A Systematic Review and Meta-analysis of Prenatal, Birth, and Postnatal Factors Associated with Attention-Deficit/Hyperactivity Disorder in Children

Predictors of preschool attention-deficit/hyperactivity disorder diagnosis: a population-based study using national registers

BACKGROUND

The diagnosis of attention-deficit/hyperactivity disorder (ADHD) in preschool years (before age 6 years) is a marker of severity and poor prognosis. This study investigated a broad range of predictors of ADHD diagnosis during preschool age.

METHODS

Population-based cohort study using Swedish registers. The final sample consisted of all children born in Sweden between 2001 and 2007 who could be linked to both of their biological parents, excluding those who died or emigrated (n = 631,695). Follow-up was completed December 31, 2013. Cox proportional-hazards models for survival analysis were used to identify the predictors that increased the risk of receiving a clinical diagnosis of ADHD from 3 to 5 years. Hazard ratios (HR) with 95% confidence intervals (CI) were presented for each of the 41 selected predictors covering early-onset psychiatric comorbidities, nonpsychiatric medical conditions, parental history and perinatal factors.

RESULTS

At the end of follow-up, 1,686 preschoolers (2.7% of the whole sample) had received a diagnosis of ADHD. We found that 39 out of 41 predictors were associated with increased risk of a later diagnosis of preschool ADHD. Novel associations with preschool ADHD diagnosis were found for gastroesophageal reflux disease (HR = 3.48), premature contractions during pregnancy (HR = 2.03), and criminal conviction history from any parent (HR = 2.14).

CONCLUSIONS

A large number of novel and well-established predictors of preschool ADHD diagnosis were identified. This broad set of early predictors may direct future clinical research and assist in early identification of preschool ADHD.

Effect of sex on neuropsychiatric comorbidities in childhood epilepsy

OBJECTIVE

Neuropsychiatric comorbidities are prevalent in children with epilepsy and often pose greater concerns than the seizures themselves. Identifying children at risk for these conditions is crucial for developing effective therapies. In prepubescent rodents, sex significantly influences cognitive dysfunction related to seizures, with prepubescent male rats exhibiting more severe adverse effects than females. However, it remains unclear whether sex plays a similar role in cognitive and behavioral outcomes in children. This review aims to assess the literature on whether sex is a biological factor affecting behavioral and cognitive outcomes in pediatric epilepsy.

MATERIALS AND METHODS

We conducted a literature review to explore the impact of sex on cognitive and behavioral outcomes in children (up to age 18 years) with epilepsy of all types. Studies were categorized into observational and interventional types. We analyzed population studies involving children with epilepsy, as well as those addressing genetic factors, surgical interventions, status epilepticus, infantile spasms, pharmacological treatments, and the ketogenic diet.

RESULTS

Few adequately powered studies have examined sex as a biological variable in relation to cognitive and behavioral impairments in children with epilepsy. In addition, many studies failed to examine sex-related differences in behavior and cognition in children without epilepsy. Generally, the sex-related differences in cognitive and behavioral impairments in children with epilepsy match those seen in children without epilepsy. One exception is that in several studies girls with epilepsy had a similar risk for attention deficit hyperactive disorder (ADHD) as boys, whereas in children without epilepsy ADHD is more common in boys than girls. Although there is a modest trend indicating worse cognitive outcomes for boys with epilepsy compared to girls, consistency across studies is lacking.

CONCLUSION

Sex is not yet a well-explored prognostic factor for outcomes following childhood epilepsy, though some small differences were identified for specific outcomes. More rigorously designed studies are necessary to report outcomes by sex while controlling for potential confounders. The variability in methods for assessing neurodevelopmental outcomes underscores the need for standardized and comprehensive evaluations of cognitive and behavior in children with epilepsy.

Prevalence and risk factors of attention deficit hyperactive disorder among children aged 6-17 years in arbaminch City, Gamo zone, Southern Ethiopia: a community-based cross-sectional study

INTRODUCTION

Attention deficit hyperactivity disorder (ADHD) is among the most common neurodevelopmental diseases affecting children and adolescents all over the world. There is limited evidence on the magnitude of ADHD among children in the Southern Nation and Nationality region in Ethiopia. Therefore, this study aimed to assess the magnitude and associated factors of ADHD among children aged 6-17 years in Arba Minch town, Southern Ethiopia.

