014 − 0.217/0.245 0.903
Executive function
SOC choice duration (s) − 0.903 − 2.028/.222 0.115 − 1.069 − 2.461/.323 0.131
SOC total correct − 0.754 − .2.004/0.497 0.235 0.194 − 1.271/1.660 0.793
EDS trials 0.030 − 0.255/0.314 0.837 0.094 − 0.208/0.396 0.538
Emotion recognition
ERT total correct (%) − 0.087 − 0.326/0.152 0.474 0.035 − 0.398/0.469 0.874
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599Journal of Occupational Rehabilitation (2021) 31:592–603
1 3
and sickness absence in a specific occupational group [43].
While the current study used objective measures of cog-
nition through computerised testing, it may be plausible
that both objective and subjective assessments of cognitive
impairments could be associated with sickness absence and
RTW. Studies using sick leave status based on self-report
have either not investigated the association between objec-
tive assessments of cognition and RTW [25, 44] or failed
to find an association despite substantial improvement in
memory and attention and an increase in RTW two years
after a workplace intervention [30, 31]. Official data from
registries, as collected in the present study, is often preferred
due to the longitudinal and validated nature of data, which is
often hard to obtain through self-report [45].
Several potential mechanisms may explain an associa-
tion between sustained attention, working memory and fewer
days on health-related benefits. While supposed to be capac-
ity limited, sustained attention is needed to keep us continu-
ously focused for more than a few seconds while ignoring
competing or distracting information. Working memory rep-
resents a cognitive function that retains information over the
short term and enables us to act on that information. As both
functions seem to have capacity limitations and depend on
each other in selecting and storing information, our atten-
tional system must select the most relevant information to
be stored in working memory [46, for a detailed review].
Working memory and attention are also dependent on the
control of the executive functions inhibition, updating, and
shifting of attention [47]. These are key factors in attention
and executive control [48, 49]. We know that engaging in
specific goal-related and repetitive tasks are important in any
work situation [50], and these tasks require working memory
to be constantly updated throughout the day with the support
of sustained attention. This is based on the argument that
being in work helps maintain both attention and working
memory to operate efficiently, because work can be seen as a
training arena for cognitive functions [2]. This gives support
to the hypothesis of «use it or lose it» [2, 51]. Our ability
to stay focused is more likely to increase if the demands at
work on sustained attention and working memory are high
[3, 50] and when we perform complex tasks either at home
or in work [2]. Therefore, occupational rehabilitation [7, 13],
physical activity [52], better emotion regulation [9, 10] or
attention bias modification training [53] also improve cogni-
tive and emotional functions and seem likely to pave the way
for better performances at work.
Table 5 Multiple linear regression analysis for the work assessment
allowance and disability pension group using significant baseline and
change score predictors together with age, gender and education to
examine the association with number of days on health-related ben-
efits up to one year after rehabilitation
Bold values denote statistical significance at the p<0.05 level
Work assessment allowance and disability pension (n = 165)
Baseline predictors Change score predictors
β, Beta 95% CI p β, Beta 95% CI p
Attention model 1 Attention
RVP latency (s) − 202.936 − 358.653/− 47.219 0.011 − 205.591 − 366.377/− 44.806 0.013
Attention and SHC model 2
RVP latency (s) − 184.489 − 350.012/− 18.966 0.029 − 207.482 − 388.808/− 26.157 0.025
SHC pseudoneurology − 0.727 − 4.550/3.097 0.708 − 0.892 − 6.603/4.819 0.758
SHC musculoskeletal pain − 2.067 − 5.379/1.245 0.219 − 2.374 − 7.257/2.508 0.337
Attention and HADS model 3
RVP latency (s) − 206.905 − 371.773/− 42.036 0.014 − 240.993 − 413.977/− 68.009 0.007
HADS anxiety − 1.236 − 5.818/3.347 0.595 0.342 − 5.841/6.525 0.913
HADS depression 0.277 − 4.435/4.990 0.116 − 6.906 − 12.658/− 1.154 0.019
Executive function model 1
SOC choice duration (s) 7.419 − 1.195/16.032 0.091
Executive function and SHC model 2
SOC choice duration (s) 6.680 − 2.436/15.795 0.149
SHC pseudoneurology − 0.156 − 5.843/5.531 0.957
SHC musculoskeletal pain − 4.015 − 8.730/0.700 0.094
Executive function and HADS model 3
SOC choice duration (s) 6.325 − 2.835/15.485 0.174
HADS anxiety 2.069 − 4.151/8.288 0.512
HADS depression − 5.814 − 11.481/− 0.148 0.044
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600 Journal of Occupational Rehabilitation (2021) 31:592–603
1 3
Clinical Implications
The current study adds further knowledge about occupa-
tional rehabilitation and presents an association between
cognition and RTW in the WAA and SL group. Previous
findings from our group have demonstrated that focused and
sustained attention and working memory improve more than
executive function and emotion recognition during rehabili-
tation [7, 13]. Although it cannot be elucidated at this stage
which interventions in the rehabilitation programme improve
attention and working memory, it can be claimed that the
combined effects of all treatment components [54], such as
physical activity, cognitive approach, collaboration with the
workplace and following an RTW plan, improve certain cog-
nitive functions more than others.
