Carsten Obel

The Strengths and Difficulties Questionnaire in the Nordic countries

Abstract.Background:The Strengths and Difficulties Questionnaire (SDQ) has been translated into the different Nordic languages between 1996 and 2003. During the past few years, SDQs have been completed for nearly 100,000 children and adolescents in population-based studies as well as in clinical samples. The largest studies have been performed in Norway and Denmark, and in these countries the diagnostic interview DAWBA has also been used in conjunction with the SDQ.Aims:In addition to a brief overview of past and ongoing SDQ work in Sweden, Finland, Norway, Denmark, and Iceland, we present scale means and standard deviations from selected community studies with comparable age groups, including parental reports for 7, 9 and 11 year-old children and self-reports of 13 and 15 year-olds.Conclusions:The descriptive statistics suggest that the distributions of SDQ scores are very similar across the Nordic countries. Further collaborative efforts in establishing norms and evaluating the validity of the SDQ as a screening instrument are encouraged.

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 childrens ADHD core symptoms.Results:Teacher rated 12u2009556 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.

Duration of breastfeeding and developmental milestones during the latter half of infancy

Several studies have suggested that breastfeeding has a long‐term influence on brain development. However, interpretation of these findings is complicated by the presence of many potential confounding factors. Only a few studies have examined infants before 1 y of age, although very early assessment might reduce the role of environmental influence. We investigated the association between exclusive breastfeeding and three developmental milestones related to general and fine motor skills and early language development at the age of 8 mo. We followed 1656 healthy, singleton, term infants, with a birthweight of at least 2500 g, born between May 1991 and February 1992 in Aarhus, Denmark. Information was collected at 16 wk gestation, at delivery and when the infant was 8 mo old. Motor skills were evaluated by measurement of crawling and pincer grip. Early language development was defined as the ability to babble in polysyllables. The proportion of infants who mastered the specific milestones increased consistently with increasing duration of breastfeeding. The relative risk for the highest versus the lowest breastfeeding category was 1.3 (95% CI: 1.0‐1.6) for crawling, 1.2 (95% CI: 1.1‐1.3) for pincer grip and 1.5 (95% CI: 1.3–1.8) for polysyllable babbling. Little change was found after adjustment for confounding. In conclusion, our data support the hypothesis that breastfeeding benefits neurodevelopment.

Coffee consumption during pregnancy and the risk of hyperkinetic disorder and ADHD: a prospective cohort study.

Aim: Based on hypotheses from experimental studies, we studied the association between intrauterine exposure to coffee and the risk of clinically verified hyperkinetic disorder and attention‐deficit hyperactivity disorder (ADHD).

Infertility, infertility treatment and psychomotor development: the Danish National Birth Cohort

Babies born of infertile couples, regardless of treatment, have a higher risk of preterm birth and low birthweight, conditions associated with delayed development. We examined developmental milestones in singletons as a function of parental infertility [time to pregnancy (TTP) > 12 months] and infertility treatment. From the Danish National Birth Cohort (1997-2003), we identified 37 897 singletons born of fertile couples (TTP < or = 12 months), 4351 born of infertile couples conceiving naturally (TTP > 12 months), and 3309 born after infertility treatment. When the children were about 18 months old, mothers reported 12 developmental milestones by responding to structured questions. We defined a failure to achieve the assessed milestone or the minimal numbers of milestones in a summary (motor, or cognitive/language skills) as delay. Naturally conceived children born of infertile couples had a pattern of psychomotor development similar to that of children born of fertile couples, but increasing TTP correlated with a modest delay. When the analysis was restricted to infertile couples (treated and untreated), children born after treatment showed a slight delay in cognitive/language development (odds ratio 1.24, [95% confidence interval 1.01, 1.53]) for not meeting at least three out of six cognitive/language milestones); children born after intracytoplasmic sperm injection (ICSI) had the highest estimated relative risk of delay for most milestones, especially motor milestones. These results suggest that a long TTP may be associated with a modest developmental delay. Infertility treatment, especially ICSI, may be associated with a slight delay for some of these early milestones.

Psychological factors in pregnancy and mixed-handedness in the offspring

Animal studies suggest that psychological factors may interfere with the development of brain asymmetry during gestation. We evaluated whether psychological exposure in pregnancy was associated with mixed‐handedness in the offspring. In a follow‐up design study, 824 Danish‐speaking women with singleton pregnancies provided information on psychological distress and the occurrence of life events in the early second and third trimesters of pregnancy. Handedness of the children was based on maternal reports when the children were 3 years of age. Among the 419 males and 405 females, 7% and 5% respectively were mixed‐handed whereas mixed‐handedness was found in 3% of the parents. Psychological distress in the third trimester as well as higher levels of stressful life events were related to a higher prevalence of mixed‐handedness in the offspring. About 16% of the women reported more than one life event in the third trimester of pregnancy and among the offspring of these women 11% were mixed‐handed (odds ratio=2.3; 95% confidence interval 1.2 to 4.4). Women who at the same time reported a high level of distress and stressful life events, had a three‐ to four‐fold higher prevalence of mixed‐handedness in their offspring.