METHODS

A community-based cross-sectional study was conducted in Arba Minch city from April 5 to May 5, 2023. A study included 520 participants. A multistage sampling followed by systematic random sampling was used to select the study participants. The Vanderbilt ADHD diagnostic DSM-IV criteria using a pre-tested, structured questionnaire with a face-to-face interview were used to assess the outcome. For data entry and analysis, Epi Info version 7 and STATA version 14 software were used, respectively. Variables with a p < 0.25 from the bivariate analysis were considered for the multivariable analysis. The multivariable logistic regression analysis was performed to identify statistically significant variables with a p-value of < 0.05. The adjusted odds ratio presented the strength of the association with a 95% confidence interval.

RESULT

The prevalence of ADHD was found to be 9.77% (95% CI; 7.47-12.66) in Arbaminch city. Family history of mental illness (AOR = 2.27; 95% CI: 1.15-4.45), children with a history of previous mental health problems (AOR = 7.11; 95% CI: 1.66-30.41), children whose mothers used alcohol during pregnancy (AOR = 3.36; 95% CI: 1.41-7.99), and children whose mothers smoked tobacco during their lifetime (AOR = 4.17; 95% CI: 1.05-16.89) were significantly associated with attention-deficit hyperactivity disorder.

CONCLUSION

According to this study, one in ten children in Arbaminch City, Ethiopia, is diagnosed with ADHD. Key predictors of ADHD include a prior history of mental illness in the child, maternal smoking, alcohol consumption during pregnancy, and a family history of mental disorders. Consequently, children with previous mental health issues and those from families with a history of mental illness should receive special attention. Additionally, expectant mothers must be informed about the harmful effects of alcohol and tobacco consumption on fetal development.

The 2D:4D ratios in the mothers of children with attention deficit hyperactivity disorder

BACKGROUND

Prenatal exposure to high levels of testosterone affects the development of the brain. The purpose of this study was to compare the mothers of children with attention deficit hyperactivity disorder (ADHD) and those of healthy children in terms of the digit ratio (2D:4D). It also examines the relationship between ADHD symptoms and the 2D:4D in mothers.

METHOD

The mothers of 120 children with ADHD and of 61 healthy children were included in the study. 2D:4D were measured for both the patients and the healthy individuals, and sociodemographic data were examined. The mothers' ADHD symptoms were measured using the Adult ADHD Self-Report Scale (ASRS). The patient and control groups were compared in terms of 2D:4D values and ADHD symptoms. The relationship between 2D:4D and ADHD was also examined in the patient group.

RESULTS

Maternal right 2D:4D (p < 0.001) and left 2D:4D (p = 0.003) values in the ADHD group were significantly lower than in the control group mothers. No association was also observed between the left hand and right 2D:4D ratios of the mothers in the case group and the ASRS- Hyperactivity or Attention Deficit subscales.

CONCLUSION

Our findings add to the literature examining the relationship between prenatal exposure to testosterone and ADHD. This study shows that the mothers of children with ADHD are exposed to greater prenatal testosterone. In addition, it does not support the hypothesis that prenatal exposure to testosterone in the mothers of children with ADHD plays a role in the development of ADHD symptoms. Further studies examining this relationship in mothers are now needed.

The association between maternal diabetes and the risk of attention deficit hyperactivity disorder in offspring: an updated systematic review and meta-analysis

Mixed results have been reported regarding the link between different types of maternal diabetes and attention deficit hyperactivity disorder (ADHD) in offspring. Hence, we conducted a systematic review and meta-analysis to explore these associations. Relevant studies on the subject were retrieved from six major databases, including PubMed, Medline, Embase, Scopus, CINAHL, and PsychINFO. The methodological quality of the included studies was evaluated using the Newcastle-Ottawa Scale, and between-study heterogeneity was assessed using the I2 statistic. Subgroup, sensitivity, and meta-regression analyses were conducted to identify the sources of heterogeneity between studies. In total, seventeen observational studies (five case-control and twelve cohort studies) with 18,063,336 study participants were included in the final analysis. Our random-effects meta-analysis revealed that exposure to any form of maternal diabetes was associated with an increased risk of ADHD in children. Specifically, we observed a heightened risk of ADHD in children exposed to gestational diabetes mellitus, any pre-existing diabetes, pre-existing type 1 diabetes mellitus, and type 2 diabetes mellitus. Our study suggests that children exposed to diabetes during prenatal development are at a higher risk of developing ADHD. These findings underscore the critical importance of early screening and timely interventions for exposed offspring.

Association of premature birth and maternal education level on attention deficit hyperactivity disorder in children: A meta-analysis

BACKGROUND

Attention deficit hyperactivity disorder (ADHD) is a prevalent neurodevelopmental disorder in childhood. There is growing evidence that both preterm birth and maternal education levels substantially affect the likelihood of ADHD in children. However, there are limited systematic reviews and meta-analyses examining these associations.

