General Population-based Birth Cohort Research Articles

Attention deficit hyperactivity and oppositional defiant disorder symptoms in adolescence and risk of substance use disorders-A general population-based birth cohort study.

Externalizing symptoms are associated with risk of future substance use disorder (SUD). Few longitudinal studies exist using general population-based samples which assess the spectrum of attention deficit hyperactivity disorder (ADHD) and oppositional defiant disorder (ODD) symptoms. We aimed to study the associations between adolescent ADHD symptoms and subsequent SUD and additionally examine whether the risk of SUD is influenced by comorbid oppositional defiant disorder (ODD) symptoms. The Northern Finland Birth Cohort 1986 was linked to nationwide health care register data for incident SUD diagnoses until age 33 years (n = 6278, 49.5% male). ADHD/ODD-case status at age 16 years was defined using parent-rated ADHD indicated by Strengths and Weaknesses of ADHD symptoms and Normal Behaviors (SWAN) questionnaire with 95% percentile cut-off. To assess the impact of ODD comorbidity on SUD risk, participants were categorized into four groups based on their ADHD/ODD case status. Cox-regression analysis with hazard ratios (HRs) and 95% confidence intervals (CIs) were used to study associations between adolescent ADHD/ODD case statuses and subsequent SUD. In all, 552 participants (8.8%) presented with ADHD case status at the age of 16 years, and 154/6278 (2.5%) were diagnosed with SUD during the follow-up. ADHD case status was associated with SUD during the follow-up (HR = 3.84, 95% CI 2.69-5.50). After adjustments for sex, family structure, and parental psychiatric disorder and early substance use the association with ADHD case status and SUD remained statistically significant (HR = 2.60, 95% CI 1.70-3.98). The risk of SUD remained elevated in individuals with ADHD case status irrespective of ODD symptoms. ADHD in adolescence was associated with incident SUD in those with and without symptoms of ODD. The association of ADHD and SUD persisted even after adjustment for a wide range of potential confounds. This emphasizes the need to identify preventative strategies for adolescents with ADHD so as to improve health outcomes.

AMH as part of the diagnostic PCOS workup in large epidemiological studies.

Previous studies have shown good correlation between polycystic ovarian morphology (PCOM) and serum anti-Müllerian hormone (AMH) levels. We evaluated the utility of AMH as a surrogate for PCOM as a part of the polycystic ovary syndrome (PCOS) diagnosis by describing how the use of different AMH cut-off values would change the prevalence of PCOS. A general population-based birth cohort study. Anti-Müllerian hormone concentrations were measured from serum samples taken at age 31 years (n = 2917) using the electrochemiluminescence immunoassay (Elecsys). Anti-Müllerian hormone data were combined with data on oligo/amenorrhoea and hyperandrogenism to identify women with PCOS. The addition of AMH as a surrogate marker for PCOM increased the number of women fulfilling at least two PCOS features in accordance with the Rotterdam criteria. The prevalence of PCOS was 5.9% when using the AMH cut-off based on the 97.5% quartile (10.35 ng/mL) and 13.6% when using the recently proposed cut-off of 3.2 ng/mL. When using the latter cut-off value, the distribution of PCOS phenotypes A, B, C, and D was 23.9%, 4.7%, 36.6%, and 34.8%, respectively. Compared with the controls, all PCOS groups with different AMH concentration cut-offs showed significantly elevated testosterone (T), free androgen index (FAI), luteinizing hormone (LH), LH/follicle-stimulating hormone (FSH) ratio, body mass index (BMI), waist circumference, and homoeostatic model assessment of insulin resistance (HOMA-IR) values, as well as significantly decreased sex hormone-binding globulin (SHBG) values. Anti-Müllerian hormone could be useful surrogate for PCOM in large data sets, where transvaginal ultrasound is not feasible, to aid the capturing of women with typical PCOS characteristics. Anti-Müllerian hormone measurement from archived samples enables retrospective PCOS diagnosis when combined with oligo/amenorrhoea or hyperandrogenism.

