Background Little is known about the role that work-related factors play in the decline of cognitive function. This study examined the association between perceived organisational justice and cognitive function among middle-aged men and women.
Methods Perceived organisational justice was measured at phases 1 (1985–8) and 2 (1989–90) of the Whitehall II study when the participants were 35–55 years old. Assessment of cognitive function at the screening clinic at phases 5 (1997–9) and 7 (2003–4) included the following tests in the screening clinic: memory, inductive reasoning (Alice Heim 4), vocabulary (Mill Hill), and verbal fluency (phonemic and semantic). Mean exposure to lower organisational justice at phases 1 and 2 in relation to cognitive function at phases 5 and 7 were analysed using linear regression analyses. The final sample included 4531 men and women.
Results Lower mean levels of justice at phases 1 and 2 were associated with worse cognitive function in terms of memory, inductive reasoning, vocabulary and verbal fluency at both phases 5 and 7. These associations were independent of covariates, such as age, occupational grade, behavioural risks, depression, hypertension and job strain.
Conclusions This study suggests an association between perceived organisational justice and cognitive function. Further studies are needed to examine whether interventions designed to improve organisational justice would affect employees' cognition function favourably.
- cognitive function
- cognitive problems
- epidemiology FQ
- health behaviour
- psychosocial factors
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- cognitive function
- cognitive problems
- epidemiology FQ
- health behaviour
- psychosocial factors
Many studies on cognitive decline target populations at the age of 60 years or older even though it is increasingly recognised that age-related changes in cognition are already evident in midlife.1 The fact that midlife cognitive changes predict old-age dementia risk sets the rationale for examining determinants of early cognitive decline.2 A recent study of a working-aged cohort found that work-related factors, such as working extremely long hours, were associated with a decline in aspects of cognitive function.3 Similar associations were not observed between job strain and cognition.4 However, very few data, to date, are available for other psychosocial factors at work.
Organisational justice, ie, the decision-making rules and managerial behaviours within the organisation that affect employees' fairness experience, may influence a range of attitudes and behaviours,5 including organisational commitment,6 job satisfaction,7 citizenship behaviour8 and turnover.9 Epidemiological studies suggest that low organisational justice may also contribute to serious health problems, such as depression10 11 and cardiovascular disease.12–15 Given that injustice has also been shown to be an important source of psychological distress,16 17 which in turn may have adverse effects on cognitive function,18–20 the association between organisational justice and cognitive function seems plausible.
According to a recent study, psychological distress affects multiple memory systems and learning strategies.21 Studies of brain regions suggest that the hippocampus, a limbic area involved in learn memory, is particularly sensitive to the effects of distress.22 Chronic distress has also been shown to be associated with other cognitive functions, such as encoding or retrieval of words.23 It may thus be reasonable to hypothesise that long-term exposure to low organisational justice, a potential source of chronic distress, may adversely affect certain aspects of cognitive function.
In this study, we examined the relationship between organisational justice and cognitive function in a cohort of British civil servants. Because an accelerated decline in cognitive function may indicate disease processes, such as depression24 and hypertension,25 we also took into account the effects of these conditions in the analyses.
Subjects and design
The target population for the Whitehall II Study was all the office staff aged 35–55 years based in 20 civil service departments in London, England. With a 73% participation rate, the cohort included 6895 men and 3413 women at study entry in 1985–8. Data on organisational justice and cognitive function were available for 4879 participants at phase 5 (1997–9) and 4531 participants at both phase 5 and phase 7 (2003–4). The sample selection is presented in figure 1. Those excluded were older (45.1 years compared with 43.4 years, p<0.001), more likely to be women (60% vs 49%, p<0.001), belonged to the lowest employment grade (58% vs 42%, p<0.001), and had both lower job demands (mean 59.1 vs 56.7, p=0.043) and lower job control (mean 67.0 vs 63.1, p<0.001) at baseline. Informed consent was gained from all participants. The University College London Medical School Committee on the Ethics of Human Research approved the protocol.
