School success in childhood and subsequent prodromal symptoms and psychoses in the Northern Finland Birth Cohort 1986.

BACKGROUND: Low IQ is a risk factor for psychosis, but the effect of high IQ is more controversial. The aim was to explore the association of childhood school success with prodromal symptoms in adolescence and psychoses in adulthood. METHODS: In the general population-based Northern Finland Birth Cohort 1986 (n = 8 229), we studied the relationship between teacher-assessed learning deficits, special talents and general school success at age 8 years and both prodromal symptoms (PROD-screen) at age 15-16 years and the occurrence of psychoses by age 30 years. RESULTS: More prodromal symptoms were experienced by those talented in oral presentation [boys: adjusted odds ratio (OR) 1.49; 95% confidence interval 1.14-1.96; girls: 1.23; 1.00-1.52] or drawing (boys: 1.44; 1.10-1.87). Conversely, being talented in athletics decreased the probability of psychotic-like symptoms (boys: OR 0.72; 0.58-0.90). School success below average predicted less prodromal symptoms with boys (OR 0.68; 0.48-0.97), whereas above-average success predicted more prodromal symptoms with girls (OR 1.22; 1.03-1.44). The occurrence of psychoses was not affected. Learning deficits did not associate with prodromal symptoms or psychoses. CONCLUSIONS: Learning deficits in childhood did not increase the risk of prodromal symptoms in adolescence or later psychosis in this large birth cohort. Learning deficits are not always associated with increased risk of psychosis, which might be due to, e.g. special support given in schools. The higher prevalence of prodromal symptoms in talented children may reflect a different kind of relationship of school success with prodromal symptoms compared to full psychoses.

Mortality by diseases and medical conditions in the offspring of parents with severe mental illness.

PURPOSE: The lifespan of people with severe mental illness (SMI) is shorter compared to the general population. There might be common familial pathway leading to a high co-occurrence of somatic disorders and SMI. To study this we explored the long-term mortality for natural causes in the offspring of people with SMI. METHODS: Participants were members of the Northern Finland Birth Cohort 1966 (NFBC1966; N = 11,325). The data on cause of deaths of the members were obtained from the Population Register Center until year 2015. The data on hospital-treated psychiatric disorders of parents were obtained from nationwide Care Register for Health Care. Cumulative incidences by age were calculated in the NFBC1966 members having a parent with SMI and those who did not have. We were able to take into account multiple confounders. RESULTS: Of the total sample of 11,325 offspring, 853 (7.4%) died during the follow-up period, 74 (8.7%) from the study cohort and 779 (91.3%) from the comparison group. These numbers included 160 stillborn children. There were 557 cases of deaths from diseases and medical conditions and 296 deaths from external causes. The adjusted risk ratio for offspring of mothers with SMI was 1.08 (0.72-1.64), and for offspring of fathers with SMI 0.58 (0.36-0.93). CONCLUSIONS: This was the first long-term follow-up study (up to age 49) of all-cause mortality in offspring of parents with SMI. Our findings were contrary to expectations. Offspring of parents with SMI had no increased risk for dying. In fact, the risk for dying in the group of offspring of fathers with SMI was lower than in the comparison group. This study does not support the assumption of common familial pathway leading to a high co-occurrence of somatic disorders and SMI.

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.

Epidemiology of psychotic depression - systematic review and meta-analysis.

Large amount of data have been published on non-psychotic depression (NPD), schizophrenia (SZ), and bipolar disorder, while psychotic depression (PD) as an own entity has received much smaller attention. We performed a systematic review and meta-analyses on epidemiology, especially incidence and prevalence, risk factors, and outcomes of PD. A systematic search to identify potentially relevant studies was conducted using four electronic databases and a manual search. The search identified 1764 unique potentially relevant articles, the final study included 99 articles. We found that the lifetime prevalence of PD varies between 0.35% and 1%, with higher rates in older age. Onset age of PD was earlier than that of NPD in younger samples, but later in older samples. There were no differences in gender distribution in PD v. NPD, but higher proportion of females was found in PD than in SZ or in psychotic bipolar disorder (PBD). Risk factors have rarely been studied, the main finding being that family history of psychosis and bipolar disorder increases the risk of PD. Outcomes of PD were mostly worse when compared with NPD, but better compared with SZ and schizoaffective disorder. The outcome compared with PBD was relatively similar, and somewhat varied depending on the measure of the outcome. Based on this review, the amount of research on PD is far from that of NPD, SZ, and bipolar disorder. Based on our findings, PD seems distinguishable from related disorders and needs more scientific attention.