Whispers of change in preschool asthma phenotypes: Findings in the French ELFE cohort

RationaleEarly life asthma phenotyping remains an unmet need in pediatric asthma. In France, severe pediatric asthma phenotyping has been done extensively; however, phenotypes in the general population remain underexplored. Based on the course and severity of respiratory/allergic symptoms, we aimed to identify and characterize early life wheeze profiles and asthma phenotypes in the general population. MethodsELFE is a general population based birth cohort; which recruited 18,329 newborns in 2011, from 320 maternity units nationwide. Data was collected using parental responses to modified versions of ISAAC questionnaire on eczema, rhinitis, food allergy, cough, wheezing, dyspnoea and sleep disturbance due to wheezing at 3 time points: post-natal (2 months), infancy (age 1) and pre-school (age 5). We built a supervised trajectory for wheeze profiles and an unsupervised approach was used for asthma phenotypes. Chi squared (χ2) test or fisher's exact test was used as appropriate (p < 0.05). ResultsWheeze profiles and asthma phenotypes were ascertained at age 5. Supervised wheeze trajectory of 9161 children resulted in 4 wheeze profiles: Persistent (0.8%), Transient (12.1%), Incident wheezers at age 5 (13.3%) and Non wheezers (73.9%). While 9517 children in unsupervised clusters displayed 4 distinct asthma phenotypes: Mildly symptomatic (70%), Post-natal bronchiolitis with persistent rhinitis (10.2%), Severe early asthma (16.9%) and Early persistent atopy with late onset severe wheeze (2.9%). ConclusionWe successfully determined early life wheeze profiles and asthma phenotypes in the general population of France.

Decreased pollen sensitization in school-age children after the COVID-19 pandemic : COCOA study

Coronavirus disease 2019 (COVID-19) pandemic has changed lifestyles dramatically. The impact of COVID-19 on inhalant sensitization remains unknown. The purpose of this study is to investigate whether the COVID-19 outbreak affects the changes of inhalant sensitization and allergic disease at age 7 according to a birth year in a general population-based birth cohort.

Increased overall morbidity in women with endometriosis: a population-based follow-up study until age 50

To investigate whether there is an association between endometriosis and nongynecological diseases in the general female population by age 50? A prospective cohort study. Study participants with and without endometriosis were identified from a general population-based birth cohort. The analyzed data, linking to the national hospital discharge registers, spanned up to the age of 50 years. Endometriosis case identification was based on national register data and self-reported diagnoses, producing a study population of 349 women with endometriosis and 3,499 women without endometriosis. International Classification of Diseases diagnosis codes from 1968 to 2016 were accumulated from the Finnish national Care Register for Health Care, whereas self-reported symptoms and continuous medication usage data were collected from the questionnaires distributed at age 46. The associations between endometriosis and comorbidities wereassessed using logistic regression models that included several covariates. The odds ratios and 95% confidence intervals (CIs) were modeled. Endometriosis subtype and temporal analyses were also performed. Women with endometriosis were on average twice as likely to have hospital-based nongynecological diagnoses as women without endometriosis (adjusted odds ratio [aOR] 2.32; 95% CI, 1.07-5.02). In more detail, endometriosis was associated with allergies, infectious diseases, pain-causing diseases, and respiratory diseases. Moreover, the affected women presented with nonspecific symptoms and signs (aOR 3.56; 95% CI, 2.73-4.64), especially abdominal and pelvic pain (aOR 4.33; 95% CI, 3.13-4.76) more often compared with nonendometriosis controls. The temporal analysis revealed that diagnoses accumulated at a significantly younger age among women with endometriosis than in nonendometriosis counterparts. Women with endometriosis have a high risk for several chronic diseases compared with women without endometriosis, underlying the need for awareness and targeted resources for these women in the health care system. Moreover, endometriosis should be considered in the presence of nonspecific symptoms and abdominal pain, as they may conceal the disease and cause considerable delay in diagnosis and treatment.

The impact of food allergy on mental health in school-age children

Few studies were suggesting that allergic diseases are associated with mental health in children. Therefore, we aimed to analyze the effect of food allergy on the Child Behavior Rating Scale (CBCL) in a general population-based birth cohort study.

