Psychiatric morbidity is related to parental age: a national cohort study

BACKGROUND: The median age at first childbirth has increased dramatically in many high-income countries during the past decades. The psychiatric consequences of this demographic change are insufficiently described on a population level. This study aimed to investigate whether parental age at childbearing is related to psychiatric morbidity among Swedish youths. METHOD: This was a cohort study based on Swedish national registers. A national cohort of 292129 children born to primiparas women during 1973-1979 was followed prospectively from 1987 to 2002 in registers. Multivariate Cox analyses of proportional hazards were used to estimate the relative risk of hospital admission for schizophrenia, alcohol and illicit drug abuse, suicide attempts and deaths. RESULTS: Youths born of teenage mothers had a high risk for suicide death [relative risk (RR) 1.9, 95% confidence interval (CI) 1.3-2.7] and hospital admissions because of suicide attempt (RR 2.0, 95% CI 1.7-2.3) and substance abuse (alcohol: RR 1.6, 95% CI 1.4-1.8; illicit drug: RR 2.2, 95% CI 1.9-2.5) after adjustments for major sociodemographic confounders, compared with children of mothers aged 25-29 years. Offspring of older parents (>34 years) had the highest risk for schizophrenia (RR 1.8, 95% CI 1.0-3.0). CONCLUSIONS: Parental age is related to psychiatric morbidity.     

Recurrence risks for schizophrenia in a Swedish national cohort

OBJECTIVE: Recurrence risk estimates for schizophrenia are fundamental to our understanding of this complex disease. Widely cited estimates are from small/older samples. If these estimates are biased upwards, then the rationale for molecular genetic studies of schizophrenia may not be as solid. METHOD: We created a population-based, Swedish national cohort by linking two Swedish national registers into a relational database (the Swedish Hospital Discharge Register and the Multi-Generation Register). Affection was defined as the lifetime presence of at least two in-patient hospitalizations with a core schizophrenia diagnosis. RESULTS: Merging the Swedish national registers created a population-based cohort of 7,739,202 individuals of known parentage. The lifetime prevalence of the narrow definition of schizophrenia was 0.407% and we estimated that one in every 79 extended Swedish families had been impacted by schizophrenia. The proportion of affected families with multiple affected members was 3.81%. Recurrence risk estimates for all relative types were strikingly similar to those reported in smaller and older studies. For example, we estimated lambda(sibs) at 8.55 [95% confidence interval (CI) 7.86-9.57] compared with a literature estimate of 8.6. CONCLUSIONS: In the largest and most comprehensive sample yet studied, we confirm the accepted estimates of recurrence risks for schizophrenia, and provide more accurate estimates of recurrence risks of schizophrenia in relatives, an estimate of the familial impact of schizophrenia, and the multiplex proportion (essential for gauging the generalizability of findings from multiplex pedigrees). These data may be valuable for planning and interpreting genetic studies of schizophrenia.     

Dimensions and classes of psychosis in a population cohort: a four-class, four-dimension model of schizophrenia and affective psychoses

BACKGROUND: Classification of psychosis lacks a biological basis and current diagnostic categories may obscure underlying continuities. Data reduction methods of symptom profiles within a population-based cohort of people with a wide range of affective and non-affective psychoses may permit an empirical classification of psychosis. METHOD: OPCRIT (operational criteria) analysis was performed on 387 adults aged 18-65 years in an attempted ascertainment of all patients with psychosis from a geographical area with a stable population. The data were analysed firstly using principal components analysis with varimax rotation to identify factors, and secondly to establish latent classes. Information relating to key variables known to be of relevance in schizophrenia was coded blind to the establishment of the classes and dimensions. RESULTS: Striking correspondence was obtained between the two methods. The four dimensions emerging were labelled 'depression', 'reality distortion', 'mania' and 'disorganization'. Latent classes identified were 'depression', 'bipolar', 'reality distortion/depression' and 'disorganization'. The latent classes corresponded well with DSM-III-R diagnoses, but also revealed groupings usually obscured by diagnostic boundaries. The latent classes differed on gender ratio, fertility, age of onset and self-harming behaviour, but not on substance misuse or season of birth. CONCLUSIONS: Both dimensional and categorical approaches are useful in tapping the latent constructs underlying psychosis. Broad agreement with other similar studies suggests such findings could represent discrete pathological conditions. The four classes described appear meaningful, and suggest that the term non-affective psychosis should be reserved for the disorganization class, which represents only a subgroup of those with schizophrenia.     

