Childhood attention-deficit hyperactivity disorder problems and mid-life cardiovascular risk: prospective population cohort study.

BACKGROUND: It is well-known that childhood attention-deficit hyperactivity disorder (ADHD) is associated with later adverse mental health and social outcomes. Patient-based studies suggest that ADHD may be associated with later cardiovascular disease (CVD) but the focus of preventive interventions is unclear. It is unknown whether ADHD leads to established cardiovascular risk factors because so few cohort studies measure ADHD and also follow up to an age where CVD risk is evident. AIMS: To examine associations between childhood ADHD problems and directly measured CVD risk factors at ages 44/45 years in a UK population-based cohort study (National Child Development Study) of individuals born in 1958. METHOD: Childhood ADHD problems were defined by elevated ratings on both the parent Rutter A scale and a teacher-rated questionnaire at age 7 years. Outcomes were known cardiovascular risk factors (blood pressure, lipid measurements, body mass index and smoking) at the age 44/45 biomedical assessment. RESULTS: Of the 8016 individuals assessed both during childhood and at the biomedical assessment 3.0% were categorised as having childhood ADHD problems. ADHD problems were associated with higher body mass index (B = 0.92 kg/m2, s.d. = 0.27-1.56), systolic (3.5 mmHg, s.d. = 1.4-5.6) and diastolic (2.2 mmHg, s.d. = 0.8-3.6) blood pressure, triglyceride levels (0.24 mol/l, s.d. = 0.02-0.46) and being a current smoker (odds ratio OR = 1.6, s.d. = 1.2-2.1) but not with LDL cholesterol. CONCLUSIONS: Childhood ADHD problems predicted multiple cardiovascular risk factors by mid-life. These findings, when taken together with previously observed associations with cardiovascular disease in registries, suggest that individuals with ADHD could benefit from cardiovascular risk monitoring, given these risk factors are modifiable with timely intervention.

Secular trends and social inequalities in child behavioural problems across three Brazilian cohort studies (1993, 2004 and 2015).

AIMS: Previous epidemiological evidence identified a concerning increase in behavioural problems among young children from 1997 to 2008 in Brazil. However, it is unclear whether behavioural problems have continued to increase, if secular changes vary between sociodemographic groups and what might explain changes over time. We aimed to monitor changes in child behavioural problems over a 22-year period from 1997 to 2019, examine changing social inequalities and explore potential explanations for recent changes in behavioural problems between 2008 and 2019. METHODS: The Child Behaviour Checklist was used to compare parent-reported behavioural problems in 4-year-old children across three Brazilian birth cohorts assessed in 1997 (1993 cohort, n = 633), 2008 (2004 cohort, n = 3750) and 2019 (2015 cohort, n = 577). Response rates across all three population-based cohorts were over 90%. Moderation analyses tested if cross-cohort changes differed by social inequalities (demographic and socioeconomic position), while explanatory models explored whether changes in hypothesized risk and protective factors in prenatal development (e.g., smoking during pregnancy) and family life (e.g., maternal depression and harsh parenting) accounted for changes in child behavioural problems from 2008 to 2019. RESULTS: Initial increases in child behavioural problems from 1997 to 2008 were followed by declines in conduct problems (mean change = -2.75; 95% confidence interval [CI]: -3.56, -1.94; P < 0.001), aggression (mean change = -1.84; 95% CI: -2.51, -1.17; P < 0.001) and rule-breaking behaviour (mean change = -0.91; 95% CI: -1.13, -0.69 P < 0.001) from 2008 to 2019. Sex differences in rule-breaking behaviour diminished during this 22-year period, whereas socioeconomic inequalities in behavioural problems emerged in 2008 and then remained relatively stable. Consequently, children from poorer and less educated families had higher behavioural problems, compared to more socially advantaged children, in the two more recent cohorts. Changes in measured risk and protective factors partly explained the reduction in behavioural problems from 2008 to 2019. CONCLUSIONS: Following a rise in child behavioural problems, there was a subsequent reduction in behavioural problems from 2008 to 2019. However, social inequalities increased and remained high. Continued monitoring of behavioural problems by subgroups is critical for closing the gap between socially advantaged and disadvantaged children and achieving health equity for the next generation.

Using a cross-cohort comparison design to test the role of maternal smoking in pregnancy in child mental health and learning: evidence from two UK cohorts born four decades apart.