Particulate matter exposure during pregnancy increases risk of childhood asthma: modified by gender and NRF2 genotype.

Exposure to particulate matter (PM) has been known to develop asthma in children and the oxidative stress-related mechanisms are suggested. For the development of asthma, not only the exposure dose but also the critical window and the risk modifying factors should be evaluated. We investigated whether prenatal exposure to PM10 increases the risk of childhood asthma and evaluated the modifying factors, such as gender and reactive oxidative stress-related gene. A general population-based birth cohort, the Panel Study of Korean Children (PSKC), including 1572 mother-baby dyads was analyzed. Children were defined to have asthma at age 7 when a parent reported physician-diagnosed asthma. Exposure to PM10 during pregnancy was estimated by land-use regression models based on national monitoring system. TaqMan method was used for genotyping nuclear factor, erythroid 2-related factor, NRF2 (rs6726395). A logistic Bayesian distributed lag interaction model (BDLIM) was used to evaluate the associations between prenatal PM10 exposure and childhood asthma by gender and NRF2. Exposure to PM10 during pregnancy was associated with the development of asthma (aOR 1.03, 95% CI 1.001.06). Stratifying by gender and NRF2 genotype, exposure to PM10 during 26-28 weeks gestation increased the risk of childhood asthma, especially in boys with NRF2 GG genotype. A critical window for PM10 exposure on the development of childhood asthma was during 26-28 weeks of gestation, and this was modified by gender and NRF2 genotype.

The High-Risk Type 1 Diabetes HLA-DR and HLA-DQ Polymorphisms Are Differentially Associated With Growth and IGF-I Levels in Infancy: The Cambridge Baby Growth Study.

This study explored the link between HLA polymorphisms that predispose to type 1 diabetes and birth size, infancy growth, and/or circulating IGF-I in a general population-based birth cohort. The Cambridge Baby Growth Study is a prospective observational birth cohort study that recruited 2,229 newborns for follow-up in infancy. Of these, 612 children had DNA available for genotyping single nucleotide polymorphisms in the HLA region that capture the highest risk of type 1 diabetes: rs17426593 for DR4, rs2187668 for DR3, and rs7454108 for DQ8. Multivariate linear regression models at critical ages (cross-sectional) and mixed-effects models (longitudinal) were performed under additive genetic effects to test for associations between HLA polymorphisms and infancy weight, length, skinfold thickness (indicator of adiposity), and concentrations of IGF-I and IGF-binding protein-3 (IGFBP-3). In longitudinal models, the minor allele of rs2187668 tagging DR3 was associated with faster linear growth (P = 0.007), which was more pronounced in boys (P = 3 × 10-7) than girls (P = 0.07), and was also associated with increasing IGF-I (P = 0.002) and IGFBP-3 (P = 0.003) concentrations in infancy. Cross-sectionally, the minor alleles of rs7454108 tagging DQ8 and rs17426593 tagging DR4 were associated with lower IGF-I concentrations at age 12 months (P = 0.003) and greater skinfold thickness at age 24 months (P = 0.003), respectively. The variable associations of DR4, DR3, and DQ8 alleles with growth measures and IGF-I levels in infants from the general population could explain the heterogeneous growth trajectories observed in genetically at-risk cohorts. These findings could suggest distinct mechanisms involving endocrine pathways related to the HLA-conferred type 1 diabetes risk.

Different Characteristics of Childhood Asthma Related to Polyhexamethylene Guanidine Exposure