A self-reported justice scale, assessed at phases 1 and 2 (1989–90) tapped the relational component of organisational justice (five items; Cronbach 0.72) and are further described in earlier studies from the Whitehall II cohort.14 17 This scale includes the following items: (1) Do you ever get criticised unfairly? (reversed) (2) Do you get consistent information from line management (your superior)? (3) Do you get sufficient information from line management (your superior)? (4) How often is your superior willing to listen to your problems? and (5) Do you ever get praised for your work?
Participants rated their response to each of these items on a four-point scale (1 indicates never; 2, seldom; 3, sometimes; and 4, often). For each participant, we averaged the scores of the five items at phases 1 and 2 and then calculated the mean of these averaged scores. The mean scores were scaled from 0 to 100, reversed so that higher scores indicate greater perceived injustice and treated as a continuous variable in the analysis.
Covariates included age, socioeconomic position, smoking, alcohol consumption, body mass index (BMI), depression, hypertension and job strain and were all measured at baseline (phase 1). Socioeconomic position was measured as civil service employment grade (administrative, professional, clerical/support). Health behaviours were smoking (self-reported cigarette smoking classified as never smoker, former smoker and current smoker), alcohol consumption (units/week, classified as: none, 1–14 units, 15–22 units, 22+ units with the highest two categories being combined in women), BMI (kg/m2, classified as under 18.5, 18.5–25, 25–30, over 30). Depressive symptoms were assessed using the four-item depression subscale of the general health questionnaire, a 30-item screening questionnaire for common mental disorders such as depression and anxiety and suitable for use in general population samples.26 Those scoring more than three out of four on the depression subscale were classified as having depressive symptoms. Subjects with systolic blood pressure of 140 mm Hg or greater and diastolic blood pressure of 90 mm Hg or greater or on antihypertensive treatment were considered to be hypertensive. Self-reported job strain was measured using the job strain questionnaire27 and was composed of the subscale job demands, assessed using four questions (α=0.67), and decision latitude/skill discretion (job control), assessed using 15 items (α=0.84). Responses on a four-point scale from ‘often’ to ‘never/almost never’ were combined into summary scales and then divided as high and low, defined as above or below the median of the summary score on the respective scale. Job strain was classified in four categories: active work (high control and high demands), low strain (high control and low demands), passive work (low control and low demands) and high strain (low control and high demands).28
Cognitive testing was introduced to the Whitehall study midway through phase 3. Consequently cognitive data are available for only 40% of the participants at phase 3 but for the entire sample at phases 5 and 7. Therefore, we used cognitive data only from phases 5 and 7.
Cognitive function was measured using the following five standard tests. Short-term memory was assessed by a 20-word free recall test. Participants were presented a list of 20 one or two-syllable words at 2 s intervals and were then asked to recall in writing as many of the words in any order within 2 min. The AH4-I29 is composed of a series of 65 items (32 verbal and 33 mathematical reasoning items) of increasing difficulty. This is a test of inductive reasoning that measures the ability to identify patterns and infer principles and rules. Participants had 10 min to complete this section. The Mill Hill vocabulary test30 assesses vocabulary and encompasses the ability to recognise and comprehend words. We used the test in its multiple format, which consists of a list of 33 stimulus words ordered by increasing difficulty, and six response choices per word. Two measures of verbal fluency: phonemic and semantic, were used.31 Phonemic fluency was assessed by ‘S’ words and semantic fluency by ‘animal’ words. Subjects were asked to recall in writing as many words beginning with ‘S’ and as many animal names as they could. One minute was allowed for each test.