AIM

To systematically review and conduct a meta-analysis on the association of preterm birth and maternal education level on the risk of ADHD in children.

METHODS

We conducted a comprehensive literature search across MEDLINE (PubMed), Web of Science, Embase, and the Cochrane Library, including studies published up to June 17, 2024. Data synthesis was performed using random-effect models, and the quality of studies was assessed using the Newcastle-Ottawa Scale.

RESULTS

This study included twelve studies, which revealed a significant association between premature delivery and an increased risk of ADHD in children [odds ratio (OR) = 2.76, 95% confidence interval (CI): 2.52-3.04, P < 0.001, I² = 1.9%). Conversely, higher maternal education levels were significantly associated with a reduced risk of ADHD in children (OR = 0.59, 95%CI: 0.48-0.73, P < 0.001, I² = 47.1%). Subgroup analysis further indicated that maternal education levels significantly influenced ADHD risk, particularly in studies conducted in China (OR = 0.59, 95%CI: 0.46-0.75, P < 0.001, I² = 81.2%), while no significant association was observed in studies from other regions (OR = 1.25, 95%CI: 0.66-2.40, P = 0.495, I² = 92.3%). The sensitivity analysis confirmed the robustness of our findings, showing no significant publication bias.

CONCLUSION

This study found that preterm birth significantly increases the risk of ADHD in children, while a higher maternal education level serves as a protective factor against ADHD. To reduce the incidence of ADHD in children, public health policies should focus on early intervention for preterm infants and improving maternal education levels.

Important Mechanisms in the Development of Anxiety in Children with ADHD: The Role of Associated Features of ADHD and Interpersonal Functioning

Over a quarter of children with Attention-deficit/hyperactivity disorder (ADHD) meet diagnostic criteria for an anxiety disorder as well. The goals of this paper are (a) to examine what is currently known about co-occurring ADHD and anxiety in children, (b) propose and outline underlying factors relevant to the development of anxiety in children with ADHD, and (c) discuss future directions and clinical implications for the prevention and identification of anxiety development in children with ADHD. It is proposed that certain associated features of ADHD (i.e., low effortful control and emotion dysregulation) as well as various interpersonal factors related to ADHD (i.e., poor parent, teacher, and peer relationships) form a negative feedback loop that increases susceptibility to anxiety in a subset of children with ADHD. The literature supports interrelations between and across the associated features and interpersonal factors. Additional research is needed to test the validity of the proposed process. Obtaining further insight into the interplay between these different factors can help identify a subset of children with ADHD who are at risk for developing anxiety, which can enhance the precision of prevention, assessment, and treatment efforts for these children.

Organic food consumption during pregnancy and symptoms of neurodevelopmental disorders at 8 years of age in the offspring: the Norwegian Mother, Father and Child Cohort Study (MoBa)

BACKGROUND

Partially driven by public concerns about modern food production practices, organic food has gained popularity among consumers. However, the impact of organic food consumption during pregnancy on offspring health is scarcely studied. We aimed to investigate the association between maternal intake of organic food during pregnancy and symptoms of attention deficit/hyperactivity disorder (ADHD) and autism spectrum disorder (ASD) in offspring at 8 years of age.

METHODS

This study was based on the Norwegian Mother, Father and Child Cohort Study (MoBa) and the Medical Birth Registry of Norway (MBRN). The total study sample included 40,707 mother-child pairs (children born 2002-2009). Organic food consumption during pregnancy was assessed by six questions from a food frequency questionnaire in mid-pregnancy (sum score 0-18). Symptoms of ADHD and ASD in the offspring aged 8 years were measured by ADHD (0-54) and ASD (0-39) symptom scores based on the Parent/Teacher Rating Scale for Disruptive Behaviour disorders and the Social Communication Questionnaire. Associations between maternal intake of organic food during pregnancy and symptoms of ADHD and ASD in the offspring were analyzed using regression models with adjustment for covariates such as maternal anxiety and depression, including sibling analysis.

RESULTS

Mean ADHD and ASD symptom scores in the offspring differed only slightly by maternal intake of organic food. The covariate-adjusted unstandardized regression coefficient (adjusted(Adj)beta) with 95% confidence interval for the ADHD symptom score with one unit increase in organic food sum score was 0.03 (0.01, 0.05). Similarly, Adjbeta for autism symptom score was 0.07 (0.04, 0.10). For ADHD, the adjusted estimates weakened when adjusting for maternal symptoms of ADHD. The sibling analyses showed no significant results with Adjbeta - 0.07 (- 0.15, 0.01) and - 0.001 (- 0.12, 0.12) for ADHD and ASD outcomes, respectively.

