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Knutsson, Anders
Publications (10 of 133) Show all publications
Kivimäki, M., Luukkonen, R., Batty, G. D., Ferrie, J. E., Pentti, J., Nyberg, S. T., . . . Jokela, M. (2018). Body mass index and risk of dementia: Analysis of individual-level data from 1.3 million individuals. Alzheimer's & Dementia, 14(5), 601-609
Open this publication in new window or tab >>Body mass index and risk of dementia: Analysis of individual-level data from 1.3 million individuals
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2018 (English)In: Alzheimer's & Dementia, ISSN 1552-5260, E-ISSN 1552-5279, Vol. 14, no 5, p. 601-609Article in journal (Refereed) Published
Abstract [en]

Introduction: Higher midlife body mass index (BMI) is suggested to increase the risk of dementia, but weight loss during the preclinical dementia phase may mask such effects. Methods: We examined this hypothesis in 1,349,857 dementia-free participants from 39 cohort studies. BMI was assessed at baseline. Dementia was ascertained at follow-up using linkage to electronic health records (N = 6894). We assumed BMI is little affected by preclinical dementia when assessed decades before dementia onset and much affected when assessed nearer diagnosis. Results: Hazard ratios per 5-kg/m2 increase in BMI for dementia were 0.71 (95% confidence interval = 0.66-0.77), 0.94 (0.89-0.99), and 1.16 (1.05-1.27) when BMI was assessed 10 years, 10-20 years, and >20 years before dementia diagnosis. Conclusions: The association between BMI and dementia is likely to be attributable to two different processes: a harmful effect of higher BMI, which is observable in long follow-up, and a reverse-causation effect that makes a higher BMI to appear protective when the follow-up is short. 

Keywords
Bias, Body mass index, Cohort study, Dementia, Obesity
National Category
Health Sciences
Identifiers
urn:nbn:se:miun:diva-32715 (URN)10.1016/j.jalz.2017.09.016 (DOI)000432438800003 ()29169013 (PubMedID)
Note

Available online 21 November 2017

Available from: 2018-01-19 Created: 2018-01-19 Last updated: 2018-07-19Bibliographically approved
Virtanen, M., Jokela, M., Madsen, I. E. H., Hanson, L. L. M., Lallukka, T., Nyberg, S. T., . . . Kivimaki, M. (2018). Long working hours and depressive symptoms: systematic review and meta-analysis of published studies and unpublished individual participant data. Scandinavian Journal of Work, Environment and Health, 44(3), 239-250
Open this publication in new window or tab >>Long working hours and depressive symptoms: systematic review and meta-analysis of published studies and unpublished individual participant data
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2018 (English)In: Scandinavian Journal of Work, Environment and Health, ISSN 0355-3140, E-ISSN 1795-990X, Vol. 44, no 3, p. 239-250Article, review/survey (Refereed) Published
Abstract [en]

Objectives This systematic review and meta-analysis combined published study-level data and unpublished individual-participant data with the aim of quantifying the relation between long working hours and the onset of depressive symptoms.

Methods We searched PubMed and Embase for published prospective cohort studies and included available cohorts with unpublished individual-participant data. We used a random-effects meta-analysis to calculate summary estimates across studies.

Results We identified ten published cohort studies and included unpublished individual-participant data from 18 studies. In the majority of cohorts, long working hours was defined as working >= 55 hours per week. In multivariable-adjusted meta-analyses of 189 729 participants from 35 countries [96 275 men, 93 454 women, follow-up ranging from 1-5 years, 21 747 new-onset cases), there was an overall association of 1.14 (95% confidence interval (CI) 1.03-1.25] between long working hours and the onset of depressive symptoms, with significant evidence of heterogeneity (I-2 = 45.1%, P=0.004). A strong association between working hours and depressive symptoms was found in Asian countries (1.50, 95% CI 1.13-2.01), a weaker association in Europe (1.11, 95% CI 1.00-1.22), and no association in North America (0.97, 95% CI 0.70-1.34) or Australia (0.95, 95% CI 0.70-1.29). Differences by other characteristics were small.

Conclusions This observational evidence suggests a moderate association between long working hours and onset of depressive symptoms in Asia and a small association in Europe.

