Maternal history of autoimmune disease and later development of tourette syndrome in offspring.

OBJECTIVE: In a nationwide prospective cohort study, we examined the possible association between maternal autoimmune disease (AD) and later diagnosis of Tourette syndrome (TS) in offspring. METHOD: Data from national Danish health registers identified a cohort consisting of all children born in Denmark between 1990 and 2007 (n = 1,116,255), followed prospectively from birth until 2011, date of TS diagnosis, death, or emigration/disappearance, whichever came first. The incidence rate ratio (IRR) of TS, dependent on whether or not the mother had a prior diagnosis of AD, was estimated by Poisson regression with 95% CIs and adjusted for age, calendar time, place of birth, maternal and paternal age, parental psychiatric diagnoses other than TS, and parental TS. RESULTS: The cohort contributed a total of 13,000,162 person years and 2,442 participants with a diagnosis of TS (414 females and 2,028 males). Prior maternal AD was found in 110 of the 2,442 children with TS, corresponding to an increased risk of TS, with an adjusted IRR of 1.22 (95% CI = 1.01-1.48). Maternal history of a prior AD increased the risk of TS in males, with an adjusted IRR of 1.29 (95% CI = 1.05-1.58), but not in females, with an adjusted IRR of 0.89 (95% CI = 0.52-1.52). CONCLUSION: Maternal AD was associated with a 29% increased incidence rate of TS in male offspring. This finding supports the hypothesis that neuroimmunological disorders may act as a component in the etiology of a subset of TS.

Suicide risk in relation to air pollen counts: a study based on data from Danish registers.

OBJECTIVES: Since the well-observed spring peak of suicide incidents coincides with the peak of seasonal aeroallergens as tree-pollen, we want to document an association between suicide and pollen exposure with empirical data from Denmark. DESIGN: Ecological time series study. SETTING: Data on suicide incidents, air pollen counts and meteorological status were retrieved from Danish registries. PARTICIPANTS: 13 700 suicide incidents over 1304 consecutive weeks were obtained from two large areas covering 2.86 million residents. PRIMARY AND SECONDARY OUTCOME MEASURES: Risk of suicide associated with pollen concentration was assessed using a time series Poisson-generalised additive model. RESULTS: We noted a significant association between suicide risk and air pollen counts. A change of pollen counts levels from 0 to '10-<30' grains/m(3) air was associated with a relative risk of 1.064, that is, a 6.4% increase in weekly number of suicides in the population, and from 0 to '30-100' grains, a relative risk of 1.132. The observed association remained significant after controlling for effects of region, calendar time, temperature, cloud cover and humidity. Meanwhile, we observed a significant sex difference that suicide risk in men started to rise when there was a small increase of air pollen, while the risk in women started to rise until pollen grains reached a certain level. High levels of pollen had slightly stronger effect on risk of suicide in individuals with mood disorder than those without the disorder. CONCLUSIONS: The observed association between suicide risk and air pollen counts supports the hypothesis that aeroallergens, acting as immune triggers, may precipitate suicide.

Autoimmune diseases and severe infections as risk factors for mood disorders: a nationwide study.