CONCLUSIONS

We observed weak positive associations between frequent maternal organic food consumption during pregnancy and offspring ADHD and ASD symptom levels at 8 years of age. This trend weakened or disappeared after adjusting for maternal symptoms of ADHD, and in sibling analyses, suggesting that the associations mainly reflect genetic confounding. Our study indicates that consumption of organic food during pregnancy should neither be considered a risk factor nor protective against symptoms of ADHD and ASD in offspring.

Occupational exposure to organic solvents during pregnancy and child behavior from early childhood to adolescence

BACKGROUND

Organic solvents are used in formulating an extensive range of products for professional use. Animal and human studies suggest that in utero solvent exposure may affect neurodevelopment. Our objective was to assess the association between occupational exposure to solvents during pregnancy and child behavior aged 2-12 years.

METHODS

The French mother-child cohort PELAGIE (2002-2006) included 3,421 women recruited in early pregnancy. Occupational exposure to solvents was self-reported. For 459 children, parents used a questionnaire derived from the Child Behavior Checklist and the Preschool Social Behavior Questionnaire to assess their child's behavior, at age 2, and the Strengths and Difficulties Questionnaire at ages 6 and 12. A cross-lagged structural equation modeling approach was used to assess direct and indirect associations between exposure and child behavior.

RESULTS

At age 2, an increased externalizing behavior score was suggested with prenatal exposure to solvents (mean change in standardized score (95%CI): 0.28 (-0.01, 0.57) for occasional exposure and 0.23 (-0.05, 0.51) for regular exposure). At ages 6 and 12, distinct sex-specific patterns were observed: among boys, no association with externalizing behavior was observed, while among girls, an association was seen for both occasional and regular exposure (total effect at age 12: 0.45 (0.06,0.83) and 0.40 (0.03, 0.76), respectively). For both sexes, occasional exposure may be associated with internalizing behavior at ages 6 and 12 (total effect at age 6: 0.37 (0.06, 0.68) and at age 12: 0.27 (-0.08, 0.62)).

CONCLUSIONS

Occupational exposure to solvents during pregnancy may impact child behavior through either direct or cumulative effects during childhood; these associations may persist until early adolescence, especially among girls.

No evidence for a causal contribution of bioavailable testosterone to ADHD in sex-combined and sex-specific two-sample Mendelian randomization studies

The higher prevalence of attention-deficit/hyperactivity disorder (ADHD) in males raises the question of whether testosterone is implicated in ADHD risk. However, cross-sectional studies did not identify an association between ADHD and testosterone levels. Mendelian randomization (MR) studies can overcome limitations inherent to association studies, especially of reverse causation and residual confounding. In the current study, sex-combined and sex-specific two-sample MR analyses were conducted to address whether testosterone has a causal influence on ADHD risk. Sex-combined as well as sex-specific target-genetic variants for bioavailable testosterone were derived from a large genome-wide association study (GWAS) on up to 382,988 adult white European UK Biobank study participants. In our sex-specific analyses for ADHD, including data from 14,154 males and 4,945 females with ADHD (17,948 and 16,246 controls respectively), no association between bioavailable testosterone and ADHD risk was found, neither in males (inverse-variance weighted (IVW): beta = 0.09, 95%-CI [-0.10, 0.27]) nor in females (IVW: beta=-0.01, 95%-CI [-0.20, 0.19]). However, in the sex-combined analysis, including 38,691 cases and 186,843 controls, genetically predicted bioavailable testosterone was associated with ADHD risk (IVW: beta = 0.24, 95%-CI [0.09, 0.39]). The inclusion of birth weight and/or SHBG as additional variables in multivariable MR analyses did not alter this result. However, when correcting for potential BMI-driven pleiotropy by a multivariable MR study, all effect estimates for testosterone showed non-significant results. Taken together, no robust evidence for a causal effect of bioavailable testosterone on the risk for ADHD was found.

Looking beyond psychosocial adversity and sex: Clinical factors associated with ADHD and other psychiatric disorders in a non-Caucasian sample of high-risk siblings

This study examined the association of clinical factors, independent of sex and high psychosocial adversity (HPAd), with the presence of ADHD or other mental disorders, specifically within a middle-income country with a non-Caucasian population. A multi-centric cross-sectional study was conducted in three sites in Colombia. Our study recruited trios of an ADHD proband, one sibling, and one parent. We used valid instruments for assessing parents and siblings. The sample included 223 siblings, an average age of 12.3 (SD 3.9), and 51.1% Females. The ADHD recurrence risk ratio (λ) was 12. The clinical factors mainly associated with the presence of ADHD, independent of sex and HPAd, were 1) Pregnancy and childbirth complications, 2) Delayed psychomotor development, 3) Temperament, and 4) Sleep disturbances. Our research showed that, independently of HPAd and the male sex, there were other clinical factors associated with ADHD and other psychiatric disorders in this population. These findings need to be replicated in similar populations globally.

