The bidirectional association between psychiatric disorders and sheltered homelessness.

BACKGROUND: Psychiatric disorders and homelessness are related, but temporal associations are unclear. We aimed to explore the overlap between hospital-based psychiatric disorders and sheltered homelessness. METHODS: This population-based cohort study was conducted using the Danish registers e.g., the Danish Homeless Register and the Danish National Patient Register. The study cohort included all individuals aged 15 years or older, living in Denmark at least one day during 2002-2021 (born 1984-2006). First psychiatric diagnosis was used to define psychiatric disorder and first homeless shelter contact to define homelessness. Adjusted incidence rate ratios (IRRs) and cumulative incidences were estimated. RESULTS: Among 1 530 325 individuals accounting for 16 787 562 person-years at risk aged 15-38 years, 11 433 (0.8%) had at least one homeless shelter contact. Among 1 406 410 individuals accounting for 14 131 060 person-years at risk, 210 730 had at least one psychiatric disorder. People with any psychiatric disorder had increased risk of sheltered homelessness relative to individuals with no psychiatric disorder [IRR 9.2, 95% confidence interval (CI) 8.8-9.6]. Ten years after first psychiatric disorder, 3.0% (95% CI 2.9-3.1) had at least one homeless shelter contact. Individuals experiencing homelessness had increased risk of any psychiatric disorder compared to individuals with no homeless shelter contact (IRR 7.0, 95% CI 6.7-7.4). Ten years after first homeless shelter contact, 47.1% (45.3-48.0) had received a hospital-based psychiatric diagnosis. CONCLUSION: Strong bidirectional associations between psychiatric disorders and homelessness were identified. Health and social care professionals should be aware of and address these high risks of accumulated psychiatric and social problems.

Association of maternal and paternal personality disorders with risk of mental disorders in children: A nationwide, register-based cohort study of 1,406,965 children.

BACKGROUND: Knowledge of the association between parental personality disorders and mental disorders in children is limited. To examine the association between parental personality disorders and the risk of mental disorders in offspring. METHODS: We linked Danish health registers to create a cohort of children born from January 1, 1995, to December 31, 2016. Children were followed until their 18th birthday, diagnosis set, emigration, death, or December 31, 2016. Parental personality disorders according to the International Classification of Diseases (ICD) Eighth or 10th Revision. Poisson regression analyses were used to estimate the incidence risk ratio (IRR) and cumulative incidence of ICD 10th mental disorders in offspring (age 0-17). RESULTS: The study cohort included 1,406,965 children. For girls, maternal or paternal personality disorder (MPD/PPD) was associated with mental disorders: MPD girls (IRR, 2.74; 95% CI, 2.59-2.89) and PPD girls (IRR, 2.10; 95% CI, 1.94-2.27). Likewise, the risk was increased for both MPD boys (IRR, 2.44; 95% CI, 2.33-2.56) and PPD boys (IRR, 2.04; 95% CI, 1.91-2.18). For girls and boys combined, exposure to two parents with a personality disorder was associated with the highest risk (IRR, 3.69; 95% CI, 3.15-4.33). At age 18, the cumulative incidence of any mental disorder in children of one or two parents with a personality disorder was 34.1% (95% CI, 33.0-35.1), which was twice the cumulative incidence of mental disorders in nonexposed children (15.2% [95% CI, 15.1-15.3]). CONCLUSION: Children of parents with a personality disorder were at a 2 to 3.5 times higher risk of mental disorders compared with nonexposed offspring. Possible mechanisms of transmission of mental disorders from parent to child involve genetic, environmental, and gene-environment pathways. More research into these mechanisms and research into preventive interventions is warranted.

A comprehensive analysis of age of onset and cumulative incidence of mental disorders: A Danish register study.