Possible linkage relationships between certain blood groups and schizophrenia or other psychoses

A reanalysis of a body of data on dizygotic twins may suggest a genetic relationship between the Gc locus and psychosis in general and the possibility of linkages between schizophrenia and theGm and the Rhesus systems.This investigation was supported by a Public Health Service Research Career Development Award (1-K3-GM-31, 732) and a research grant (GM HD 16697) from the National Institute of General Medical Sciences.     

Tonsillectomy associated with an increased risk of autoimmune diseases: A national cohort study

BackgroundTonsillectomy is a common surgical procedure. Recent evidence suggests that tonsils play an important role in our immune system. We thus hypothesize that individuals with tonsillectomy may face an increased incidence of autoimmune diseases in their later life.MethodsAll individuals that had a tonsillectomy in Sweden between 1997 and 2012 were identified from the Swedish Hospital Discharge and Outpatient Register, and were followed until the diagnosis of a set of autoimmune diseases. Standardized incidence ratios (SIRs) were used to calculate the risk of autoimmune diseases as compared to the general population.ResultsA total of 179,875 individuals received a tonsillectomy in Sweden and 5357 of them were subsequently diagnosed with autoimmune diseases, giving an overall SIR of 1.34 (95%CI 1.30–1.37). For specific autoimmune diseases, 16 of them showed a significantly increased SIR, ranging between 1.21 and 2.97. The increased incidence was largely consistent irrespective of gender, age at operation, and underlying indications of tonsillectomy.ConclusionsThe incidence of a group of autoimmune diseases was higher in individuals operated with a tonsillectomy. Immune dysfunction due to tonsillectomy may partly explain the observed association. However, the underlying mechanisms need to be explored in future studies.     

Early life risk factors for adult asthma: a birth cohort study of subjects at risk.

BACKGROUND: Prediction of adult asthma is important, and early prevention strategies should be targeted at those most at risk. Identifying high-risk children at an early age, however, is currently difficult. OBJECTIVE: We sought to determine those factors present in early life that predict an increased risk of adult asthma. METHODS: A prospective cohort study of subjects at risk of asthma and atopy was undertaken in Poole, England. One hundred babies of atopic parents were recruited at birth. During the first 5 years of life, subjects were recalled annually, all respiratory events were reported, and skin prick tests and total serum IgE measurements were performed. At 11 and 22 years, bronchial hyperresponsiveness was also measured. Seventy-three subjects were followed up at 5 years, 67 at 11 years, and 63 at 22 years. RESULTS: Twenty-three (37%) adult subjects reported wheezing within the previous 12 months. Fifteen (25%) of these subjects showed signs of bronchial hyperresponsiveness and were regarded as asthmatic. Wheezing before the age of 2 years occurred in 28% and was not significantly related to adult asthma (odds ratio, 0.3; 95% CI, 0.03-1.7; P = .19). A positive skin prick test response to hen's egg, cow's milk, or both in the first year was independently predictive of adult asthma (odds ratio, 10.7; 95% CI, 2.1-55.1; P = .001; sensitivity, 57%; specificity, 89%). CONCLUSION: Prediction of adult asthma remains difficult. In this study of subjects at risk of atopy, skin sensitivity to hen's egg or cow's milk in the first year was predictive of adult asthma.     

Gestational age and occurrence of atopy at age 31—a prospective birth cohort study in Finland

BACKGROUND: It has been suggested that main risk factors for development of allergic diseases operate already during pregnancy and in early childhood. OBJECTIVE: To study the association between gestational age, birth weight, parity and parental farming with the risk of atopy and asthma in young adults. METHODS: In a prospective birth cohort study, 5192 subjects born in Northern Finland in 1966 were followed up at the age of 31. Skin prick tests were done to three of the most common allergens in Finland and to house dust mite. Data on doctor-diagnosed asthma was obtained from questionnaires. Perinatal data had already been collected during pregnancy. RESULTS: The risk of atopy increased linearly with increasing length of pregnancy among babies born in the 35th weak of gestation or later. Gestational age equal to, or over 40 weeks compared with less than 36 weeks was associated with an increased risk of atopy (multivariate odds ratio 1.65, 95% CI 1.16, 2.34). The association was stronger among farmers' children (P for interaction 0.01). High parity and being a farmer's child (multivariate odds ratio 0.50, 95% CI 0.42-0.60) was associated with decreased risk of atopy. In contrast, no associations were observed for doctor-diagnosed asthma. CONCLUSIONS: The results underline the importance of pregnancy and very early childhood in the development of atopy, and suggest that timing of the environmental exposure is of importance for the immune system. No association was observed for asthma, which may be due to the multifactorial origins of asthma.     

