Interaction between parental psychosis and risk factors during pregnancy and birth for schizophrenia - the Northern Finland 1966 Birth Cohort study

Birth Weight and Childhood Psychopathology in the ABCD Cohort: Association is Strongest for Attention Problems and is Moderated by Sex

Many studies have shown low birth weight is associated with psychopathology later in life, particularly attention-deficit/hyperactivity disorder (ADHD). The association is well-replicated, independent from a variety of potential familial confounds, and follows a dose-response curve (decreasing birth weight linked with increasing odds of disorder). However, the specificity of the association to attention problems is called into question by the extent of comorbidity in ADHD, and recent findings that the association is stronger for autism than ADHD. We test the relative dose-response strength of birth weight on multiple aspects of behavior to explore specificity of the effect to attention problems. We also test recent suggestions that the association between birth weight and attention problems is driven by males. Our sample consisted of 9,076 children aged 9-10 from the United States (Adolescent Brain Cognitive Development study). Outcomes included 9 problem-scales and the total problems scale from the Child Behavior Checklist (CBCL). Attention problems were the most strongly associated with birth weight after controlling for gestational age, potential familial confounds, and multiple testing, supporting the outcome-specificity of this association. Contrary to recent registry-based findings, an association between birth weight and an autism scale was not observed. Sex moderated the effect of birth weight on total problems, attention problems and aggressive behavior such that these inverse associations were strongly driven by males. Our findings have strong implications for sex-specific prediction and etiological models of childhood psychopathology.

The Association Between High Birth Weight and Long-Term Outcomes-Implications for Assisted Reproductive Technologies: A Systematic Review and Meta-Analysis

Background: Studies have shown that the prevalence of children born with high birth weight or large for gestational age (LGA) is increasing. This is true for spontaneous pregnancies; however, children born after frozen embryo transfer (FET) as part of assisted reproductive technology (ART) also have an elevated risk. In recent years, the practice of FET has increased rapidly and while the perinatal and obstetric risks are well-studied, less is known about the long-term health consequences. Objective: The aim of this systematic review was to describe the association between high birth weight and LGA on long-term child outcomes. Data Sources: PubMed, Scopus, and Web of Science were searched up to January 2021. Exposure included high birth weight and LGA. Long-term outcome variables included malignancies, psychiatric disorders, cardiovascular disease, and diabetes. Study Selection: Original studies published in English or Scandinavian languages were included. Studies with a control group were included while studies published as abstracts and case reports were excluded. Data Extraction: The methodological quality, in terms of risk of bias, was assessed by pairs of reviewers. Robins-I (www.methods.cochrane.org) was used for risk of bias assessment in original articles. For systematic reviews, AMSTAR (www.amstar.ca) was used. For certainty of evidence, we used the GRADE system. The systematic review followed PRISMA guidelines. When possible, meta-analyses were performed. Results: The search included 11,767 articles out of which 173 met the inclusion criteria and were included in the qualitative analysis, while 63 were included in quantitative synthesis (meta-analyses). High birth weight and/or LGA was associated with low to moderately elevated risks for certain malignancies in childhood, breast cancer, several psychiatric disorders, hypertension in childhood, and type 1 and 2 diabetes. Conclusions: Although the increased risks for adverse outcome in offspring associated with high birth weight and LGA represent serious health effects in childhood and in adulthood, the size of these effects seems moderate. The identified risk association should, however, be taken into account in decisions concerning fresh and frozen ART cycles and is of general importance in view of the increasing prevalence in high birthweight babies.

Robust data-driven identification of risk factors and their interactions: A simulation and a study of parental and demographic risk factors for schizophrenia

OBJECTIVES

Few interactions between risk factors for schizophrenia have been replicated, but fitting all such interactions is difficult due to high-dimensionality. Our aims are to examine significant main and interaction effects for schizophrenia and the performance of our approach using simulated data.

METHODS

We apply the machine learning technique elastic net to a high-dimensional logistic regression model to produce a sparse set of predictors, and then assess the significance of odds ratios (OR) with Bonferroni-corrected p-values and confidence intervals (CI). We introduce a simulation model that resembles a Finnish nested case-control study of schizophrenia which uses national registers to identify cases (n = 1,468) and controls (n = 2,975). The predictors include nine sociodemographic factors and all interactions (31 predictors).

