Reading intervention with a growth mindset approach improves children's skills.

Laboratory experiments have shown that parents who believe their child's abilities are fixed engage with their child in unconstructive, performance-oriented ways. We show that children of parents with such "fixed mindsets" have lower reading skills, even after controlling for the child's previous abilities and the parents' socioeconomic status. In a large-scale randomized field trial (Nclassrooms = 72; Nchildren = 1,587) conducted by public authorities, parents receiving a reading intervention were told about the malleability of their child's reading abilities and how to support their child by praising his/her effort rather than his/her performance. This low-cost intervention increased the reading and writing achievements of all participating children-not least immigrant children with non-Western backgrounds and children with low-educated mothers. As expected, effects were even bigger for parents who before the intervention had a fixed mindset.

Playing the Fertility Game at Work: An Equilibrium Model of Peer Effects.

We study workplace peer effects in fertility decisions using a game theory model of strategic interactions among coworkers that allows for multiple equilibria. Using register-based data on fertile-aged women working in medium sized establishments in Denmark, we uncover negative average peer effects. Allowing for heterogeneous effects by worker type, we find that positive effects dominate across worker types defined by age or education. Negative effects dominate within age groups and among low-education types. Policy simulations show that these estimated effects make the distribution of where women work an important consideration, beyond simply if they work, in predicting population fertility.

Effect of drugs on the risk of injuries in children with attention deficit hyperactivity disorder: a prospective cohort study.

BACKGROUND: Injuries represent the largest disease burden and most common cause of death in children. Attention deficit hyperactivity disorder (ADHD) is associated with increased mortality, with accidents being the most common cause of death in ADHD. However, it is not known whether pharmacological treatment has any modifying effect on the risk of injuries in children and adolescents with ADHD. METHODS: Using Danish national registers, we followed a cohort of 710 120 individuals, including 4557 individuals diagnosed with ADHD before age 10 years. Using a quasi-experimental, difference-in-difference design, we estimated the odds ratios (ORs) for injuries and the mean change in prevalence rates of injuries and emergency ward visits before and after treatment, with matched untreated children with ADHD at the same age serving as controls. FINDINGS: Children with ADHD were more likely to sustain injuries, compared with children without ADHD, at age 10 years (adjusted OR=1·29, 95% CI 1·22-1·37) and at age 12 years (adjusted OR=1·30, 1·23-1·37). From age 5 to 10 years, the prevalence of injuries in children with ADHD who were treated with ADHD drugs decreased from 19% to 14%, compared with a prevalence of about 17% in non-treated children with ADHD. This corresponded to an adjusted difference-in-difference reduction in prevalence of injuries at age 10 years of 31·5% (8·2-54·8) and 43·5% (18·1-69·0) at age 12 years due to treatment. Pharmacological treatment also reduced the prevalence of emergency ward visits at age 10 years (28·2%, 6·3-50·1) and age 12 years (45·7%, 25·8-65·7). INTERPRETATION: Children with ADHD had an increased risk of injuries compared with other children. Treatment with ADHD drugs reduced the risk of injuries by up to 43% and emergency ward visits by up to 45% in children with ADHD. Taken together with previous findings of accidents being the most common cause of death in individuals with ADHD, these results are of major public health importance. FUNDING: The Lundbeck Foundation, the Danish Council for Independent Research, Centre For Integrated Register-based Research at Aarhus University, the Region of Southern Denmark Research Foundation, and Wørzner's Foundation.

Consequences of ADHD medication use for children's outcomes.

This paper estimates effects of early ADHD medication use on key human capital outcomes for children diagnosed with ADHD while using rarely available register based data on diagnoses and prescription drug purchases. Our main identification strategy exploits plausible exogenous assignment of children to hospitals with specialist physicians, while our analysis of health outcomes also allows for an individual level panel data strategy. We find that the behavior of specialist physicians varies considerably across hospitals and that the prescribing behavior does affect the probability that a given child is treated. Results show that children diagnosed with ADHD in pharmacological treatment have fewer hospital contacts if treated and that treatment to some extent protects against criminal behavior.

