Incidence of hospitalised schizophrenia in Finland since 1980: decreasing and increasing again

Association between Arachidonic Acid and the Risk of Schizophrenia: A Cross-National Study and Mendelian Randomization Analysis

Polyunsaturated fatty acids (PUFAs), especially long-chain PUFAs (LCPUFAs), are crucial for both the structural and functional integrity of cells. PUFAs have been reported to be insufficient in schizophrenia, and the resulting cell membrane impairments have been hypothesized as an etiological mechanism. However, the impact of PUFA deficiencies on the onset of schizophrenia remain uncertain. We investigated the associations between PUFAs consumption and schizophrenia incidence rates through correlational analyses and conducted Mendelian randomization analyses to reveal the causal effects. Using dietary PUFA consumption and national schizophrenia incidence rates in 24 countries, we found that incidence rates of schizophrenia were inversely correlated with arachidonic acid (AA) and ω-6 LCPUFA consumption (r_AA = -0.577, p < 0.01; r_{ω-6 LCPUFA} = -0.626, p < 0.001). Moreover, Mendelian randomization analyses revealed that genetically predicted AA and gamma-linolenic acid (GLA) were protective factors against schizophrenia (OR_AA = 0.986, OR_GLA = 0.148). In addition, no significant relationships were observed between schizophrenia and docosahexaenoic acid (DHA) or other ω-3 PUFAs. These findings show that the deficiencies of ω-6 LCPUFAs, especially AA, are associated with schizophrenia risk, which sheds novel insight into the etiology of schizophrenia and a promising diet supplementation for the prevention and treatment of schizophrenia.

Incidence of schizophrenia and influence of prenatal and infant exposure to viral infectious diseases

OBJECTIVE

There is conflicting evidence in recent literature about whether the incidence of schizophrenia is increasing or decreasing. A role for prenatal and early childhood viral infections in the aetiology of schizophrenia has also been debated. We examined the incidence of schizophrenia and the catatonic subtype of schizophrenia over a 30-year period in Finland. We also investigated whether the incidence rate of the catatonic subtype of schizophrenia was linked to changes in exposure to viral infection (polio and measles) during the prenatal or infant period.

METHODS

Persons with schizophrenia were identified from the Hospital Discharge Register. Cumulative incidence of schizophrenia from 1956 to 1989 in 4 age groups was calculated with follow-up from 1972 to 2014. Annual rates of polio and measles were derived from nationwide registers. The association between log-transformed polio and measles incidence and incidence of schizophrenia, and specifically catatonic schizophrenia, were analysed using linear models.

RESULTS

Cumulative incidence of schizophrenia among individuals born 1956-1989 decreased by 23% (from 13 to 10 cases per 1000 live births). The decline was the most prominent in those with onset of schizophrenia diagnosed 16-25 years of age (-41%). The incidence of catatonic schizophrenia declined by 90% over three decades, and there was a significant association between annual polio incidence during the birth year and incidence of catatonic schizophrenia.

CONCLUSIONS

The results indicate that the incidence of schizophrenia in Finland has declined for individuals born between 1956 and 1989, and that the decline of catatonic schizophrenia may be partially attributable to eradication of polio.

The impact of study design on schizophrenia incidence estimates: A systematic review of Northern European studies 2008-2019

The best estimates of the incidence of schizophrenia range more than 25-fold from 3 to 80 per 100,000 person-years. To what extent do differences in study design explain this wide variation? We selected all studies published between 2008-2019 reporting the incidence of schizophrenia in general populations of Northern Europe. We identified 17 estimates covering 85 million person-years and more than 15,000 individual cases. The estimates ranged from 4-72 per 100,000 person-years (median 30; interquartile range 13-41). We classified the estimates in terms of three study design factors (coverage of services, time frame, and diagnostic quality) and two population factors (urbanicity and age). A meta-regression model of the three design factors, using the two population factors as covariates, explained 91% of between-study variation. Studies performed in general psychiatric services reported similar estimates [incidence rate ratio 1.12 (95% confidence interval 0.88 to 1.43)] to those performed in specialized services. But studies applying a cumulative time frame to diagnosis reported fourfold higher estimates [4.04 (3.14 to 5.2)] than those applying a first-contact time frame. And studies based on clinical diagnoses reported lower estimates [0.55 (0.43 to 0.72)] than those based on standardized research diagnoses. The three study design factors by themselves explained 67% of between-study variation. When comparing incidence rates from different populations, distorsions arising from differences in study design can eclipse differences caused by schizophrenia risk factors, such as gender, age or migrant status.