Smokin' hot: adolescent smoking and the risk of psychosis.

OBJECTIVE: Daily smoking has been associated with a greater risk of psychosis. However, we are still lacking studies to adjust for baseline psychotic experiences and other substance use. We examined associations between daily smoking and psychosis risk in a 15-year follow-up while accounting for these covariates in a prospective sample (N = 6081) from the Northern Finland Birth Cohort 1986. METHODS: Self-report questionnaires on psychotic experiences (PROD-screen), tobacco smoking and other substance use were completed when the cohort members were 15-16 years old. Tobacco smoking was categorized into three groups (non-smokers, 1-9 cigarettes and ≥10 cigarettes/day). Psychosis diagnoses were obtained from national registers until the age of 30 years. RESULTS: Subjects in heaviest smoking category were at increased risk of subsequent psychosis (unadjusted HR = 3.15; 95% CI 1.94-5.13). When adjusted for baseline psychotic experiences the association persisted (HR = 2.87; 1.76-4.68) and remained significant even after adjustments for multiple known risk factors such as cannabis use, frequent alcohol use, other illicit substance use, parental substance abuse, and psychosis. Furthermore, number of smoked cigarettes increased psychosis risk in a dose-response manner (adjusted OR = 1.05; 1.01-1.08). CONCLUSION: Heavy tobacco smoking in adolescence was associated with a greater risk for psychosis even after adjustment for confounders.

The prevalence of medication-related adverse events in inpatients-a systematic review and meta-analysis.

PURPOSE: Adverse drug events (ADEs) have been internationally recognized as a major threat to patient safety. The purpose of this study was to conduct a meta-analysis focusing on inpatient ADEs in the Western World to provide better estimate of the current state of medication safety in these countries. METHODS: The studies for meta-analysis were identified through electronic search in Cochrane, Scopus, Medline, and Web of science databases. Included articles focused on adult inpatient ADEs, had commonly accepted definition for ADE, and were conducted between 2000 and 2016. Disease or ADE-specific studies were excluded. Meta-analysis was conducted on the prevalence of inpatient ADEs and fatal adverse drug reactions (FADRs). RESULTS: The pooled estimate of the prevalence of inpatient ADEs was formed by 46,626 patient records included in 9 articles. Inpatient ADE prevalence was 19 and 32.3% of these ADEs were assessed preventable (MD 28.6%, SD 22.6%). Three articles including 3385 patients focused on inpatient FADRs, but the pooled estimate of this was disregarded due to low number and high heterogeneity of the included studies. CONCLUSIONS: ADEs are estimated to affect 19% of inpatients during hospitalization. Most of the ADEs are moderate in severity causing no permanent harm to the patient. Only a small amount of ADEs cause inpatient deaths, but in this meta-analysis, however, we were unable to give direct estimate of the prevalence.

Latent variable mixture modeling in psychiatric research--a review and application.

Latent variable mixture modeling represents a flexible approach to investigating population heterogeneity by sorting cases into latent but non-arbitrary subgroups that are more homogeneous. The purpose of this selective review is to provide a non-technical introduction to mixture modeling in a cross-sectional context. Latent class analysis is used to classify individuals into homogeneous subgroups (latent classes). Factor mixture modeling represents a newer approach that represents a fusion of latent class analysis and factor analysis. Factor mixture models are adaptable to representing categorical and dimensional states of affairs. This article provides an overview of latent variable mixture models and illustrates the application of these methods by applying them to the study of the latent structure of psychotic experiences. The flexibility of latent variable mixture models makes them adaptable to the study of heterogeneity in complex psychiatric and psychological phenomena. They also allow researchers to address research questions that directly compare the viability of dimensional, categorical and hybrid conceptions of constructs.

Use of antiepileptic or benzodiazepine medication and suicidal ideation--The Northern Finland Birth Cohort 1966.

