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fpsyg-10-02233 October 8, 2019 Time: 11:30 # 1
ORIGINAL RESEARCH
published: 10 October 2019
doi: 10.3389/fpsyg.2019.02233
Edited by:
Federica Scarpina,
Italian Auxological Institute (IRCCS),
Italy
Reviewed by:
Remko Soer,
University Medical Center Groningen,
Netherlands
Paula Goolkasian,
The University of North Carolina
at Charlotte, United States
Sudha Perilakalathil Pandalai,
Centers for Disease Control
and Prevention (CDC), United States
*Correspondence:
Thomas Johansen
thomas.johansen@arbeidoghelse.no
Specialty section:
This article was submitted to
Psychology for Clinical Settings,
a section of the journal
Frontiers in Psychology
Received: 22 May 2019
Accepted: 17 September 2019
Published: 10 October 2019
Citation:
Johansen T, Jensen C,
Eriksen HR, Lyby PS, Dittrich WH,
Holsen IN, Jakobsen H and
Øyeflaten I (2019) Occupational
Rehabilitation Is Associated With
Improvements in Cognitive
Functioning. Front. Psychol. 10:2233.
doi: 10.3389/fpsyg.2019.02233
Occupational Rehabilitation Is
Associated With Improvements in
Cognitive Functioning
Thomas Johansen1*, Chris Jensen1,2 , Hege R. Eriksen3, Peter S. Lyby4,
Winand H. Dittrich5, Inge N. Holsen6, Hanne Jakobsen7and Irene Øyeflaten1,8
1National Advisory Unit on Occupational Rehabilitation, Rauland, Norway, 2Department of Public Health and Nursing,
Norwegian University of Science and Technology, Trondheim, Norway, 3Department of Sport, Food and Natural Sciences,
Western Norway University of Applied Sciences, Bergen, Norway, 4CatoSenteret Rehabilitation Center, Son, Norway, 5FOM
Hochschule, KCI Competence Center for Behavioral Economics, Frankfurt, Germany, 6Red Cross Haugland Rehabilitation
Center, Flekke, Norway, 7Valnesfjord Health Sports Center, Fauske, Norway, 8Norwegian Research Centre, Bergen, Norway
Introduction: Occupational rehabilitation may be offered to workers on long-term sick
leave who often report problems with cognitive functioning, anxiety, depression, pain,
and reduced work ability. The empirical knowledge is sparce on how occupational
rehabilitation may influence cognitive and emotional functioning and patients have not
previously been subjected to comprehensive objective testing. The main aim of this
study was to assess possible changes in cognitive and emotional functioning such
as memory, attention, executive function, and emotion recognition among patients in
occupational rehabilitation.
Methods: A large sample of 280 sick-listed workers referred to inpatient and outpatient
occupational rehabilitation was recruited. The rehabilitation programs had a mean
duration of 28 days and comprised physical activity, cognitive behavior treatment
components and collaboration with the workplace. A pre–post design was applied to
investigate possible changes in cognitive and emotional functioning (primary outcomes)
and work and health measures (secondary outcomes), comparing the rehabilitation
group with a control group of 70 healthy workers. Individuals in the control group
were tested at random time points with an approximately 28 day interval between pre-
and post-test, thus coinciding with the duration of rehabilitation. Repeated measures
analysis of variance was used for the main analyses.
Results: Compared to the control group, the rehabilitation group had greater gains from
pre- to post-test in focused and sustained attention, as well as greater improvements
in work ability and reduction in subjective health complaints (SHC), helplessness, pain,
pain related to work, anxiety, and depression. In the rehabilitation group, exploratory
correlational analysis indicated that improvements in focused and sustained attention
were associated with improvements in return-to-work self-efficacy, work ability as well
as a reduction in SHC.
Conclusion: The sick-listed workers improved in focused and sustained attention and
work and health measures after participating in occupational rehabilitation. This study
is one of the first to systematically investigate changes in cognitive and emotional
functioning during occupational rehabilitation. Clinical practice should benefit from
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Johansen et al. Occupational Rehabilitation and Cognitive Functioning
increased knowledge about all cognitive functions and should be specifically aware
of the improvements in focused and sustained attention, while memory, executive
function and emotion recognition remained unchanged. The results can be used as
a motivation to tailor specific interventions to gain further improvements in all cognitive
and emotional functions.
Keywords: occupational rehabilitation, cognition, attention, work ability, sick leave
INTRODUCTION
Workers on long-term sick leave referred to occupational
rehabilitation report memory and attention problems, symptoms
of anxiety, depression and pain, and reduced work ability
(Aasvik et al., 2015;Johansen et al., 2016;Aasdahl et al.,
2017). These factors are assumed to negatively affect the
ability to concentrate on work tasks, process information
and shift attention when required in working life. On the
other hand, well-preserved cognitive functioning improves
flexibility and the capacity to regulate our thoughts, emotions
and behavior (Dajani and Uddin, 2015). Understanding how
occupational rehabilitation affects cognitive functioning,
work ability and health related factors is important because
it can be assumed that improvements in these measures
contribute positively to return to work (RTW) (Eskildsen
et al., 2016;Johansen et al., 2016). However, the investigation
of changes in cognitive functioning during occupational
rehabilitation has so far been an understudied topic relying
only on preliminary evidence (Johansen et al., 2016;Aasvik
et al., 2017). This is a highly relevant topic because anxiety,
depression and pain are associated with impairments in cognitive
functioning (Yiend, 2010;Landrø et al., 2013;Snyder et al.,
2015) and because maintaining good cognitive processing
is an important premise for adaptive emotion regulation
(Ochsner and Gross, 2005). If cognitive impairments in
attention, memory and executive function are present in
workers on long-term sick leave (Eskildsen et al., 2015, 2016;
Johansen et al., 2016) it is relevant to assess if improvements in
cognitive functioning occur during occupational rehabilitation
and whether these improvements are associated with
work ability, anxiety, depression and subjective health
complaints (SHC).