Annual Prevalence and Incidence of Schizophrenia and Similar Psychotic Disorders in the Republic of Korea: A National Health Insurance Data-Based Study

OBJECTIVE

We conducted this study to address the incidence and prevalence of schizophrenia and similar psychosis in South Korea with Health Insurance Review and Assessment (HIRA) database.

METHODS

We used HIRA database, which includes diagnostic information of nearly all Korean nationals to collect number of cases with diagnosis of schizophrenia and schizophrenia-similar disorders (SSP), including schizophreniform, acute/transient psychotic disorders, schizoaffective disorders, and other/unspecific nonorganic psychosis (ICD-10 codes F20/23/25/28/29) between 2010 and 2015. The annual prevalence and incidence were calculated using the population data from the Korean Statistical Office.

RESULTS

The 12-month prevalence of SSP of Korea between 2010 and 2015 were 0.48-0.66%. The 12-month prevalence of schizophrenia were 0.40-0.52%; The annual incidence rates (IR) of SSP between 2010 and 2015 were 118.8-148.7 per 100,000 person-year (PY). For schizophrenia, IR per 100,000 PY were 77.6-88.5 between 2010 and 2015.

CONCLUSION

The 12-month prevalence found in the present study was higher than that reported in community-based epidemiologic studies in South Korea but similar to those from other countries. The annual incidence of SSP and schizophrenia was found to steadily increase and was higher than that of other countries. The high incidence rate observed in the current study needs to be studied further.

Mortality in schizophrenia: 30-year nationwide follow-up study

OBJECTIVE

Recent reports suggest that the mortality gap between persons with schizophrenia and the general population is increasing. We investigated the mortality, age at death, and causes of death among persons diagnosed with schizophrenia and the general population in Finland during 1984-2014.

METHODS

All persons with schizophrenia in Finland were identified from hospital discharge register, and compared with the Finnish population aged 16 years and older during 1984-2014, based on data from Statistics Finland. Age at death and standardized mortality ratio (SMR) were calculated for each follow-up year.

RESULTS

Mean age at death increased from 57.6 years in 1984 to 70.1 years in 2014 in persons with schizophrenia, and from 70.9 to 77.5 years in the general population. All-cause SMR remained stable during the follow-up (2.6 in 1984 and 2.7 in 2014). A major change was observed in SMR for suicides which decreased from 11.0 in 1984 to 6.6 in 2014 (-40%). The SMRs for cardiovascular and cancer deaths showed increasing trends.

CONCLUSION

The longevity of persons with schizophrenia is improving at approximately the same rate as the general population but suicide rates have declined substantially. However, there is still a major disparity in mortality compared with general population.

Social inequality, scientific inequality, and the future of mental illness

BACKGROUND

Despite five decades of increasingly elegant studies aimed at advancing the pathophysiology and treatment of mental illness, the results have not met expectations. Diagnoses are still based on observation, the clinical history, and an outmoded diagnostic system that stresses the historic goal of disease specificity. Psychotropic drugs are still based on molecular targets developed decades ago, with no increase in efficacy. Numerous biomarkers have been proposed, but none have the requisite degree of sensitivity and specificity, and therefore have no usefulness in the clinic. The obvious lack of progress in psychiatry needs exploration.

METHODS

The historical goals of psychiatry are reviewed, including parity with medicine, a focus on diagnostic reliability rather than validity, and an emphasis on reductionism at the expense of socioeconomic issues. Data are used from Thomas Picketty and others to argue that our failure to advance clinical care may rest in part on the rise in social and economic inequality that began in the 1970s, and in part on our inability to move beyond the medical model of specificity of disease and treatment.