Cardiovascular safety of stimulants in children with attention-deficit/hyperactivity disorder: a nationwide prospective cohort study.

OBJECTIVE: The purpose of this study was to determine whether stimulant users are at higher risk of a later cardiovascular event than are non-users, examining this association in both a national cohort and a population-based sample of children and adolescents diagnosed with attention-deficit/hyperactivity disorder (ADHD). We also aim to examine a possible dose-response relationship in such an association. METHODS: We conducted a longitudinal, prospective cohort study of all children born in Denmark between 1990 and 1999. Within this cohort, children with ADHD were identified. Data from national health registers on psychiatric and somatic diagnoses, stimulant prescriptions, cardiovascular risk factors, pre- and perinatal and sociodemographic covariates in all children and their parents were merged, using the unique personal identification number. Hazard ratios (HR) for cardiovascular events were estimated using Cox regression, adjusted for other known risk factors. RESULTS: In the total population (n=714,258 contributing a total of 6,767,982 person-years) use of stimulants increased the risk of a cardiovascular event; adjusted HR=1.83 (1.10-3.04). In children with ADHD (n=8300) stimulant treatment also increased the risk of a cardiovascular event (adjusted HR=2.20 [2.15-2.24]), with a complex time-dependent dose-response relationship. CONCLUSIONS: This is the first nationwide cohort study of the cardiovascular safety of stimulants in children and adolescents, and it represents, to our knowledge, the longest prospective follow-up study. Cardiovascular events were rare but twice as likely in stimulant users as in non-users, both in the total national population and in children with ADHD. We found a complex, time- and dose-dependent interrelationship between cardiovascular adverse events and stimulant treatment in children and adolescents. Our results suggest a safety signal with an increased risk of cardiovascular disease associated with stimulant treatment in children and adolescents, even after adjusting for a number of potential confounders.

Gender and injuries predict stimulant medication use.

OBJECTIVE: The purpose of this article was to examine whether injuries in early childhood and gender predict prescriptions of stimulant medication in three groups of children: With attention-deficit/hyperactivity disorder (ADHD), autism spectrum disorder (ASD), and other psychiatric disorders (OPD). METHODS: This was a population-based study with prospective and complete follow-up of children with ADHD (n=11,553), ASD (n=9698), and OPD (n=48,468), of whom 61%, 16%, and 3%, respectively, were treated with stimulants. For all 69,719 individual children data on psychiatric diagnoses, injuries, and drug prescriptions were obtained from national registers and merged. RESULTS: Having sustained an injury before 5 years of age increased the likelihood of later stimulant treatment, in children with ADHD (odds ratio [OR]=1.09; 95% confidence interval [CI]=1.01-1.21), ASD (OR=1.19; 95% CI=1.02-1.40), and OPD (OR=1.24; 95% CI=1.08-1.42), with each injury increasing the likelihood by 3%, 10%, and 7%, respectively. Head injury did not increase the likelihood of later stimulant treatment. Within each of the three groups, ADHD, ASD, and OPD boys were more likely than girls to receive stimulant medication, OR=1.17 (95% CI=1.07-1.28); OR=1.71 (95% CI=1.47-2.01), and OR=2.41 (95% CI=2.16-2.71), respectively. CONCLUSIONS: To our knowledge, this is the first prospective study assessing early life predictors of later ADHD medication in children with a psychiatric disorder, taken from a national cohort with complete follow-up of all cases. We found that the number of injuries prior to diagnosis was associated with initiation of stimulant treatment in all three groups of patients. In addition, male gender predicted treatment with ADHD medications. Our results suggest that the number of injuries early in life prior to diagnosis is associated with stimulant treatment, and may serve as a proxy for the level of later severity of ADHD symptoms, as it is universally associated with pharmacological treatment for ADHD.