RESULTS

In the simulation, interactions with OR = 3 and prevalence = 4% were identified with <5% false positive rate and ≥80% power. None of the studied interactions were significantly associated with schizophrenia, but main effects of parental psychosis (OR = 5.2, CI 2.9-9.7; p < .001), urbanicity (1.3, 1.1-1.7; p = .001), and paternal age ≥35 (1.3, 1.004-1.6; p = .04) were significant.

CONCLUSIONS

We have provided an analytic pipeline for data-driven identification of main and interaction effects in case-control data. We identified highly replicated main effects for schizophrenia, but no interactions.

Early environmental factors and somatic comorbidity in schizophrenia and nonschizophrenic psychoses: A 50-year follow-up of the Northern Finland Birth Cohort 1966

Background.

We studied the cumulative incidence of physical illnesses, and the effect of early environmental factors (EEFs) on somatic comorbidity in schizophrenia, in nonschizophrenic psychosis and among nonpsychotic controls from birth up to the age of 50 years.

Methods.

The sample included 10,933 members of the Northern Finland Birth Cohort 1966, of whom, 227 had schizophrenia and 205 had nonschizophrenic psychosis. Diagnoses concerning physical illnesses were based on nationwide registers followed up to the end of 2016 and classified into 13 illness categories. Maternal education and age, family type at birth and paternal socioeconomic status were studied as EEFs of somatic illnesses.

Results.

When adjusted by gender and education, individuals and especially women with nonschizophrenic psychosis had higher risk of morbidity in almost all somatic illness categories compared to controls, and in some categories, compared to individuals with schizophrenia. The statistically significant adjusted hazard ratios varied from 1.27 to 2.42 in nonschizophrenic psychosis. Regarding EEFs, single-parent family as the family type at birth was a risk factor for a higher somatic score among men with schizophrenia and women with nonschizophrenic psychosis. Maternal age over 35 years was associated with lower somatic score among women with nonschizophrenic psychosis.

Conclusions.

Persons with nonschizophrenic psychoses have higher incidence of somatic diseases compared to people with schizophrenia and nonpsychotic controls, and this should be noted in clinical work. EEFs have mostly weak association with somatic comorbidity in our study.

Antisocial and borderline personality disorders in the offspring of antenatally depressed mothers - a follow-up until mid-adulthood in the Northern Finland 1966 birth cohort

Background: Maternal depression is common during pregnancy, affecting 10-15% of mothers. In previous reports, the offspring of antenatally depressed mothers have had an elevated risk for antisocial, criminal and violent behaviour in adolescence, and for borderline personality features in childhood, but long-term outcomes are unknown.Aims: To study whether the adult offspring of antenatally depressed mothers have an elevated risk for antisocial (ASPD) or borderline personality disorder (BPD) when followed until mid-adulthood.Methods: In the general population-based Northern Finland 1966 Birth Cohort, mothers of 12,058 children were asked during mid-gestation if they felt depressed. Of the mothers, 14% reported being depressed. The offspring were followed for 49 years. The diagnoses of in- and outpatient-treated ASPD and BPD in the offspring were detected using the Finnish Care Register for Healthcare. Maternal antenatal smoking, newborn´s low birthweight or short gestational age, father's social class, and family type at birth were considered as confounding variables. Logistic regression analyses on the potential confounders were performed. Maternal postnatal depression and paternal ASPD information was not available.Results: In the male offspring of antenatally depressed mothers, the risk for ASPD was elevated (adjusted odds ratio 5.6; 95% confidence interval 1.8-17.8), but not in female offspring. The risk for BPD was not elevated in the offspring of antenatally depressed mothers in this study.Conclusions: The sons of antenatally depressed mothers had an increased risk for ASPD. Prevention and treatment of antenatal depression might present an opportunity to decrease the risk of antisocial personality in the offspring.

Early childhood and adolescent risk factors for psychotic depression in a general population birth cohort sample

BACKGROUND AND PURPOSE

In the group of severe mental disorders, psychotic depression (PD) is essentially under-researched. Knowledge about the risk factors is scarce and this applies especially to early risk factors. Our aim was to study early childhood and adolescent risk factors of PD in a representative birth cohort sample with a follow-up of up to 50 years.