Identifying Risk Factors for Attention-Deficit/Hyperactivity Disorder (ADHD): a Public Health Concern and Opportunity

Attention-deficit/hyperactivity disorder (ADHD) is one of the most common neurodevelopmental disorders with significant individual and societal negative impacts of the disorder continuing into adulthood (Danielson et al. in Journal of Clinical Child and Adolescent Psychology, in press; Landes and London in Journal of Attention Disorders 25:3-13, 2021). Genetic and environmental risk (e.g., modifiable exposures such as prenatal tobacco exposure and child maltreatment) for ADHD is likely multifactorial (Faraone et al. in Neuroscience & Biobehavioral Reviews 128:789-818, 2021). However, the evidence for potentially modifiable contextual risks is spread across studies with different methodologies and ADHD criteria limiting understanding of the relationship between early risk factors and later childhood ADHD. Using common methodology across six meta-analyses (Bitsko et al. in Prevention Science, 2022; Claussen et al. in Prevention Science 1-23, 2022; Dimitrov et al. in Prevention Science, 2023; Maher et al. in Prevention Science, 2023; Robinson, Bitsko et al. in Prevention Science, 2022; So et al. in Prevention Science, 2022) examining 59 risk factors for childhood ADHD, the papers in this special issue use a public health approach to address prior gaps in the literature. This introductory paper provides examples of comprehensive public health approaches focusing on policy, systems, and environmental changes across socio-ecological contexts to improve health and wellbeing through prevention, early intervention, and support across development using findings from these meta-analyses. Together, the findings from these studies and a commentary by an author independent from the risk studies have the potential to minimize risk conditions, prioritize prevention efforts, and improve the long-term health and wellbeing of children and adults with ADHD.

Systematic Review and Meta-analysis of the Relationship Between Exposure to Parental Substance Use and Attention-Deficit/Hyperactivity Disorder in Children

Attention-deficit/hyperactivity disorder (ADHD) is characterized by persistent patterns of inattention, hyperactivity, and impulsiveness. Among US children and adolescents aged 3-17 years, 9.4% have a diagnosis of ADHD. Previous research suggests possible links between parental substance use and ADHD among children. We conducted a systematic review and meta-analysis of 86 longitudinal or retrospective studies of prenatal or postnatal alcohol, tobacco, or other parental substance use and substance use disorders and childhood ADHD and its related behavioral dimensions of inattention and hyperactivity-impulsivity. Meta-analyses were grouped by drug class and pre- and postnatal periods with combined sample sizes ranging from 789 to 135,732. Prenatal exposure to alcohol or tobacco and parent substance use disorders were consistently and significantly associated with ADHD among children. Other parental drug use exposures resulted in inconsistent or non-significant findings. Prevention and treatment of parental substance use may have potential for impacts on childhood ADHD.

Understanding Environmental Exposures and ADHD: a Pathway Forward

This commentary addresses a series of articles in Prevention Science about environmental causes of attention deficit hyperactivity disorder (ADHD). It provides an overview of their key findings and places them in a broader context to facilitate their interpretation. Each of the articles included in the special issue is a meta-analysis assessing the association of ADHD with several environmental exposures. Each of the author teams systematically searched for articles and defined eligibility criteria. They assured that the measurement of risk factors preceded the measurement of ADHD. Most of the analyses are based on many studies with many participants in the constituent studies. As is typical of any observational epidemiologic study, the constituent studies could not correct for all possible confounds because some were not measured, and some are unknown. For this reason, these meta-analyses may have documented confounded associations, which calls for cautious interpretations. None of the constituent studies assessed what might be the most important type of confounding, familial, and genetic confounding, which occurs when the environmental exposure being studied is correlated with the genetic risk of the disorder being studied or other familial risk factors. Addressing familial/genetic confounding requires a genetically informed study. Because of these issues, the results presented here are intriguing but require further examination before one can conclude that the reported associations correspond to causal events for ADHD. A pathway forward is suggested by drawing parallels between genomic and exposure research.