Rationale: Exposure to humidifier disinfectants (HDs) can increase the risk of asthma, but the characteristics of HD-related asthma are currently unclear. Polyhexamethylene guanidine (PHMG)-containing HD was the most commonly used and the most frequently associated with HD-associated lung injury. Objectives: To investigate the characteristics of PHMG-induced asthma. Methods: This general population-based birth cohort study used data from the Panel Study of Korean Children from 2008 (n = 846). Spirometry, bronchial provocation tests, detailed history recording, and physical examinations were performed on 7-year-old patients (n = 362). Exploratory analysis of plasma proteomics was performed. Results: Compared with the healthy control group, forced expiratory volume in 1 second was the lowest in PHMG-exposed asthma group (z-score = -0.806; 95% confidence interval, -1.492 to -0.119). The positive rate of bronchial hyperresponsiveness was lower in children with PHMG-exposed asthma compared with children with asthma without HD exposure (13.3% vs. 47.4%). Long-term exposure to low-intensity PHMG before the age of 3 years was associated with asthma symptoms. Periostin was higher in subjects with asthma without HD exposure compared with the healthy control subjects. The inducible T-cell costimulator ligand and hepatocyte growth factor activator werelower in PHMG-exposed asthma compared with asthma without exposure. Hepatocyte growth factor activator had a positive correlation with forced vital capacity (z-score) in asthma with PHMG exposure (r = 0.78; P < 0.01). Conclusions: The asthma associated with low-intensity exposure to PHMG is characterized by lower lung function, lower positive rates of bronchial hyperresponsiveness, and varied distributions of plasma proteins. These findings suggest that asthma related to PHMG exposure may constitute a different mechanism of asthma pathophysiology.

Blood eosinophils associate with reduced lung function growth in adolescent asthmatics.

Background and ObjectiveSome children with asthma have low lung growth, putting them at increased risk for COPD later in life. However, it is currently not clear who will experience this adverse growth pattern. We therefore investigated the predictive role of blood eosinophils as a type 2 inflammation marker in lung growth, focusing on the presence and severity of asthma.MethodsWe investigated blood eosinophils and lung function growth (percentage of predicted values) using linear mixed models in children and adolescents from two longitudinal cohorts. One cohort was hospital‐based and consisted of asthmatic children at their first outpatient clinic visit after referral by the general practitioner (n = 133, mean age 9.8), while the second was a general population‐based birth cohort (PIAMA, asthma n = 52 and non‐asthma n = 433, mean age 8.1). The hospital‐based cohort had not been treated with inhaled corticosteroids (ICS) before referral.ResultsSubjects in the hospital‐based asthma cohort had more severe asthma compared with the asthmatic subjects in the population‐based cohort, defined by lower lung function levels and a higher prevalence of bronchial hyper‐responsiveness. In the asthma cohort, higher blood eosinophil numbers were associated with less growth in FEV1 (estimated change in lung function per 1 unit increase in ln blood eosinophils (B): −0.66%/year (95% confidence interval (CI): −1.11 to −0.20, p < .01)) and FVC (B: −0.40%/year (95% CI: −0.75 to −0.05), p = .025)) during follow‐up in adolescence (min 7, max 17 years). These associations were not observed in the general population‐based birth cohort, regardless of asthma status during follow‐up (age 8–16).Conclusions and Clinical RelevanceBlood eosinophil counts in children with asthma not treated with ICS at referral were predictive of lower growth in FEV1 and FVC during follow‐up in adolescence. Our findings indicate that this association is dependent on the degree of asthma severity. Future studies should address whether anti‐eosinophilic treatments preserve lung function growth in children with asthma.

Continuity of health anxiety from childhood to adolescence and associated healthcare costs: a prospective population-based cohort study.

Severe health anxiety (HA) is characterized by excessive and impairing worry and preoccupation with health issues and can cause increased and unnecessary medical examinations. HA in childhood and adolescence is scarcely explored, hindering the potential for prevention and early intervention. HA was assessed in 1,278 children/youths at two time points at ages 11 and 16years in a general population-based birth cohort. Register-based data on costs related to nonhospital-based primary and secondary somatic health services were obtained over the follow-up period. The presence of functional somatic symptoms, emotional disorders and chronic somatic illness at baseline were included as covariates. High HA (top 10% score) at age 11 predicted high HA at age 16 (relative risk [RR] 2.03, 95% CI: 1.26-3.31). The group with persistent HA was small (n=17, 1.3%), resulting in broad confidence intervals. The statistical effect of HA at age 11 on HA at age 16 was heavily reduced after adjustment for sex and all covariates (RR: 1.49, 95% CI: 0.85-2.60). In the adjusted model, somatic illness at age 11 (RR: 1.91, 95% CI: 1.22-2.98) and female sex (RR: 3.33, 95% CI: 2.01-5.50) were independently associated with HA at age 16. Persistent HA was associated with approximately doubled healthcare costs compared to the group with consistently low HA. Incident HA at age 16 was associated with increased costs over follow-up. The increased costs were not explained by chronic somatic illness. A small subgroup of children had persistent high levels of HA from late childhood to adolescence and displayed increased healthcare costs. Female sex and chronic somatic disorders at age 11 were independent risk factors of HA at age 16. These findings provide potential means of early identification and of therapeutic levers. Further intervention development and evaluation are needed.