METHODS

The study was carried out using the Northern Finland Birth Cohort 1966 (NFBC 1966). We used non-psychotic depression (NPD) (n = 746), schizophrenia (SZ) (n = 195), psychotic bipolar disorder (PBD) (n = 27), other psychoses (PNOS) (n = 136) and healthy controls (HC) (n = 8200) as comparison groups for PD (n = 58). We analysed several potential early risk factors from time of birth until the age of 16 years.

RESULTS

The main finding was that parents' psychiatric illness [HR 3.59 (1.84-7.04)] was a risk factor and a high sports grade in school was a protective factor [HR 0.29 (0.11-0.73)] for PD also after adjusting for covariates in the multivariate Cox regression model. Parental psychotic illness was an especially strong risk factor for PD. The PD subjects had a parent with psychiatric illness significantly more often (p < 0.05) than NPD subjects. Differences between PD and other disorder groups were otherwise small.

CONCLUSIONS

A low sports grade in school may be a risk factor for PD. Psychiatric illnesses, especially psychoses, are common in the parents of PD subjects. A surprisingly low number of statistically significant risk factors may have resulted from the size of the PD sample and the underlying heterogeneity of the etiology of PD.

Antipsychotic-induced weight gain and birth weight in psychosis: A fetal programming model

Antipsychotic induced weight gain is a frequent reason for treatment discontinuation in psychosis, subsequently increasing the risk of relapse and negatively affecting patient well-being. The metabolic effect of weight gain and the subsequent risk of obesity constitute a major medical problem on the long term. Despite its consequences, to date few risk factors have been identified (age, gender, body mass index at baseline), with some authors suggesting the implication of early life stressful events, such as perinatal conditions. We aim to describe if a surrogate marker of intrauterine environment (birth weight) might predict weight gain in a cohort of 23 antipsychotic naïve patients at the onset of the psychotic disease evaluated during 16 weeks with olanzapine treatment and in another cohort of 24 psychosis-resistant patients initiating clozapine assessed for 18 weeks. Two independent linear mixed model analyses were performed in each cohort of patients, with prospective weight gain as the dependent variable, age, gender, body mass index, duration of treatment and time as independent variables. Only in naïve patients, weight gain due to antipsychotics was significantly associated with birth weight, while male gender and body mass index at baseline were associated in both cohorts of patients. Treatment-resistant psychotic patients under clozapine were older, had previous antipsychotic treatment and more years of disease, confounders that might have influence a non significant association. Our results suggest that early environmental events might be playing a role in weight evolution in naïve patients treated with antipsychotics.

Severe mood disorders and schizophrenia in the adult offspring of antenatally depressed mothers in the Northern Finland 1966 Birth Cohort: Relationship to parental severe mental disorder

BACKGROUND

Maternal antenatal depression may alter offspring neurodevelopment, but long follow-up studies are lacking. We studied the risks for mood disorders and schizophrenia in adult offspring of antenatally depressed mothers, taking account parental severe mental disorders.

METHODS

In the general population-based Northern Finland 1966 Birth Cohort with 12,058 children, 13.9% of the mothers reported themselves depressed at mid-gestation. The offspring were followed 43 years. Severe mood disorders and schizophrenia in the offspring and severe mental disorders in the parents were detected using the Care Register for Healthcare. Maternal smoking during pregnancy, perinatal complications, fathers´ social class, family type at birth, and grand multiparity were considered as confounding variables.

RESULTS

The offspring of antenatally depressed mothers had an elevated risk for depression (adjusted OR 1.5; 95% CI 1.03-2.2), compared to cohort members without maternal antenatal depressed mood. The offspring with maternal antenatal depressed mood and parental severe mental disorder had markedly elevated risks for depression (3.3; 1.8-6.2), and schizophrenia (3.9; 2.0-7.5), compared to the offspring without one or both of these risk factors.

LIMITATIONS

Maternal antenatal depressed mood was determined by one question and did not necessarily signify a clinical condition. Data on maternal postnatal mood was not available.

CONCLUSION

The offspring with maternal antenatal depressed mood and parental severe mental disorder had high risk for depression and schizophrenia. Early interventions in parental severe mental disorder might present an opportunity for decreasing the risk for mood disorders and schizophrenia in the offspring.

Search for protective factors for psychosis - a population-based sample with special interest in unaffected individuals with parental psychosis

AIM

To find factors that are associated with not having psychotic illness in a prospective general population sample, with a special interest in individuals with parental psychosis.