BACKGROUND: The age of onset (AOO), incidence and cumulative incidence of mental disorders are critical epidemiological measures, providing essential insights into the development and course of these disorders across the lifespan. This study aims to provide up-to-date estimates of the AOO, age-specific incidence, and cumulative incidence for a comprehensive range of mental disorders using data from Danish registers. METHODS: We conducted a follow-up study encompassing all Danish residents from January 1, 2004, to December 31, 2021, totaling 91,613,465 person-years. Data were sourced from the Danish Psychiatric Central Research Register, identifying individuals treated for various mental disorders in psychiatric hospitals, outpatient departments, and accident/emergency departments, that is, treated in secondary care settings. We investigated specific categories of mental disorders, including substance abuse disorders, schizophrenia, mood disorders, anxiety, eating disorders, borderline personality disorders, intellectual disabilities, pervasive developmental disorders, and behavioral and emotional disorders. Age-sex-specific incidence rates were estimated using Poisson generalized linear models, and cumulative incidence was calculated using Aalen-Johansen's competing risks model. The study provides estimates of AOO, incidence, and cumulative incidence for various mental disorders, including their age and sex distributions. RESULTS: The cumulative incidence by age 80 years for any mental disorder was 30.72% (95% confidence interval: 30.62%-30.83%) for males and 34.46% (34.35%-34.57%) for females. The most common types of mental disorders were anxiety-related disorders 16.27% (16.19%-16.36%) for males and 23.39% (23.29%-23.50%) for females, and followed by mood disorder 10.34% (10.27%-10.41%) for males and 16.67% (16.58%-16.77%) for females. For those who develop mental disorder, half will have developed their disorder by approximately age 22 years (median and interquartile range: males 21.37 (11.85-36.00); females 22.55 (16.31-36.08)). CONCLUSIONS: Approximately one in three individuals will seek treatment for at least one mental disorder in a secondary care setting by age 80. Given that half of these individuals develop mental disorders before age 22, it is crucial to tailor service planning to meet the specific needs of young individuals. Web-based interactive data-visualization tools are provided for clinical utility.

Cause-specific mortality and life years lost in people with epilepsy: a Danish cohort study.

Mortality rates are two to three times higher in people with epilepsy than in the general population. This study aimed to quantify how this increased mortality translates into reduced life expectancy and to identify the underlying causes of deaths, thereby offering suggestions for how to reduce mortality associated with epilepsy. In this population-based cohort study, we included all individuals aged 0-94 years who were living in Denmark between 2000 and 2015. Using the nationwide registers, we identified people diagnosed with epilepsy and estimated the excess of life years lost due to 13 overall and nine specific causes of death. Among 6 022 160 people, we identified 129 598 with epilepsy (52.6% males), with a mean age of epilepsy onset of 36.5 years (standard deviation = 26.3 years). During the 16 years of follow-up, 851 087 individuals died, and of these 36 923 had been diagnosed with epilepsy. The average reduction in life expectancy in people with epilepsy was 11.84 years in males (95% confidence interval: 11.66-12.00) and 10.91 years in females (95% confidence interval: 10.70-11.11) compared to the general population. Life expectancy was reduced irrespective of epilepsy aetiology (symptomatic ∼14 years; idiopathic ∼8-10 years), and in particular in people with epilepsy and psychiatric comorbidity (∼13-16 years). Excess mortality was evident across all causes of death including cardiovascular disorders, accidents, and suicide. People with epilepsy experience a substantial reduction in lifespan that can only partly be explained by underlying conditions. Prevention of epilepsy-related deaths should focus on the consequences of psychiatric comorbidity and on modifiable risk factors associated with preventable causes of death such as accidents and neurological and cardiovascular disorders.

Proton pump inhibitors and dementia: A nationwide population-based study.

INTRODUCTION: Proton pump inhibitors (PPIs) may increase dementia risk. However, it is currently unknown whether timing of exposure or age at dementia diagnosis influence the risk. METHODS: We assessed associations between cumulative PPI use and dementia at different ages in a nationwide Danish cohort of 1,983,785 individuals aged 60 to 75 years between 2000 and 2018. RESULTS: During follow-up, there were 99,384 all-cause dementia incidences. Incidence rate ratio (IRR) of dementia with PPI ever-use compared with never-use was 1.36 (95% CI, 1.29 to 1.43) for age 60 to 69 years at diagnosis, 1.12 (1.09 to 1.15) for 70 to 79 years, 1.06 (1.03 to 1.09) for 80 to 89 years, and 1.03 (0.91 to 1.17) for 90+ years. Longer treatment duration yielded increasing IRRs. For cases below 90 years, increased dementia rate was observed regardless of treatment initiation up to >15 years before diagnosis. DISCUSSION: Regardless of timing of treatment initiation, PPI use was associated with increased dementia rate before age 90 years. Dementia rates increased with younger age at diagnosis. HIGHLIGHTS: After following 1,983,785 individuals for a median of 10 years, 99,384 developed dementia PPIs were used by 21.2% of cases and 18.9% of controls PPI use was associated with increased dementia rate regardless of time of treatment onset Magnitude of associations increased with younger age at diagnosis PPI use was not associated with dementia occurring after age 90 years.

