Introduction:The aim of this study was to investigate the registry-based national time trends in incidence and prevalence rates of dementia from 1996 to 2015. Methods: We assessed annual incidence and prevalence using longitudinal data from nationwide registries on dementia status and demographics on all residents 65 years old in Denmark. Results: Our population comprised 2 million people, of whom 152,761 were diagnosed with dementia. The age-and sex-adjusted incidence rate increased, on average, by 9% annually from 1996 to 2003, followed by a 2% annual decline, while total prevalence increased during the whole period. Discussion: This is the first study to report continuous time trends of incidence and prevalence in an entire national population. The incidence rate has declined steadily since 2003, while the total prevalence is still increasing. Future health care planning on prevention and treatment of dementia should take these findings into account.

Background: Previous studies found an association between migraine and dementia, which are two leading causes of disability. However, these studies did not differentiate between migraine types and did not investigate all prevalent dementia subtypes. The main objective of this national register-based study was to investigate whether migraine was a risk factor for dementia. Additionally, we explored potential differences in dementia risk for migraine with and without aura. Methods: We obtained data on birth cohorts born between 1935 and 1956 (n = 1,657,890) from Danish national registers. Individuals registered with migraine before age 59 (n = 18,135) were matched (1:5) on sex and birthdate with individuals without migraine (n = 1,378,346). Migraine was defined by International Classification of Diseases (ICD) diagnoses and dementia was defined by ICD diagnoses and anti-dementia medication. After matching, 62,578 individuals were eligible for analysis. For the statistical analyses, we used Cox regression models and adjusted for socio-demographic factors and several psychiatric and somatic morbidities. Results: During a median follow-up time of 6.9 (IQR: 3.6-11.2) years, 207 individuals with migraine developed dementia. Compared with individuals without migraine, we found a 50% higher rate of dementia among individuals with migraine (HR = 1.50; 95% CI: 1.28-1.76). Individuals without aura had a 19% higher rate of dementia (HR = 1.19; 95% CI: 0.84-1.70), and individuals with aura had a two times higher rate of dementia (HR = 2.11; 95% CI: 1.48-3.00). Conclusions: Our findings support the hypothesis that migraine is a midlife risk factor for dementia in later life. The higher rate of dementia in individuals with a hospital-based diagnosis of migraine with aura emphasizes the need for studies on pathological mechanisms and potential preventative measures. Furthermore, given that only hospitalbased migraine diagnoses were included in this study, future research should also investigate migraine cases derived from the primary healthcare system to include less severe migraine cases.

Recent reviews and meta-analyses consistently support that physical activity (PA) has a positive effect on incident dementia. 1-3 Some of the suggested main mechanisms linking PA with dementia are improved cerebral blood flow, neurogenesis, and preservation of hippocampal volume. 2,3 Yet, the available epidemiological evidence for a positive effect of PA on dementia is actually restricted to leisure-time physical activity (LTPA), for example, sports, recreation, and transportation. Nevertheless, current guidelines recommend moderate to vigorous PA as a means to reduce dementia risk. 4 Still, despite the limited knowledge on the effect of OPA on, for instance, dementia neither general nor the dementia-specific guidelines for PA explicitly differentiate between LTPA and occupational physical activity (OPA). 5,6 Additionally, even for LTPA and cognitive health, little is known about the necessary dose, for example, in terms of duration, frequency, or intensity. 4

ObjectiveShift work and long working hours are potential risk factors for dementia, but previous studies on shift work, long working hours and dementia are sparse and their findings are conflicting. Therefore, we investigated the effect of night shift work and long working hours on dementia.DesignA longitudinal study.SettingDenmark.Participants3435 occupationally active men and women from the general working population.MethodsWork schedule covered day work (reference) and shift schedules without/with night work. Working hours covered <27, 28–36, 37 (reference), 38–44, and ≥45 hours/week. As the primary outcome, we used register-based information about dementia, and estimated incidence rate ratios (IRR) and 95% CI. Estimates were adjusted for gender, age, psychosocial work factors and cardiovascular risk factors.ResultsWe identified 85 dementia cases during a mean of 9.8 years of follow-up. We found a positive, but statistically insignificant association between night shift work and dementia (IRR=2.01; 95% CI: 0.87-4.65). Post hoc analyses indicated that this was only due to a higher risk in permanent night workers (IRR=3.25; 95% CI: 1.35-7.83). The dementia risk was also significantly higher among participants working 38–44 hours/week (IRR=2.08; 95% CI: 1.11-3.90) compared with those working 37 hours/week. We found no indications of a higher risk of dementia in participants working <37 hours/week or ≥45 hours/week.ConclusionWe did not find arguments that night shift work or long working hours increased dementia risk in general. However, we found a higher risk of dementia in specific subgroups, that is, permanent night workers and employees with moderately longer weekly working hours than the standard.

Background Migrants and ethnic minorities have been shown to be at increased risk of hospitalization from COVID-19, our aim was to analyze the contribution of socioeconomic and demographic risk factors on hospital admissions for COVID-19 among migrants and ethnic minorities compared to the majority population. Methods We used nationwide register data on all hospitalized COVID-19 cases between February and June 2020 (n = 2232) and random controls from the general population (n = 498117). We performed logistic regression analyses, adjusting for age, sex, comorbidity, and socioeconomic and demographic factors. Main outcome measure was Hospitalization with COVID-19. Odds ratios (OR) and 95% confidence intervals (95% CI) are estimated by using logistic regression analyses, adjusting for age, sex, comorbidity, and socioeconomic and demographic factors. Results Among 2232 COVID-19 cases, the OR of hospitalization with COVID-19 among immigrants and descendants of Non-Western origin was 2.5 times higher (95% CI: 2.23 to 2.89) than that of the majority population, with most pronounced results among individuals from Iraq, Morocco, Pakistan, and Somalia. The OR was largely attributed to comorbidity and socioeconomic factors, especially household size, occupation, and population density. Conclusion There is a significantly higher OR of hospitalization with COVID-19 among Non-Western migrants and ethnic minorities compared with ethnic Danes. This knowledge is crucial for health policymakers and practitioners in both the current and future pandemics to identify more vulnerable groups and target prevention initiatives.