Cigarette smoking during pregnancy and hyperactive-distractible preschooler's: a follow-up study.

AIMnTo study the association between intrauterine exposure to tobacco smoke and behavioural disorders in preschool children, primarily symptoms of inattention, hyperactivity and impulsivity but also hostile-aggressive and anxious-fearful symptoms.nnnMETHODSnWe conducted a follow-up study in 1355 singletons born to Danish-speaking mothers. Information on smoking habits during pregnancy and other lifestyle factors was obtained from self-administered questionnaires filled in during second and third trimester. Approximately 3.5 years later, the parents provided information on their childs behaviour using the self-administered Preschool Behaviour Questionnaire. The children were categorized into three not mutually exclusive behaviour groups: hyperactive - distractible (13.6%), hostile-aggressive (4.6%), and anxious-fearful (6.4%) children.nnnRESULTSnCompared with children of non-smokers, children born to women who smoked 10 or more cigarettes per day had a 60% increased risk of hyperactivity and distractibility perceived by the parents (OR 1.6; 95% CI 1.0-2.3; P < 0.05). The results were adjusted for maternal lifestyle factors and socioeconomic characteristics. Additional adjustment for perinatal factors and parental psychiatric hospitalization did not change the results substantially (OR 1.7; 95% CI 1.1-2.6). We found no statistically significant association between maternal smoking in pregnancy and hostile-aggressive and anxious-fearful behaviour in the offspring.nnnCONCLUSIONnExposure to tobacco smoke in utero was associated with hyperactive-distractible behaviour in preschool children.

The association between preschool behavioural problems and internalizing difficulties at age 10-12 years.

The aim was to study the association between preschool behavioural problems and emotional symptoms in 10- to 12-year-old children. The study was based on the Aarhus Birth cohort, Denmark, and included 1,336 children. Based on the parent-administered preschool behaviour questionnaire (PBQ), we identified three not mutually exclusive preschool behavioural categories: anxious–fearful (nxa0=xa0146), hyperactive–distractible (nxa0=xa098), and hostile–aggressive (nxa0=xa0170). Children without any known symptoms were considered well adjusted (nxa0=xa01,000). Borderline emotional (nxa0=xa0105) and emotional difficulties (nxa0=xa0136) were measured at age 10–12xa0years with the parent-administered strength and difficulties questionnaire (SDQ). Multinomial logistic regression analyses were used to adjust for potential confounding factors. We found that anxious–fearful behaviour and hostile–aggressive preschool behaviour were associated with twice the risk of school-age emotional difficulties. Comorbidity or confounding failed to explain these results. Hyperactive–distractible preschool behaviour was not associated with school-age emotional difficulties. Preschool anxious–fearful behaviour was associated with school-age emotional difficulties, suggesting internalizing symptom stability in some children from early childhood. Preschool hostile–aggressive behaviour was also associated with school-age emotional difficulties, which suggests transformation of one behavioural dimension into another through childhood, and the need to focus on both early internalizing difficulties and hostile–aggressive behaviour as risk factors for later internalizing difficulties.

Antenatal maternal bereavement and childhood cancer in the offspring: a population-based cohort study in 6 million children

Background:Prenatal stress may increase the susceptibility to childhood cancer by affecting immune responses and hormonal balance. We examined whether antenatal stress following maternal bereavement increased the risk of childhood cancer.Methods:All children born in Denmark from 1968 to 2007 (N=2 743 560) and in Sweden from 1973 to 2006 (N=3 400 212) were included in this study. We compared cancer risks in children born to women who lost a first-degree relative (a child, spouse, a parent, or a sibling) the year before pregnancy or during pregnancy with cancer risks in children of women who did not experience such bereavement.Results:A total of 9795 childhood cancer cases were observed during follow-up of 68u2009360u2009707 person years. Children born to women who lost a child or a spouse, but not those who lost other relatives, had an average 30% increased risk of any cancer (hazard ratio (HR) 1.30, 95% confidence interval (CI) 0.96–1.77). The HRs were the highest for non-Hodgkin disease (512 cases in total, HR 3.40, 95% CI 1.51–7.65), hepatic cancer (125 cases in total, HR 5.51, 95% CI 1.34–22.64), and testicular cancer (86 cases in total, HR 8.52, 95% CI 2.03–37.73).Conclusion:Our data suggest that severe antenatal stress following maternal bereavement, especially due to loss of a child or a spouse, is associated with an increased risk of certain childhood cancers in the offspring, such as hepatic cancer and non-Hodgkin disease, but not with childhood cancer in general.

Stressful life events in pregnancy and head circumference at birth

A strong association between stress in pregnancy and small head circumference in infants at birth was reported in 1994. This important finding has never been replicated. In a follow-up study of 4211 participants with singleton pregnancies, information on life events was collected twice during pregnancy and head circumference measured shortly after birth following standard procedures. No association was found between experienced or perceived stress as a result of life events during pregnancy and head circumference in the infants. In conclusion, stress in pregnancy may influence foetal brain development in many ways, but we found no support for an effect on the size of the brain as measured by head circumference at birth.