METHODS

Data from the Northern Finland Birth Cohort 1966 (n = 10 458) and several registers were used to detect individuals with and without parental psychosis. Altogether, 594 persons had parent(s) with psychosis and 48 of them also had psychosis subsequently. Variables related to pregnancy and birth, family and childhood, health and habits in adolescence, school performance and physical activity were studied to identify determinants of unaffected status among individuals with and without parental psychosis.

RESULTS

In the parental psychosis group, the unaffected persons had more likely a mother who was non-depressed during pregnancy, and who worked outside the home or studied than among those who developed psychosis.

CONCLUSIONS

Protective factors for psychosis were surprisingly few in this sample. These factors were related to the mother's non-depressed mood and the mother's work outside the home or studies. This could relate to better health and functioning of a mother. This work highlights the need for more research on protective factors for psychosis in order to identify methods for prevention of psychosis.

Interaction between compound genetic risk for schizophrenia and high birth weight contributes to social anhedonia and schizophrenia in women

Schizophrenia is a highly heritable disease, but despite extensive study, its genetic background remains unresolved. The lack of environmental measures in genetic studies may offer some explanation. In recent Finnish studies, high birth weight was found to increase the risk for familial schizophrenia. We examined the interaction between a polygenic risk score for schizophrenia and high birth weight on social anhedonia and schizophrenia in a general population birth cohort. The study sample included 4223 participants from the 1966 Northern Finland Birth Cohort. As a replication sample we used 256 participants from a systematically collected sample of Finnish schizophrenia families. The polygenic risk score comprised of variants published in the large genome-wide meta-analysis for schizophrenia. We found the association between the polygenic risk score and social anhedonia stronger among those with high birth weight, and the same phenomenon was seen for schizophrenia among women, suggesting a gene-environment interaction. Similar results were found within the replication sample. Our results suggest a role for gene-environment interactions in assessing the risk of schizophrenia. Failure to take environmental effects into account may be one of the reasons why identifying significant SNPs for schizophrenia in genome-wide studies has been challenging.

Clinical, Cognitive, and Neuroimaging Evidence of a Neurodevelopmental Continuum in Offspring of Probands With Schizophrenia and Bipolar Disorder

BACKGROUND

Studies in child and adolescent offspring of patients with schizophrenia or bipolar disorders may help understand the influence of neurodevelopmental factors on the premorbid phenotype of these disorders.

AIMS

To assess whether a combination of neurodevelopmental factors discriminates between young offspring of patients with schizophrenia (SzO) or bipolar disorder (BpO) and community controls (CcO). To assess the association between these factors and rates of psychiatric diagnoses in high risk (HR) youth.

METHODS

One hundred thirty-three HR offspring (47 SzO and 86 BpO) and 84 CcO, aged 6-17, underwent cross-sectional clinical, neurocognitive, and structural neuroimaging assessment. Information on perinatal events and early childhood development was also obtained. General linear mixed models were performed to assess group discrimination and association with lifetime axis I psychiatric disorders.

RESULTS

Multivariate analyses revealed that greater neurological soft signs (NSS), less total grey matter volume (GMV) and a higher frequency of obstetric complications discriminated HR offspring from CcO. When comparing each group individually, greater NSS and a higher frequency of obstetric complications discriminated SzO from CcO, and BpO from CcO, while lower intelligence also discriminated SzO from CcO and from BpO. Within HR offspring, lower intelligence and less total GMV were associated with lifetime incidence of psychiatric disorders.

CONCLUSIONS

Both SzO and BpO showed evidence of neurodevelopmental insult, although this may have a greater impact in SzO. Lower intelligence and less total GMV hold potential as biomarkers of risk for psychiatric disorders in HR youth.

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.

Do adverse perinatal events predict mortality in schizophrenia during midlife?

BACKGROUND

We examined mortality in schizophrenia spectrum disorder (SSD) and non-schizophrenic psychosis (NSSD) compared to individuals without psychosis, and whether perinatal factors predict mortality.

METHODS

Within Northern Finland Birth Cohort 1966 (n=10 933; 203 with SSD, 178 with NSSD), mortality was followed until end of 2011 by national register. Wantedness of pregnancy, mother's antenatal depression, smoking and age, parity, paternal socio-economic status (SES) and family type at birth were examined as predictors of mortality.

