Finnish Prenatal Study of Bipolar Disorders (FIPS-B): overview, design and description of the sample

Selective mutism and the risk of mental and neurodevelopmental disorders among siblings

The siblings of children with mental disorders are more likely to experience mental health issues themselves, but there has been a lack of sibling studies on selective mutism (SM). The aim of this population-based study was to use national registers to examine associations between children with SM and diagnoses of various mental disorder in their siblings. All singleton children born in Finland from 1987 to 2009, and diagnosed with SM from 1998 to 2012, were identified from national health registers and matched with four controls by age and sex. Their biological siblings and parents were identified using national registries and the diagnostic information on the siblings of the subjects and controls was obtained. The final analyses comprised 658 children with SM and their 1661 siblings and 2092 controls with 4120 siblings. The analyses were conducted using generalized estimating equations. Mental disorders were more common among the siblings of the children with SM than among the siblings of the controls. The strongest associations were observed for childhood emotional disorders and autism spectrum disorders after the data were adjusted for covariates and comorbid diagnoses among SM subjects. The final model showed associations between SM and a wide range of disorders in siblings, with strongest associations with disorders that usually have their onset during childhood. Our finding showed that SM clustered with other mental disorders in siblings and this requires further research, especially the association between SM and autism spectrum disorders. Strong associations with childhood onset disorders may indicate shared etiologies.

Time trends in treated incidence, sociodemographic risk factors and comorbidities: a Finnish nationwide study on anxiety disorders

BACKGROUND

There has been a lack of research about the time trends and socio-demographic risk factors for children and adolescents who receive treatment for anxiety disorders. This study aimed to fill these gaps in our knowledge by examining a nationwide sample of Finnish children and adolescents diagnosed in specialized healthcare settings.

METHODS

This study comprised national register data of all singleton children born in Finland from 1992-2006 who were diagnosed with anxiety disorders from 1998-2012. The changes in time trends in incidence were studied by dividing the study sample into three cohorts by birth years: 1992-1996, 1997-2001 and 2002-2006, who were followed up until the age of 20, 15 and 10 years, respectively. The 22,388 individuals with anxiety disorders were age and gender matched with 76,139 controls from the general population. Logistic regression was used to examine the socio-demographic risk factors and anxiety disorders in the entire sample. Comorbid disorders were examined in the oldest birth cohort (1992-1996 born).

RESULTS

Comparing the 1992-1996 and 2002-2006 cohorts showed that the cumulative incidence of treated anxiety disorders at the age of 10 increased from 0.3 to 1.2% among females and 0.46 to 1.9% among males. Subjects had higher likelihood for being diagnosed with an anxiety disorder if their mothers had low maternal socio-economic status class at birth (OR 1.53, 95% CI 1.45-1.61) compared to higher SES class, and marital status was single at the time of birth (OR 2.02, 95% CI 1.87-2.17) compared to married or in a relationship. They had lower risk of anxiety disorders diagnosis if born in rural (OR 0.82, 95% CI 0.79-0.86) or semi-urban areas (OR 0.79, 95% CI 0.76-0.82) when compared to urban residence. There was a wide range of psychiatric comorbidities, and unipolar depression was the most common (31.2%).

CONCLUSION

Anxiety disorders diagnosed by specialized Finnish services increased from 1998-2012 in both genders. This could indicate a real increase in overall anxiety disorders or an increase in treatment seeking. The findings on maternal socioeconomic status and single parenting improve the recognition of the environmental risk factors for anxiety disorders among children and adolescents.

Preterm Birth Is Associated With Depression From Childhood to Early Adulthood

OBJECTIVE

There have been inconsistent findings on the associations among prematurity, poor fetal growth, and depression. We examined the associations among gestational age, poor fetal growth, and depression in individuals aged 5 to 25 years.

METHOD

We identified 37,682 case subjects based on International Classification of Diseases, Ninth Revision code 2961 and International Classification of Diseases, Tenth Revision codes F32.0-F32.9 and F33.0-F33.9 from the Care Register for Health Care, and 148,795 matched controls from the Finnish Central Population Register. Conditional logistic regression examined the associations between gestational age by each gestational week, poor fetal growth, and depression. The associations were adjusted for parental age and psychopathology, paternal immigrant status, maternal substance abuse, depression, number of previous births, marital status, socio-economic status, smoking during pregnancy, and the infant's birthplace.