Association between SARS-CoV-2 infection and self-harm: Danish nationwide register-based cohort study.

BACKGROUND: Case studies have linked SARS-CoV-2 infection to suicidal behaviour. However, conclusive evidence is lacking. AIMS: To examine whether a history of SARS-CoV-2 infection or SARS-CoV-2-related hospital admission was associated with self-harm in the general population and in high-risk groups. METHOD: A cohort design was applied to nationwide data on all people aged ≥15 years and living in Denmark between 27 February 2020 and 15 October 2021. Exposure was identified as having had a positive SARS-CoV-2 PCR test, and further assessed as SARS-CoV-2-related hospital admission. Rates of probable self-harm were examined using adjusted incidence rate ratios (aIRRs). The following subgroups were identified: (a) lower educational level, (b) chronic medical conditions, (c) disability pension, (d) mental disorders, (e) substance use disorders, and history of (f) homelessness and (g) imprisonment. RESULTS: Among 4 412 248 included individuals, 260 663 (5.9%) had tested positive for SARS-CoV-2. Out of 5453 individuals presenting with self-harm, 131 (2.4%) had been infected. Individuals with a history of a positive SARS-CoV-2 test result had an aIRR for self-harm of 0.86 (95% CI 0.72-1.03) compared with those without. High rates were found after a SARS-CoV-2-related hospital admission (aIRR = 7.68; 95% CI 5.61-10.51) or a non-SARS-CoV-2-related admission (aIRR = 10.27; 95% CI 9.65-10.93) versus non-infected and not admitted. In sensitivity analyses with a more restrictive definition of self-harm, a positive PCR test was associated with lower rates of self-harm. CONCLUSIONS: Individuals with a PCR-confirmed SARS-CoV-2 infection did not have higher rates of self-harm than those without. Hospital admission in general, rather than being SARS-CoV-2 positive. seemed to be linked to elevated rates of self-harm.

Analysis of mortality metrics associated with a comprehensive range of disorders in Denmark, 2000 to 2018: A population-based cohort study.

BACKGROUND: The provision of different types of mortality metrics (e.g., mortality rate ratios [MRRs] and life expectancy) allows the research community to access a more informative set of health metrics. The aim of this study was to provide a panel of mortality metrics associated with a comprehensive range of disorders and to design a web page to visualize all results. METHODS AND FINDINGS: In a population-based cohort of all 7,378,598 persons living in Denmark at some point between 2000 and 2018, we identified individuals diagnosed at hospitals with 1,803 specific categories of disorders through the International Classification of Diseases-10th Revision (ICD-10) in the National Patient Register. Information on date and cause of death was obtained from the Registry of Causes of Death. For each of the disorders, a panel of epidemiological and mortality metrics was estimated, including incidence rates, age-of-onset distributions, MRRs, and differences in life expectancy (estimated as life years lost [LYLs]). Additionally, we examined models that adjusted for measures of air pollution to explore potential associations with MRRs. We focus on 39 general medical conditions to simplify the presentation of results, which cover 10 broad categories: circulatory, endocrine, pulmonary, gastrointestinal, urogenital, musculoskeletal, hematologic, mental, and neurologic conditions and cancer. A total of 3,676,694 males and 3,701,904 females were followed up for 101.7 million person-years. During the 19-year follow-up period, 1,034,273 persons (14.0%) died. For 37 of the 39 selected medical conditions, mortality rates were larger and life expectancy shorter compared to the Danish general population. For these 37 disorders, MRRs ranged from 1.09 (95% confidence interval [CI]: 1.09 to 1.10) for vision problems to 7.85 (7.77 to 7.93) for chronic liver disease, while LYLs ranged from 0.31 (0.14 to 0.47) years (approximately 16 weeks) for allergy to 17.05 (16.95 to 17.15) years for chronic liver disease. Adjustment for air pollution had very little impact on the estimates; however, a limitation of the study is the possibility that the association between the different disorders and mortality could be explained by other underlying factors associated with both the disorder and mortality. CONCLUSIONS: In this study, we show estimates of incidence, age of onset, age of death, and mortality metrics (both MRRs and LYLs) for a comprehensive range of disorders. The interactive data visualization site (https://nbepi.com/atlas) allows more fine-grained analysis of the link between a range of disorders and key mortality estimates.