In Norway, the rehabilitation programs often consist of work-
related, physical and cognitive behavior treatment components
(Øyeflaten et al., 2016). These components include adapted
physical activity as well as a cognitive approach based
on principles from cognitive behavior therapy, acceptance
and commitment therapy, psychoeducation and motivational
interviewing. The positive effects of physical activity on
cognitive functioning (Ratey and Loehr, 2011), anxiety and
depression (Hovland et al., 2013;Kvam et al., 2016) are well
documented. Collaboration with the employer, the general
practitioner and the social security offices is also a key component
(Fimland et al., 2014;National Advisory Unit on Occupational
Rehabilitation, 2017). During rehabilitation, there is a strong
emphasis on improving patients’ work ability, self-efficacy, and
RTW expectation.
Similar patient populations to those being referred to
occupational rehabilitation have been subjected to cognitive
testing. Eskildsen et al. (2015, 2016) retested a group of patients
on sick leave due to work-related stress 1 year after being
referred to occupational and psychological therapy. It was
found that patients improved more in prospective memory
and processing speed compared to a healthy control group.
In two separate studies, conducting pre-test and 1 year follow
up assessment, it was reported that women sick-listed for
work-related stress and depression, and receiving 10 weeks
of cognitive group therapy addressing work-related challenges,
improved in depressive symptoms as well as in cognitive
functioning compared to a control group (Rydmark et al.,
2006;Wahlberg et al., 2009). On a general note, it can be
assumed that impairments in attention, memory and executive
function might contribute to symptoms of anxiety, depression
and pain, however, it could also be argued that symptoms of
anxiety, depression and pain are associated with impairments
in cognitive functioning. There seems to be a debate about
the direction of influence (Legrain et al., 2009;Yiend, 2010;
Snyder et al., 2015). The two positions are not mutually
exclusive and may differ depending on individual differences,
health status and type of cognitive or executive impairment
(Snyder et al., 2015).
Following previous studies reporting on changes in cognitive
functioning (Eskildsen et al., 2015, 2016;Johansen et al.,
2016;Aasvik et al., 2017), it was important in the current
study to analyse a broad spectrum of functions such as
attention, memory, executive function and emotion using
validated and computerized cognitive and emotional tests. In
addition, the recognition of facial expressions was measured
as cognitive and emotional processing is strongly related
(Yiend, 2010;Pessoa, 2013). For example, individuals reporting
anxiety seem to have an attentional bias toward fear, while
depression is related to a bias toward sadness (Yiend, 2010).
The aim of the current study was to compare possible
changes in cognitive and emotional functioning and work
and health measures between sick-listed workers and healthy
workers, and to explore the degree of association between
changes in cognitive and emotional functioning and work and
health measures.
MATERIALS AND METHODS
Participants
A total of 280 patients who were either on partial or full
sick leave, volunteered to take part in the study. 187
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Johansen et al. Occupational Rehabilitation and Cognitive Functioning
participated in an inpatient occupational rehabilitation
program and 93 in an outpatient program. Seventy
workers in the control group who volunteered to take
part were all working full time and had no sick leave
during the testing period. They were recruited from the
wider community and employees from three rehabilitation
clinics and included a wide selection of different blue- and
white-collar workers. The two groups were matched for
age, gender and number of days between pre- and post-
test. 80% of the patients had an ICD-10 diagnosis either
in the categories F, mental and behavioral disorders or
M, diseases of the musculoskeletal system and connective
tissue. Exclusion criteria for the rehabilitation and control
group were a history of head injury or having applied for
disability pension.
Design
This study had a non-randomized pre–post measures controlled
design. All participants in the study were assessed with cognitive
and emotional tests and work and health questionnaires.
The study was designed to analyse differences between-
subjects (intervention vs. control group) and within-subjects
(cognitive and emotional tests and questionnaires at pre-
and post-test).
Occupational Rehabilitation
The patients were referred to occupational rehabilitation
by general practitioners or social security offices. The main
aim of rehabilitation was RTW and the programs lasted
between three and 12 weeks. The patients were followed
up by an interdisciplinary team including at least four
of the following professionals: physician, physiotherapist,
psychologist, work consultant, coach, nurse/psychiatric
nurse, and sports pedagogue. Assessment of work ability,
physical fitness and current work and health situation
was carried out to tailor rehabilitation efforts. Key
interventions were adapted physical activity, cognitive
behavior treatment components and collaboration with the
workplace, general practitioner and social security office.
Adapted physical activity included supervised exercise
individually adjusted to needs and physical capacity.
Exercise types included ergometer cycling, outdoor walking,
resistance exercise, and enduring exercise. The cognitive
behavior treatment components focusing on work and
health included principles based on cognitive behavior
therapy and psychoeducation for anxiety, depression, pain;
adapted physical activity and the effects on body and
mind; behavioral activation relevant for depression; skills
training in problem solving; mindfulness; pain education; fear
avoidance beliefs and exposure principles at work and during
physical activity.
Norwegian Sickness Insurance
Individuals who are unable to work due to illness or injury
are entitled to sick leave benefits from the Norwegian
sickness insurance scheme for a maximum of 52 weeks.
For the first 16 days, full compensation is provided by the
employer and thereafter by the tax-paid national insurance
system. If the individual is still unable to resume partial
or full-time work after 1 year, a work ability assessment
will determine if further benefits for up to 3 years may
be granted. The benefits after the first year are normally
two thirds of the wages the individual had prior to
sick leave. The benefits can be combined with partial
work resumption.
Outcome Measures
The primary outcome measures were performance changes
from pre- to post-test on the cognitive and emotional
tests targeting attention, memory, executive function and
emotion. The secondary outcome measures were changes from
pre- to post-test on the questionnaires targeting work and
health characteristics.
Materials
Cognitive and Emotional Tests (Primary Outcomes)
Eight validated tests from the Cambridge Neuropsychological
Test Automated Battery (CANTAB) were used to assess
cognitive and emotional functioning on a touch screen
(Table 1). The order of the tests was fully counterbalanced
across participants at each testing session and within
each group. All participants were introduced to the touch
screen by way of a motor screening task performed prior
to testing both at pre- and post-test. This screening was
performed to familiarize the participants with the touch screen
and reduce as much as possible any initial apprehension
prior to testing.