Common Danish standards in prescribing medication for children and adolescents with ADHD.

Assessing whether symptoms of attention-deficit hyperactivity disorder (ADHD) in children are age-inappropriate is essential. Hence, comparing children within one school grade is problematic and the risk of applying relative standards is inherent. Being young-for-grade increases the likelihood of receiving medication in countries with high prevalence of ADHD medication. We test the same hypothesis in a cohort of 418,396 children and find no difference between children who are young-for-grade and old-for-grade. The Danish system, with its restrictive approach to medication and clear diagnostic guidelines seems to have avoided a systematic bias of ADHD medication in young children reported in other countries.

Five-fold increase in national prevalence rates of attention-deficit/hyperactivity disorder medications for children and adolescents with autism spectrum disorder, attention-deficit/hyperactivity disorder, and other psychiatric disorders: a Danish register-based study.

OBJECTIVE: The purpose of this study was to estimate the prevalence and time trends in prescriptions of methylphenidate, dexamphetamine, and atomoxetine in children and adolescents, within three diagnostic groups: 1) autism spectrum disorder (ASD), 2) attention-deficit/hyperactivity disorder (ADHD), and 3) other psychiatric disorders. METHODS: Data from six different national registers were used and merged to identify a cohort of all children and adolescents born in Denmark between 1990 and 2001 (n=852,711). Sociodemographic covariates on cohort members and their parents and lifetime prescriptions of methylphenidate, dexamphetamine, and atomoxetine were extracted from the registers. Prescriptions were also stratified by duration (<6 months. vs.≥ 6 months). RESULTS: Sixteen percent of 9698 children and adolescents with ASD (n=1577), 61% of 11,553 children and adolescents with ADHD (n=7021) and 3% of 48,468 children and adolescents with other psychiatric disorders (n=1537) were treated with one or more ADHD medications. There was a significant increase in prescription rates of these medications for all three groups. From 2003 to 2010, youth 6-13 years of age with ASD, ADHD, and other psychiatric disorders had 4.7-fold (4.4-4.9), 6.3-fold (6.0-6.4), and 5.5-fold (5.0-5.9) increases, respectively, in prescription rates of ADHD medications. CONCLUSION: This is the largest study to date assessing stimulant treatment in children and adolescents with ASD, and is the first prospective study quantifying the change over time in the prevalence of treatment with ADHD medications in a population-based national cohort of children and adolescents with ASD. The prevalence of stimulant treatment in youth with ASD of 16% is consistent with earlier studies. The past decade has witnessed a clear and progressive increase in the prescription rates of medications typically used to treat ADHD in children and adolescents in Denmark. This increase is not limited to only those with ADHD, but includes others with neuropsychiatric disorders, including ASD. The risks and benefits of this practice await further study.

The importance of children's ADHD for parents' relationship stability and labor supply.

Children with attention-deficit/hyperactivity disorder (ADHD) have much worse long-term outcomes than other children. This paper uses Danish register-based data on children born from 1990 to 1997 to investigate the significance of children's ADHD for parents' outcomes. We observe 172,299 pairs of parents from 1990 to 2007 of which 2457 have a firstborn child diagnosed with ADHD and 169,842 have a firstborn child without ADHD. Ten years after the birth of the child, parents of children diagnosed with ADHD have a 75% higher probability of having dissolved their relationship and a 7-13% lower labor supply. Parents of children with ADHD are, however, particularly disadvantaged in terms of socioeconomic background and mental health. We explain about half of the gaps in partnership stability and labor supply when these factors are taken into consideration, but a statistically and economically significant gap remains to be explained. Additionally, we find that the receipt of a diagnosis to some extent moderates the influence of underlying ADHD on partnership stability. Still, our study concludes that poor child health in terms of ADHD reduces parental socioeconomic status (SES) by lowering their labor supply (and earnings) and reducing relationship stability.