A Systematic Review and Meta-analysis of Parental Depression, Antidepressant Usage, Antisocial Personality Disorder, and Stress and Anxiety as Risk Factors for Attention-Deficit/Hyperactivity Disorder (ADHD) in Children

Poor parental mental health and stress have been associated with children's mental disorders, including attention-deficit/hyperactivity disorder (ADHD), through social, genetic, and neurobiological pathways. To determine the strength of the associations between parental mental health and child ADHD, we conducted a set of meta-analyses to examine the association of parent mental health indicators (e.g., parental depression, antidepressant usage, antisocial personality disorder, and stress and anxiety) with subsequent ADHD outcomes in children. Eligible ADHD outcomes included diagnosis or symptoms. Fifty-eight articles published from 1980 to 2019 were included. We calculated pooled effect sizes, accounting for each study's conditional variance, separately for test statistics based on ADHD as a dichotomous (e.g., diagnosis or clinical cutoffs) or continuous measurement (e.g., symptoms of ADHD subtypes of inattentiveness and hyperactivity/impulsivity). Parental stress and parental depression were significantly associated with increased risk for ADHD overall and both symptoms and diagnosis. Specifically, maternal stress and anxiety, maternal prenatal stress, maternal depression, maternal post-partum depression, and paternal depression were positively associated with ADHD. In addition, parental depression was associated with symptoms of ADHD inattentive and hyperactive/impulsive subtypes. Parental antisocial personality disorder was also positively associated with ADHD overall and specifically ADHD diagnosis. Prenatal antidepressant usage was associated with ADHD when measured dichotomously only. These findings raise the possibility that prevention strategies promoting parental mental health and addressing parental stress could have the potential for positive long-term impacts on child health, well-being, and behavioral outcomes.

A Systematic Review and Meta-analysis of Chemical Exposures and Attention-Deficit/Hyperactivity Disorder in Children

Exposure to certain chemicals prenatally and in childhood can impact development and may increase risk for attention-deficit/hyperactivity disorder (ADHD). Leveraging a larger set of literature searches conducted to synthesize results from longitudinal studies of potentially modifiable risk factors for childhood ADHD, we present meta-analytic results from 66 studies that examined the associations between early chemical exposures and later ADHD diagnosis or symptoms. Studies were eligible for inclusion if the chemical exposure occurred at least 6 months prior to measurement of ADHD diagnosis or symptomatology. Included papers were published between 1975 and 2019 on exposure to anesthetics (n = 5), cadmium (n = 3), hexachlorobenzene (n = 4), lead (n = 22), mercury (n = 12), organophosphates (n = 7), and polychlorinated biphenyls (n = 13). Analyses are presented for each chemical exposure by type of ADHD outcome reported (categorical vs. continuous), type of ADHD measurement (overall measures of ADHD, ADHD symptoms only, ADHD diagnosis only, inattention only, hyperactivity/impulsivity only), and timing of exposure (prenatal vs. childhood vs. cumulative), whenever at least 3 relevant effect sizes were available. Childhood lead exposure was positively associated with ADHD diagnosis and symptoms in all analyses except for the prenatal analyses (odds ratios (ORs) ranging from 1.60 to 2.62, correlation coefficients (CCs) ranging from 0.14 to 0.16). Other statistically significant associations were limited to organophosphates (CC = 0.11, 95% confidence interval (CI): 0.03-0.19 for continuous measures of ADHD outcomes overall), polychlorinated biphenyls (CC = 0.08, 95% CI: 0.02-0.14 for continuous measures of inattention as the outcome), and both prenatal and childhood mercury exposure (CC = 0.02, 95% CI: 0.00-0.04 for continuous measures of ADHD outcomes overall for either exposure window). Our findings provide further support for negative impacts of prenatal and/or childhood exposure to certain chemicals and raise the possibility that primary prevention and targeted screening could prevent or mitigate ADHD symptomatology. Furthermore, these findings support the need for regular review of regulations as our scientific understanding of the risks posed by these chemicals evolves.