RESULTS

It is demonstrated herein that the historical goal of specificity of disease and treatment has not only impeded the advance of diagnosis and treatment of mental illness, but, in combination with a rapid increase in socioeconomic inequality, has led to poorer outcomes and rising mortality rates in a number of disorders, including schizophrenia, anxiety, and depression.

CONCLUSIONS

It is proposed that Psychiatry should recognize the fact of socioeconomic inequality and its effects on mental disorders. The medical model, with its emphasis on diagnostic and treatment specificity, may not be appropriate for investigation of the brain, given its complexity. The rise of scientific inequality, with billions allocated to connectomics and genetics, may shift attention away from the need for improvements in clinical care. Unfortunately, the future prospects of those suffering from mental illness appear dim.

A comparison of the cumulative incidence and early risk factors for psychotic disorder in young adults in the Northern Finland Birth Cohorts 1966 and 1986

AIMS

Few studies have compared time trends for the incidence of psychosis. To date, the results have been inconsistent, showing a decline, an increase or no significant change. As far as we know, no studies explored changes in prevalence of early risk factors. The aim of this study was to investigate differences in early risk factors and cumulative incidences of psychosis by type of psychosis in two comparable birth cohorts.

METHODS

The Northern Finland Birth cohorts (NFBCs) 1966 (N = 12 058) and 1986 (N = 9432) are prospective general population-based cohorts with the children followed since mother's mid-pregnancy. The data for psychoses, i.e. schizophrenia (narrow, spectrum), bipolar disorder with psychotic features, major depressive episode with psychotic features, brief psychosis and other psychoses (ICD 8-10) were collected from nationwide registers including both inpatients and outpatients. The data on early risk factors including sex and place of birth of the offspring, parental age and psychosis, maternal education at birth were prospectively collected from the population registers. The follow-up reached until the age of 27 years.

RESULTS

An increase in the cumulative incidence of all psychoses was seen (1.01% in NFBC 1966 v. 1.90% in NFBC 1986; p < 0.001), which was due to an increase in diagnosed affective and other psychoses. Earlier onset of cases and relatively more psychoses in women were observed in the NFBC 1986. Changes in prevalence of potential early risk factors were identified, but only parental psychosis was a significant predictor in both cohorts (hazard ratios ≥3.0; 95% CI 1.86-4.88). The difference in psychosis incidence was not dependent on changes in prevalence of studied early risk factors.

CONCLUSIONS

Surprisingly, increase in the cumulative incidence of psychosis and also changes in the types of psychoses were found between two birth cohorts 20 years apart. The observed differences could be due to real changes in incidence or they can be attributable to changes in diagnostic practices, or to early psychosis detection and treatment.

Late new morbidity in survivors of adolescent and young-adulthood brain tumors in Finland: a registry-based study

BACKGROUND

Brain tumors (BTs) in adolescence and young adulthood (AYA) differ from those in childhood or late adulthood. However, research concerning late effects in this particular survivor group is limited. This study evaluates late morbidity of survivors diagnosed in AYAs.

METHODS

We identified from the Finnish Cancer Registry all survivors diagnosed with BT at the ages 16-24 years between 1970 and 2004 (N = 315) and used data from the Hospital Discharge Registry to evaluate their late (≥5 y after diagnosis) morbidity requiring treatment in a specialized health care setting. A sibling cohort of BT patients diagnosed before the age of 25 years was used as a comparison cohort (N = 3615).

RESULTS

The AYA BT survivors had an increased risk for late-appearing endocrine diseases (HR, 2.9; 95% CI, 1.1-8.0), psychiatric disorders (HR, 2.0; 95% CI, 1.2-3.2), diseases of the nervous system (HR, 9; 95% CI, 6.6-14.0), disorders of vision/hearing loss (HR, 3.6; 95% CI, 1.5-8.5), diseases of the circulatory system (HR, 4.9; 95% CI, 2.9-8.1), and diseases of the kidney (HR, 5.9; 95% CI, 2.5-14.1). Survivors with irradiation had an increased risk for diseases of the nervous system compared with non-irradiated survivors (HR, 3.3; 95% CI, 1.8-6.2). The cumulative prevalence for most of the diagnoses remained significantly increased for survivors even 20 years after cancer diagnosis.