Intergenerational transmission of suicide attempt in a cohort of 4.4 million children.

BACKGROUND: The association between suicide attempts (SAs) in parents and children is unclear, and risk indicators for intergenerational transmission remain undocumented. We aimed to assess this association, considering the child's developmental period at the time of parents' attempted suicide, and the parental relation. METHODS: Using a prospective cohort design, nationwide population data were linked to the Psychiatric Central Register and National Patient Register for all individuals aged 10 years or older living in Denmark between 1980 and 2016. We assessed incidence rate ratios (IRRs) and cumulative hazards for children's first SA. RESULTS: In a cohort of 4 419 651 children, 163 056 (3.7%) had experienced a parental SA. An SA was recorded among 6996 (4.3%) of the exposed children as opposed to 70112 (1.6%) in unexposed individuals. Higher rates were noted when a parental SA occurred during early childhood (0 ⩽ age < 2) [IRR, 4.7; 95% confidence interval (CI) 4.2-5.4] v. late childhood (6 ⩽ age < 13) (IRR, 3.6; 95% CI 3.4-3.8) when compared to those unexposed. Children exposed prior to age 2 had the highest rates of all sub-groups when reaching age 13-17 (IRR, 6.5; 95% CI 6.0-7.1) and 18-25 years (IRR, 6.8; 95% CI 6.2-7.4). Maternal SA (IRR, 3.4; 95% CI 3.2-3.5) was associated with higher rates than paternal (IRR, 2.8; 95% CI 2.7-2.9). CONCLUSION: Parental SA was associated with children's own SA. Exposure during early developmental stages was associated with the highest rates. Early preventive efforts are warranted as is monitoring of suicide risk in the children from age 13.

Hospital-diagnosed sleep disorders and incident dementia: a nationwide observational cohort study.

BACKGROUND AND PURPOSE: Several smaller, community-based studies have suggested a link between sleep disorders and dementia with a focus on sleep as a modifiable risk factor for dementia. Studies on neurodegenerative diseases are prone to reverse causation, and few studies have examined the association with long follow-up time. Our aim was to explore the possible association between sleep disorders and late-onset dementia in an entire population. METHODS: In a nationwide cohort with 40-year follow-up, associations between hospital-based sleep disorder diagnoses and late-onset dementia were assessed. Incidence rate ratios (IRR) were calculated using Poisson regression. RESULTS: The cohort consisted of 1,491,276 people. Those with any sleep disorder had a 17% higher risk of dementia (IRR 1.17, 95% confidence interval [CI] 1.11-1.24) compared to people with no sleep disorder, adjusted for age, sex, calendar year, highest attained educational level at age 50, and somatic and psychiatric comorbidity. The risk of dementia was significantly increased 0-5 years after sleep disorder diagnosis (IRR 1.35, 95% CI 1.25-1.47), whilst the association after 5 years or more was non-significant (1.05, 95% CI 0.97-1.13). CONCLUSIONS: Our findings show an increased short-term risk of dementia following a hospital-based sleep disorder diagnosis, whilst weaker evidence of a long-term risk was found. This could potentially point towards sleep disorders as an early symptom of dementia. Further research is needed to distinguish sleep disorders as an early symptom of dementia, a risk factor, or both.

Incidence rates and employment trends in schizophrenia spectrum disorders, bipolar affective disorders and recurrent depression in the years 2000-2013: a Danish nationwide register-based study.