Age at puberty in relation to age at marriage and parenthood: A national longitudinal study

A longitudinal study of a British cohort has collected information on puberty, judged by menarcheal age for the girls and the pubertal stage of the boys at age 14 3/4. This information has now been related to the ages at which these young people married and became parents. For the young men there was evidence of a direct relationship between degree of sexual maturity at age 14 3/4 and their ages at entry into marriage and fatherhood. For the young women, if pregnancy did not intervene between menarche and marriage, there was evidence of a direct relationship between menarcheal age and marriage age. But there was no evidence that these earlier-maturing young women became mothers at earlier ages than later maturers. This arose through the later-maturing young women having shorter first birth intervals than the earlier maturers. Premarital conceptions were also more prevalent amongst the later maturers.     

Incidence of schizophrenia and other psychoses in ethnic minority groups: results from the MRC AESOP Study

BACKGROUND: The incidence of schizophrenia in the African-Caribbean population in England is reported to be raised. We sought to clarify whether (a) the rates of other psychotic disorders are increased, (b) whether psychosis is increased in other ethnic minority groups, and (c) whether particular age or gender groups are especially at risk. METHOD: We identified all people (n=568) aged 16-64 years presenting to secondary services with their first psychotic symptoms in three well-defined English areas (over a 2-year period in Southeast London and Nottingham and a 9-month period in Bristol). Standardized incidence rates and incidence rate ratios (IRR) for all major psychosis syndromes for all main ethnic groups were calculated. RESULTS: We found remarkably high IRRs for both schizophrenia and manic psychosis in both African-Caribbeans (schizophrenia 9.1, manic psychosis 8.0) and Black Africans (schizophrenia 5.8, manic psychosis 6.2) in men and women. IRRs in other ethnic minority groups were modestly increased as were rates for depressive psychosis and other psychoses in all minority groups. These raised rates were evident in all age groups in our study. CONCLUSIONS: Ethnic minority groups are at increased risk for all psychotic illnesses but African-Caribbeans and Black Africans appear to be at especially high risk for both schizophrenia and mania. These findings suggest that (a) either additional risk factors are operating in African-Caribbeans and Black Africans or that these factors are particularly prevalent in these groups, and that (b) such factors increase risk for schizophrenia and mania in these groups.     

Social adversity contributes to high morbidity in psychoses in immigrants--a national cohort study in two generations of Swedish residents

BACKGROUND: Recent reports have indicated that immigrants have an elevated risk of schizophrenia as well as an increasing tendency for social exclusion. The aim of this study was to compare rates of schizophrenia and other psychoses in immigrants and their children of different ethnic groups with the majority population in Sweden in relation to social adversity. METHOD: The study population consists of a national cohort of 1.47 million adults (born 1929-1965) and 1.16 million children and youth (born 1968-1979) in family households from the national census of 1985. Multivariate Cox regression analyses was used to study hospital discharge data during 1991-2000 in relation to socio-economic household indicators from 1985 and 1990 (single adult household, adults having received social welfare, parental unemployment, urban residency, housing and socio-economic status). RESULTS: First as well as second generation immigrants had higher age and sex adjusted risk ratios for schizophrenia as well as for other psychoses (RRs 1.4-3.1 and 1.0-2.0 respectively) compared with the Swedish majority population. These risk ratios decreased considerably after adjusting for socio-economic indicators, for all groups, but particularly for the non-European immigrants. However, an elevated risk still remained in the Finnish and Eastern and Southern European study groups. CONCLUSIONS: A higher risk of schizophrenia and psychoses was found in two generations of immigrants of diverse ethnicity. The results indicate that social adversity contributes to the higher risk.     

Risk of schizophrenia in second-generation immigrants: a Danish population-based cohort study

BACKGROUND: Urban birth, a risk factor for schizophrenia, is more frequent among second-generation immigrants. The aim of the current study was to determine whether the increased risk for schizophrenia found in second-generation immigrants is explained by the degree of urbanization of birthplace and/or factors related to parentage, such as geographic origin or history of residence abroad during upbringing. METHOD: Using data from the Danish Civil Registration System (CRS), we established a population-based cohort of 2.0 million Danes (persons born in Denmark). Schizophrenia in cohort members was identified by cross-linkage with the Danish Psychiatric Central Register. RESULTS: The relative risk of developing schizophrenia was 1.93 [95% confidence interval (CI) 1.79-2.08] and 2.96 (95% CI 2.49-3.51) among persons with one or both parents foreign-born respectively compared to native Danes. Adjustment for urbanization of birthplace and parental characteristics reduced these risks slightly. However, urbanization had a lesser effect in second-generation immigrants than in Danes. History of residence abroad was a risk factor for schizophrenia, regardless of whether parents were foreign-born or native Danes. CONCLUSION: The increased risk found in second-generation immigrants cannot be explained by urbanization or parental characteristics pertaining to age, mental illness, geographic origin or residence abroad during a child's upbringing.     