Work and Health Questionnaires (Secondary
Outcomes)
The participants in the control group completed all
questionnaires except Return to Work Self-Efficacy (RTWSE-
19 items; Shaw et al., 2011;Nøttingnes et al., 2019). Work
ability was assessed using one item from the work ability
index comparing current work ability with the lifetime best
(Ahlstrøm et al., 2010); RTWSE-19 (Shaw et al., 2011) assessed
the participants’ belief in their own ability to resume normal
work tasks according to the following factors: meeting job
demands, modify job tasks and communicating needs to
others; The importance of performing well on the cognitive
tests was assessed on a five-point rating scale using a newly
developed item by the project group (“To what degree is it
important for you to perform well on the cognitive tests?”);
Two subscales from the SHC inventory (Eriksen et al.,
1999) assessed participants’ health complaints during the
last 30 days according to pseudoneurology (extra heartbeats,
heat sensation, sleep problems, tiredness, dizziness, anxiety,
sad/depression) and musculoskeletal pain (headache, neck
pain, upper back pain, low back pain, arm pain, shoulder
pain, migraine, leg pain during physical activity); Theoretically
Originated Measure of the Cognitive Activation Theory of
Stress (TOMCATS; Odeen et al., 2012) assessed positive,
negative and no response outcome expectancies i.e., one item
for coping, three items for hopelessness and three items for
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TABLE 1 | Description of computerized cognitive and emotional tests.
Test Description Outcome variables Cognitive
function
Simple reaction time Participants must press as fast as they can a button on a
press pad when they see a white square in the middle of a
computer screen. The task consists of one block of 24
practice trials and two assessment blocks each with 50
trials
Mean correct reaction time Focused attention
Choice reaction time Participants must press as fast as they can the left hand
button on a press pad when they see an arrow pointing to
the left and press the right hand button when an arrow is
pointing to the right. The task consists of a block of 24
practice trials and two assessment blocks each with 50
trials
Mean correct reaction time Selective attention
Rapid visual information processing Participants have to detect and respond by pressing a
button on a press pad to target sequences 3-5-7, 2-4-6,
and 4-6-8, from digits between 2 and 9 appearing one at a
time in a pseudo-random order lasting 4 min
Mean correct response latency,
probability of hits
Sustained attention
Spatial working memory The participants must search for blue tokens hidden inside
boxes and the trial is completed when a token has been
found in each box. Four practice trials are given each with
three boxes and the assessed trials include two blocks of
four, six, and eight boxes
Mean number of between errors
(revisiting boxes which have already
been found to contain a token)
Visuospatial
working memory
Spatial recognition memory In the presentation phase five white squares appear one at
a time in different locations on a computer screen and then
in the assessed stage the participant is presented with two
squares in different locations and must touch the square
that was in the correct location in the presentation phase.
The task consists of four blocks each with five new
locations
Mean correct response latency, mean
percentage correct
Visuospatial
recognition memory
and short term
memory
Stockings of Cambridge Participants are asked to copy a predetermined
arrangement of balls. Only one ball can be moved at a time
to an empty pocket or on top of another ball. The aim is to
use the minimum number of moves required to solve each
problem (2 ×2 move, 2 ×3 move, 4 ×4 move and 4 ×5
move)
Mean choice duration, mean number of
problems completed in the minimum
number of moves (maximum 12)
Executive spatial
planning and spatial
working memory
Intra-extra dimensional set shift Participants are shown two stimuli and must touch the
correct one taking into account feedback provided on each
trial and can thus learn which one is correct. The task
consists of nine stages and to pass each stage a criterion
of six consecutive correct responses is required
Mean number of trials to reach criterion
at the extradimensional shift stage
(stage 8; attentional shifting away from
a previously relevant stimulus
dimension)
Attentional shifting
and flexibility
Emotion recognition task A face showing either happiness, sadness, anger, fear,
disgust or surprise is shown and participants must touch
the emotion they believe is correct by selecting one of six
written emotions on the screen directly after each face
disappear. Each facial emotion has 15 different levels from
hardly any emotional expression to a clear expression and
they see all emotions once. The task consists of one block
of 90 faces
Mean percentage correct Emotion and social
cognition
helplessness; the Fear Avoidance Beliefs Questionnaire (FABQ;
Waddell et al., 1993) measured avoidance beliefs for physical
activity (four items) and work (seven items), on separate
scales; Items seven and eight from the short form 36 health
survey (SF-36; Ware and Sherbourne, 1992) assessed pain and
pain related to work respectively; the Hospital Anxiety and
Depression Scale (HADS; Zigmond and Snaith, 1983) covered
seven items for symptoms of anxiety and seven items for
symptoms of depression.
All measures described above are validated except the single
items pain and pain related to work from SF-36 and “to
what degree is it important for you to perform well on the
cognitive tests?”
Statistical Analyses
Data were analyzed using SPSS version 25 (SPSS Inc., 2019).
The categorical variables gender and education were compared
between the intervention and control group using chi-square
analysis and the variable age was subjected to independent
samples t-test. Demographic, work and health measures at
baseline were analyzed with independent samples t-tests. To
investigate changes in cognitive and emotional functioning and
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Johansen et al. Occupational Rehabilitation and Cognitive Functioning
work and health measures from pre- to post-test a repeated-
measures analysis of variance was conducted using a 2 ×2
mixed design with group (intervention, control) as a between-
subjects factor and time (pre-test, post-test) as a within-subjects
factor. The interaction effects were tested using the multivariate
criterion of Wilks’ lambda for all Ftests to overcome the
assumptions of univariate testing. Education was included as
a covariate because it differed between the two groups and
estimated marginal means are indicated. Significance threshold
was p<0.05. It was not adjusted for the cognitive tests
since they are assumed to target separate cognitive processes
having different ecological validity (Levine et al., 2011). If
assumptions of homogeneity of variance and normality were
not met, logarithmic (Base 10) transformations were performed
(Tabachnick and Fidell, 2001). When data transformation
procedures were undertaken it was decided to display the
means and standard deviations for the untransformed scores
for standardization and clarity purposes to enable comparison
of performance data across different studies while the statistics
for transformed scores were reported in the text and tables.