RESULTS

In the adjusted models, increased risk of depression was found in children born ≤25 weeks (adjusted odds ratio [aOR] 1.89, 95% CI 1.08-3.31), at 26 weeks (aOR 2.62, 95% CI 1.49-4.61), at 27 weeks (aOR 1.93, 95% CI 1.05-3.53), and ≥42 weeks (aOR 1.11, 95% CI 1.05-1.19). In girls, extremely preterm birth was associated with depression diagnosed at 5 to 12 years (aOR 2.70, 95% CI 1.83-3.98) and 13 to 18 years (aOR 2.97, 95% CI 1.84-4.78). In boys, postterm birth (≥42 weeks) was associated with depression diagnosed at 19 to 25 years (aOR 1.28, 95% CI 1.07-1.54). Poor fetal growth was associated with an increased risk of depression in full-term infants (aOR 1.06, 95% CI 1.03-1.10) and postterm infants (aOR 1.24, 95% CI 1.08-1.43).

CONCLUSION

Preterm birth before 28 weeks of gestation appeared to play a role in the development of childhood depression. Smaller effects were also seen in postterm births, especially in boys.

Prenatal and perinatal risk factors for anxiety disorders among children and adolescents: A systematic review

BACKGROUND

Prenatal and perinatal risk factors for anxiety disorders have rarely been studied, even though they are highly prevalent in children and adolescents. It is important to identify the common risk factors, so that targeted preventive care and early interventions can be provided.

METHODS

A systematic review of the PubMed and PsycInfo databases was conducted to 25 October 2019, according to the Preferred Reporting Items of Systematic Reviews and Meta-analyses guidelines. The protocol was registered on the Prospective Register of Systematic Reviews and the quality assessment was carried out using the Joanna Briggs tools.

RESULTS

The review identified 31 studies from eight countries, including three register studies. Cohort sizes ranged from 69 to 89,404 and diagnoses cases ranged from 4 to 7867. Although various risk factors had been researched, only few of them had been repeatedly studied and the findings were highly inconsistent. The associations between the different risk factors and anxiety disorders seemed weak compared to many other psychiatric disorders, but preterm birth and maternal somatic illnesses may increase the risk for anxiety disorders in offspring.

LIMITATIONS

The studies varied considerably by study design, risk factors and anxiety disorders studied, sample sizes and follow up periods.

CONCLUSIONS

Prenatal and perinatal risk factors for anxiety disorders have been under-researched, compared to other psychiatric disorders. Our systematic review found weak links to prenatal events, but flagged up preterm birth and maternal somatic illnesses as possible avenues for future research.

Time trends in the incidence of diagnosed depression among people aged 5-25 years living in Finland 1995-2012

Background: Knowledge of time trends for depression is important for disease prevention and healthcare planning. Only a few studies have addressed these questions regarding the incidence and cumulative incidence of diagnosed depression from childhood to early adulthood and findings have been inconclusive. Aim: The aim of this national register-based Finnish study was to report the time trends of the age-specific and gender-specific incidence and cumulative incidence of diagnosed depression. Methods: The study sample included all 1,245,502 singletons born in Finland between 1 January 1987 and 31 December 2007 and still living in Finland at the end of 2012. The participants were divided into three cohorts by birth year: 1987-1993, 1994-2000 and 2001-2007. Depression diagnoses (ICD-9: 2961; ICD-10: F32, F33) given in 1995-2012 were available and identified from the Care Register for Health Care. Results: Ten percent of the females and five percent of the males were diagnosed with depression in specialized services by age 25 years. The cumulative incidence of depression by age 15 years rose from 1.8% (95% CI 1.8-1.9) to 2.9% (95% CI 2.8-3.0) in females and from 1.0% (95% CI 1.1-1.2) to 1.6% (95% CI 1.6-1.7) in males when the cohorts born 1987-1993 and 1994-2000 were compared. Conclusions: A larger proportion of young people in Finland are diagnosed with depression in specialized services than before. This can be due to better identification, more positive attitudes to mental health problems and increased availability of the services.