IMPORTANCE: Mood disorders frequently co-occur with medical diseases that involve inflammatory pathophysiologic mechanisms. Immune responses can affect the brain and might increase the risk of mood disorders, but longitudinal studies of comorbidity are lacking. OBJECTIVE: To estimate the effect of autoimmune diseases and infections on the risk of developing mood disorders. DESIGN: Nationwide, population-based, prospective cohort study with 78 million person-years of follow-up. Data were analyzed with survival analysis techniques and adjusted for calendar year, age, and sex. SETTING: Individual data drawn from Danish longitudinal registers. PARTICIPANTS: A total of 3.56 million people born between 1945 and 1996 were followed up from January 1, 1977, through December 31, 2010, with 91, 637 people having hospital contacts for mood disorders. MAIN OUTCOMES AND MEASURES: The risk of a first lifetime diagnosis of mood disorder assigned by a psychiatrist in a hospital, outpatient clinic, or emergency department setting. Incidence rate ratios (IRRs) and accompanying 95% CIs are used as measures of relative risk. RESULTS: A prior hospital contact because of autoimmune disease increased the risk of a subsequent mood disorder diagnosis by 45% (IRR, 1.45; 95% CI, 1.39-1.52). Any history of hospitalization for infection increased the risk of later mood disorders by 62% (IRR, 1.62; 95% CI, 1.60-1.64). The 2 risk factors interacted in synergy and increased the risk of subsequent mood disorders even further (IRR, 2.35; 95% CI, 2.25-2.46). The number of infections and autoimmune diseases increased the risk of mood disorders in a dose-response relationship. Approximately one-third (32%) of the participants diagnosed as having a mood disorder had a previous hospital contact because of an infection, whereas 5% had a previous hospital contact because of an autoimmune disease. CONCLUSIONS AND RELEVANCE: Autoimmune diseases and infections are risk factors for subsequent mood disorder diagnosis. These associations seem compatible with an immunologic hypothesis for the development of mood disorders in subgroups of patients.

Familial predisposition for psychiatric disorder: comparison of subjects treated for cannabis-induced psychosis and schizophrenia.

CONTEXT: Cannabis-induced psychosis is considered a distinct clinical entity in the existing psychiatric diagnostic systems. However, the validity of the diagnosis is uncertain. OBJECTIVES: To establish rate ratios of developing cannabis-induced psychosis associated with predisposition to psychosis and other psychiatric disorders in a first-degree relative and to compare them with the corresponding rate ratios for developing schizophrenia spectrum disorders. DESIGN: A population-based cohort was retrieved from the Danish Psychiatric Central Register and linked with the Danish Civil Registration System. History of treatment of psychiatric disorder in family members was used as an indicator of predisposition to psychiatric disorder. Rate ratios of cannabis-induced psychosis and schizophrenia associated with predisposition to psychiatric disorders were compared using competing risk analyses. SETTING: Nationwide population-based sample of all individuals born in Denmark between January 1,1955, and July 1, 1990 (N = 2,276,309). Patients During the 21.9 million person-years of follow-up between 1994 and 2005, 609 individuals received treatment of a cannabis-induced psychosis and 6476 received treatment of a schizophrenia spectrum disorder. RESULTS: In general, the rate ratios of developing cannabis-induced psychosis and schizophrenia spectrum disorder associated with predisposition to schizophrenia spectrum disorder, other psychoses, and other psychiatric disorders in first-degree relatives were of similar magnitude. However, children with a mother with schizophrenia were at a 5-fold increased risk of developing schizophrenia and a 2.5-fold increased risk of developing cannabis-induced psychosis. The risk of a schizophrenia spectrum disorder following a cannabis-induced psychosis and the timing of onset were unrelated to familial predisposition. CONCLUSIONS: Predisposition to both psychiatric disorders in general and psychotic disorders specifically contributes equally to the risk of later treatment because of schizophrenia and cannabis-induced psychoses. Cannabis-induced psychosis could be an early sign of schizophrenia rather than a distinct clinical entity.

Early infections of Toxoplasma gondii and the later development of schizophrenia.

Early exposure to several infectious agents has been associated with the later development of schizophrenia. Two recent studies assessed in utero or early postnatal exposure to Toxoplasma gondii. In one study of 63 individuals, who developed schizophrenia spectrum disorders, maternal sera obtained during pregnancy showed an increased risk (OR 2.61) of having IgG antibodies to T. gondii. In the other study of 71 individuals who developed schizophrenia, sera obtained shortly after birth also showed an increased risk (OR 1.79) of having IgG antibodies to T. gondii. Causal linking mechanisms are at present speculative but include possible direct effects of maternal IgG on the developing central nervous system (CNS) of the offspring. Additional studies are underway.