Consequently, a logarithmic (Base 10) transformation was used
on the following task measures in both groups; simple and choice
reaction time, response latency for rapid visual information
processing, response latency for spatial recognition memory and
choice duration for stockings of Cambridge to reduce skewness
and kurtosis in the distributions. To explore whether changes
in cognitive, emotional, work and health measures correlated,
the difference in the significant outcome variables between pre-
and post-test was calculated in the intervention group only.
The effect size measure for partial eta-squared (ANOVA) was
interpreted according to the following values (Cohen, 1988):
below 0.06 small, 0.06–0.14 moderate and above 0.14 large. For
Pearson product-moment correlational coefficients the following
values were used (Cohen, 1988): 0.10 small, 0.30 moderate,
and 0.50 large.
A priori power calculations for Ftests using G∗Power (Faul
et al., 2007) were performed to check which sample size was
required to detect differences between groups in scores on
cognitive and emotional tests and work and health questionnaires
using repeated-measures analysis of variance. Results indicated
that with a power of 0.90, moderate effect size set at 0.10 and a
two-tailed alpha level of 0.05, the total number of participants
needed would be 58 in each group.
RESULTS
For the total sample, floor and ceiling effects on the cognitive
and emotional measures for correct responses were considered
low, ranging from 0.3 to 4.6%, except for between search errors
in spatial working memory, where floor effects were 12% both at
pre- and post-test, and number of problems solved in stockings of
Cambridge, where ceiling effects were 9.7% at pre-test and 15.1%
at post-test. On the reaction time variables for simple reaction
time and choice reaction time, there were no false alarm scores
indicating responses below 100 ms or above 1000 ms, and thus
floor and ceiling effects were zero.
Baseline Demographic, Work and Health
Characteristics
Mean age was similar between the rehabilitation (mean
45.1, standard deviation 9.6) and control group (mean 46.6,
standard deviation 9.7), while at baseline, level of education
differed because more participants in the control group had
completed higher education (Table 2). The primary diagnoses
of the rehabilitation participants were according to ICD-
10 musculoskeletal (53%) and mental and behavioral (27%)
disorders, while all other diagnostic categories accounted for 20%.
Details about the range and scoring direction of each
questionnaire can be seen in Table 3. Individuals in the
rehabilitation group had on average been on partial or full
sick leave for more than 6 months. The rehabilitation group
found it more important to perform well on the computerized
tests compared to the control group. The rehabilitation group
scored lower than the control group in work ability and had
higher levels of anxiety, depression, pain (SF-36 item seven),
pain related to work (SF-36 item eight), fear avoidance for work,
fear avoidance for physical activity, SHC pseudoneurology and
SHC musculoskeletal pain. On the TOMCATS, the rehabilitation
group scored worse than controls in coping, hopelessness
and helplessness.
Changes in Cognitive Functioning
The between group scores from pre- to post-test showed that the
intervention group had greater improvements in reaction time on
the simple reaction time test [3= 0.99, F(1, 345) = 3.93, p= 0.048]
and in response latency [3= 0.99, F(1, 338) = 4.17, p= 0.042]
and hits [3= 0.98, F(1, 339) = 6.43, p= 0.012] on the rapid
visual information processing test compared to the control group
(Figure 1 and Table 4).
Changes in Work and Health
Characteristics
Between group differences showed that the rehabilitation group
had greater improvements compared to controls from pre-
to post-test in work ability, reported more reduction in
pseudoneurology and musculoskeletal pain (SHC), helplessness
(TOMCATS), pain and pain related to work (SF-36 items seven
and eight) and anxiety and depression (HADS) (Table 5).
Correlations
An exploratory correlational analysis was conducted for the
rehabilitation group only (Table 6). Results showed that
simple reaction time was positively correlated with SHC
pseudoneurology, r(240) = 0.13, p= 0.044, where faster reaction
time was associated with fewer SHC. Response latency in
the rapid visual information processing task was negatively
correlated with work ability, r(240) = −0.16, p= 0.012,
where faster reaction time was associated with higher work
ability scores. Response latency in rapid visual information
processing was also negatively correlated with the RTWSE-
19 factor “modifying job tasks,” r(205) = −0.14, p=−0.043,
where faster reaction time was associated with higher self-efficacy
in modifying job tasks. Hits in the rapid visual information
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TABLE 2 | Demographic characteristics in the intervention and control group.
Intervention group Control group
(n= 280) (n= 70) Difference
n%n% X2(df)
Gender 3.65 (1)
- Female 187 67 55 79
- Male 93 33 15 21
Education 35.31∗∗∗ (2)
- Elementary 38 14 1 1.5
- Secondary 124 44 12 17
- Higher 118 42 57 81.5
Work status Not relevant
- Not in work 161 57.5 0 0
- Part time work 118 42 0 0
- Full time work 1 0.5 70 100
Diagnostic codes from the ICD-10:
C. Malignant neoplasms 4 1.5
E. Endocrine, nutritional and metabolic diseases 1 0.5
F. Mental and behavioral disorders 73 27
G. Diseases of the nervous system 21 7.5
I. Diseases of the circulatory system 6 2
J. Diseases of the respiratory system 1 0.5
K. Diseases of the digestive system 1 0.5
L. Diseases of the skin and subcutaneous tissue 1 0.5
M. Diseases of the musculoskeletal system and connective tissue 144 53
R. Symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified 4 1.5
S. Injury, poisoning and certain other consequences of external causes 2 0.5
Z. Factors influencing health status and contact with health services 14 5
Diagnostic codes applicable only to the intervention group (codes not retrievable for eight patients).
processing task was negatively correlated with work ability,
r(245) = −0.16, p= 0.015, where more hits was associated with
lower work ability.