Both antiepileptic drugs (AEDs) and benzodiazepines (BZDs) have previously been associated with an increased risk of suicidality. Our aim was to study the association between the use of conventional AEDs and BZDs and suicidal ideation in a large population-based cohort. Information on the medications used in the Northern Finland Birth Cohort 1966 was collected from the subjects at the age of 31 years, using a postal questionnaire (N=8211). The presence of suicidal ideation and other symptoms of depression and anxiety was assessed via the Hopkins Symptom Checklist - 25 questionnaire. The associations between medications and suicidal ideation were studied in different diagnostic groups and adjusted for symptoms of depression and anxiety. No difference was observed in suicidal ideation between AED users (n=54) and nonusers (n=8157). Subjects using BZDs (n=147) had greater suicidal ideation compared with nonusers (n=8064). Antiepileptic drug and benzodiazepine users more often exhibited other depression and anxiety symptoms. After adjustment for these symptoms, both AED and BZD users had less suicidal ideation compared with nonusers. In conclusion, in this population-based cohort, neither the use of AEDs nor that of BZDs was found to be associated with increased suicidal ideation when the symptoms of depression and anxiety were taken into account.

The onset and offset of psychosis--and what happens in between--a commentary on 'Reappraising the long-term course and outcome of psychotic disorders: the AESOP-10 Study' by Morgan et al. (2014).

As one would expect for a heterogeneous syndrome like schizophrenia, at the individual level the course of symptoms and disability vary widely. Mindful that the definition of recovery/remission varies widely between studies, a recent systematic review and meta-analysis reported that the proportion of those with schizophrenia who recover on both symptom and functional outcome is modest (approximately 14%). A 10-year follow-up of the English multicentre AESOP incidence study provides more 'fine-grained' insights into the time course of symptom fluctuation for schizophrenia and other psychotic disorders. We highlight selected findings from the new study and speculate on the role of different outcome domains for future study (e.g., symptom, occupational/functional, cognition, physical health, patient-nominated outcomes). Because recovery is a multifaceted process, we need to develop a panel of practical and operationalizable criteria for remission and recovery.

Longitudinal associations between childhood and adulthood externalizing and internalizing psychopathology and adolescent substance use.

BACKGROUND: Emotional and behavioral problems are commonly associated with substance use in adolescence but it is unclear whether substance use precedes or follows mental health problems. The aim was to investigate longitudinal associations between externalizing and internalizing psychopathology and substance use in a prospective population study design. METHOD: The sample was the Northern Finland Birth Cohort 1986 Study (NFBC 1986; n = 6349; 3103 males). Externalizing and internalizing mental health problems were assessed at age 8 years (Rutter scales), substance use and externalizing and internalizing problems [Youth Self-Report (YSR)] at age 15-16 years, and hospital diagnoses for internalizing disorders (age 25) and criminal offences (age 20) from nationwide registers in adulthood. RESULTS: Externalizing problems at age 8 were associated with later substance use. After adjustment for sociodemographic factors, parental alcohol use and psychiatric disorders, and earlier externalizing and internalizing problems, substance use predicted criminality, especially among males, with the highest odds ratio (OR) for cannabis use [adjusted OR 6.2, 95% confidence interval (CI) 3.1-12.7]. Early internalizing problems were not a risk for later substance use. Female adolescent cannabis (OR 3.2, 95% CI 1.4-7.3) and alcohol (OR 2.1, 95% CI 1.1-4.2) use predicted internalizing disorders in adulthood. CONCLUSIONS: Externalizing problems precede adolescent substance use in both genders, whereas, among boys, substance use also precedes criminal offences. Internalizing problems may follow substance use in females. These associations were robust even when taking into account previous mental health problems.

Family history of psychosis and social, occupational and global outcome in schizophrenia: a meta-analysis.

OBJECTIVE: We aimed to investigate associations between family history of psychosis and long-term occupational, social and global (i.e. combined occupational, social and clinical) outcome in schizophrenia. METHOD: A systematic search to identify potentially relevant studies was conducted using seven electronic databases and a manual search of literature. Only observational studies with a follow-up period of at least 2 years were included. RESULTS: The search identified 4081 unique potentially relevant articles, of which 14 met our inclusion criteria. The presence of family history of psychosis was associated with poor occupational and global outcome (n=3; r=0.17; P=0.008, n=11; r=0.13; P=0.002, respectively). CONCLUSION: This was the first systematic review on the effects of family history of psychosis on occupational and social outcome in schizophrenia. Based on the review, the presence of family history of psychosis has a relatively small but statistically significant association with long-term occupational and global outcome in patients with schizophrenia.