AIMS: The study aimed to investigate time trends in incidence rates in schizophrenic spectrum disorders (ICD-10: F20-F29), bipolar affective disorder (ICD-10: F30, F31), and recurrent depression (ICD-10: F33) and to investigate the rates of employment for all incident cases. METHOD: We used nationwide longitudinal data from 2000 to 2013 on all psychiatric inpatients and outpatients contacts in Denmark. Age-adjusted incidence rate ratios were calculated for the three diagnostic groups, and rates of employment, education, and disability pension were measured 1 year before and 2 years after the diagnosis for all the incident cases. RESULTS: The incidence rates increased significantly in all diagnostic groups and both sexes. Comparing the incidence rates in 2013 with 2000 yielded an incidence rate ratio of 1.67 (95% CI 1.51-1.84) for schizophrenic spectrum disorders, 3.82 (95% CI 3.23-4.52) for bipolar affective disorder, and 2.80 (95% CI 2.58-3.04) for recurrent depression. During the same observation period, the employment rates decreased, both 1 year before and 2 years after diagnosis in all three subgroups. In the year 2002, employment rates, 2 years after diagnosis, were 24.6% for schizophrenia spectrum disorder, 35.0% for bipolar affective disorder and 47.1% for recurrent depression. These rates had declined to 15.8%, 26.8%, and 34.7%, respectively, in 2013. CONCLUSION: This study of three severe mental illness subgroups shows significant increasing incidence rates and decreasing employment rates both before and after the diagnosis between 2000 and 2013, highlighting the importance of timely and correct volume of the psychiatric treatment and vocational rehabilitation programs.

Hospital readmissions following infections in dementia: a nationwide and registry-based cohort study.

INTRODUCTION: We aimed to investigate readmission risks following infections in dementia, identify the types of infections behind the risks, and highlight the reasons for readmissions. METHODS: Acute inpatient hospital admissions for infections in Danish residents were included from 1 January 2000, or age 65 years. Primary outcomes were 7-day readmissions risk ratios (RRs; risk following infection index admissions of people with dementia relative to those without dementia), risks by infection site, and reasons for readmission. Secondary outcomes were 30- and 90-day readmission risks. Competing risk of death was estimated. RESULTS: Seven-day readmission RR was increased in all age groups and was highest in the youngest patients (women RR: 1.37, 95% confidence interval [CI] 1.22-1.53; men RR: 1.23, 95% CI 1.12-1.35). RRs decreased with increasing age and longer follow-up. The most notable common readmissions were for infections and dehydration in dementia. CONCLUSIONS: We conclude that there is a substantially increased readmission risk in people with dementia than in those without dementia, particularly within 7 days, and for the youngest in the cohort. Readmission risks were higher for infection index admissions than for admissions for causes other than infection, and readmissions were mostly due to infections. Our findings highlight the burden of infections in people with dementia and call for in-depth investigations of determinants related to readmission risks, to inform public policy and identify avenues for interventions that can decrease or prevent potentially avoidable readmissions.

Dementia increases mortality beyond effects of comorbid conditions: A national registry-based cohort study.

BACKGROUND AND PURPOSE: Mortality is known to be markedly increased in people with dementia. However, the association between multiple chronic conditions and mortality in dementia is not well clarified. The aim of this study was to investigate the impact of somatic and psychiatric diseases on mortality in dementia compared with the general elderly population. METHODS: Using a cohort study design, nationwide registry data from 2006 to 2015 on dementia and psychiatric and somatic comorbidities defined by the Charlson Comorbidity Index (CCI) were linked. Impact of chronic conditions was assessed according to mortality rate ratios (MRRs) in all Danish residents aged ≥65 years with and without dementia. RESULTS: Our population comprised 1,518,917 people, of whom 114,109 people were registered with dementia. The MRRs was 2.70 (95% confidence interval 2.68, 2.72) in people with dementia after adjusting for sex, age, calendar year, and comorbidities. MRRs increased with higher CCI score, and when comparing people with a similar comorbidity load, MRRs were significantly higher for people with dementia. CONCLUSIONS: The comorbidity load was associated with increased mortality in both people with and without dementia. Mortality in dementia remained increased, even after adjusting for psychiatric and chronic somatic comorbidities. Our findings suggest that dementia disorders alone contribute to excess mortality, which may be further increased by comorbidities.

Risk of hospitalization and hip fracture associated with psychotropic polypharmacy in patients with dementia: A nationwide register-based study.