Keywords
depression, mental health, overtime, psychological distress, working life, working time
National Category
Health Sciences
Identifiers
urn:nbn:se:miun:diva-33676 (URN)10.5271/sjweh.3712 (DOI)000431142500003 ()29423526 (PubMedID)2-s2.0-85046491041 (Scopus ID)
Available from: 2018-05-30 Created: 2018-05-30 Last updated: 2018-07-02Bibliographically approved
Hermansson, J., Hallqvist, J., Karlsson, B., Knutsson, A. & Gillander Gådin, K. (2018). Shift work, parental cardiovascular disease and myocardial infarction in males. Occupational Medicine, 68(2), 120-125
Open this publication in new window or tab >>Shift work, parental cardiovascular disease and myocardial infarction in males
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2018 (English)In: Occupational Medicine, ISSN 0962-7480, E-ISSN 1471-8405, Vol. 68, no 2, p. 120-125Article in journal (Refereed) Published
Abstract [en]

Background Shift work has been associated with an increased risk of cardiovascular disease (CVD). However, there is a need for more studies to determine whether there is an interaction between shift work and other risk factors of CVD, thereby increasing the risk of CVD in shift workers. Aims To discern whether shift work and parental mortality from myocardial infarction (MI) or sudden cardiac death (SCD) interact to increase the risk of MI in men. Methods A case-control dataset was used to assess interaction between shift work and parental history of CVD, using death from MI or SCD, or death before age 65, on an additive scale. Results were reported as relative excess risk due to interaction, attributable proportion due to interaction (AP) and synergy index (SI). Results There was an interaction between shift work and paternal mortality from MI or SCD, when both factors were present [SI = 2.39; 95% confidence interval (CI) 1.02. 5.6 and AP = 0.4; 95% CI 0.08. 0.73]. Conclusions Paternal mortality from MI or SCD interacts with shift work to increase the risk of MI in men.

National Category
Health Sciences
Identifiers
urn:nbn:se:miun:diva-33588 (URN)10.1093/occmed/kqy008 (DOI)000429448800010 ()29444274 (PubMedID)2-s2.0-85045523319 (Scopus ID)
Available from: 2018-05-08 Created: 2018-05-08 Last updated: 2018-05-16Bibliographically approved
du Prel, J.-B., Runeson-Broberg, R., Westerholm, P., Alfredsson, L., Fahlen, G., Knutsson, A., . . . Peter, R. (2018). Work overcommitment: Is it a trait or a state?. International Archives of Occupational and Environmental Health, 91(1), 1-11
Open this publication in new window or tab >>Work overcommitment: Is it a trait or a state?
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2018 (English)In: International Archives of Occupational and Environmental Health, ISSN 0340-0131, E-ISSN 1432-1246, Vol. 91, no 1, p. 1-11Article in journal (Refereed) Published
Abstract [en]

Effort-reward imbalance (ERI) is a well-tested work-related stress model with three components, the two extrinsic components "efforts" and "rewards" and the one intrinsic component "overcommitment". While an imbalance between "efforts" and "rewards" leads to strain reactions, "work-related overcommitment" (OC) has been described as a personal characteristic with a set of attitudes, behaviours, and emotions reflecting excessive striving combined with a strong desire for approval. However, the question whether OC is a personality trait or a response pattern sensitive to changes in the work context (state) is still open. 2940 Swedish industrial employees were included in this longitudinal analysis of the WOLF-Norrland data over 5 years. A change of OC index or its subscales were regressed against a change of freedom of choice at work, extra work, and ERI adjusted for age, sex, and education. While OC was insensitive to changes in freedom of choice at work and extra work, it was clearly associated with changes of work-related stress over time. Three of four OC subscales exhibited statistically significant associations with ERI. For the first time, we studied fundamental characteristics of OC as an independent personality variable (trait) or an outcome variable subject to changes in the work environment (state). The association between external ERI and OC over time supports our hypothesis of OC being a state. Further investigations are needed to establish OC as a trait or a state.

