Simon Øverland

The epidemiology of insomnia: associations with physical and mental health. The HUNT-2 study.

OBJECTIVE The aim of the present study was to examine the association of insomnia symptoms with demographic and physical and mental conditions in a large population-based study. METHODS Cross-sectional data on insomnia and comorbid conditions were gathered from 47,700 individuals aged 20-89 in Norway. Comorbid conditions included anxiety and depression and the following physical conditions: asthma, allergy, cancer, hypertension, diabetes, migraine, headache, osteoporosis, fibromyalgia rheumatoid arthritis, arthrosis, Bechterews disease, musculoskeletal disorders, and obesity (body mass index >30). RESULTS Insomnia symptoms were found in 13.5% of the population and were more prevalent among women, older adults, and in individuals with less education. Reporting insomnia symptoms significantly increased the associations with a range of conditions, especially mental conditions, pain conditions with uncertain etiology and, to a lesser extent, chronic pain conditions. These findings remained significant also when adjusting for a range of potential confounders, whereas the association between insomnia and somatic conditions was largely reduced to a nonsignificant level in the fully adjusted analyses. CONCLUSION This study demonstrates that insomnia symptoms are associated with a range of different conditions. The findings suggest that the independent contribution of insomnia is strongest on conditions characterized by some level of psychological or psychosomatic properties.

Anxiety, depression, and cause-specific mortality: the HUNT study.

Objective: To investigate empirically the association between anxiety/depression and cause-specific mortality with particular attention to the underlying mechanisms and causes of death. Depression reportedly increases general mortality. For cause-specific mortality, there is evidence depression has an effect on cardiovascular disease (CVD) mortality and suicide. Less information is known as to other mortality diagnoses. There is scarce and conflicting literature on anxiety in relation to mortality. Methods: Employing a historical cohort design, we used a link between an epidemiological cohort study and a comprehensive national mortality database. We gathered baseline information on physical and mental health (Hospital Anxiety and Depression Scale, HADS) from the population-based health study (n = 61,349). Causes of death were registered with International Classification of Diagnoses, 10th edition (ICD-10) during mean follow-up of 4.4 years. Results: Case-level depression increased the mortality rate for all major disease-related causes of death, whereas case-level anxiety and comorbid anxiety/depression did not. The effect of depression was similar for cardiac mortality compared with all other causes combined, and confounding effects were also very similar. Symptom load of anxiety was associated negatively with both CVD and other cause mortality in fully adjusted models. Accidents and suicide were associated primarily with comorbid anxiety/depression. Conclusions: Depression is a risk factor for all major disease-related causes of death; it is not limited to CVD mortality or suicide. Because the association between depression and cardiac mortality was comparable to the other causes of death combined and confounding and mediating factors were markedly similar, future investigation as to the mechanisms underlying the effect of depression on mortality should not be limited to CVD mortality. BMI = body mass index; CAGE = screening instrument for alcohol problems; CVD = cardiovascular disease; HADS = Hospital Anxiety and Depression Scale (A or D for subscales); ICD-8/9/10 = International Classification of Diagnoses, 8th/9th/10th edition; OR = odds ratio; HUNT = Health Study of Nord-Trøndelag County, Norway.

The Health Status of Nonparticipants in a Population-based Health Study The Hordaland Health Study

The authors aimed to examine whether nonparticipation in a population-based health study was associated with poorer health status; to determine whether specific health problems were overrepresented among nonparticipants; and to explore potential consequences of participation bias on associations between exposures and outcomes. They used data from the Hordaland Health Study (HUSK), conducted in western Norway in 1997-1999. Of 29,400 persons invited, 63.1% participated in the study. Information from HUSK was linked with the Norwegian national registry of disability pensions (DPs), including information about DP diagnosis. The risk of DP receipt was almost twice as high among nonparticipants as participants (relative risk = 1.88, 95% confidence interval: 1.81, 1.95). The association was strongest for DPs received for mental disorders, with a 3-fold increased risk for nonparticipation. Substance abuse, psychotic disorders, and personality disorders were especially overrepresented among nonparticipants. The authors simulated the impact of nonparticipation on associations between exposures and outcomes by excluding HUSK participants with higher symptoms of common mental disorders (exposure) and examining the impact on DP (outcome). This selective exclusion modestly reduced associations between common mental disorders and DP. The authors conclude that nonparticipants have poorer health, but this is disorder-dependent. Participation bias is probably a greater threat to the validity of prevalence studies than to studies of associations between exposures and outcomes.