RESULTS

Mortality was higher in SSD (hazard ratio (HR) 3.60; 95% confidence interval (CI) 2.38-5.45) and NSSD (4.05; 2.65-6.17) compared to persons without psychoses after adjustment for gender. HR for natural death was 2.01 (0.82-4.91) in SSD and 4.63 (2.43-8.80) in NSSD after adjustment for gender. Corresponding figures for unnatural deaths were 4.71 (2.94-7.54) and 2.94 (1.56-5.55), respectively. Among non-psychotic persons, mother's depression, smoking and low SES predicted mortality after adjustment for gender and parental psychoses (and SES), whereas among psychosis those whose father was a farmer had lower risk of mortality compared to those with high SES.

CONCLUSIONS

Individuals with SSD had a higher risk of unnatural death and individuals with NSSD of natural and unnatural deaths. Perinatal factors seem to be more important predictors of mortality in individuals without psychoses than with psychoses. According to population-based long follow-up data, it is important to pay attention to somatic morbidity behind natural causes of death in psychoses and to prevent suicides in order to prevent excess mortality.

The C9ORF72 expansion sizes in patients with psychosis: a population-based study on the Northern Finland Birth Cohort 1966

Patients with behavioral variant frontotemporal dementia (bvFTD) have many psychotic symptoms, especially at the onset of the disease. The C9ORF72 expansion is the most common genetic etiology observed with bvFTD and the prevalence of the expansion is notably high among Finnish bvFTD patients. The aim of this study was to evaluate the prevalence of the C9ORF72 expansion among the clearly characterized patients with psychosis, mainly schizophrenia, in early midlife. The C9ORF72 repeat sizes were analyzed in 130 (48% women) patients with psychosis from the Northern Finland Birth Cohort 1966 (N=11,017), the mean onset age being 27.9 (SD 7.0) years. Despite the high frequency of psychiatric symptoms in bvFTD patients and the extremely high prevalence of the C9ORF72 expansion in Finland, pathogenic expansion (>40 repeats) was not detected among the Northern Finland Birth Cohort 1966 individuals with psychosis, indicating that these disorders, especially schizophrenia before the age of 43 years, may not be associated with the C9ORF72 expansion. However, we identified four cases with intermediate size repeats (17-26), but the role of the intermediate repeats in the etiology of psychosis is unknown.

Prognosis of schizophrenia spectrum disorder may not be predetermined during early development--the Northern Finland Birth Cohort 1966

BACKGROUND

Little is known about whether factors during the first years of life predict later outcomes in schizophrenia spectrum disorder (SSD). As part of the Northern Finland Birth Cohort 1966, we examined if prospectively collected early parenthood-related and developmental factors predict employment and hospitalization in individuals with and without SSD.

METHODS

Overall, 161 individuals with SSD and 10,116 without SSD were included in the study. Outcomes were analysed at age of 44-45years, defining "employment" as being employed for at least 25% of working days and "hospitalization" as having psychiatric hospitalization at least once during the last two years of follow-up. Maternal age, wantedness of pregnancy, grand multiparity, parental psychoses, birth weight, birth height, age of standing up and standing and walking without support were analysed as predictors.

RESULTS

Of the individuals with SSD, only 11.2% were employed, although 77.6% remained not hospitalized. In individuals with SSD, only young maternal age was associated with lower probability (OR 0.25, CI 0.08-0.77) of being non-hospitalized after controlling for sex and onset age of illness. Among persons without SSD, almost all parenthood-related and developmental factors were related to employment, while grand multiparity and parental psychosis were related to hospitalization after controlling for sex.

CONCLUSIONS

Only one of the early parenthood-related and developmental factors analysed in this study predicted outcome in individuals with SSD, while among those without SSD almost all factors were related to employment. Thus, prognosis of SSD does not seem to be predetermined much by early development.