National Category
Health Sciences
Identifiers
urn:nbn:se:miun:diva-32743 (URN)10.1007/s00420-017-1253-8 (DOI)000419350600001 ()28801694 (PubMedID)2-s2.0-85027327139 (Scopus ID)
Available from: 2018-01-25 Created: 2018-01-25 Last updated: 2018-02-22Bibliographically approved
Kivimäki, M., Pentti, J., Ferrie, J. E., Batty, G. D., Nyberg, S. T., Jokela, M., . . . Deanfield, J. (2018). Work stress and risk of death in men and women with and without cardiometabolic disease: a multicohort study. The Lancet Diabetes and Endocrinology, 6(9), 705-713
Open this publication in new window or tab >>Work stress and risk of death in men and women with and without cardiometabolic disease: a multicohort study
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2018 (English)In: The Lancet Diabetes and Endocrinology, ISSN 2213-8587, E-ISSN 2213-8595, Vol. 6, no 9, p. 705-713Article in journal (Refereed) Published
Abstract [en]

Background Although some cardiovascular disease prevention guidelines suggest a need to manage work stress in patients with established cardiometabolic disease, the evidence base for this recommendation is weak. We sought to clarify the status of stress as a risk factor in cardiometabolic disease by investigating the associations between work stress and mortality in men and women with and without pre-existing cardiometabolic disease. Methods In this multicohort study, we used data from seven cohort studies in the IPD-Work consortium, initiated between 1985 and 2002 in Finland, France, Sweden, and the UK, to examine the association between work stress and mortality. Work stress was denoted as job strain or effort-reward imbalance at work. We extracted individual-level data on prevalent cardiometabolic diseases (coronary heart disease, stroke, or diabetes [without differentiation by diabetes type]) at baseline. Work stressors, socioeconomic status, and conventional and lifestyle risk factors (systolic and diastolic blood pressure, total cholesterol, smoking status, BMI, physical activity, and alcohol consumption) were also assessed at baseline. Mortality data, including date and cause of death, were obtained from national death registries. We used Cox proportional hazards regression to study the associations of work stressors with mortality in men and women with and without cardiometabolic disease. Results We identified 102 633 individuals with 1 423 753 person-years at risk (mean follow-up 13.9 years [SD 3.9]), of whom 3441 had prevalent cardiometabolic disease at baseline and 3841 died during follow-up. In men with cardiometabolic disease, age-standardised mortality rates were substantially higher in people with job strain (149.8 per 10 000 person-years) than in those without (97.7 per 10 000 person-years; mortality difference 52.1 per 10 000 person-years; multivariable-adjusted hazard ratio [HR] 1.68, 95% CI 1.19-2.35). This mortality difference for job strain was almost as great as that for current smoking versus former smoking (78.1 per 10 000 person-years) and greater than those due to hypertension, high total cholesterol concentration, obesity, physical inactivity, and high alcohol consumption relative to the corresponding lower risk groups (mortality difference 5.9-44.0 per 10 000 person-years). Excess mortality associated with job strain was also noted in men with cardiometabolic disease who had achieved treatment targets, including groups with a healthy lifestyle (HR 2.01, 95% CI 1.18-3.43) and those with normal blood pressure and no dyslipidaemia (6.17, 1.74-21.9). In all women and in men without cardiometabolic disease, relative risk estimates for the work stress-mortality association were not significant, apart from effort-reward imbalance in men without cardiometabolic disease (mortality difference 6.6 per 10 000 person-years; multivariable-adjusted HR 1.22, 1.06-1.41). Interpretation In men with cardiometabolic disease, the contribution of job strain to risk of death was clinically significant and independent of conventional risk factors and their treatment, and measured lifestyle factors. Standard care targeting conventional risk factors is therefore unlikely to mitigate the mortality risk associated with job strain in this population.