Response initiation in young adults at risk for psychosis in the Northern Finland 1986 Birth Cohort.

INTRODUCTION: This is one of the very few studies to investigate the specific executive function/processing speed component of response initiation in subjects at familial risk (FR) for psychosis, and the first such study in subjects at clinical risk (CR) for psychosis. METHODS: Participants (N = 177) were members of the general population-based Northern Finland 1986 Birth Cohort in the following four groups: FR for psychosis (n = 62), CR for psychosis (n = 21), psychosis (n = 25) and control subjects (n = 69). The response initiation of these groups was compared in three different tests: Semantic fluency, Stockings of Cambridge and Spatial working memory. RESULTS: The two risk groups did not differ significantly from control group, but differed from, and outperformed the psychosis group in semantic fluency response initiation. CONCLUSIONS: Response initiation deficits were not evident in a non-help seeking psychosis high-risk sample.

Is prenatal alcohol exposure related to inattention and hyperactivity symptoms in children? Disentangling the effects of social adversity.

BACKGROUND: Studies concerning whether exposure to low levels of maternal alcohol consumption during fetal development is related to child inattention and hyperactivity symptoms have shown conflicting results. We examine the contribution of covariates related to social adversity to resolve some inconsistencies in the extant research by conducting parallel analyses of three cohorts with varying alcohol consumption and attitudes towards alcohol use. METHODS: We compare three population-based pregnancy-offspring cohorts within the Nordic Network on ADHD from Denmark and Finland. Prenatal data were gathered via self-report during pregnancy and birth outcomes were abstracted from medical charts. A total of 21,678 reports concerning inattention and hyperactivity symptoms in children were available from the Strengths and Difficulties Questionnaire or the Rutter Scale completed by parents and/or teachers. RESULTS: Drinking patterns differed cross-nationally. Women who had at least some social adversity (young, low education, or being single) were more likely to drink than those better off in the Finnish cohort, but the opposite was true for the Danish cohorts. Prenatal alcohol exposure was not related to risk for a high inattention-hyperactivity symptom score in children across cohorts after adjustment for covariates. In contrast, maternal smoking and social adversity during pregnancy were independently and consistently associated with an increase in risk of child symptoms. CONCLUSIONS: Low doses of alcohol consumption during pregnancy were not related to child inattention/hyperactivity symptoms once social adversity and smoking were taken into account.

Prevalence of alcohol use disorders in schizophrenia--a systematic review and meta-analysis.

OBJECTIVE: Our aim was to present recent studies of alcohol use disorders (AUDs) in patients with schizophrenia, estimate overall prevalence and characteristics affecting the prevalence of AUDs. METHOD: We conducted a search using three literature databases and a manual search on articles published in 1996-2008. Meta-regression was used to study how prevalence is affected by different study characteristics. Articles that reported diagnoses according to DSM or ICD diagnostic systems were included. RESULTS: Altogether 60 studies met our criteria. The median of current AUD prevalence was 9.4% (inter-quartile range, IQR 4.6-19.0, 18 studies) and median of lifetime AUD prevalence 20.6% (IQR 12.0-34.5, 47 studies). In studies using DSM-III-R median prevalence was higher than that in studies using DSM-IV, ICD-9 or ICD-10 (32/17/11/6%). CONCLUSION: Approximately every fifth patient with schizophrenia had lifetime AUD diagnosis. When contrasted with the most recent review, there might be a descending trend in AUD prevalence in patients with schizophrenia.

Development and validation of a psychometric scale for assessing healthcare professionals' knowledge in radiation protection.