Risk Factors and Comorbidities Associated With the Allergic Rhinitis Phenotype in Children According to the ARIA Classification.

PurposeData are lacking on the association between the allergic rhinitis (AR) phenotype and sensitization to specific allergens or bronchial hyperresponsiveness (BHR) in children. We here investigated risk factors and comorbidities, including sensitization to specific allergens and BHR, for the AR phenotype by AR and its Impact on Asthma (ARIA) classification in a general population-based birth cohort study.MethodsWe enrolled 606 children aged 7 years from the Panel Study of Korean Children. The AR phenotype was assigned in accordance with the ARIA classification in children. Skin prick tests and Provocholine provocation test were performed. Risk factors and comorbidities for AR phenotypes were then analyzed.ResultsThe prevalence of mild and moderate to severe AR in our study cohort was 37.2% and 8.8%, respectively. Recent use of analgesics or antipyretics and current cat ownership were associated with the risk of mild persistent AR. Sensitizations to Dermatophagoides Pteronyssinus (Der p), Japanese hop and cat were associated with moderate to severe persistent AR. Children with moderate to severe AR had a higher risk of current asthma and BHR compared to mild AR cases (adjusted odds ratio [aOR], 5.26; 95% confidence interval [CI], 1.77–15.62). Moderate to severe AR with allergic sensitization was associated with the highest risk of BHR (aOR, 11.77; 95% CI, 3.40–40.74).ConclusionsModerate to severe-persistent AR is more closely related to respiratory comorbidities and sensitizations than mild AR. Stratifying the AR phenotype by ARIA classification may assist in disease management.

104. Association Between Serum C-Reactive Protein, Positive and Negative Symptoms of Psychosis in a General Population-Based Birth Cohort

104. Association Between Serum C-Reactive Protein, Positive and Negative Symptoms of Psychosis in a General Population-Based Birth Cohort

Prenatal 25-hydroxyvitamin D deficiency affects development of atopic dermatitis via DNA methylation

Prenatal 25-hydroxyvitamin D deficiency affects development of atopic dermatitis via DNA methylation

Rate of humidifier and humidifier disinfectant usage in Korean children: A nationwide epidemiologic study

In South Korea, a cluster of humidifier disinfectant-induced lung injury (HDLI) cases developed between 2006 and 2011. There are no existing reports regarding the rate of humidifier disinfectant (HD) usage in the general population of Korean children. The purpose of this study was to investigate the rate of humidifier and HD usage in the general population of Korean children. This is a general population-based birth cohort multicenter study, Panel Study of Korean Children (PSKC) from 2008, a humidifier and HD-related questionnaire administered to 1577 subjects (809 male, 768 female) in 2015 (n=1577). The questionnaire consisted of four categories (humidifier usage, HD usage, exposure duration, and type of HD brands). A total of 75.6% (1192/1577) had used a humidifier, and the rate of HD usage was found to be 31.1% (409/1316). Polyhexamethylene guanidine (PHMG), used as a disinfectant, was found to have the highest usage rate (62.0%). HD was used for less than 3 months of the entire lifetime of most of the subjects. In conclusion, approximately 30% of young Korean children were exposed to HD. PHMG-containing HD was the most commonly used. These results suggest that a nationwide epidemiologic investigation is needed urgently, and children exposed to HD should be investigated regarding their status of lung injury, including a pulmonary function test. Moreover, a long-term follow-up period may be required to evaluate HD usage-associated lung injury.