BACKGROUND: Maternal smoking in pregnancy is associated with low birth weight (LBW), child conduct problems, hyperactivity and lower cognitive attainment, but associations may reflect measured and unmeasured confounding. Cross-cohort designs can aid causal inference through comparison of associations across populations with different confounding structures. We compared associations between maternal smoking in pregnancy and child conduct and hyperactivity problems, cognition and LBW across two cohorts born four decades apart. METHODS: Two national UK cohorts born in 1958 (n = 12 415) and 2000/01 (n = 11 800) were compared. Maternal smoking in pregnancy and child birth weight was assessed at or shortly after birth. Parents rated children's conduct problems and hyperactivity, and children completed standardized tests of reading and mathematics. RESULTS: Maternal smoking in pregnancy was less common and more strongly associated with social disadvantage in 2000/01 compared with 1958 (interactions P < 0.001). Maternal smoking in pregnancy was robustly and equivalently associated with infant LBW in both cohorts [interactions: boys odds ratio (OR) = 1.01 (0.89, 1.16), P = 0.838; girls OR = 1.01 (0.91, 1.17), P = 0.633]. Maternal smoking was more strongly associated with conduct problems, hyperactivity and reading in the 2000/01 cohort (interactions P < 0.001). CONCLUSIONS: Marked cross-cohort change in associations between maternal smoking and child conduct problems, hyperactivity and reading highlights the likely role of confounding factors. In contrast, association with LBW was unaffected by change in prevalence of maternal smoking and patterns of confounding. The study highlights the utility of cross-cohort designs in helping triangulate conclusions about the role of putative causal risk factors in observational epidemiology.

Adult mood problems in children with neurodevelopmental problems: evidence from a prospective birth cohort followed to age 50.

PURPOSE: Specific child neurodevelopmental (ND) disorders such as ADHD and learning problems are associated with concurrent and future (up to early adulthood) mood problems. However, it is unclear whether findings generalise to population traits as well as diagnoses, to general as well as specific neurodevelopmental domains, and whether risk associations extend to later adulthood or diminish with age. METHODS: We used data from a UK cohort of children born in 1958, the National Child Development Study (NCDS). ND problems were assessed at ages 7 and 11 years with parent- and teacher ratings of restlessness, hyperactivity and motor co-ordination difficulties, and by individual tests of reading, arithmetic and general cognitive ability. Mood (depression/anxiety) problems were assessed using the Malaise symptom screen at 23, 33, 42, and 50 years. Factor analyses were conducted to assess whether the specific neurodevelopmental domains could be aggregated into a general "ND" latent factor as well as specific factors. Associations with mood outcomes were then tested. RESULTS: A bi-factor model with a general "ND" latent factor and specific "motor" and "cognition" factors fits the data well. The specific cognition and motor factor scores were associated with mood problems in early adulthood only. The "ND" factor demonstrated associations with mood problems at each adult follow-up (men - age 23 years: ß = 0.17; age 33: ß = 0.16; age 42: ß = 0.14; age 50: ß = 0.16; women - 23 years: ß = 0.25; 33 years: ß = 0.26; 42 years: ß = 0.14; 50 years: ß = 0.16; all ps < 0.01). Interactions by sex indicated that the association between this general factor and mood problems was more pronounced for women than men at ages 23 years (ß = 0.09, p = 0.005) and 33 years (ß = 0.10, p = 0.003), but not at 42 or 50 years (ps > 0.8). CONCLUSIONS: Our results suggest that, in a population-based cohort, a general, childhood neurodevelopmental difficulty factor is stably associated with mood problems in adult life.

Using a genetically informative design to examine the relationship between breastfeeding and childhood conduct problems.

A number of public health interventions aimed at increasing the uptake of breastfeeding are in place in the United States and other Western countries. While the physical health and nutritional benefits of breastfeeding for the mother and child are relatively well established, the evidence for psychological effects is less clear. This study aimed to examine whether there is an association between breastfeeding and later conduct problems in children. It also considered the extent to which any relationship is attributable to maternally-provided inherited characteristics that influence both likelihood of breastfeeding and child conduct problems. A prenatal cross-fostering design with a sample of 870 families with a child aged 4-11 years was used. Mothers were genetically related or unrelated to their child as a result of assisted reproductive technologies. The relationship between breastfeeding and conduct problems was assessed while controlling for theorised measured confounders by multivariate regression (e.g. maternal smoking, education, and antisocial behaviour), and for unmeasured inherited factors by testing associations separately for related and unrelated mother-child pairs. Breastfeeding was associated with lower levels of conduct disorder symptoms in offspring in middle childhood. Breastfeeding was associated with lower levels of conduct problems even after controlling for observed confounders in the genetically related group, but not in the genetically unrelated group. In contrast, maternal antisocial behaviour showed robust associations with child conduct problems after controlling for measured and inherited confounders. These findings highlight the importance of using genetically sensitive designs in order to test causal environmental influences.