OBJECTIVE: To investigate the association of benzodiazepines and antidepressants on the risk of hospitalization and hip fracture in patients with dementia initiating antipsychotic drug treatment. METHODS: A register-based retrospective cohort study using data on all incident dementia cases (≥65 years) initiating antipsychotic treatment as monotherapy or in combination with benzodiazepines and/or antidepressants in Denmark from 2000 to 2015. The outcomes of interest were all-cause hospitalization and hip fracture. Cox proportional hazards models with adjustment for multiple variables were used to investigate risk of hospitalization and hip fracture within 180 days. RESULTS: The risk of all-cause hospitalization during 180-days follow-up was significantly increased by 55% (adjusted HR: 1.55, 95% CI: 1.29-1.86, p < 0.0001), when antipsychotic use was combined with benzodiazepines, when compared to antipsychotic monotherapy. The association between the combination of antipsychotics and benzodiazepines with the risk of hip fracture did not reach statistical significance (adjusted HR: 1.50, 95% CI: 0.99-2.26, p = 0.0534). CONCLUSIONS: The observed increased risk of all-cause hospitalization and hip fracture may indicate increased drug-related adverse events. Thus, careful and regular monitoring is needed to assess response to treatment and decrease the risk of adverse events, when antipsychotics are combined with BZDs, albeit confounding cannot be fully excluded within the current design.

Self-harm in women with postpartum mental disorders.

BACKGROUND: Women suffering from first onset postpartum mental disorders (PPMD) have a highly elevated risk of suicide. The current study aimed to: (1) describe the risk of self-harm among women with PPMD and (2) investigate the extent to which self-harm is associated with later suicide. METHODS: We conducted a register-based cohort study linking national Danish registers. This identified women with any recorded first inpatient or outpatient contact to a psychiatric facility within 90 days after giving birth to their first child. The main outcome of interest was defined as the first hospital-registered episode of self-harm. Our cohort consisted of 1 202 292 women representing 24 053 543 person-years at risk. RESULTS: Among 1554 women with severe first onset PPMD, 64 had a first-ever hospital record of self-harm. Women with PPMD had a hazard ratio (HR) for self-harm of 6.2 (95% CI 4.9-8.0), compared to mothers without mental disorders; but self-harm risk was lower in PPMD women compared to mothers with non-PPMD [HR: 10.1, (95% CI 9.6-10.5)] and childless women with mental disorders [HR: 9.3 (95% CI 8.9-9.7)]. Women with PPMD and records of self-harm had a significantly greater risk for later suicide compared with all other groups of women in the cohort. CONCLUSIONS: Women with PPMD had a high risk of self-harm, although lower than risks observed in other psychiatric patients. However, PPMD women who had self-harmed constituted a vulnerable group at significantly increased risk of later suicide.

Risk of psychiatric diagnoses in children and adolescents of parents with torture trauma and war trauma.

OBJECTIVE: Evidence point to intergenerational effects of trauma in refugee populations. This study estimates the risk of psychiatric diagnoses in children of severely traumatized refugees. The unique clinical sample consisted of refugee parents treated for torture trauma and war trauma, and outcomes were investigated using population-level data. METHOD: A nationwide register study, following all children residing in Denmark. The exposure was parental torture trauma and war trauma, and outcomes were any psychiatric disorder, mood, neurotic, behavioural and emotional disorders and disorders of psychological development. Children's hazard of being diagnosed was estimated using Cox proportional hazards regression. Study participants were followed from the date of birth or immigration to their 18th birthday. RESULTS: The cohort included 3 346 993 children of which 19 294 were identified as offspring to traumatized refugees. During the study period, 205 610 children were diagnosed with a psychiatric disorder. Children with parents from the Middle East and Northern Africa had a hazard ratio of 0.78 (95% CI: 0.72, 0.84) for those treated for parental trauma and 0.79 (95% CI: 0.76, 0.81) for those not treated compared with children of non-traumatized Danish-born parents. For children of parents from former Yugoslavia, the corresponding estimates were 0.69 (95% CI: 0.58, 0.81) and 0.69 (95% CI: 0.65, 0.73). CONCLUSION: The results suggest that children of parents with and without registered torture trauma and war trauma have a lower risk of being diagnosed with a psychiatric disorder compared to children of Danish-born parents. These findings contradict research done on the transmission of trauma but supports evidence suggesting mental health services underutilization by refugee and ethnic minority populations.

Declining incidence of dementia: A national registry-based study over 20 years.

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.

Out-of-home placement to age 18 years in children exposed to a postpartum mental disorder.