Levels of anxiety and depression as predictors of mortality: the HUNT study

BACKGROUND Depression is reported to be associated with increased mortality, although underlying mechanisms are uncertain. Associations between anxiety and mortality are also uncertain. AIMS To investigate associations between individual and combined anxiety/depression symptom loads (using the Hospital Anxiety and Depression Scale (HADS)) and mortality over a 3-6 year period. METHOD We utilised a unique link between a large population survey (HUNT-2, n = 61 349) and a comprehensive mortality database. RESULTS Case-level depression was associated with increased mortality (hazard ratio (HR) = 1.52, 95% CI 1.35-1.72) comparable with that of smoking (HR = 1.59, 95% CI 1.44-1.75), and which was only partly explained by somatic symptoms/conditions. Anxiety comorbid with depression lowered mortality compared with depression alone (anxiety depression interaction P = 0.017). The association between anxiety symptom load and mortality was U-shaped. CONCLUSIONS Depression as a risk factor for mortality was comparable in strength to smoking. Comorbid anxiety reduced mortality compared with depression alone. The relationship between anxiety symptoms and mortality was more complex with a U-shape and highest mortality in those with the lowest anxiety symptom loads.

Work and common psychiatric disorders

Psychiatric disorders are now the most common reason for long-term sickness absence. The associated loss in productivity and the payment of disability benefits places a substantial burden on the economies of many developed countries. The occupational dysfunction associated with psychiatric disorders can also lead to poverty and social isolation. As a result the area of work and psychiatric disorders is a high priority for policymakers. There are two main agendas: for many researchers and clinicians the focus is on the need to overcome stigma and ensure people with severe psychiatric disorders have meaningful work; however the public health agenda predominantly relates to the more common disorders such as depression and anxiety, which contribute a greater burden of disability benefits and pensions. In this review we attempt to address this second agenda. The relatively sparse evidence available reveals a complex field with significant interplay between medical, psychological social and cultural factors. Sick leave can be a ‘process’ as well as an ‘event’. In this review we propose a staged model where different risk and protective factors contribute to the onset of psychiatric disorders in the working population, the onset of short-term sickness absence, and the transition from short- to long-term absence. We also examine strategies to manage psychiatric disorder in the workforce with a view towards returning the employee to work. Our aim in this review is to highlight the complexity of the area, to stimulate debate and to identify important gaps in knowledge where further research might benefit both patients and wider society.

Physical activity and common mental disorders

BACKGROUND Previous studies have suggested that physical activity may have antidepressant and/or anti-anxiety effects. AIMS To examine the bidirectional relationship between physical activity and common mental disorders and establish the importance of context, type and intensity of activity undertaken. METHOD A clinical examination of 40 401 residents of Norway was undertaken. Participants answered questions relating to the frequency and intensity of both leisure-time and workplace activity. Depression and anxiety were measured using the Hospital Anxiety and Depression Scale (HADS). Biological and social data were also collected. RESULTS There was an inverse relationship between the amount of leisure-time physical activity and case-level symptoms of depression. This cross-sectional association was only present with leisure-time (as opposed to workplace) activity and was not dependent on the intensity of activities undertaken. Higher levels of social support and social engagement were important in explaining the relationship between leisure activity and depression. Biological changes such as alterations to parasympathetic vagal tone (resting pulse) and changes to metabolic markers had a less important role. CONCLUSIONS Individuals who engage in regular leisure-time activity of any intensity are less likely to have symptoms of depression. The context and social benefits of exercise are important in explaining this relationship.

The bidirectional association between depression and insomnia: the HUNT study.

Objective Depression and insomnia are closely linked, yet our understanding of their prospective relationships remains limited. The aim of the current study was to investigate the directionality of association between depression and insomnia. Methods Data were collected from a prospective population-based study comprising the most recent waves of the Nord-Trøndelag Health Study (HUNT) (the HUNT2 in 1995–1997 and the HUNT3 in 2006–2008). A total of 24,715 persons provided valid responses on the relevant questionnaires from both surveys. Study outcomes were onset of depression or insomnia at HUNT3 in persons not reporting the other disorder in HUNT2. Results Both insomnia and depression significantly predicted the onset of the other disorder. Participants who did not have depression in HUNT2 but who had insomnia in both HUNT2 and HUNT3 had an odds ratio (OR) of 6.2 of developing depression at HUNT3. Participants who did not have insomnia in HUNT2 but who had depression in both HUNT2 and HUNT3 had an OR of 6.7 of developing insomnia at HUNT3. ORs were only slightly attenuated when adjusting for potential confounding factors. Conclusions The results support a bidirectional relationship between insomnia and depression. This finding stands in contrast to the previous studies, which have mainly focused on insomnia as a risk factor for the onset of depression.

