Andreas Moses Appel

Background: WHO considers mental disorders a significant disease burden among children and adolescents. However, there is a lack of population-based studies on the time trends of mental disorder diagnosis in this group. Objective: To investigate changes in the incidence of clinical diagnoses of mental disorders among all Danish children and adolescents in the past 3 decades. Methods: In this retrospective cohort study, we included all Danish-born individuals from 1976. Follow-up started in 1994 until first diagnosis of a mental disorder, 18th birthday, emigration from Denmark, death or end of study on 30 June 2023. Sex-specific cumulative incidences of diagnosis by age 18 were calculated in 5-year birth cohorts from 1976–1980 to 2001–2005 using the Kaplan-Meier estimator. Poisson regression was used to estimate the age-specific and sex-specific incidence rates. Findings: From 1994 to 2023, a total of 193 354 children and adolescents received a mental disorder diagnosis. Over 3 decades the cumulative incidence of any mental disorder diagnosis before age 18 increased from 1.46% (95% CI 1.40% to 1.52%) to 14.56% (95% CI 14.36% to 14.76%) among females and from 1.22% (95% CI 1.16% to 1.27%) to 14.77% (95% CI 14.57% to 14.96%) among males. A lower mean age at first diagnosis accounted for an estimated 15–22% of the observed incidence in the most recent years. Conclusions: This study demonstrates a large increase in mental disorder diagnoses. Observed rates were in part accounted for by decreasing age at first diagnosis. While some of the remaining increase may reflect a true rise in the underlying prevalence of mental disorders, changes in diagnostic practice and greater awareness of mental disorders are probable contributors. Clinical implications: Estimates of specific diagnostic rates are essential for appropriate healthcare planning and resource allocation to accommodate the increasing number of mental disorder diagnoses among children and adolescents.

Introduction: People with dementia have an increased risk for infection‐related complications, which may be mitigated by common vaccinations. The aim was to investigate the association between influenza vaccination and the rates of all‐cause and influenza‐related hospitalizations and deaths among older adults with dementia. Methods: We followed all Danish residents with dementia aged 65 and above from September 1, 2002, to August 31, 2018. Dementia was defined from records in the Danish national registries (positive predictive value 85.8%). People with dementia were identified on September 1 of each year. On this date, vaccination status was also reset, and the status of covariates was assessed. We used proportional hazard Cox regression to compare rates of all‐cause hospitalization, hospitalization with a respiratory infection, hospitalization with influenza or pneumonia, and all‐cause mortality for vaccinated and unvaccinated. Results: Across the entire study period, we included 134,002 people with dementia. Rates of hospitalization were 9%–10% lower, and the mortality rate 9% lower, for vaccinated compared to unvaccinated among people with dementia. Discussion: Influenza vaccination was associated with lower rates of hospitalization and mortality among people with dementia. Further exploration of the preventive potential of influenza vaccination among people with dementia is important for shaping interventions in this vulnerable group.

Background and Purpose: Previous studies have reported conflicting results regarding the association between influenza vaccination and dementia. This association was investigated in a nationwide register‐based cohort study.Methods: Using nationwide registries, dementia‐free adults aged ≥65 years in Denmark from 2002 to 2018 without previous influenza vaccinations were included. Poisson regression facilitated confounder‐adjusted comparisons of dementia rates for ever versus never vaccinated, number of vaccinations and within/after 5 years from first vaccination. Sensitivity analyses included stratification on age and sex.Results: Vaccination during follow‐up was associated with a slightly higher rate of dementia when adjusted for sociodemographic factors and comorbidities, both within and after the first 5 years from first vaccination (incidence rate ratio [IRR] 1.04; 95% confidence interval [CI] 1.03–1.05). The rate of dementia decreased with increasing number of vaccinations. The highest rate was amongst those with only one vaccination (IRR 1.14; 95% CI 1.12–1.17) and the rate of dementia was only decreased amongst those with six or more vaccinations (IRR 0.95; 95% CI 0.93–0.97). Applying the same models to control outcomes of hip fracture and cancer resulted in higher rates amongst vaccinated people of 6% and 7%, respectively. Vaccinated people also had a 10% higher mortality rate.Discussion: Our results do not support the case for a preventive effect of influenza vaccination on the risk of dementia in the general population, as reported by some previous studies. However, the higher dementia rate amongst vaccinated people found in this study is probably due to residual confounding, indicated by a higher rate for control outcomes and mortality.

Objectives: Previous research on the association between socioeconomic position (SEP) and dementia has not sufficiently accounted for the complex relationship between education and occupation. We investigated the independent and joint effects of educational attainment and occupation-based SEP on dementia. Methods: We used register-based information about educational attainment, occupation-based SEP, and dementia from 1,210,720 individuals. Information about cognitive ability at conscription was available for a subsample of men. Results: When mutually adjusted, lower educational attainment and occupation-based SEP were associated with higher dementia risk in a dose–response manner. Higher occupation-based SEP partly mitigated the higher dementia risk associated with lower educational attainment. After adjusting for cognitive ability in a subgroup of men, only unskilled work was associated with higher dementia risk. Discussion: Occupation-based SEP is independently associated with dementia and may mitigate the higher dementia risk associated with short education. Future research should elucidate the mechanisms underlying social inequality in dementia.

Purpose We investigated the effect of shift work on headache. Furthermore, we investigated whether the association between shift work and headache was explained by potential mediators in terms of perceived stress, poor sleep and health behaviors. Methods In this longitudinal study, we used questionnaire data (collected in 2007 and 2009) from civil servants and hospital employees from the PRISME study. 2952 individuals were available for the analyses of shift work and headache and 2272 individuals were available for the analyses of shift work and migraine. Headache was operationalized as the participants’ experience of “being bothered by headache during the past 4 weeks”. Migraine was operationalized as “ever being diagnosed with migraine by a medical doctor”. We used binary logistic regression to compare shift workers with permanent day workers and adjusted for socio-demographic factors. In a subsequent step, we adjusted for potential mediators. Results We found higher odds of unspecific headache (OR = 1.25; 95% CI 1.02–1.54) and migraine (OR = 1.72; 95% CI 1.04–2.86) among shift workers compared with day workers. Our results suggest that the effect of shift work on headache and migraine differ between men and women. Inclusion of potential mediators in the analyses did not attenuate the associations. Conclusion Shift workers have higher risk of reporting being bothered by headache as well as reporting being diagnosed with migraine. Future research is needed to disentangle the underlying mechanisms with the aim of reducing headache related to occupational exposures.