DISCUSSION
This study is the first to systematically compare a broad range of
cognitive and emotional functions in occupational rehabilitation
patients on long-term sick leave with a healthy working control
group. The results showed that patients improved more from
pre- to post-test in focused and sustained attention compared
to the control group. The changes in performance on memory,
executive function and emotion did not differ between the two
groups. The rehabilitation group also improved more than the
control group in work ability, SHC, helplessness, pain, pain
related to work, anxiety and depression. Effect sizes for the
cognitive, emotional and questionnaire measures were below
0.06, indicating small effects (Cohen, 1988). The results of
the present study suggest that occupational rehabilitation may
be associated with improvements in cognitive functioning, in
addition to, work and health measures and corroborate the
findings of a smaller study conducted in the same clinical
setting (Johansen et al., 2016). The fact that all patients were
given occupational rehabilitation and a healthy control group
were twice administered the same measures as the rehabilitation
group is a substantial strength of this study, compared to
previous studies where patients seemed to receive several non-
related interventions (Eskildsen et al., 2015, 2016) or where a
healthy control group was recruited twice (Rydmark et al., 2006;
Wahlberg et al., 2009).
In the following we chose to elaborate on the attention findings
and its clinical implications. However, this is not ruling out the
fact that occupational rehabilitation also seem to positively affect
memory, executive function and emotion. Similar to the findings
in the current study, improvement in sustained attention has
also been reported in individuals on sick leave that received
workplace interventions for work-related stress and burnout to
increase RTW (Österberg et al., 2012), while a cross sectional
study reported impaired sustained attention in burnout patients
(Van der Linden et al., 2005). Individuals diagnosed with work-
related stress and receiving RTW consultations and/or cognitive
behavior therapy at an occupational medicine outpatient clinic
showed improvement in prospective memory and processing
speed compared to controls (Eskildsen et al., 2015, 2016).
However, patients did not receive therapy in a systematic manner
and even several patients sought private therapy in addition
to the occupational therapy offered during the study. This
makes the interpretation about the effects of specific therapies
on cognitive functioning challenging. In another study, women
on sick leave for work-related stress and depression receiving
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TABLE 3 | Baseline characteristics for demographic, work and health measures for intervention and control group.
Intervention group (n= 280) Control group (n= 70) Difference
Mean (SD) Mean (SD) T (df#)
Number of days between pre- and post-test 28.2 (23.3) 28.3(6.1)0.04 (364)
Full or part time sick leave prior to rehabilitation (months) 6.5 (4.1) Not relevant
Performance on computerized tests (range 1–5; 5 = most important) 2.9 (1.1) 2.5(1.1)2.32 (314)∗
Work ability (range 0–10; 10 = best work ability) 3.8 (2.4) 8.8(1.3)15.86 (326)∗∗∗
Return-to-Work Self-Efficacy-19
- Meeting job demands (range 1–70; 70 = highest self-efficacy) 34.0 (18.4) Not relevant
- Modifying job tasks (range 1–60; 60 = highest self-efficacy) 28.6 (13.2) Not relevant
- Communicating needs (range 1–60; 60 = highest self-efficacy) 36.2 (14.6) Not relevant
Subjective Health Complaints Inventory
- Pseudoneurology (range 0–21; 21 = highest severity) 7.1 (4.0) 2.0(2.5)9.05 (319)∗∗∗
- Musculoskeletal pain (range 0–24; 24 = highest severity) 9.9 (5.0) 3.2(3.5)9.52 (318)∗∗∗
Theoretically Originated Measure of the Cognitive Activation Theory of Stress
- Coping (range 1–4; 1 = best coping) 2.0 (0.6) 1.7(0.6)3.65 (317)∗∗∗
- Hopelessness (range 1–12; 1 = most hopelessness) 9.1 (1.9) 10.7(1.8)5.72 (318)∗∗∗
- Helplessness (range 1–12; 1 = most helplessness) 9.6 (2.0) 11.2(1.6)5.31 (315)∗∗∗
Fear Avoidance Beliefs Questionnaire
- Work (range 0–42; 0 = no fear avoidance) 20.4 (11.5) 2.6(5.6)9.52 (283)∗∗∗
- Physical activity (range 0–24; 0 = no fear avoidance) 8.9 (5.9) 2.2(4.3)6.94 (288)∗∗∗
36-Item Short Form Health Survey
- Pain (item seven) (range 1–6; 1 = no pain) 4.5 (1.1) 2.5(1.3)12.17 (315)∗∗∗
- Pain related to work (item eight) (range 1–5; 1 = not affected) 3.4 (1.1) 1.6(0.9)11.62 (315)∗∗∗
Hospital Anxiety and Depression Scale
- Anxiety (range 0–21; 0 = no anxiety) 8.3 (4.4) 4.2(3.6)6.42 (311)∗∗∗
- Depression (range 0–21; 0 = no depression) 6.4 (4.0) 2.3(2.9)7.05 (311)∗∗∗
n, sample size; SD, standard deviation; T, T statistic; df, degrees of freedom. #All participants did not respond to all questionnaire items or single item questions. ∗p<0.05.
∗∗∗p<0.001.
10 weeks of cognitive group therapy with a focus on work-
related challenges showed at 1 year follow up no impairments
compared to a healthy control group in attention and working
memory (Rydmark et al., 2006;Wahlberg et al., 2009). Before
therapy, all 29 women were on full time sick leave while 18
were in work after therapy. A methodological weakness in
these studies, as pointed out by Österberg et al. (2012), was
the fact that a new control group was recruited at post-test
(Wahlberg et al., 2009) instead of administering the same tests
to the controls recruited at pre-test (Rydmark et al., 2006).
Finally, a group of patients with fatigue and burnout, receiving
cognitive therapy did not show greater gains in executive
function related to updating, inhibition and switching compared
to a control group (Oosterholt et al., 2012). Although the
patient groups in the above studies share overlapping work
and health characteristics with the patients in the present
study, it is challenging to interpret these results because the
RTW or healthcare interventions do not seem comparable.
However, in a comparable setting, individuals going through
occupational rehabilitation and receiving working memory
training have been found to improve more in inhibiting
prepotent responses, but not spatial working memory, compared
to individuals receiving treatment as usual (Aasvik et al.,
2017). This may indicate that adding an extra intervention
focusing on cognitive training may improve certain functions
more than others.