The present findings emphasise the importance of assess-
ing cognitive functioning in different patient groups based
on the length of sick leave. If such assessments are not con-
ducted, clinicians are left with only self-reported assess-
ments of work and health and may fail to meet the goal of a
holistic [55] and comprehensive assessment [4]. The impli-
cations for clinical practice revolve around the issue of iden-
tifying those individuals displaying cognitive impairments
at baseline while at the same time investigating both their
benefit and work status. This adds to the debate about when
different work-related interventions could be applied and for
whom [56]. It could be argued that WAA individuals may
require more specific interventions related to the cognitive
function sustained attention, while SL individuals may ben-
efit from working memory interventions. This postulation is
worth following up as sick leave is associated with a dete-
rioration in health and quality of life [57, 58], but also the
fact that improvements in attention are associated with better
work ability and a reduction in subjective health complaints
[7]. The treatment success of occupational rehabilitation
may depend, at least partly, on improving cognitive function-
ing, specifically sustained attention, to increase the chances
of RTW for individuals having been away from work for
more than a year [7, 14].
Specific cognitive training may improve certain cogni-
tive functions, and this has been carried out for chronic
pain [59], depression, [53] and occupational rehabilitation
patients [12]. However, these training methods have to be
carefully selected bearing in mind that working memory
training does not seem transferable to cognitive abilities
required at work or in everyday life [60]. Currently, it seems
more fruitful to develop training programmes that show an
Table 6 Multiple linear regression analysis for the sick leave group using significant baseline and change score predictors together with age, gen-
der and education to examine the association with number of days on health-related benefits up to one year after rehabilitation
Bold values denote statistical significance at the p<0.05 level
Sick leave (n = 132)
Baseline predictors Change score predictors
β, Beta 95% CI p β, Beta 95% CI p
Memory
SWM total errors 0.288 0.012/0.564 0.041 0.238 − 0.125/0.601 0.197
Memory and SHC Model 2
SWM total errors 0.384 0.084/0.684 0.013 0.293 − 0.147/0.734 0.189
SHC pseudoneurology 0.418 − 0.275/1.111 0.235 − 0.126 − 1.289/1.037 0.830
SHC musculoskeletal pain 0.087 − 0.488/0.661 0.766 0.011 − 0.896/0.918 0.981
Memory and HADS Model 3
SWM total errors 0.286 − 0.005/0.576 0.054 0.252 − 0.158/0.663 0.226
HADS anxiety 0.612 − 0.200/1.424 0.138 − 0.485 − 1.695/0.724 0.428
HADS depression 0.073 − 0.903/1.048 0.883 0.036 − 1.084/1.157 0.949
Executive function model 1
SOC choice duration (s) − 1.105 − 2.277/0.068 0.065 − 1.191 − 2.608/0.226 0.099
Executive function and SHC Model 2
SOC choice duration (s) − 1.215 − 2.436/0.006 0.051 − 1.417 − 3.089/0.255 0.096
SHC pseudoneurology 0.339 − 0.360/1.037 0.339 − 0.247 − 1.414/0.919 0.675
SHC musculoskeletal pain 0.210 − 0.380/0.800 0.483 − 0.069 − 0.970/0.832 0.879
Executive function and HADS Model 3
SOC choice duration (s) − 1.261 − 2.479/− 0.043 0.043 − 1.357 − 2.956/0.242 0.095
HADS anxiety 0.543 − 0.273/1.359 0.190 − 0.580 − 1.781/0.621 0.340
HADS depression 0.098 − 0.881/1.077 0.843 0.131 − .994/1.256 0.817
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601Journal of Occupational Rehabilitation (2021) 31:592–603
1 3
effect on work-related factors [61] to improve work-related
working memory and sustained attention. The promising
attention bias modification task [53] could be adapted to
work settings and is a fruitful avenue to pursue. Such train-
ing, in combination with the cognitive approach, physical
activity and collaboration with the workplace, may be worth
piloting in collaboration between researchers and clinicians.