Schizotypal and affective traits in the offspring of antenatally depressed mothers – Relationship to family history of psychosis in the Northern Finland 1966 Birth Cohort

BackgroundMaternal depression is relatively common during pregnancy. However, follow-ups of the adult offspring of antenatally depressed mothers are scarce. Previously we found the risk of schizophrenia to be higher in the adult offspring with antenatally depressed mothers and parents with psychosis than in subjects with only one or neither of these risk factors. The aim was to study whether the risk of schizotypal or affective traits differ among adult offspring with antenatally depressed mothers with or without a parental history of psychosis when compared with offspring without antenatally depressed mothers and without parental psychosis. MethodsIn the general population-based Northern Finland 1966 Birth Cohort (NFBC 1966), the mothers of the cohort members were asked at mid-gestation whether they felt depressed. Parental psychosis (Familial Risk, FR) was detected using the Finnish Care Register for Health Care. In the 31-year field study, seven psychometric questionnaires surveyed schizotypal and affective traits in the offspring. The final sample included 4928 individuals (2203 males). ResultsThere were no statistically significant differences in mean scores on the schizotypal and affective scales between offspring with and without antenatally depressed mothers, or between subjects with and without parental psychosis. The scores were not highest in the subjects with both maternal antenatal depressed mood and FR. ConclusionSurprisingly, maternal depressed mood during pregnancy was unlikely to increase the risk of schizotypy or affective traits in adult offspring, and not even with parental psychosis (FR) in this general population-based birth cohort with about 5000 subjects.

Longitudinal changes in total brain volume in schizophrenia: relation to symptom severity, cognition and antipsychotic medication.

Studies show evidence of longitudinal brain volume decreases in schizophrenia. We studied brain volume changes and their relation to symptom severity, level of function, cognition, and antipsychotic medication in participants with schizophrenia and control participants from a general population based birth cohort sample in a relatively long follow-up period of almost a decade. All members of the Northern Finland Birth Cohort 1966 with any psychotic disorder and a random sample not having psychosis were invited for a MRI brain scan, and clinical and cognitive assessment during 1999–2001 at the age of 33–35 years. A follow-up was conducted 9 years later during 2008–2010. Brain scans at both time points were obtained from 33 participants with schizophrenia and 71 control participants. Regression models were used to examine whether brain volume changes predicted clinical and cognitive changes over time, and whether antipsychotic medication predicted brain volume changes. The mean annual whole brain volume reduction was 0.69% in schizophrenia, and 0.49% in controls (p = 0.003, adjusted for gender, educational level, alcohol use and weight gain). The brain volume reduction in schizophrenia patients was found especially in the temporal lobe and periventricular area. Symptom severity, functioning level, and decline in cognition were not associated with brain volume reduction in schizophrenia. The amount of antipsychotic medication (dose years of equivalent to 100 mg daily chlorpromazine) over the follow-up period predicted brain volume loss (p = 0.003 adjusted for symptom level, alcohol use and weight gain). In this population based sample, brain volume reduction continues in schizophrenia patients after the onset of illness, and antipsychotic medications may contribute to these reductions.

Menstrual disorders in adolescence: a marker for hyperandrogenaemia and increased metabolic risks in later life? Finnish general population-based birth cohort study