Childhood Physical Health and Attention Deficit/Hyperactivity Disorder: A Systematic Review and Meta-Analysis of Modifiable Factors

Although neurobiologic and genetic factors figure prominently in the development of attention deficit/hyperactivity disorder (ADHD), adverse physical health experiences and conditions encountered during childhood may also play a role. Poor health is known to impact the developing brain with potential lifelong implications for behavioral issues. In attempt to better understand the relationship between childhood physical health and the onset and presence of ADHD symptoms, we summarized international peer-reviewed articles documenting relationships between a select group of childhood diseases or health events (e.g., illnesses, injuries, syndromes) and subsequent ADHD outcomes among children ages 0-17 years. Drawing on a larger two-phase systematic review, 57 longitudinal or retrospective observational studies (1978-2021) of childhood allergies, asthma, eczema, head injury, infection, or sleep problems and later ADHD diagnosis or symptomatology were identified and subjected to meta-analysis. Significant associations were documented between childhood head injuries, infections, and sleep problems with both dichotomous and continuous measures of ADHD, and between allergies with dichotomous measures of ADHD. We did not observe significant associations between asthma or eczema with ADHD outcomes. Heterogeneity detected for multiple associations, primarily among continuously measured outcomes, underscores the potential value of future subgroup analyses and individual studies. Collectively, these findings shed light on the importance of physical health in understanding childhood ADHD. Possible etiologic links between physical health factors and ADHD are discussed, as are implications for prevention efforts by providers, systems, and communities.

Effect of cesarean section on the risk of autism spectrum disorders/attention deficit hyperactivity disorder in offspring: a meta-analysis

PURPOSE

This study was conducted to investigate the relationship between cesarean section (CS) offspring and autism spectrum disorders (ASD)/attention deficit hyperactivity disorder (ADHD).

METHODS

Searching of the databases (PubMed, Web of Science, Embase, and Cochrane Library) for studies on the relationship between mode of delivery and ASD/ADHD until August 2022. The primary outcome was the incidence of ASD/ADHD in the offspring.

RESULTS

This meta-analysis included 35 studies (12 cohort studies and 23 case-control studies). Statistical results showed a higher risk of ASD (odds ratio (OR) = 1.25, P < 0.001) and ADHD (OR = 1.11, P < 0.001) in CS offspring compared to the VD group. Partial subgroup analysis showed no difference in ASD risk between CS and VD offspring in sibling-matched groups (OR = 0.98, P = 0.625). The risk of ASD was higher in females (OR = 1.66, P = 0.003) than in males (OR = 1.17, P = 0.004) in the CS offspring compared with the VD group. There was no difference in the risk of ASD between CS under regional anesthesia group and VD group (OR = 1.07, P = 0.173). However, the risk of ASD was higher in the CS offspring under general anesthesia than in the VD offspring (OR = 1.62, P < 0.001). CS offspring developed autism (OR = 1.38, P = 0.011) and pervasive developmental disorder-not otherwise specified (OR = 1.46, P = 0.004) had a higher risk than VD offspring, but there was no difference in Asperger syndrome (OR = 1.19, P = 0.115). Offspring born via CS had a higher incidence of ADHD in different subgroup analyses (sibling-matched, type of CS, and study design).

CONCLUSIONS

In this meta-analysis, CS was a risk factor for ASD/ADHD in offspring compared with VD.

Neonatal risk factors associated with attention-deficit/hyperactivity disorder: an umbrella review

BACKGROUND

Attention deficit hyperactivity disorder (ADHD) is a neurodevelopmental disorder that is being encountered more frequently.

PURPOSE

In this study, by compiling the evidence from available meta-analyses, an umbrella systematic review was performed of the neonatal risk factors associated with ADHD.

METHODS

The PubMed, Scopus, and Web of Science databases were searched for eligible studies. Only systematic reviews were included. Using a random-effects model, 95% prediction intervals were reported for each risk factor. Three studies were ultimately included in the review.

RESULTS

Congenital heart disease, short-duration or incomplete breastfeeding, low birth weight, and 5-minute Apgar scores <7 were significant risk factors for ADHD. However, the quality of the included systematic reviews was low to moderate and the evidence credibility level was suggestive to weak.

CONCLUSION

The results of this umbrella review proposed that congenital anomalies, short-duration or incomplete breastfeeding, low birth weight, and low Apgar scores were important factors for the manifestation of ADHD symptoms. However, the inclusion of more high-quality studies is needed to validate our results.

Uncertainty in Developmental Origins of Health and Disease research: commentary on Nomura et al. (2023)

Nomura et al. (Journal of Child Psychology and Psychiatry, 2023) reported that children whose mothers were pregnant when Superstorm Sandy struck the Eastern Seaboard of the United States had elevated risk of psychopathology. Their study leverages data from a unique cohort of children established prior to Sandy that enabled researchers to investigate children's mental health depending on their prenatal exposure to the storm. Their findings add to mounting evidence that various types of prenatal stressors instigate stress responses that are transmitted to the developing fetus and impart enduring risk for neuropsychiatric disorders.