INTRODUCTION: Healthcare professionals must sufficiently understand ionising radiation and the associated protection measures to avoid unnecessarily exposing patients and staff to ionising radiation. Hence, a proper safety culture is important to lowering health risks. The development and establishment of an instrument that can indicate healthcare professionals' understanding/knowledge of radiation protection concepts can greatly contribute to a good safety culture. The purpose of the present study was to develop and psychometrically test the Healthcare Professional Knowledge of Radiation Protection (HPKRP) self-evaluation scale, which was designed to measure the knowledge level of radiation protection by healthcare professionals working with ionising radiation in a clinical environment. METHODS: The presented research employed a cross-sectional study design. Data were collected from eight Finnish hospitals in 2017. A total of 252 eligible nurses responded to the newly developed HPKRP scale. The face and content validity were tested with the Content Validity Index (CVI). Explorative factor analysis was used to test construct validity, whereas reliability was tested with Cronbach's alpha. RESULTS: Overall S-CVI for the HPKRP scale was 0.83. Exploratory factor analysis revealed a three-factor model for the HcPCRP scale containing 33 items. The first factor was defined by Radiation physics and principles of radiation usage, the second factor by Radiation protection, and the third factor by Guidelines of safe ionising radiation usage. These three factors explained 72% of the total variance. Cronbach's alpha coefficient for the scale ranged from 0.93 to 0.96. CONCLUSION: The results provide strong evidence for the validity and reliability of the HPKRP scale. Additionally, educators can use the scale to evaluate healthcare students' understanding in radiation safety before and after education.

Vitamin D status and correlates of low vitamin D in schizophrenia, other psychoses and non-psychotic depression - The Northern Finland Birth Cohort 1966 study.

There is limited knowledge available on the association of vitamin D with psychiatric disorders in young adults. We aimed to investigate vitamin D levels and associating factors in schizophrenia, other psychoses and non-psychotic depression. We studied 4,987 participants from the Northern Finland Birth Cohort 1966 (31 years) with available serum 25-hydroxyvitamin D [25(OH)D] measurements. The final sample was divided into four groups: schizophrenia (n = 40), other psychoses (n = 24), non-psychotic depression (n = 264) and control (n = 4659). To account for the influence of environmental and technical covariates, we generated a vitamin D score variable with correction for season, sex, batch effect and latitude. We further examined how vitamin D levels correlate with anthropometric, lifestyle, socioeconomic and psychiatric measures. Neither serum 25(OH)D concentration nor vitamin D score differed between schizophrenia, other psychoses, non-psychotic depression and control group. The prevalence of vitamin D deficiency was 3.2%, insufficiency 25.5%, and sufficiency 71.3%. Low vitamin D score correlated with regular smoking in the group with schizophrenia. No difference was observed in other psychiatric conditions. We did not find any difference in vitamin D status between schizophrenia, psychoses, non-psychotic depression and control groups, but future studies are warranted to elucidate the role of vitamin D in psychiatric conditions.

Nurses' knowledge of radiation protection: A cross-sectional study.

INTRODUCTION: Nursing roles are changing, as several countries have amended legislation so that nurses can make referrals for medical imaging examination that utilize ionising radiation. Nevertheless, nurses' radiation knowledge remains a poorly studied concept. The aim of the study was to characterize Finnish nurses' knowledge of radiation use and radiation safety. In this study, nurses were working in operating theaters, first aid clinics and cardiology laboratories. METHODS: A cross-sectional design was applied in which data were simultaneously collected from nurses working in eight hospitals. All nurses working in operating theaters, first aid clinics and cardiology laboratories (N = 1500) at the hospitals in Finland were invited to participate in the study. The response rate was 17% (n = 252). The employed Healthcare Professional Knowledge of Radiation Protection (HPKRP) scale included three areas of knowledge: radiation physics, biology and principles of radiation use; radiation protection; and guidelines of safe ionizing radiation use. Descriptive statistics and logistic regression analyses were used to identify factors that influence these three areas. RESULTS: Nurses reported high knowledge levels in radiation protection but low knowledge levels in radiation physics, biology and principles of radiation use. Moreover, nurses who had not received radiation education reported lower knowledges across all three areas than the nurses who had completed education. CONCLUSION: This study identified one major factor that significantly affects nurses' radiation knowledge, namely, having completed medical radiation education, as this factor positively influenced all three of the included areas of radiation knowledge factors. Therefore, healthcare organizations should concentrate on providing education to all nurses working with, or exposed to, radiation.