An interaction between NDE1 and high birth weight increases schizophrenia susceptibility

Pre- and perinatal environmental factors have been shown to increase schizophrenia risk particularly when combined with genetic liability. The investigation of specific gene environment interactions in the etiology of psychiatric disorders has gained momentum. We used multivariate GEE regression modeling to investigate the interaction between genes of the DISC1 pathway and birth weight, in relation to schizophrenia susceptibility in a Finnish schizophrenia family cohort. The study sample consisted of 457 subjects with both genotype and birth weight information. Gender and place of birth were adjusted for in the models. We found a significant interaction between birth weight and two NDE1 markers in relation to increased schizophrenia risk: a four SNP haplotype spanning NDE1 (b=1.26, SE=0.5, p=0.012) and one of its constituent SNPs rs4781678 (b=1.33, SE=0.51, p=0.010). Specifically, high birth weight (>4000g) was associated with increased schizophrenia risk among subjects homozygous for the previously identified risk alleles. The study was based on a family study sample with high genetic loading for schizophrenia and thus our findings cannot directly be generalized as representing the general population. Our results suggest that the functions mediated by NDE1 during the early stages of neurodevelopment are susceptible to the additional disruptive effects of pre- and perinatal environmental factors associated with high birth weight, augmenting schizophrenia susceptibility.

Interaction between parental psychosis and early motor development and the risk of schizophrenia in a general population birth cohort

Background

Delayed motor development in infancy and family history of psychosis are both associated with increased risk of schizophrenia, but their interaction is largely unstudied.

Aim

To investigate the association of the age of achieving motor milestones and parental psychosis and their interaction in respect to risk of schizophrenia.

Methods

We used data from the general population-based prospective Northern Finland Birth Cohort 1966 (n = 10,283). Developmental information of the cohort members was gathered during regular visits to Finnish child welfare clinics. Several registers were used to determine the diagnosis of schizophrenia among the cohort members and psychosis among the parents. Altogether 152 (1.5%) individuals had schizophrenia by the age of 46 years, with 23 (15.1%) of them having a parent with psychosis. Cox regression analysis was used in analyses.

Results

Parental psychosis was associated (P < 0.05) with later achievement of holding the head up, grabbing an object, and walking without support. In the parental psychosis group, the risk for schizophrenia was increased if holding the head up (hazard ratio [HR]: 2.46; degrees of freedom [df] = 1; 95% confidence interval [95% CI]: 1.07–5.66) and touching the thumb with the index finger (HR: 1.84; df = 1; 95% CI: 1.11–3.06) was later. In the group without parental psychosis, a delay in the following milestones increased the risk of schizophrenia: standing without support and walking without support. Parental psychosis had an interaction with delayed touching thumb with index finger (HR: 1.87; df = 1; 95% CI: 1.08–3.25) when risk of schizophrenia was investigated.

Conclusions

Parental psychosis was associated with achieving motor milestones later in infancy, particularly the milestones that appear early in a child's life. Parental psychosis and touching the thumb with the index finger had a significant interaction on risk of schizophrenia. Genetic risk for psychosis may interact with delayed development to raise future risk of schizophrenia, or delayed development may be a marker of other risk processes that interact with genetic liability to cause later schizophrenia.

Late preterm birth, post-term birth, and abnormal fetal growth as risk factors for severe mental disorders from early to late adulthood

BACKGROUND

Late preterm births constitute the majority of preterm births. However, most evidence suggesting that preterm birth predicts the risk of mental disorders comes from studies on earlier preterm births. We examined if late preterm birth predicts the risks of severe mental disorders from early to late adulthood. We also studied whether adulthood mental disorders are associated with post-term birth or with being born small (SGA) or large (LGA) for gestational age, which have been previously associated with psychopathology risk in younger ages.

METHOD

Of 12 597 Helsinki Birth Cohort Study participants, born 1934-1944, 664 were born late preterm, 1221 post-term, 287 SGA, and 301 LGA. The diagnoses of mental disorders were identified from national hospital discharge and cause of death registers from 1969 to 2010. In total, 1660 (13.2%) participants had severe mental disorders.

RESULTS

Individuals born late preterm did not differ from term-born individuals in their risk of any severe mental disorder. However, men born late preterm had a significantly increased risk of suicide. Post-term birth predicted significantly increased risks of any mental disorder in general and particularly of substance use and anxiety disorders. Individuals born SGA had significantly increased risks of any mental and substance use disorders. Women born LGA had an increased risk of psychotic disorders.

CONCLUSIONS

Although men born late preterm had an increased suicide risk, late preterm birth did not exert widespread effects on adult psychopathology. In contrast, the risks of severe mental disorders across adulthood were increased among individuals born SGA and individuals born post-term.