The Finnish psychiatric birth cohort consortium (PSYCOHORTS) - content, plans and perspectives

Background: Psychiatric disorders tend to be developmental, and longitudinal settings are required to examine predictors of psychiatric phenomena. Replicating and combining data and results from different birth cohorts, which are a source of reliable data, can make research even more valuable. The Finnish Psychiatric Birth Cohort Consortium (PSYCOHORTS) project combines birth cohorts in Finland. Aim: The aim of this paper is to introduce content, plans and perspectives of the PSYCOHORTS project that brings together researchers from Finland. In addition, we illustrate an example of data harmonization using available data on causes of death. Content: PSYCOHORTS includes eight Finnish birth cohorts. The project has several plans: to harmonize different data from birth cohorts, to incorporate biobanks into psychiatric birth cohort research, to apply multigenerational perspectives, to integrate longitudinal patterns of marginalization and inequality in mental health, and to utilize data in health economics research. Data on causes of death, originally obtained from Finnish Cause of Death register, were harmonized across the six birth cohorts using SAS macro facility. Results: Harmonization of the cause of death data resulted in a total of 21,993 observations from 1965 to 2015. For example, the percentage of deaths due to suicide and the sequelae of intentional self-harm was 14% and alcohol-related diseases, including accidental poisoning by alcohol, was 13%. Conclusions: PSYCOHORTS lays the foundation for complex examinations of psychiatric disorders that is based on compatible datasets, use of biobanks and multigenerational approach to risk factors, and extensive data on marginalization and inequality.

Parental Risk Factors among Children with Reactive Attachment Disorder Referred to Specialized Services: A Nationwide Population-Based Study

This nationwide population-based register study examined the family and parental risk factors associated with offspring reactive attachment disorder (RAD). We identified 614 children diagnosed with RAD from the Finnish Care Register for Health Care and each case was matched with four controls. Univariate and multivariate models examined the associations between risk factors and RAD. In the multivariate model, offspring RAD was associated with only mother, only father and both parents having psychiatric diagnoses. Increased odds were observed for maternal smoking during pregnancy, single motherhood and paternal age ≥ 45 years. This study provides information on several parental adversities and offspring RAD that have important implications for public health, when planning early prevention and interventions in infant mental health.

Register-based study of the incidence, comorbidities and demographics of obsessive-compulsive disorder in specialist healthcare

BACKGROUND

Incidence of obsessive-compulsive disorder (OCD) has been suspected to increase but nationwide epidemiological studies are limited. This study aims to examine sex-specific incidence time trends and characterize psychiatric and neurodevelopmental comorbidities and sociodemographic risk factors of OCD in specialist healthcare in Finland.

METHODS

A nationwide register-based study using data from four Finnish registers identified 3372 OCD cases and 13,372 matched controls (1:4). Cumulative incidence in subjects born between 1987 and 2001 was estimated at ages of 10, 15, 20 and 23 years. Conditional logistic regression was used to examine the sociodemographic factors.

RESULTS

The cumulative incidence of OCD was 0.4% by age 23. Incidence by age 15 among three cohorts increased from 12.4 to 23.7 /10000 live born males and 8.5 to 28.0 /10000 live born females. 73% of the sample had a comorbid condition. Males were significantly more comorbid with psychotic and developmental disorders; females were more comorbid with depressive and anxiety disorders (p <0.001). Higher maternal SES was associated with an increased risk of OCD (OR 1.4; 95% CI 1.1-1.6).

CONCLUSIONS

These findings suggest that incidence of treated OCD in specialist healthcare has increased. The reason may be increased awareness and rate of referrals but a true increase cannot be ruled out. Further research on risk factors of OCD is warranted.

Gestational maternal C--reactive protein and risk of bipolar disorder among young individuals in a Nationwide Birth Cohort

OBJECTIVES

C-reactive protein (CRP) is a well-established general marker of inflammation from both infectious and noninfectious exposures. Previous studies have shown that maternal CRP is associated with an increased risk of autism and schizophrenia. The aim of this study was to examine the association between early to mid-gestational serum CRP levels, prospectively assayed in maternal sera, and the risk of bipolar disorder (BPD).

METHODS

This study is derived from the Finnish Prenatal Study of Bipolar Disorder (FIPS-B), based on a nested case-control study design. A total of 378 BPD cases and 378 controls, matched on date of birth and sex, with available maternal sera were identified from Finnish nationwide registers. Maternal CRP levels were assessed using a latex immunoassay from archived maternal serum specimens, collected primarily during the first and second trimesters of pregnancy.

RESULTS

Increasing maternal CRP, examined as a continuous variable, was not associated with BPD (OR=0.92, 95% CI: 0.81-1.05, p=0.24). The result did not change appreciably following adjustment for potential confounders. There were no associations between CRP in the highest quintile or decile, compared with their respective reference groups, and BPD.