CLINICAL IMPLICATIONS
A key component in occupational rehabilitation programs is the
cognitive approach (Aasdahl et al., 2018). The programs utilize
treatment principles from cognitive behavior therapy, acceptance
and commitment therapy, psychoeducation and motivational
interviewing. These are evidence-based psychological treatments
commonly applied to reduce sickness absence (Salomonsson
et al., 2018). The present results support the argument that
complex interventions, such as occupational rehabilitation, have
an effect on cognitive, work and health measures (Costa-
Black, 2013). To claim a direct relationship between cognitive
approaches and improvements in cognitive functioning is
spurious because the main treatment components also include
physical activity and collaboration with the workplace. It is
well documented that physical activity has positive effects on
cognition (Ratey and Loehr, 2011) and anxiety and depression
(Hovland et al., 2013;Kvam et al., 2016), while the effects
on reducing symptoms of pain seem small to moderate
(Geneen et al., 2017).
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FIGURE 1 | Improvement in attention from pre- to post-test comparing the intervention and control group with errors bars showing ±1 standard error.
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Johansen et al. Occupational Rehabilitation and Cognitive Functioning
TABLE 4 | Pre- and post-test scores for intervention and control group on cognitive and emotional tests with group by time effect.
Intervention group (n= 280) Control group (n= 70) Group by time effect
Test Time Mean (SD) EMM Mean (SD) EMM F(df) pη2
p
Simple reaction time
Reaction time (ms) Pre-test 253.6(52.6)253.5 239.8(34.8)240.2 3.93 (1,345)0.048 0.011
Post-test 248.0(52.1)247.9 244.1(41.9)244.6
Choice reaction time
Reaction time (ms) Pre-test 322.2(65.1)321.8 307.8(39.2)309.2 1.58 (1,344)0.210 0.005
Post-test 312.0(53.9)311.5 305.8(41.1)307.9
Rapid visual information processing
Response latency (ms) Pre-test 408.6(89.6)407.9 387.6(67.8)390.2 4.17 (1,338)0.042 0.012
Post-test 381.6(68.4)381.6 379.8(65.3)379.9
Probability of hits Pre-test 0.61 (0.18)0.62 0.70 (0.18)0.67 6.43 (1,339)0.012 0.019
Post-test 0.71 (0.18)0.72 0.74 (0.17)0.72
Spatial working memory
Total between errors Pre-test 12.4(9.8)12.3 11.1(9.1)11.5 0.74 (1,347)0.392 0.002
Post-test 10.5(9.2)10.4 10.0(9.8)10.6
Spatial recognition memory
Response latency (ms) Pre-test 2726 (978)2719 2467 (1077)2495 3.24 (1,347)0.073 0.009
Post-test 2240 (690)2234 2138 (601)2160
Total correct (%) Pre-test 80.6(10.1)80.6 81.4(11.4)81.4 0.03 (1,347)0.854 0.000
Post-test 81.0(10.8)81.1 82.1(9.8)81.7
Stockings of Cambridge
Choice duration (ms) Pre-test 4149 (2256)4128 4213 (1954)4297 1.85 (1,346)0.175 0.005
Post-test 3600 (1697)3608 3501 (1435)3470
Total correct Pre-test 8.9(2.0)8.9 9.3(1.7)9.3 1.01 (1,347)0.315 0.003
Post-test 9.7(1.8)9.7 9.8(1.9)9.8
Intra-extra dimensional set shift
Trials extradimensional shift stage Pre-test 9.4(9.2)9.3 10.3(9.8)10.6 0.01 (1,347)0.961 0.000
Post-test 6.1(8.1)5.9 6.7(9.1)7.2
Emotion recognition task
Total correct (%) Pre-test 59.0(10.0)59.3 60.5(8.7)59.5 3.09 (1,347)0.079 0.009
Post-test 62.0(10.1)62.2 62.0(10.2)60.8
n, sample size; SD, standard deviation; EMM, estimated marginal means evaluated with covariate in model (Education); df, degrees of freedom; η2
p, partial eta squared;
The multivariate test statistic Wilks’ lambda was used to display the F ratio; The drop out rate for each cognitive and emotional outcome variable varied in the intervention
group from n = 315 to 307 at pre-test to n = 280 to 276 at post-test. In the control group, 70 out of the 73 participants completing pre-test were able to come back and
participate at post-test.
Attention, as cognitive function, is implicated in the
development and maintenance of pain, anxiety and depression
symptoms (Legrain et al., 2009;Yiend, 2010). The finding
that improvements in focused attention were associated
with a reduction in SHC related to pseudoneurological
complaints indicate that attentional mechanisms were
influenced by several factors. Moreover, the application of
various forms of cognitive training in chronic pain (Baker
et al., 2018), depression (Jonassen et al., 2019) and on
patients in occupational rehabilitation (Aasvik et al., 2017)
has shown promising effects on cognitive functioning and
clinical symptoms. The treatment components in occupational
rehabilitation do influence cognitive functioning as shown
in the present study, making it relevant to assess possible
improvements in cognitive functioning. This could also lead to
the development of systematic and evidenced based cognitive
training components, implemented as new interventions in
future programs, where testing for transfer effects to working
life seem important.
Lack of attentional resources may affect the ability to stay
focused, for example in a complex work environment. Thus,
improvements in focused and sustained attention increase our
ability to focus on specific work and daily life tasks for a
longer time period without being distracted by symptoms and
thoughts, colleagues or background noise. Attention is a crucial
cognitive function, underlying many cognitive processes such
as memory, planning and decision making (Gazzaniga et al.,
2002) together with executive control over attention switching
(Miyake et al., 2000). Attentional resources are distributed both
unconsciously and consciously (Pashler, 1999), and if impaired,
will reduce the ability to concentrate, as well as automatically
inhibit irrelevant information or noise from entering our mind.
It might therefore reinforce attentional bias toward anxiety,
depression, and pain. The assumption here is that increased
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TABLE 5 | Pre- and post-test scores for intervention and control group on work and health measures with group by time effect.