National Category
Health Sciences
Identifiers
urn:nbn:se:miun:diva-34520 (URN)10.1016/S2213-8587(18)30140-2 (DOI)000442438000017 ()29884468 (PubMedID)
Available from: 2018-09-26 Created: 2018-09-26 Last updated: 2018-09-26Bibliographically approved
Runeson-Broberg, R., du Prel, J.-B., Westerholm, P., Nordin, M., Knutsson, A., Alfredsson, L., . . . Peter, R. (2017). Age-related associations between work over-commitment and zest for work among Swedish employees from a cross-sectional and longitudinal perspective. Work: A journal of Prevention, Assesment and rehabilitation, 57(2), 269-279
Open this publication in new window or tab >>Age-related associations between work over-commitment and zest for work among Swedish employees from a cross-sectional and longitudinal perspective
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2017 (English)In: Work: A journal of Prevention, Assesment and rehabilitation, ISSN 1051-9815, E-ISSN 1875-9270, Vol. 57, no 2, p. 269-279Article in journal (Refereed) Published
Abstract [en]

BACKGROUND: In aging societies, zest for work may be pivotal when deciding to stay occupationally active longer. Psychosocial work stress is a prevalent public health problem and may have an impact on zest for work. Work over-commitment (WOC) is a personal coping strategy for work stress with excessive striving and a health risk. However, the long-term effect of WOC on zest for work is poorly understood. OBJECTIVE: To investigate the age-related associations of work over-commitment with zest for work. METHODS: During 1996-1998 and 2000-2003, predominantly industrial workers (n = 2940) participated in the WOLF-Norrland study and responded to a questionnaire referring to socio-demographics, WOC, zest for work, effort-reward imbalance proxies, and mental health. Age-adjusted multiple logistic regressions were performed with original and imputed datasets. RESULTS: Cross-sectionally, work overcommitted middle-aged employees had an increased prevalence of poor zest for work compared to their contemporaries without WOC (OR: 3.74 [95%-CI 2.19; 6.40]). However, in a longitudinal analysis associations between onset of 'poor zest for work' and the WOC subscales 'need for approval' (OR: 3.29 [95%-CI 1.04; 10.37]) and 'inability to withdraw from work' (OR: 5.14 [95%-CI 1.32; 20.03]) were observed. CONCLUSION: The longitudinal findings among older employees could be relevant regarding the expected need to remain occupationally active longer.

Keywords
Work stress, WOC, ERI, coping
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:miun:diva-31350 (URN)10.3233/WOR-172555 (DOI)000404774400013 ()28582947 (PubMedID)2-s2.0-85021818266 (Scopus ID)
Available from: 2017-08-08 Created: 2017-08-08 Last updated: 2017-08-11Bibliographically approved
Dragano, N., Siegrist, J., Nyberg, S. T., Lunau, T., Fransson, E. I., Alfredsson, L., . . . Kivimäki, M. (2017). Effort-Reward Imbalance at Work and Incident Coronary Heart Disease A Multicohort Study of 90,164 Individuals. Epidemiology, 28(4), 619-626
Open this publication in new window or tab >>Effort-Reward Imbalance at Work and Incident Coronary Heart Disease A Multicohort Study of 90,164 Individuals
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2017 (English)In: Epidemiology, ISSN 1044-3983, E-ISSN 1531-5487, Vol. 28, no 4, p. 619-626Article in journal (Refereed) Published
Abstract [en]

Background: Epidemiologic evidence for work stress as a risk factor for coronary heart disease is mostly based on a single measure of stressful work known as job strain, a combination of high demands and low job control. We examined whether a complementary stress measure that assesses an imbalance between efforts spent at work and rewards received predicted coronary heart disease.

Methods: This multicohort study (the "IPD-Work" consortium) was based on harmonized individual-level data from 11 European prospective cohort studies. Stressful work in 90,164 men and women without coronary heart disease at baseline was assessed by validated effort-reward imbalance and job strain questionnaires. We defined incident coronary heart disease as the first nonfatal myocardial infarction or coronary death. Study-specific estimates were pooled by random effects meta-analysis.

Results: At baseline, 31.7% of study members reported effort-reward imbalance at work and 15.9% reported job strain. During a mean follow-up of 9.8 years, 1,078 coronary events were recorded. After adjustment for potential confounders, a hazard ratio of 1.16 (95% confidence interval, 1.00-1.35) was observed for effort-reward imbalance compared with no imbalance. The hazard ratio was 1.16 (1.01-1.34) for having either effort-reward imbalance or job strain and 1.41 (1.12-1.76) for having both these stressors compared to having neither effort-reward imbalance nor job strain.