The multivariate relationships between organisational justice at phases 1 and 2 and cognitive function at phases 5 and 7 were analysed using linear regression analyses with continuous measures of the cognitive tests as outcomes. The measures of organisational justice (skewness −0.6, kurtosis 0.4) and cognitive functions (skewness range −1.3–0.1, and kurtosis range 0.2–2.6) were relatively normally distributed. Statistical models were sequentially adjusted for age, employment grade, alcohol consumption, smoking status, BMI, depressive symptoms, hypertension and job strain. The regression analyses were performed with statistical analysis system version 9.01. Statistical significance was inferred at a two-tailed p value of less than 0.05.
Sensitivity analyses included three set of analyses. First, to take into account the potential effects of a subjective perception of unfair treatment, which may be related to the individual's characteristics, we additionally adjusted the final model for negative affectivity measured at phase 1 using the negative affect subscale of the affect balance scale (Cronbach's α=0.67).32 The psychometric properties of the negative affectivity measure in this sample have been reported elsewhere.33 Second, we replicated our analyses with multilevel modelling (random intercept model), to take into account the fact that each participant is working in a particular department. The participants worked at 23 departments, and the range of the number of participants working in each department was from 60 to 607. Third, we reran our final analyses using multiple multivariate imputation to evaluate the effect of sample attrition from the baseline study phase (using STATA 10, ice/micombine procedures).
The characteristics of the study participants are shown in table 1. The mean age of the participants at baseline was 43.9 years (range 34–56). The majority of the participants worked in the professional grades, more than half of them were never smokers, approximately 20% experienced depressive symptoms and 7% were hypertensive. The changes in mean cognitive scores between phases 5 and 7 were relatively small.
The association between organisational justice and cognitive function at phases 5 and 7 are shown in table 2. Lower justice across phases 1 and 2 was associated with worse cognitive functions measured at phase 5; associations with all cognitive tests were robust to adjustments for covariates. Similarly, lower perceived justice at phases 1 and 2 was associated with worse cognitive functions at phase 7 and very small changes in associations were detected after adjustments for covariates.
Additionally adjusting the final steps in the regression models for negative affectivity, did not produce changes in any of the associations (the standardised estimate ranged from −0.04 to −0.05 and non-standardised from −0.13 to −0.45 and p values were from 0.028 to <0.001 (see supplementary table S1, available online only). Replicating the final step of regression models with multilevel modelling produced significant associations between organisational justice and all cognitive functions (p values ranged from <0.001 to 0.034 (see supplementary table S1, available online only). The association between organisational justice and cognitive functions were stronger (regression coefficient range from 0.12 to 0.56) when using data (n=10308) from multiple multivariate imputation (all p values <0.001) and were adjusted for age, sex and occupational grade (data not shown).
In this prospective study of a large working-age population, we found lower organisational justice to be associated with worse scores in memory, inductive reasoning, vocabulary and phonemic and semantic fluency tests. The associations were not explained by the covariates included in the present analyses; age, health-related behaviours, depressive symptoms, hypertension or job strain. We did not find significant weakening of the effects with longer follow-up.
Age, low employment grade, vascular problems, hypertension and teetotalism have all been associated with poor cognitive function in previous investigations.34–38 Furthermore, a large body of research has shown that depression is associated with cognitive decline.20 None of these factors explained the increased risk of poor cognitive function associated with long-term organisational injustice. However, as we had no measure of cognitive function at baseline, the possibility of reverse causation (ie, cognitive function affecting organisational justice perceptions) cannot be ruled out in this set of analyses. It is also possible that the perception of organisational justice may be related to the individual's characteristics, such as personality traits, such as negative affectivity. Negative affectivity is the disposition to respond negatively to environmental stimuli and to questionnaires and may inflate correlations between self-reported work characteristics and cognitive performance tests.39 40 However, taking into account the effect of negative affectivity did not account for the associations between justice evaluations and cognitive performance.