Intervention
group (n= 280)
Control group
(n= 70)
Group by time effect
Variable Time Mean (SD) EMM Mean (SD) EMM F(df#)p-value η2
p
Performance computerized tests Pre-test 2.9(1.1)2.9 2.6(1.1)2.6 0.66 (1,287)0.418 0.002
Post-test 2.9(1.1)2.9 2.8(1.2)2.7
Work ability Pre-test 3.7(2.4)3.8 8.8(1.4)8.7 12.32 (1,299)0.001 0.040
Post-test 4.8(2.5)4.8 8.8(1.3)8.7
Return-to-Work Self-Efficacy-19
- Meeting job demands Pre-test 34.0(18.7)Not relevant
Post-test 39.2(18.4)
- Modifying job tasks Pre-test 29.3(13.4)Not relevant
Post-test 33.2(13.2)
- Communicating needs Pre-test 36.9(14.5)Not relevant
Post-test 38.7(13.6)
Subjective Health Complaints Inventory
- Pseudoneurology Pre-test 7.2(4.0)7.2 2.1(2.5)2.1 12.64 (1,285) < 0.001 0.042
Post-test 5.5(3.5)5.5 1.9(2.5)2.0
- Musculoskeletal pain Pre-test 9.9(5.0)9.8 3.4(3.6)4.0 6.58 (1,285)0.011 0.023
Post-test 8.0(4.5)7.8 3.0(3.2)3.6
Theoretically Originated Measure of the Cognitive Activation Theory of Stress
- Coping Pre-test 2.0(0.6)2.0 1.7(0.6)1.7 0.78 (1,287)0.379 0.003
Post-test 1.9(0.6)1.9 1.6(0.5)1.6
- Hopelessness Pre-test 9.1(1.9)9.1 10.6(1.8)10.5 1.61 (1,287)0.206 0.006
Post-test 9.3(2.0)9.4 10.6(1.9)10.5
- Helplessness Pre-test 9.6(2.0)9.6 11.1(1.7)11.0 4.36 (1,285)0.038 0.015
Post-test 10.0(1.9)10.1 11.1(1.7)10.9
Fear Avoidance Beliefs Questionnaire
- Work Pre-test 20.0(11.5)19.7 2.9(5.9)4.8 0.26 (1,255)0.611 0.001
Post-test 18.6(11.6)18.4 2.4(5.0)4.1
- Physical activity Pre-test 9.0(5.9)8.9 2.5(4.7)3.0 3.61 (1,259)0.059 0.014
Post-test 8.0(5.9)7.9 3.4(5.2)4.0
36-Item Short Form Health Survey
- Pain Pre-test 4.5(1.1)4.5 2.6(1.3)2.8 7.48 (1,287)0.007 0.025
Post-test 4.0(1.1)4.0 2.6(1.4)2.8
- Pain related to work Pre-test 3.4(1.1)3.4 1.7(0.9)1.8 15.33 (1,286) < 0.001 0.051
Post-test 2.7(1.1)2.7 1.7(1.0)1.8
Hospital Anxiety and Depression Scale
- Anxiety Pre-test 8.3(4.4)8.3 4.2(3.7)4.2 5.89 (1,283)0.016 0.020
Post-test 7.0(4.2)6.9 3.8(3.4)4.0
- Depression Pre-test 6.4(3.9)6.4 2.3(2.7)2.3 8.85 (1,283)0.003 0.030
Post-test 4.7(3.8)4.9 2.0(2.5)2.2
n, sample size; SD, standard deviation; EMM, estimated marginal means evaluated with covariate in model (Education); df, degrees of freedom; η2
p, partial eta squared.
#All participants did not respond to all questionnaire items or single item questions. The multivariate test statistic Wilks’ lambda was used to display the F ratio.
mental resources, i.e., improvements in attention, could also
lead to greater self-efficacy, a factor found to be important for
RTW (Lagerveld et al., 2017). The association between attention
and self-efficacy for “modifying work tasks” gives some support
to this argument.
Recently, a stronger focus on the relationship between clinical
(e.g., occupational rehabilitation) and cognitive approaches
(cognitive testing) has raised the awareness of this often neglected
association (Snyder et al., 2015). It is therefore, highly relevant to
better understand the cognitive profile of patients and types of
cognitive change to improve clinical practice. Not only attention
but all cognitive and emotional functions. Bearing in mind the
aim of occupational rehabilitation to increase RTW and increase
working life performances (Beier and Oswald, 2012;Loisel and
Anema, 2013). Another focus to consider is whether the present
study population, representing different occupational groups
and status, has general or specific attentional challenges when
compared to the general population. This may require more
refined validation of the cognitive tests because the target groups
are also likely to have occupationally related illness/injury status
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Johansen et al. Occupational Rehabilitation and Cognitive Functioning
and not traditionally individuals with psychological and pain
related disorders in which the current cognitive and emotional
tests have been validated on.
Both cognitive behavior treatment components as well as
physical activities in the rehabilitation program may influence
cognitive, emotional and behavioral changes underpinning
improvements in attention. Examples of cognition and emotion
are maladaptive coping strategies such as rumination and worry
that maintain symptoms of depression and anxiety because
individuals fail to shift focus away from inappropriate thoughts
(Williams et al., 1997;Joormann and Gotlib, 2010). For example,
the usage of principles based on cognitive therapy may have
resulted in improvements in attention and a change to positive
coping expectation and cognitive reassessment of the situation,
i.e., reappraisal (Ursin and Eriksen, 2004;Joormann and Gotlib,
2010). Related to behavior are low levels of daily life activity
resulting in inappropriate coping strategies, that is, cognitive
changes, leading to depression and anxiety (Stubbs et al.,
2018;Vancampfort et al., 2018). Behavioral activation and
adapted training focusing on fear avoidance during physical
activity and work situations, may have contributed to attentional
improvements and better coping. These changes in attention
and coping strategies, related to cognition and behavior, are
associated with positive affect, increased quality of life and
better functioning in everyday life (Gross and John, 2003).
The associations between improvements in attention, better
work ability and reduction in pseudoneurological complaints
support this line of argument. Here, we focus on how
attention is linked to the behavior treatment components
without dismissing the link to memory, executive function
and emotion. This indicates a relationship between cognitive,
work and health measures based on the knowledge that work
ability in sick-listed workers has been found to be negatively
associated with musculoskeletal pain (Rashid et al., 2018) and
co-morbid health complaints (Kamaleri et al., 2009). With
the clinical implications in mind it is highly recommended
that clinicians are aware of how attentional functions change
during a life course perspective and also depending on
different contexts.