Maternal adiposity prior to pregnancy is associated with ADHD symptoms in offspring: evidence from three prospective pregnancy cohorts.

OBJECTIVES: We examine whether pregnancy weight (pre-pregnancy body mass index (BMI) and/or weight gain) is related to core symptoms of attention deficit hyperactivity disorder (ADHD) in school-age offspring. DESIGN: Follow-up of prospective pregnancy cohorts from Sweden, Denmark and Finland within the Nordic Network on ADHD. METHODS: Maternal pregnancy and delivery data were collected prospectively. Teachers rated inattention and hyperactivity symptoms in offspring. High scores were defined as at least one core symptom rated as 'severe' and two as 'present' (approximately 10% of children scored in this range). Logistic regression and latent class analyses were used to examine maternal pregnancy weight in relation to children's ADHD core symptoms. RESULTS: Teacher rated 12 556 school-aged children. Gestational weight gain outside of the Institute of Medicine guidelines was not related to ADHD symptoms (below recommendations: odds ratio (OR): 0.96; 95% confidence interval (CI): 0.81, 1.14; above recommendations: OR: 0.98; 95% CI: 0.82, 1.16). To examine various patterns of pre-pregnancy BMI and weight gain, we used latent class analysis and found significant associations between classes that included pre-pregnancy overweight or obesity and a high ADHD symptom score in offspring, ORs ranged between 1.37 (95% CI: 1.07, 1.75) and 1.89 (95% CI: 1.13, 3.15) adjusted for gestational age, birth weight, weight gain, pregnancy smoking, maternal age, maternal education, child gender, family structure and cohort country of origin. Children of women who were both overweight and gained a large amount of weight during gestation had a 2-fold risk of ADHD symptoms (OR: 2.10, 95% CI: 1.19, 3.72) compared to normal-weight women. CONCLUSIONS: We show for the first time that pre-pregnancy BMI is associated with ADHD symptoms in children. Our results are of public health significance if the associations are causal and will then add ADHD symptoms in offspring to the list of deleterious outcomes related to overweight and obesity in the prenatal period.

Insulin resistance and lipid levels in adolescents with familial risk for psychosis.

OBJECTIVE: Type 2 diabetes and dyslipidemias co-occur frequently with schizophrenia. It is not known how common they are in adolescents with a familial risk for psychosis. METHOD: The Northern Finland 1986 Birth Cohort consists of 9432 children born alive in the two Northernmost provinces in Finland. At the age of 15/16 they participated in clinical examination including measurements of glucose, lipids and IR, and a questionnaire including items about their diet and physical activity. The Finnish Hospital Discharge Register was used to find out non-organic psychoses in parents during 1972-2000. This familial risk was found out in 54 boys and 68 girls. Their results were compared with other cohort members. RESULTS: No differences were observed in the cardiometabolic risk factors between the study groups. CONCLUSION: Our results suggest that familial risk for psychosis is not directly associated with disturbances of glucose and lipid metabolism among adolescents.

Childhood family structure and personality disorders in adulthood.

BACKGROUND: The association between childhood family structure and sociodemographic characteristics and personality disorders (PDs) in a general population sample was studied. METHODS: This study is a substudy of the prospective Northern Finland 1966 Birth Cohort Project with 1588 young adult subjects. The case-finding methods according to the DSM-III-R criteria for PDs were: (1) Structured Clinical Interview for DSM-III-R (SCID) for 321 cases who participated in a 2-phase field study, (2) Finnish Hospital Discharge Register data, and (3) analysis of the patient records in public outpatient care in 1982-1997. Statistical analyses were performed on the association between PDs and family background factors. RESULTS: Altogether 110 (7.0%) of the subjects had at least one probable or definite PD. After adjusting for confounders (gender, parental social class and parental psychiatric disorder) the results indicated that single-parent family type in childhood was associated with cluster B PDs in adulthood. Being an only child in childhood was associated with cluster A PDs. No special childhood risk factors were found for cluster C PDs. CONCLUSIONS: Results suggest that single-parent family type at birth and being an only child in the 1960s are associated with PD in adulthood. Further studies are needed to explore the psychosocial aspects of family environment which may nowadays promote vulnerability to PDs in adulthood.