Are self-reported menstrual disorders associated with hyperandrogenaemia and metabolic disturbances as early as in adolescence? Menstrual disorders at the age 16 are a good marker of hyperandrogenaemia, and an adverse lipid profile was associated with higher androgen levels. Hyperandrogenism per se has been suggested to be a significant metabolic risk factor in women and a cause of physical and psychological morbidity in adolescent girls. A weak positive correlation has been described between hyperandrogenaemia and obesity in adolescent girls, but the clinical consequences are still poorly understood. Hyperandrogenism and insulin resistance are also key features of polycystic ovary syndrome (PCOS), and women with PCOS are consequently at an increased risk of developing type 2 diabetes mellitus and/or metabolic syndrome, and may have increased cardiovascular morbidity. Our findings confirm that the association between menstrual disorders, hyperandrogenism, obesity and metabolic risks is already evident in adolescence. This population-based, cross-sectional study used postal questionnaires to targeting 15-16-year-old girls in the Northern Finland Birth Cohort 1986 (n= 4567). There were 3669 girls who answered the postal questionnaire and out of 3373 girls who also underwent clinical examinations and blood tests, 2448 were included in the analyses. The questionnaire included one question about the regularity and length of the menstrual cycle: 'Is your menstrual cycle (the interval from the beginning of one menstrual period to the beginning of the next period) often (more than twice a year) longer than 35 days?' The girls who answered 'yes' to this question were considered to be suffering from menstrual disorders and were classified as 'symptomatic'. The girls who answered 'no' were defined as 'non-symptomatic'. There were 709 (29%) girls who reported menstrual disorders (symptomatic girls) and 1739 who had regular periods (non-symptomatic girls). In the whole population and in both study groups, there were significant correlations between body mass index (BMI) (and waist-to-hip ratio), hyperandrogenaemia and metabolic parameters. Symptomatic girls exhibited significantly higher serum concentrations of testosterone (P= 0.010), lower levels of sex hormone-binding globulin (P =0.042) and higher free androgen indices [FAIs; geometric mean 3.38 (interquartile range (IQR): 2.27, 5.18) versus 3.08 (IQR: 2.15, 4.74), P= 0.002]. The two groups had comparable BMI and insulin sensitivity, and serum levels of glucose, insulin and lipids. There was a significant linear trend towards higher FAI values in the higher BMI quartiles in both symptomatic and non-symptomatic girls. In the whole population, there was a statistically significant linear decrease in high-density lipoprotein concentrations (P < 0.001) and higher triglyceride concentrations (P =0.004) in the upper FAI quartile. Information regarding menstrual disorders in adolescence is a good marker of hyperandrogenaemia and may be an early risk factor for the development of PCOS in adulthood. The association between obesity, hyperandrogenism and metabolic risks is already evident in adolescence, which strengthens the importance of noting menstrual disorders at an early stage. BIAS, LIMITATIONS, GENERALIZABILITY: The cross-sectional nature of the study does not allow us to draw conclusions concerning the metabolic risks of this population in later life. The diagnosis of menstrual disorders was based on a questionnaire, suggesting a risk of information bias in reporting the symptoms. This study was not designed to diagnose PCOS, as ultrasonography was not available and there was no clinical evaluation of hyperandrogenism (i.e. hirsutism). However, we were able to take into account potential confounding factors in the analyses. This work was supported by grants from the Finnish Medical Society Duodecim, the North Ostrobothnia Regional Fund, the Academy of Finland (project grants 104781, 120315, 129269, 1114194, SALVE), University Hospital Oulu, Biocenter, University of Oulu, Finland (75617), the European Commission (EURO-BLCS, Framework 5 award QLG1-CT-2000-01643) and the Medical Research Council, UK (PrevMetSyn/SALVE). None of the authors have any conflict of interest to declare.

Increased lifetime prevalence of dental trauma is associated with previous non-dental injuries, mental distress and high alcohol consumption.

The purpose of the study was to assess the lifetime prevalence of dental injuries and risk factors involved in a general population-based birth cohort. The study population consisted of 5737 subjects who had participated in a health survey at the age of 31 years. Altogether 52% of the participants were women. This partly computer-based health survey included two questionnaires on previous dental and non-dental injuries, general health, occupational status and lifestyle. The current study was based on these questionnaires. The lifetime prevalence of dental fractures was 43% and the lifetime prevalence of dental luxations and exarticulations 14%. Men more commonly had dental injuries than women. Particularly mental distress and a history of previous injuries were shown to increase the risk for dental injuries. Furthermore, overweight and high alcohol consumption were positively associated with a high lifetime prevalence of tooth trauma. Regular physical activity decreased trauma occurrence. Socioeconomic status further affected the lifetime prevalence of dental injuries. The conclusion of the study was that personal, social and physical factors played a role in the occurrence of dental trauma.