Twenty Years of Schizophrenia Research in the Northern Finland Birth Cohort 1966: A Systematic Review

Birth cohort designs are useful in studying adult disease trajectories and outcomes, such as schizophrenia. We review the schizophrenia research performed in the Northern Finland Birth Cohort 1966 (NFBC 1966), which includes 10,934 individuals living in Finland at 16 years of age who have been monitored since each mother's mid-pregnancy. By the age of 44, 150 (1.4%) had developed schizophrenia. There are 77 original papers on schizophrenia published from the NFBC 1966. The early studies have found various risk factors for schizophrenia, especially related to pregnancy and perinatal phase. Psychiatric and somatic outcomes were heterogeneous, but relatively poor. Mortality in schizophrenia is high, especially due to suicides. Several early predictors of outcomes have also been found. Individuals with schizophrenia have alterations in brain morphometry and neurocognition, and our latest studies have found that the use of high lifetime doses of antipsychotics associated with these changes. The schizophrenia research in the NFBC 1966 has been especially active for 20 years, the prospective study design and long follow-up enabling several clinically and epidemiologically important findings. When compared to other birth cohorts, the research in the NFBC 1966 has offered also unique findings on course and outcome of schizophrenia.

Maternal Grand Multiparity and the Risk of Severe Mental Disorders in Adult Offspring

BACKGROUND

Previous studies have shown that maternal grand multiparity may predict an increased risk of mental disorders in young adult offspring, but whether such effects persist throughout adulthood remains unknown. The current study examined if maternal grand multiparity predicts the risks of severe mental disorders, suicides, suicide attempts and dementias throughout adult life.

METHODS

Our study sample comprised 13243 Helsinki Birth Cohort Study 1934-1944 participants (6905 men and 6338 women). According to hospital birth records, 341 offspring were born to grand multiparous mothers. From Finnish national hospital discharge and causes of death registers, we identified 1682 participants diagnosed with mental disorders during 1969-2010.

RESULTS

Maternal grand multiparity predicted significantly increased risks of mood disorders (Hazard Ratio = 1.64, p = 0.03), non-psychotic mood disorders (Hazard Ratio = 2.02, p = 0.002), and suicide attempts (Hazard Ratio = 3.94, p = 0.01) in adult offspring. Furthermore, women born to grand multiparous mothers had significantly increased risks of any severe mental disorder (Hazard Ratio = 1.79, p = 0.01), non-psychotic substance use disorders (Hazard Ratio = 2.77, p = 0.02) schizophrenia, schizotypal and delusional disorders (Hazard Ratio = 2.40, p = 0.02), mood disorders (Hazard Ratio = 2.40, p = 0.002), non-psychotic mood disorders (Hazard Ratio = 2.91, p<0.001), and suicide attempts (Hazard Ratio = 5.05, p = 0.01) in adulthood. The effects of maternal grand multiparity on offspring psychopathology risk were independent of maternal age and body mass index at childbirth, and of year of birth, sex, childhood socioeconomic position, and birth weight of the offspring. In contrast, no significant effects were found among men.

CONCLUSIONS

Women born to grand multiparous mothers are at an increased risk of severe mental disorders and suicide attempts across adulthood. Our findings may inform the development of preventive interventions for mental disorders.

Exposure to stressful life events during pregnancy predicts psychotic experiences via behaviour problems in childhood

BACKGROUND

Exposure to stressful life events during pregnancy has been associated with later schizophrenia in offspring. We explore how prenatal stress and neurodevelopmental abnormalities in childhood associate to increase the risk of later psychotic experiences.

METHODS

Participants from the Mater University Study of Pregnancy (MUSP), an Australian based, pre-birth cohort study were examined for lifetime DSM-IV positive psychotic experiences at 21 years by a semi-structured interview (n = 2227). Structural equation modelling suggested psychotic experiences were best represented with a bifactor model including a general psychosis factor and two group factors. We tested for an association between prenatal stressful life events with the psychotic experiences, and examined for potential moderation and mediation by behaviour problems and cognitive ability in childhood.

RESULTS

Prenatal stressful life events predicted psychotic experiences indirectly via behaviour problems at child age five years, and this relationship was not confounded by maternal stressful life events at child age five. We found no statistical evidence for an interaction between prenatal stressful life events and behaviour problems or cognitive ability.

CONCLUSION

The measurable effect of prenatal stressful life events on later psychotic experiences in offspring manifested as behaviour problems by age 5. By identifying early abnormal behavioural development as an intermediary, this finding further confirms the role of prenatal stress to later psychotic disorders.