STRENGTHS AND LIMITATIONS
The strengths of this study include recruitment of a large sample
of patients and comparing pre- and post-test performances to a
control group on several aspects of cognition including attention,
memory, executive function and emotion. This is believed to be
one of the first studies to comprehensively assess cognitive and
emotional functions in occupational rehabilitation patients. The
diagnostic profile of the patients was mainly related to depression,
anxiety, musculoskeletal pain, and comorbid symptoms. Patients
exhibiting such profiles have commonly been subjected to
cognitive testing with the added factor that the present sample
had RTW as the main aim.
Limitations include the recruitment of individuals from
both inpatient and outpatient occupational rehabilitation. This
could have introduced a bias in the results due to different
TABLE 6 | Correlations between cognitive, work and health measures using
change scores from pre- to post-test in the intervention group only.
SRT RVP, latency RVP, hits
Work ability −0.03 −0.16∗−0.16∗
SHC pseudoneurology 0.13∗0.05 0.04
SHC musculoskeletal pain 0.08 0.02 0.00
TOMCATS helplessness 0.05 −0.03 −0.03
HADS anxiety 0.05 −0.02 0.03
HADS depression −0.02 0.09 0.07
RTWSE-19 Meeting job demands −0.05 −0.11 −0.10
RTWSE-19 Modifying job tasks 0.03 −0.14∗−0.12
RTWSE-19 Communicating needs −0.00 −0.11 −0.09
SHC, Subjective Health Complaints Inventory; TOMCATS, Theoretically Originated
Measure of the Cognitive Activation Theory of Stress; HADS, Hospital Anxiety
and Depression Scale; RTWSE-19, Return-to-Work Self-Efficacy-19; SRT, Simple
Reaction Time; RVP, Rapid Visual Information Processing; ∗p<0.05.
criteria used to assign individuals to inpatient versus outpatient
rehabilitation. On the contrary, the rehabilitation programs for
inpatient versus outpatient do not differ in content, however,
the outpatient programs may be experienced as less intense
compared to inpatient, which may have implications for the
construct of attention assessed in the current study. Five
cognitive measures were transformed because the assumptions
of homogeneity of variance and normality were violated. Since,
three of the five transformed measures were from the attention
function, with one measure each from memory and executive
function, it could be argued that the transformations were
not equally distributed across different functions. However, all
transformed variables were related to reaction and response
latencies and it is not uncommon to transform these variables
given the large variance related to performances on such tasks
(Baayen and Milin, 2010). A number of differences between
the two groups were not controlled for at baseline and could
have affected the results. Factors such as medication, circadian
rhythms, motivation and group and individual activities in
rehabilitation may have affected cognitive and emotional
functioning (Lezak et al., 2012).
CONCLUSION
This study has generated new knowledge about changes
in focused and sustained attention during occupational
rehabilitation. We assume that cognitive behavioral treatment
components, physical activity and collaboration with the
workplace affect cognitive, work and health measures. The
elucidation of greater gains in focused and sustained attention
compared to memory, executive function and emotion may
benefit clinical practice, such as increasing the awareness to which
degree the treatment components affect cognitive and emotional
functions differently. This may enhance clinical practice because
tailoring specific interventions further may result in greater
improvements in all cognitive and emotional functions. Thus,
it is recommended that cognitive and emotional functioning
is systematically assessed in clinics offering interdisciplinary
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Johansen et al. Occupational Rehabilitation and Cognitive Functioning
occupational rehabilitation, similar to physical activity, raising
the quality of assessments and enabling individually tailored
rehabilitation when baseline cognitive and emotional functioning
is taken into account. This may require more refined measures
of not only attention, but also memory, executive function and
emotion, to elucidate how individuals respond to rehabilitation,
time to RTW and to which degree greater or lesser focus
should be on various cognitive and emotion related interventions
during rehabilitation. This study is a step in the direction
toward documenting which cognitive, emotional, work and
health changes occur during rehabilitation, where the aim is to
tailor treatment components to maximize the benefits for all
rehabilitation individuals to increase the chances of RTW.
DATA AVAILABILITY STATEMENT
The datasets generated for this study are available on request to
the corresponding author.
ETHICS STATEMENT
This study involving human participants were reviewed
and approved by the South-East Regional Committee
for Medical and Health Research Ethics (2013/1559). All
participants provided written informed consent prior to
participation, and all procedures were conducted according to the
Helsinki declaration.
AUTHOR CONTRIBUTIONS
TJ wrote the manuscript. TJ, CJ, and IØ performed the statistical
analysis. TJ, CJ, HE, PL, WD, and IØ contributed to the
conception and design of the study. TJ, IH, and HJ performed the
assessments and data collection. All authors contributed to the
interpretation of the data and critically revised the manuscript on
several occasions.
FUNDING
This study was funded by the Norwegian Directorate of
Labour and Welfare and the Northern Norway Regional Health
Authority (SFP1173-14).
ACKNOWLEDGMENTS
Gratitude goes to all who participated in the study. A special
thank you to Erik Storli at CatoSenteret Rehabilitation Center,
Ann Marit Flokenes at Valnesfjord Health Sports Center, and
Olav Hahn at the National Advisory Unit on Occupational
Rehabilitation for the data collection. We also thank Heidi Bjorå
Arset and Lena Klasson Heggebø, Idrettens Helsesenter, Oslo,
Norway and Anders Sandvik and Tone Hild Sørland Lyslid at
Vinje Municipality, Åmot, Norway for the support. Thank you
also to Keith Smolkowski, Oregon Research Insitute, Eugene,
United States and Jan Stubberud, University of Oslo, Norway for
the correspondence about statistical analyses.
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Disclosure: All review comments and conclusions are those of the reviewer SP and
do not reflect any policy or determination of the Centers for Disease Control and
Prevention or the National Institute for Occupational Safety and Health.
Conflict of Interest: The authors declare that the research was conducted in the
absence of any commercial or financial relationships that could be construed as a
potential conflict of interest.
Copyright © 2019 Johansen, Jensen, Eriksen, Lyby, Dittrich, Holsen, Jakobsen and
Øyeflaten. This is an open-access article distributed under the terms of the Creative
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are credited and that the original publication in this journal is cited, in accordance
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