CONCLUSIONS

The AYA BT survivors have an increased risk of morbidity for multiple new outcomes for ≥5 years after their primary diagnosis. This emphasizes the need for structured late-effect follow-up for this patient group.

Mortality in schizophrenia and other psychoses: a 10-year follow-up of the ӔSOP first-episode cohort

The excess mortality in people with psychotic disorders is a major public health concern, but little is known about the clinical and social risk factors which may predict this health inequality and help inform preventative strategies. We aimed to investigate mortality in a large epidemiologically characterized cohort of individuals with first-episode psychosis compared with the general population and to determine clinical and social risk factors for premature death. All 557 individuals with first-episode psychosis initially identified in 2 areas (Southeast London and Nottinghamshire, United Kingdom) were traced over a 10-year period in the ӔSOP-10 study. Compared with the general population, all-cause (standardized mortality ratio [SMR] 3.6, 95% confidence interval [CI] 2.6-4.9), natural-cause (SMR 1.7, 95% CI 1.0-2.7) and unnatural-cause (SMR 13.3, 95% CI 8.7-20.4) mortality was very high. Illicit drug use was associated with an increased risk of all-cause mortality (adj. rate ratio [RR] 2.31, 95% CI 1.06-5.03). Risk of natural-cause mortality increased with a longer time to first remission (adj. RR 6.61, 95% CI 1.33-32.77). Family involvement at first contact strongly reduced risk of unnatural-cause mortality (adj. RR 0.09, 95% CI 0.01-0.69). Our findings suggest that the mortality gap in people with psychotic disorders remains huge and may be wider for unnatural-cause mortality than previously reported. Efforts should now focus on further understanding and targeting these tractable clinical and social risk factors of excess mortality. Early intervention and dual diagnosis services may play a key role in achieving more rapid remission and carer involvement and addressing substance use problems to reduce excess mortality in psychosis.

Direct comparison of first-contact versus longitudinal register-based case finding in the same population: early evidence that the incidence of schizophrenia may be three times higher than commonly reported

BACKGROUND

The incidence of schizophrenia is commonly estimated by screening for psychosis among subjects presenting to psychiatric services. This approach (using a first-contact sampling frame) cannot account for cases that did not meet criteria for schizophrenia at first contact. We compared the usual approach directly with a register-based approach (using a longitudinal sampling frame) that also includes subjects initially diagnosed with other non-schizophrenic disorders.

METHOD

We compared data from the Longitudinal Psychiatric Register (LPR) of The Hague over 1980-2009 with data previously collected in a first-contact study, and applied both methods to calculate the incidence of schizophrenia for subjects aged 20-54 years in the same catchment area and over the same period (October 2000 to September 2005). We reconstructed treatment pathways and diagnostic histories up to the end of 2009 and performed sensitivity analyses.

RESULTS

The LPR identified 843 first onsets of schizophrenia, corresponding to a treated incidence rate (IR) of 69 per 100,000 person-years [95% confidence interval (CI) 64-74]. The first-contact study identified 254 first onsets, corresponding to a treated IR of 21 per 100,000 person-years (95% CI 18-23). Two-thirds of the difference was accounted for by subjects treated for other disorders before the onset of psychosis, and by patients in older age groups.

CONCLUSIONS

The incidence of schizophrenia was three times higher in a longitudinal register study than in a high-quality first-contact study conducted in the same population. Risk estimates based only on first-contact studies may have been affected by selection bias.

Increasing mortality gap for patients diagnosed with schizophrenia over the last three decades--a Danish nationwide study from 1980 to 2010

OBJECTIVE

The objective of this study is to describe secular trends in the average age of death in patients with schizophrenia and to compare these with the general population.

METHODS

This is a longitudinal linkage study from 1 January 1980 to 31 December 2010 using the Danish Psychiatric Research Register and the Danish Cause of Death Register. Data were analyzed using descriptive statistics and survival analysis.