One potential pathway linking organisational justice and cognitive function is physical health status, including high long-term levels of inflammatory markers41 and coronary heart disease.36 These conditions have previously been found to be associated with both cognitive function and organisational justice perception.14 36 41 42 It is also possible that poor physical health status intensifies negative perceptions of environmental stressors or that mild cognitive decline adversely affects justice evaluation by deteriorated work performance. An employee may fail the duties that were earlier easy and get into conflict with co-workers and supervisors because of being late with tasks, forgetting or misunderstanding things. These experiences might make him/her feel unjustly treated. A further potential pathway linking organisational justice and cognitive decline is psychological stress or distress. An alternative psychosocial factor at work that may increase stress measured in the present cohort is high job strain. Adjusting the models for job strain had a minimal effect on the associations between justice and cognition. This result is in line with a previous study of the Whitehall ll cohort, which suggested that job strain did not have an independent effect on cognitive functions.4
The strength of this study is repeat measures on both organisational justice and cognitive function. Clinic measures covered the major components of cognitive function, such as memory, reasoning, vocabulary and fluency, and the availability of data on known risk factors enabled adjustment for a range of potential confounding and mediating factors. However, in interpreting the present results, it is important to note some limitations. First, although our measure of justice is predictive of various health outcomes and comparable with the standard measures of justice,16 17 it does not capture more extreme sources of injustice (including coercion, intimidation, discrimination and denigration), which might have particularly strong effects on stress-related outcomes. Second, all the analyses were conducted using participants with complete data on organisational justice and cognitive outcome variables at the last study phase, phase 7. This meant that more than half the original population was excluded raising concerns about potential selection effects leading to over or underestimation of associations. However, differences in baseline characteristics between the included and excluded civil servants were relatively small and we adjusted for these baseline characteristics in the analyses. We also replicated the analyses using multiple imputation methods and using the imputed data produced stronger associations between organisational justice and cognitive functions. Third, as with most of the organisational studies, our analyses were based on individual-level data although multilevel analyses, with work unit as the second level, would take into accounts effects associated with the fact that all employees work in some work unit or department. Although the rotation of higher-grade civil servants, changes of departments and turnover of staff during the follow-up makes the multilevel approach problematical in our cohort, we replicated our findings using multilevel regression modelling (random intercept), which produced similar results to the regression analyses using only individual-level data.
These findings suggest that low levels of perceived organisational justice are associated with impaired cognitive function in midlife. Further longitudinal studies are needed to examine whether interventions designed to improve organisational justice would alter cognitive function among employees.
What is already known on this subject
Low organisational justice has been shown to be associated with an increased risk of health problems.
A potential mechanism through which perceived organisational injustice may affect health-related issues is prolonged stress.
Prolonged stress affects cognitive functions especially in old age.
What this study adds
Our results suggest that unfair treatment by supervisors is associated with an increased risk of poor cognitive function.
The association between repeated exposure to organisational justice and cognitive function may already be apparent in middle ge.
In occupational health research, increasing attention should be focused on organisational decision-making and managerial procedures.
The authors would like to thank all participating civil service departments and their welfare, personnel and establishment officers, the Occupational Health and Safety Agency, the Council of Civil Service Unions, all participating civil servants in the Whitehall II study and all members of the Whitehall II study team.
Funding The Whitehall II study has been supported by grants from the Medical Research Council, British Heart Foundation, Health and Safety Executive, Department of Health, National Heart Lung and Blood Institute (R01HL036310); US, NIH: National Institute on Ageing (R01AG013196; R01AG034454), US, NIH: Agency for Health Care Policy Research (HS06516). JEF is supported by the MRC (G8802774), MJS by a grant from the British Heart Foundation, MGM by an MRC fesearch professorship, MK by the Academy of Finland (projects 117604 and 132944) and BUPA Foundation, JV and MK by the Academy of Finland (projects 124271 and 129262), ME by the Academy of Finland (128002) and WEF (project 203533) and ASM by a EURYI award from the European Science Foundation.
Competing interests None declared.
Patient consent Obtained.
Ethics approval Ethics approval for the Whitehall II study was obtained from the University College London Medical School Committee on the Ethics of Human Research.
Provenance and peer review Not commissioned; externally peer reviewed.
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