Association Between Magnesium Intake and Depression and Anxiety in Community-Dwelling Adults: The Hordaland Health Study:

Objective: Systemic inflammation is associated with both the dietary intake of magnesium, and depression. Limited experimental and clinical data suggest an association between magnesium and depression. Thus, there are reasons to consider dietary magnesium as a variable of interest in depressive disorders. The aim of the present study was to examine the association between magnesium intake and depression and anxiety in a large sample of community-dwelling men and women. This sample consisted of 5708 individuals aged 46–49 or 70–74 years who participated in the Hordaland Health Study in Western Norway. Methods: Symptoms of depression and anxiety were self-reported using the Hospital Anxiety and Depression Scale, and magnesium intake was assessed using a comprehensive food frequency questionnaire. Results: There was an inverse association between standardized energy-adjusted magnesium intake and standardized depression scores that was not confounded by age, gender, body habitus or blood pressure (β=−0.16, 95% confidence interval (CI)=−0.22 to −0.11). The association was attenuated after adjustment for socioeconomic and lifestyle variables, but remained statistically significant (β=−0.11, 95%CI=−0.16 to −0.05). Standardized magnesium intake was also related to case-level depression (odds ratio (OR)=0.70, 95%CI=0.56–0.88), although the association was attenuated when adjusted for socioeconomic and lifestyle factors (OR=0.86, 95%CI=0.69–1.08). The inverse relationship between magnesium intake and score and case-level anxiety was weaker and not statistically significant in the fully adjusted models. Conclusion: The hypothesis that magnesium intake is related to depression in the community is supported by the present findings. These findings may have public health and treatment implications.

Insomnia as a risk factor for ill health: results from the large population-based prospective HUNT Study in Norway

Insomnia co‐occurs with many health problems, but less is known about the prospective associations. The aim of the current study was to investigate if insomnia predicts cumulative incidence of mental and physical conditions. Prospective population‐based data from the two last Nord‐Trøndelag Health Studies (HUNT2 in 1995–97 and HUNT3 in 2006–08), comprising 24 715 people in the working population, were used to study insomnia as a risk factor for incidence of physical and mental conditions. Insomnia was defined according to the 4th edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM‐IV). Insomnia at HUNT2 was a significant risk factor for incidence of a range of both mental and physical conditions at HUNT3 11 years later. Most effects were only slightly attenuated when adjusting for confounding factors, and insomnia remained a significant risk factor for the following conditions in the adjusted analyses: depression [odds ratio (OR): 2.38, 95% confidence interval (CI): 1.91–2.98], anxiety (OR: 2.08, 95% CI: 1.63–2.64), fibromyalgia (OR: 2.05, 95% CI: 1.51–2.79), rheumatoid arthritis (OR: 1.87, 95% CI: 1.29–2.52), whiplash (OR: 1.71, 95% CI: 1.21–2.41), arthrosis (OR: 1.68, 95% CI: 1.43–1.98), osteoporosis (OR: 1.52, 95% CI: 1.14–2.01, headache (OR: 1.50, 95% CI: 1.16–1.95, asthma (OR: 1.47, 95% CI: 1.16–1.86 and myocardial infarction (OR: 1.46, 95% CI: 1.06–2.00). Insomnia was also associated significantly with incidence of angina, hypertension, obesity and stroke in the crude analyses, but not after adjusting for confounders. We conclude that insomnia predicts cumulative incidence of several physical and mental conditions. These results may have important clinical implications, and whether or not treatment of insomnia would have a preventive value for both physical and mental conditions should be studied further.

Common mental disorders and long-term sickness absence in a general working population. The Hordaland Health Study.

Objective:  To examine and compare the prospective effect of the common mental disorders (CMD) anxiety and depression on duration and recurrence of sickness absence (SA), and to investigate whether the effect of CMD on SA is detectable over time.