RESULTS

The average age of death in the schizophrenia population (62.2 years; 95% CI, 61.9-62.5) was lower compared to the general population (73.4 years; 95% CI, 73.4-73.4), P<0.001. In the general population we found, for men, an average increase in the age of death of 0.28 years (95% CI, 0.27-0.28) per calendar year, and for women an increase in age of death of 0.31 years (95% CI, 0.31-0.32) per calendar year (both P<0.001). In contrast, age of death decreased in the schizophrenia population: the change in average age of death for males was 0.04 years (95% CI, -0.09 to 0.00) per calendar year (P<0.05), and the comparable estimate for females was -0.05 years (95% CI, -0.09 to 0.01) per calendar year (P<0.05). A similar pattern existed after acts of self-harm as cause of death were excluded from the analyses. Patients diagnosed with schizophrenia had an increased mortality rate compared with the general population (hazard ratio, 2.05; 95% CI, 2.01-2.09).

CONCLUSIONS

On average, patients with schizophrenia die younger than the general population, independent of intentional self-harm as cause of death.

Changes in the diagnosed incidence of early onset schizophrenia over four decades

OBJECTIVE

To explore changes in the diagnosed incidence of early onset schizophrenia (EOS) from 1971 to 2010.

METHOD

Examination of incidence rates of schizophrenia in patients under 18 years of age, using a nationwide, population-based, mental health register.

RESULTS

The age-standardized incidence rate (IR) of EOS in the period 1971-2010 was 3.17 (95% CI: 3.16, 3.18) per 100 000 person years in the age group 0-18 years, and 9.10 (95% CI: 9.00, 9.21) in the age group 12-18 years. In the period 1971-1993, the age-standardized IR of EOS was 1.80 (95% CI: 1.79, 1.82) per 100 000 person years in the age group 0-18 years, and 5.02 (95% CI: 4.92, 5.11) in the age group 12-18 years. In the period 1994-2010, the age-standardized IR of EOS was 5.15 (95% CI: 5.10, 5.20) per 100 000 person years in the age group 0-18 years, and 15.73 (95% CI: 15.22, 16.22) in the age group 12-18 years. The IR was higher for males than females in the periods 1971-1993 and 1971-2010, but in the period 1994-2010 the IR was higher for females than males.

CONCLUSION

In recent years, the diagnosed incidence of EOS has increased and the usual male excess has disappeared. The changes in IR could be a result of changes in the diagnostic system, increased awareness of early psychosis or a reflection of actual underlying incidence of the disorder.

Treatment prevalence and incidence of schizophrenia in Quebec using a population health services perspective: different algorithms, different estimates

PURPOSE

Using a population health services perspective, this article defines and assesses an efficient criteria-based algorithm to identify treatment prevalent and incident cases of schizophrenia. We refer here "treatment" prevalence and incidence since its evaluation depends on a patient receiving a health care service with a diagnosis of schizophrenia.

METHODS

A population-based cohort study was conducted among all adults having a hospital discharge or a physician claim for schizophrenia in the public health plan databases between January 1996 and December 2006. Four algorithms to characterize patients with schizophrenia were defined. To identify treatment incident cases in 2006, we removed from the treatment prevalent pool patients with a previous record of schizophrenia between 1996 and 2006 (10-year clearance period). Using this 10-year period as reference, Kappa coefficients (KC) and positive predictive values (PPV) were calculated to determine the "optimal" length of clearance period to identify incident cases.

RESULTS

The lifetime treatment prevalence and incidence of schizophrenia varied from 0.59 to 1.46% and from 42 to 94 per 100,000, respectively. When compared to the 10-year clearance period, the KC is excellent in a clearance period of 6-7 years. To achieve a PPV of 90%, a clearance period of 7-8 years would be necessary.

CONCLUSIONS

With an appropriate algorithm, treatment prevalence and incidence of schizophrenia can be conveniently estimated using administrative data. These estimates are a vital step toward appropriate planning of services for schizophrenia.