LIMITATIONS

The limitations of the study include: relative young age of the cohort and availability only of a single marker of inflammation.

CONCLUSIONS

In contrast to previous findings on schizophrenia and autism, gestational maternal serum CRP levels were not associated with an increased risk of BPD. It is likely that maternal inflammation may be an additional factor that differentiates schizophrenia from BPD.

Parental and comorbid migraine in individuals with bipolar disorder: A nationwide register study

BACKGROUND

Genetic studies imply a shared genetic etiology between bipolar disorder (BD) and migraine. Epidemiological studies have demonstrated elevated comorbidity between these disorders, but haven't controlled for parental psychopathology. No previous nationally representative studies exist on familial clustering of BD and migraine. This study examines the association between parental and comorbid migraine and BD, controlling for potential confounders.

METHODS

We identified 1861 cases aged ≤25 years, 3643 matched controls, and their parents from Finnish national registers. Conditional logistic regression was used to calculate odds ratios (ORs) with 95% confidence intervals (CIs) and two-sided significance limits of p<0.05.

RESULTS

Parental migraine, controlling for parental BD, was associated with offspring BD diagnosed at age ≥18 years (OR 1.52, 95%CI: 1.08-2.14). Associations between BD and comorbid migraine persisted following adjustment for parental BD and parental migraine in all subjects (OR=2.46, 95% CI: 1.76-3.42), both age groups of BD-diagnosis (<18 years,≥18 years) and both sexes.

LIMITATIONS

The diagnoses were register-based, not directly ascertained.

CONCLUSIONS

This study indicates that parental migraine, even in the absence of parental BD, is a risk factor for offspring BD. Thus, a genetic link between BD and migraine could potentially explain some of the elevated comorbidity between these disorders. However, BD shows a stronger association with comorbid migraine than with parental migraine, suggesting that much of the elevated comorbidity is related to non-genetic factors. Increased understanding of mechanisms underlying the comorbidity of BD and migraine is important since it is associated with poorer health-related outcomes compared with BD alone.

Demographic Characteristics and Psychiatric Comorbidity of Children and Adolescents Diagnosed with ADHD in Specialized Healthcare

Recent studies have shown an increasing incidence of attention-deficit/hyperactivity disorder (ADHD) among children diagnosed in specialized services. This study aims to describe children with ADHD in Finnish specialized healthcare by reporting the demographic characteristics, time trends in diagnosis, psychiatric comorbidity, and the validity of register-based diagnoses. All the singletons born in Finland between 1991 and 2005 and diagnosed with ADHD by 2011 were identified and their psychiatric comorbidity data was obtained from the Finnish Hospital Discharge Register (FHDR). Parents of 69 patients were interviewed via telephone for a diagnostic validation. A total of 10,409 children were identified with ADHD, with a male: female ratio of 5.3:1 and a psychiatric comorbidity rate of 76.7 %. Of the validation sample 88 % met the diagnostic criteria of ADHD for DSM-IV. There is an increasing trend of ADHD diagnosis among both males and females. Psychiatric comorbidity is common and includes a wide range of disorders among children with ADHD. There was an increase of ADHD diagnoses especially among boys. More attention is needed to detect ADHD among girls in health services. Diagnoses in the FHDR show diagnostic validity and their sociodemographic patterns are in line with previous studies.

Parental and comorbid epilepsy in persons with bipolar disorder

BACKGROUND

Population-based studies have demonstrated an overrepresentation of bipolar disorder (BPD) in individuals with epilepsy. However, few studies have examined the reverse association, i.e. comorbid epilepsy in individuals selected based on BPD diagnosis. No previous population-based study having examined the co-occurrence of BPD and epilepsy has adjusted for parental psychopathology. Such an adjustment is motivated by population-based studies reporting an overrepresentation of various types of parental psychiatric disorders in both BPD and epilepsy. Furthermore, an association between epilepsy in first-degree relatives and BPD has previously only been examined and demonstrated in a small clinical sample. The objective of this study is to examine the associations between parental and comorbid epilepsy and BPD, adjusting for parental psychopathology.

METHODS

This nested case-control study identified 1861 cases with BPD, age up to 25 years, 3643 matched controls, and their parents from Finnish national registers. Conditional logistic regression was used to calculate odds ratios (ORs) with 95% confidence intervals (CIs) and two-sided significance limits of p<0.05.