Conclusions: Individuals with effort-reward imbalance at work have an increased risk of coronary heart disease, and this appears to be independent of job strain experienced. These findings support expanding focus beyond just job strain in future research on work stress.

National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:miun:diva-31343 (URN)10.1097/EDE.0000000000000666 (DOI)000402541400028 ()28570388 (PubMedID)2-s2.0-85016586911 (Scopus ID)
Available from: 2017-08-08 Created: 2017-08-08 Last updated: 2018-03-01Bibliographically approved
Madsen, I. E., Nyberg, S. T., Magnusson Hanson, L. L., Ferrie, J. E., Ahola, K., Alfredsson, L., . . . Kivimäki, M. (2017). Job strain as a risk factor for clinical depression: Systematic review and meta-analysis with additional individual participant data. Psychological Medicine, 47(8), 1342-1356
Open this publication in new window or tab >>Job strain as a risk factor for clinical depression: Systematic review and meta-analysis with additional individual participant data
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2017 (English)In: Psychological Medicine, ISSN 0033-2917, E-ISSN 1469-8978, Vol. 47, no 8, p. 1342-1356Article in journal (Refereed) Published
Abstract [en]

Background Adverse psychosocial working environments characterized by job strain (the combination of high demands and low control at work) are associated with an increased risk of depressive symptoms among employees, but evidence on clinically diagnosed depression is scarce. We examined job strain as a risk factor for clinical depression. Method We identified published cohort studies from a systematic literature search in PubMed and PsycNET and obtained 14 cohort studies with unpublished individual-level data from the Individual-Participant-Data Meta-analysis in Working Populations (IPD-Work) Consortium. Summary estimates of the association were obtained using random-effects models. Individual-level data analyses were based on a pre-published study protocol. Results We included six published studies with a total of 27 461 individuals and 914 incident cases of clinical depression. From unpublished datasets we included 120 221 individuals and 982 first episodes of hospital-treated clinical depression. Job strain was associated with an increased risk of clinical depression in both published [relative risk (RR) = 1.77, 95% confidence interval (CI) 1.47-2.13] and unpublished datasets (RR = 1.27, 95% CI 1.04-1.55). Further individual participant analyses showed a similar association across sociodemographic subgroups and after excluding individuals with baseline somatic disease. The association was unchanged when excluding individuals with baseline depressive symptoms (RR = 1.25, 95% CI 0.94-1.65), but attenuated on adjustment for a continuous depressive symptoms score (RR = 1.03, 95% CI 0.81-1.32). Conclusions Job strain may precipitate clinical depression among employees. Future intervention studies should test whether job strain is a modifiable risk factor for depression.

Keywords
Observational studies, occupational health, work stress
National Category
Health Sciences
Identifiers
urn:nbn:se:miun:diva-31133 (URN)10.1017/S003329171600355X (DOI)000401293800002 ()28122650 (PubMedID)2-s2.0-85010872142 (Scopus ID)
Available from: 2017-07-03 Created: 2017-07-03 Last updated: 2017-11-29Bibliographically approved
Kivimäki, M., Nyberg, S. T., Batty, G. D., Kawachi, I., Jokela, M., Alfredsson, L., . . . Tabak, A. G. (2017). Long working hours as a risk factor for atrial fibrillation: a multi-cohort study. European Heart Journal, 38(34), 2621-2628
Open this publication in new window or tab >>Long working hours as a risk factor for atrial fibrillation: a multi-cohort study
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2017 (English)In: European Heart Journal, ISSN 0195-668X, E-ISSN 1522-9645, Vol. 38, no 34, p. 2621-2628Article in journal (Refereed) Published
Abstract [en]

Aims Studies suggest that people who work long hours are at increased risk of stroke, but the association of long working hours with atrial fibrillation, the most common cardiac arrhythmia and a risk factor for stroke, is unknown. We examined the risk of atrial fibrillation in individuals working long hours (>= 55 per week) and those working standard 35-40 h/week.