Environmental pollution and attention deficit hyperactivity disorder: A meta-analysis of cohort studies

There is already knowledge of the extensive risk factors for attention deficit hyperactivity disorder (ADHD) and recent studies suggest that environmental pollution may contribute to an increase in the incidence of the disorder. The aim of our study was to perform a systematic review and meta-analysis of the risk of ADHD in people younger than 18 years old after exposure to environmental pollution. We searched the MEDLINE, Embase, SciELO, CINAHL, LILACS, Cochrane Central, and Web of Science databases and investigated the grey literature from inception until May 31, 2021. All cohort studies that provided data on exposure to environmental pollutants and ADHD in children and adolescents aged from zero to 18 years old were included. Two reviewers independently selected the studies and applied the quality criteria. If there was a divergence, a third reviewer contributed to the final decision. For the meta-analysis, risk ratios and their confidence intervals were calculated with the MetaXL 5.3 program, using the random effects model. In total, 21 articles were included in this systematic review, and 18 studies met the criteria for the meta-analysis, involving 134,619 participants. The meta-analysis suggested that children exposed to higher levels of heavy metal (RR: 2.41, 95% CI: 1.49-3.90), with low heterogeneity (I² = 39%), and lead (RR: 2.37, 95% CI: 1.28-4.40), with moderate heterogeneity (I² = 54%), are at greater risk of developing ADHD than those exposed to lower levels. This meta-analysis suggests that children exposed to higher levels of lead and heavy metal pollution are at greater risk of developing ADHD than those exposed to lower levels.

A Critical Analysis of the Automated Hematology Assessment in Pregnant Women at Low and at High Altitude: Association between Red Blood Cells, Platelet Parameters, and Iron Status

The objectives of the study were to determine differences in the parameters of red blood cells (RBC), white blood cells (WBC), and platelets at low altitude (LA) and at high altitude (HA) and with the gestation being advanced, and to determine correlations between parameters of RBC and platelets. We also studied the association of RBC and platelets with markers of iron status. In addition, markers of iron status and inflammation were measured and compared at each trimester of gestation in pregnant women at LA and HA. A cross-sectional comparative study was conducted at Lima (150 m above sea level) and Cusco at 3400 m above sea level from May to December 2019. Hematological parameters in pregnant women (233 at LA and 211 at HA) were analyzed using an automated hematology analyzer. Serum ferritin levels, soluble transferrin receptor (sTfR), hepcidin, erythropoietin, testosterone, estradiol, and interleukin-6 (IL6) levels were measured by ELISA. One-way ANOVA supplemented with post hoc test, chi-square test, and Pearson correlation test statistical analyses were performed. p < 0.05 was considered significant. Pregnant woman at HA compared to LA had significantly lower WBC (p < 0.01), associated with higher parameters of the RBC, except for the mean corpuscular volume (MCV) that was no different (p > 0.05). Platelets and mean platelet volume (MPV) were higher (p < 0.01), and platelet distribution width (PDW) was lower at HA than at LA (p < 0.01). A higher value of serum ferritin (p < 0.01), testosterone (p < 0.05), and hepcidin (p < 0.01) was observed at HA, while the concentration of sTfR was lower at HA than at LA (p < 0.01). At LA, neutrophils increased in the third trimester (p < 0.05). RBC parameters decreased with the progress of the gestation, except RDW-CV, which increased. The platelet count decreased and the MPV and PDW were significantly higher in the third trimester. Serum ferritin, hepcidin, and serum testosterone decreased, while sTfR and serum estradiol increased during gestation. At HA, the WBC and red blood cell distribution width- coefficient of variation (RDW-CV), PCT, and serum IL-6 did not change with gestational trimesters. RBC, hemoglobin (Hb), hematocrit (Hct), mean corpuscular hemoglobin concentration (MCHC), and platelet count were lower as gestation advanced. MCV, MPV, and PDW increased in the third trimester. Serum ferritin, testosterone, and hepcidin were lower in the third trimester. Serum estradiol, erythropoietin, and sTfR increased as gestation progressed. Direct or inverse correlations were observed between RBC and platelet parameters and LA and HA. A better number of significant correlations were observed at HA. Hb, Hct, and RDW-CV showed a significant correlation with serum ferritin at LA and HA. Of these parameters, RDW-CV and PDW showed an inversely significant association with ferritin (p < 0.05). In conclusion, a different pattern was observed in hematological markers as well as in iron status markers between pregnant women at LA and HA. In pregnant women a significant correlation between several RBC parameters with platelet marker parameters was also observed. Data suggest that pregnant women at HA have adequate iron status during pregnancy as reflected by higher serum ferritin levels, lower sTfR levels, and higher hepcidin values than pregnant women at LA.