RESULTS

BPD was associated with comorbid epilepsy (adjusted OR 2.53, 95% CI: 1.73-3.70) but not with parental epilepsy. Epilepsy was found in 3.33% of cases versus 1.29% of controls, 2.69% of cases' parents versus 2.53% of controls' parents.

LIMITATIONS

The diagnoses were register-based, not based on standardized procedures with direct ascertainment.

CONCLUSIONS

An association between BPD and comorbid epilepsy persists even after adjusting for parental psychopathology. Lack of familial clustering of BPD and epilepsy would suggest that the elevated co-occurrence of these disorders is influenced by non-genetic factors.

The Kraepelinian Dichotomy From the Perspective of Prenatal Infectious and Immunologic Insults

The "Kraepelinian dichotomy" between schizophrenia (SZ) and bipolar disorder (BD) has been a dominant force in our thinking on the classification of these mental disorders. Emerging evidence indicates that these 2 disorders overlap significantly with regard to epidemiology, clinical presentation, genetic susceptibility, structural neuroanatomy, and treatment. Prenatal infection and immunologic dysfunction appear to be risk factors for both SZ and BD; some of these gestational exposures are present in both disorders while others may be specific to 1 or the other of the 2 syndromes. In this paper, we shall review prior studies of prenatal infections and immunologic insults in schizophrenia and BD, including exposures which overlap and which differ between these disorders, discuss the potential utility of maternal infection as one strategy toward developing a more biologically meaningful diagnostic classification system, and propose new recommendations for future research aimed at dissecting these 2 disorders from one another at the etiologic level.

Is maternal smoking during pregnancy associated with bipolar disorder in offspring?

BACKGROUND

Prenatal smoking exposure affects fetal growth and development and is associated with increased risk of various neurodevelopmental disorders. Only one previous study has examined the association between maternal smoking during pregnancy and the risk of bipolar disorder (BPD).

METHODS

In this nested case control study derived from all singleton live births in Finland between January 1st 1987 and December 31st 1998, we identified 724 children diagnosed and/or treated with BPD until 2008 and 1419 matched controls from four nationwide registers. Conditional logistic regression was used to examine the association between maternal smoking during pregnancy and BPD adjusting for potential confounding due to parental psychiatric history, maternal age and education level.

RESULTS

18.5% of offspring were exposed to maternal smoking during pregnancy. In the unadjusted analysis, smoking during pregnancy was associated with a 1.41-fold (95% CI 1.12-1.79, P=0.004) increased risk of BPD. In the final model adjusting for potential covariates, the risk was 1.14-fold (95% CI 0.88-1.49, P=0.323).

LIMITATIONS

The limitations of this study include: hospital based clinical diagnosis for case ascertainment, inclusion of early onset BPD cases, and lack of information on alcohol or other substance abuse during pregnancy.

CONCLUSION

This study demonstrated that, in this sample, an increased risk of BPD among offspring of mothers who smoked during pregnancy is most likely due to confounding by familial background factors. Future studies including information on serological measures of smoking exposure in pregnancy e.g. cotinine are warranted to further clarify this association.

Perinatal factors and the risk of bipolar disorder in Finland

BACKGROUND

Complications during the perinatal period have been associated with neurodevelopmental disorders like schizophrenia and autism. However, similar studies on bipolar disorder (BPD) have been limited and the findings are inconsistent. The aim of this study was to examine the association between perinatal risk factors and BPD.

METHODS

This nested case-control study, based on the Finnish Prenatal Study of Bipolar Disorders (FIPS-B), identified 724 cases and 1419 matched controls from population based registers. Conditional logistic regression was used to examine the associations between perinatal factors and BPD adjusting for potential confounding due to maternal age, psychiatric history and educational level, place of birth, number of previous births and maternal smoking during pregnancy.

RESULTS

Children delivered by planned cesarean section had a 2.5-fold increased risk of BPD (95% CI: 1.32-4.78, P<0.01). No association was seen between other examined perinatal risk factors and BPD.

LIMITATIONS

The limitations of this study include: the restriction in the sample to treated cases of BPD in the population, and usage of hospital based clinical diagnosis for case ascertainment. In addition, in spite of the large sample size, there was low power to detect associations for certain exposures including the lowest birth weight category and pre-term birth.

CONCLUSIONS

Birth by planned cesarean section was associated with risk of BPD, but most other perinatal risk factors examined in this study were not associated with BPD. Larger studies with greater statistical power to detect less common exposures and studies utilizing prospective biomarker-based exposures are necessary in the future.