OBJECTIVES: Little is known about risk of custody loss or out-of-home placement among children whose mothers experience postpartum mental disorders, and whether this risk differs from that of children whose mothers had earlier onset of their mental disorder. METHODS: National Danish registers comprising 1 868 467 births (1982-2012) were used to determine how the timing of maternal illness onset influences out-of-home placement risk up to age 18 years among children exposed to a maternal mental disorder. RESULTS: Compared to children unexposed to maternal mental illness, risk was higher for children exposed to a maternal mental disorder whose mothers had a first contact for a mental disorder in the 0-12 months of predelivery (8.17/1000 person-years; aIRR 4.56, 95% CI 4.08-5.09), the first 3 months postpartum (4.60/1000 person-years; 3.55, 2.95-4.26) and 4-12 months postpartum (6.49/1000 person-years; 3.93, 3.50-4.41). Risk was even higher for children exposed to a maternal mental disorder when illness onset was more than 1-year predelivery (9.11/1000 person-years; 5.48, 5.32-5.66). CONCLUSION: Risk of out-home placement in children exposed to mothers with a new-onset postpartum mental disorder is almost as high as in children whose mothers have long-standing illness. A better understanding of the trajectories of these mothers and children is warranted.

Homelessness as a predictor of mortality: an 11-year register-based cohort study.

PURPOSE: The purpose of this study was to examine the association between homelessness and psychiatric disorders, including substance use disorders, on one hand, and cause-specific and all-cause mortality on the other in a high-income country. METHODS: A historical nationwide register-based cohort study of the Danish population from 15 years of age between 2000 and 2011 was conducted. The association between homelessness, psychiatric disorders, and mortality was analysed by Poisson Regression adjusting for important confounders. Standardised mortality ratios (SMRs) were calculated for people with a history of homelessness compared with the general population using direct age-standardisation. RESULTS: During 51,892,324 person-years of observation, 656,448 died. People with at least one homeless shelter contact accounted for 173,592 person-years with 4345 deaths. The excess mortality in the population experiencing homelessness compared with the general population was reduced by 50% after adjusting for psychiatric diagnoses, including substance use disorders (mortality rate ratio (MRR) for men 3.30, 95% CI 3.18-3.41; women 4.41, 95% CI 4.14-4.71). Full adjustment including physical comorbidity and socioeconomic factors in a sub-cohort aged 15-29 years resulted in an MRR of 3.94 (95% CI 3.10-5.02) compared with the general population. The excess mortality associated with homelessness differed according to psychiatric diagnosis, sex, and cause of death. CONCLUSIONS: A mental health or a substance use disorder combined with homelessness considerably increases the risk of death. However, homelessness is also independently associated with high mortality. Differences in the association between homelessness and mortality in men and women suggest the need for sex-tailored interventions.

Comorbidity of schizophrenia and infection: a population-based cohort study.

PURPOSE: In this paper, we investigate the hypothesis that there is an overlap between infection and schizophrenia. Infections have been identified as a risk factor for schizophrenia, but the possible overlap between schizophrenia and infections remains unidentified so far. Here, we describe the use of the comorbidity index, a method for objectively integrating associations into a single measure estimating overlap. METHODS: Data were drawn from three population-based registers, the Civil Registration Register, the Danish Psychiatric Central Research Register, and the Danish National Hospital Register. We selected a cohort of 1,403,183 persons born in Denmark 1977-2002. RESULTS: Our results indicate that persons who have had a hospital contact with an infection (IRR 1.53, CI 1.46-1.61) are more likely to develop schizophrenia than persons who have not had such a contact. Persons who have had a diagnosis with schizophrenia are more likely to have had a hospital contact with an infection (IRR 1.73, 95 % CI 1.57-1.91) than persons who have had no schizophrenia diagnosis. A comorbidity index of 1.40 (95 % CI 1.34-1.46) was found, indicating an overlap between schizophrenia and infection. CONCLUSION: Our findings indicate that schizophrenia and infections overlap and that they share risk factors. The comorbidity index showed that the co-occurrence of schizophrenia and infection was 40 % higher than if the two disorders had occurred independently. Although the incidence of schizophrenia and infection was associated with each factor, the overlap could not be explained by urbanicity, parental history of psychiatric admission and infection.