Onset of schizophrenia at age 100

Schizophrenia is generally regarded as a disease starting in adolescence and early adulthood. Cases beginning after the age of 60 are rare. The authors present the case of a woman who, at the age of 100, developed an illness marked by delusions and hallucinations and who was diagnosed with schizophrenia, paranoid type. Authors discuss the differential diagnosis of psychotic symptoms presenting late in life.     

A genomewide linkage study of age at onset in schizophrenia.

There is strong evidence for a genetic contribution to age at onset of schizophrenia, which probably involves both susceptibility loci for schizophrenia and modifying loci acting independent of disease risk. We sought evidence of linkage to loci that influence age at onset of schizophrenia in a sample of 94 affected sibling pairs with DSM-IV schizophrenia or schizoaffective disorder, and age at first psychiatric contact of 45 years or less. Individuals were genotyped for 229 microsatellite markers spaced at approximately 20 cM intervals throughout the genome. Loci contributing to age at onset were sought by a quantitative maximum-likelihood multipoint linkage analysis using MAPMAKER/SIBS. A nonparametric multipoint analysis was also performed. The genomewide significance of linkage results was assessed by simulation studies. There were six maximum-likelihood LOD score peaks of 1.5 or greater, the highest being on chromosome 17q (LOD = 2.54; genomewide P = 0.27). This fulfils Lander and Kruglyak's [1995: Nat Genet 11:241-247] criteria for suggestive linkage in that it would be expected to occur once or less (0.3 times) per genome scan. However, this finding should be treated with caution because the LOD score appeared to be almost solely accounted for by the pattern of ibd sharing at one marker (D17S787), with virtually no evidence of linkage over flanking markers. None of the linkage results achieved genomewide statistical significance, but the LOD score peak on chromosome 13q (LOD = 1.68) coincided with the region showing maximum evidence for linkage in the study by Blouin et al. [1998: Nat Genet 20:70-73] of categorical schizophrenia.     

Childhood psychiatric disorder and unintentional injury: findings from a national cohort study

OBJECTIVE: We set out to examine the relationship between unintentional injury and common child psychiatric disorders, including both internalizing and externalizing diagnoses. METHODS: The 1999 British Child and Adolescent Mental Health Survey provided a nationally representative sample of over 10,000 children aged 5-15 years. Measures included assessment of diagnoses of psychiatric disorder from the Diagnostic and Statistical Manual of Mental Disorders, fourth edition, unintentional injury, and a range of potentially related psychosocial factors. RESULTS: Children with psychiatric disorders had higher rates of unintentional injury. After accounting for psychosocial risk factors and comorbid psychopathology, oppositional defiant disorder (ODD) was independently associated with burns and poisoning. Attention deficit hyperactivity disorder (ADHD) was related to fractures, and depression and anxiety also showed independent links to some injury types. CONCLUSIONS: ODD and ADHD, rather than conduct disorder, appear to be the externalizing disorders associated with unintentional injury. We discuss possible models of the relationships between internalizing disorders and unintentional injury.     

Low control at work and the risk of suicide in Japanese men: a prospective cohort study

BACKGROUND: Although adverse psychosocial job characteristics are suspected predictors of suicide death, prospective studies based on established stress instruments are limited. METHODS: In a multicenter community-based Japanese cohort study, we prospectively investigated the association between psychosocial job characteristics and the risk of death from suicide among male workers. Baseline examination was conducted from 1992 to 1995 to determine the socioeconomic, behavioural and biological variables in addition to the psychosocial job characteristics of 3,125 male workers aged 65 and under and free from major illness. Low job control and high job demands were measured as adverse psychosocial job characteristics according to a job demand-control model questionnaire. Suicide deaths were identified using the Cause-of-Death Register. RESULTS: During the 9-year follow-up, 14 suicides were identified. The suicide death rate was 48.1 per 100,000 person years. Multivariate analysis revealed a more than fourfold increase in the risk of suicide among men with low control at work (relative risk: 4.10; 95% confidence interval: 1.31-12.83) compared with counterpart men after adjustment for age, marital status, educational attainment, occupation, smoking status, alcohol consumption, total cholesterol level, and study area. Job demands were not associated with risk of death from suicide. CONCLUSIONS: By using a job demand-control model questionnaire, low control at work was revealed as a predictor of suicide death among Japanese male workers. The finding implies that job redesign aimed at increased worker control could be a worthwhile strategy in preventing, or at least reducing, the risk of suicide death.