Methods and results In this prospective multi-cohort study from the Individual-Participant-Data Meta-analysis in Working Populations (IPD-Work) Consortium, the study population was 85 494 working men and women (mean age 43.4 years) with no recorded atrial fibrillation. Working hours were assessed at study baseline (1991-2004). Mean follow-up for incident atrial fibrillation was 10 years and cases were defined using data on electrocardiograms, hospital records, drug reimbursement registers, and death certificates. We identified 1061 new cases of atrial fibrillation (10-year cumulative incidence 12.4 per 1000). After adjustment for age, sex and socioeconomic status, individuals working long hours had a 1.4-fold increased risk of atrial fibrillation compared with those working standard hours (hazard ratio = 1.42, 95% CI= 1.13-1.80, P= 0.003). There was no significant heterogeneity between the cohort-specific effect estimates (I-2= 0%, P = 0.66) and the finding remained after excluding participants with coronary heart disease or stroke at baseline or during the follow-up (N= 2006, hazard ratio= 1.36, 95% CI= 1.05-1.76, P = 0.0180). Adjustment for potential confounding factors, such as obesity, risky alcohol use and high blood pressure, had little impact on this association.

Conclusion Individuals who worked long hours were more likely to develop atrial fibrillation than those working standard hours.

Keywords
Atrial fibrillation, Life stress, Risk factors, Cohort study
National Category
Public Health, Global Health, Social Medicine and Epidemiology
Identifiers
urn:nbn:se:miun:diva-31874 (URN)10.1093/eurheartj/ehx324 (DOI)000409542800012 ()28911189 (PubMedID)2-s2.0-85029764375 (Scopus ID)
Available from: 2017-10-17 Created: 2017-10-17 Last updated: 2017-12-04Bibliographically approved
Yang, F., Pedersen, N. L., Ye, W., Liu, Z., Norberg, M., Forsgren, L., . . . Wirdefeldt, K. (2017). Moist smokeless tobacco (Snus) use and risk of Parkinson's disease. International Journal of Epidemiology, 46(3), 872-880, Article ID dyw294.
Open this publication in new window or tab >>Moist smokeless tobacco (Snus) use and risk of Parkinson's disease
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2017 (English)In: International Journal of Epidemiology, ISSN 0300-5771, E-ISSN 1464-3685, Vol. 46, no 3, p. 872-880, article id dyw294Article in journal (Refereed) Published
Abstract [en]

Background: Cigarette smoking is associated with a lower risk of Parkinson's disease. It is unclear what constituent of tobacco smoke may lower the risk. Use of Swedish moist smokeless tobacco (snus) can serve as a model to disentangle what constituent of tobacco smoke may lower the risk. The aim of this study was to determine whether snus use was associated with a lower risk of Parkinson's disease. Methods: Individual participant data were collected from seven prospective cohort studies, including 348 601 men. We used survival analysis with multivariable Cox regression to estimate study-specific relative risk of Parkinson's disease due to snus use, and random-effects models to pool estimates in a meta-analysis. The primary analyses were restricted to never-smokers to eliminate the potential confounding effect of tobacco smoking. Results: During a mean follow-up time of 16.1 years, 1199 incident Parkinson's disease cases were identified. Among men who never smoked, ever-snus users had about 60% lower Parkinson's disease risk compared with never-snus users [pooled hazard ratio (HR) 0.41, 95% confidence interval (CI) 0.28-0.61]. The inverse association between snus use and Parkinson's disease risk was more pronounced in current (pooled HR 0.38, 95% CI 0.23-0.63), moderate-heavy amount (pooled HR 0.41, 95% CI 0.19-0.90) and long-term snus users (pooled HR 0.44, 95% CI 0.24-0.83). Conclusions: Non-smoking men who used snus had a substantially lower risk of Parkinson's disease. Results also indicated an inverse dose-response relationship between snus use and Parkinson's disease risk. Our findings suggest that nicotine or other components of tobacco leaves may influence the development of Parkinson's disease.

Keywords
Parkinson's disease, individual participant data, risk factors, epidemiology, nicotine
National Category
Health Sciences
Identifiers
urn:nbn:se:miun:diva-31833 (URN)10.1093/ije/dyw294 (DOI)000406242600021 ()2-s2.0-85027731926 (Scopus ID)
Available from: 2017-10-12 Created: 2017-10-12 Last updated: 2017-11-29Bibliographically approved
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