These suggestions may result in occupational rehabilitation
programmes becoming more individually tailored accord-
ing to benefit status, while still maintaining the group-based
approach in most interventions.
Study Limitations
Recruiting patients from four different clinics could be a
potential confounder in the study. Despite that all patients
received the same treatment components in occupational
rehabilitation, differences in procedures, intervention dosage
and alliances with the patients at the four clinics could not be
accounted for. Only the first item in the work ability index
(current work ability compared with the lifetime best) was
used as opposed to the entire measure of seven items [62],
and we cannot claim that we measured the whole concept of
work ability. The rationale for using one item, as opposed to
the entire measure, was due to its predictive value on RTW
[33] and the fact thatnot all items were applicable to this
patient group. Another limitation of our study is that the
findings cannot explain which treatment components in the
rehabilitation programme positively affected sustained atten-
tion and working memory which were associated with fewer
health-related benefit days in the year after rehabilitation. It
can only be assumed that the combination of all interven-
tions contributed to the association between cognition and
RT W.
Conclusion
This study has demonstrated that better sustained attention
and working memory are associated with fewer health-
related benefit days in the year following rehabilitation.
These results showed that baseline and change scores in cog-
nitive performance during occupational rehabilitation could
be an indicator of future days on health-related benefits after
rehabilitation. Sustained attention and working memory are
interlinked and important functions to keep intact to enable
performances in most occupations. The quality of occupa-
tional rehabilitation programmes could be enhanced if work-
related sustained attention and working memory interven-
tions are respectively targeted in individuals on sick leave or
work assessment allowance and disability pension.
Acknowledgements We thank all participants who volunteered to
participate in this study. We are particularly grateful to Erik Storli at
Catosenteret Rehabilitation Center and Ann Marit Flokenes at Val-
nesord Health Sports Centre for the data collection as well as Heidi
Bjorå Arset and Lena Klasson, Idrettens Helsesenter, Oslo, Norway for
the continuous support. Thank you also to psychologist Magnus Lia,
Skogli Health and Rehabilitation Center, Lillehammer, Norway, for
fruitful discussions about cognition, mental health and return to work.
Funding The funding was provided by the Norwegian Labour and
Welfare Administration and the Northern Norway Regional Health
Authority (grant number SFP1173-14).
Compliance with Ethical Standards
Conflict of interest The authors declare that they have no conflict of
interest.
Ethical Approval The study was approved by the South-East Regional
Committee for Medical and Health Research Ethics, Norway
(2013/1559). All procedures followed were in accordance with the ethi-
cal standards of the responsible committee on human experimentation
(institutional and national) and with the Helsinki Declaration of 1975,
as revised in 2000. Informed consent was obtained from all patients
before being included in the study.
Open Access This article is licensed under a Creative Commons Attri-
bution 4.0 International License, which permits use, sharing, adapta-
tion, distribution and reproduction in any medium or format, as long
as you give appropriate credit to the original author(s) and the source,
provide a link to the Creative Commons licence, and indicate if changes
were made. The images or other third party material in this article are
included in the article’s Creative Commons licence, unless indicated
otherwise in a credit line to the material. If material is not included in
the article’s Creative Commons licence and your intended use is not
permitted by statutory regulation or exceeds the permitted use, you will
need to obtain permission directly from the copyright holder. To view a
copy of this licence, visit http://creat iveco mmons .org/licen ses/by/4.0/.
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