The impact of gestational thyroid hormone concentrations on ADHD symptoms of the child

Treatment of Hypothyroidism and Stress Using Neuro-Emotional Technique (NET): A Case Study

Hypothyroidism is generally considered an autoimmune condition, and typical medical management involves taking levothyroxine (synthetic thyroid hormone) for life. This case report details the results of a mind-body intervention (MBI) called the Neuro-Emotional Technique (NET) used to treat a 28-year-old Caucasian female presenting with symptoms and bloodwork markers associated with two years of hypothyroidism and a long history of stress. The patient's medical doctor provided a diagnosis of hypothyroidism after blood tests showed that thyroid-stimulating hormone (TSH) levels were high at 6.87 mIU/L (where the acceptable range is 0.40-3.50 mIU/L) and free T4 (FT4) levels were low at 8.6 pmol/L (where the acceptable range is 9.0-19.0 pmol/L). Psychometric tests were completed at baseline and after 12 weeks of treatment to evaluate changes in mental health and emotional well-being. The Adverse Childhood Experiences Questionnaire (ACE-Q) revealed a high degree of childhood trauma that may have predisposed to the underlying autoimmune thyroid dysfunction. At the conclusion of the treatment period, serum thyroid-stimulating hormone (TSH) and free T4 were within normal ranges and psychometric indicators normalized. We hypothesize that these changes may be due to the stress-reducing mechanism of NET and outline possible mechanisms via the Psycho-Immune-Neuroendocrine (PINE) network. The PINE network model asserts that chronic stress acts as a potential driver of pathophysiology that can lead to one or more medical and mental health conditions. While further studies with larger sample sizes are required to establish whether these results could be extrapolated to a wider population, the results of this case suggest that it may be pertinent to consider co-management of subclinical hypothyroidism with a relatively quick and cost-effective MBI such as NET.

Emerging research themes in maternal hypothyroidism: a bibliometric exploration

Background

Hypothyroidism, a prevalent endocrine disorder, carries significant implications for maternal and infant health, especially in the context of maternal hypothyroidism. Despite a gradual surge in recent research, achieving a comprehensive understanding of the current state, focal points, and developmental trends in this field remains challenging. Clarifying these aspects and advancing research could notably enhance maternal-infant health outcomes. Therefore, this study employs bibliometric methods to systematically scrutinize maternal hypothyroidism research, serving as a reference for further investigations.

Objective

Through bibliometric analysis, this study seeks to unveil key research focus areas, developmental trends, and primary contributors in Maternal Hypothyroidism. The findings offer insights and recommendations to inform future research endeavors in this domain.

Methods

Literature metrics analysis was performed on data retrieved and extracted from the Web of Science Core Collection database. The analysis examined the evolution and thematic trends of literature related to Maternal Hypothyroidism. Data were collected on October 28, 2023, and bibliometric analysis was performed using VOSviewer, CiteSpace, and the Bibliometrix software package, considering specific characteristics such as publication year, country/region, institution, authorship, journals, references, and keywords.

Results

Retrieved from 1,078 journals, 4,184 articles were authored by 18,037 contributors in 4,580 institutions across 113 countries/regions on six continents. Maternal Hypothyroidism research publications surged from 44 to 310 annually, a 604.54% growth from 1991 to 2022. The USA (940 articles, 45,233 citations), China Medical University (82 articles, 2,176 citations), and Teng, Weiping (52 articles, 1,347 citations) emerged as the most productive country, institution, and author, respectively. "Thyroid" topped with 233 publications, followed by "Journal of Clinical Endocrinology & Metabolism" (202) with the most citations (18,513). "Pregnancy" was the most cited keyword, with recent high-frequency keywords such as "outcome," "gestational diabetes," "iodine intake," "preterm birth," "guideline," and "diagnosis" signaling emerging themes in Maternal Hypothyroidism.

Conclusions

This study unveils developmental trends, global collaboration patterns, foundational knowledge, and emerging frontiers in Maternal Hypothyroidism. Over 30 years, research has predominantly focused on aspects like diagnosis, treatment guidelines, thyroid function during pregnancy, and postpartum outcomes, with a central emphasis on the correlation between maternal and fetal health.

Thyroid function test abnormalities-isolated TPOAb+, SCH and hypothyroxinemia and preschool children's neurodevelopment

OBJECTIVE

Thyroid function test abnormalities are frequent and associated with the offspring's adverse neurodevelopment. This study aimed to examine the relationship between maternal thyroid function test abnormalities before 20 gestational weeks and children's cognitive, emotional and behavioural development at 3-6 years of age.

PATIENTS AND MEASUREMENTS

A total of 2243 mother-child pairs were included in the final analysis. Maternal thyroid function was evaluated retrospectively during the children's preschool period. The serum thyrotrophin, free thyroxine and thyroid peroxidase antibodies (TPOAb) were detected by chemiluminescence immunoassay during the follow-up period. The neurodevelopmental status of preschoolers aged 3-6 years was evaluated by parental versions of The Behavior Rating Inventory of Executive Function-Preschool and The Strengths and Difficulties Questionnaires. The associations between maternal thyroid function test abnormalities and preschoolers' neurodevelopment were examined using Poisson regression models.

RESULTS

After adjusting for potential confounders in Poisson regression analyses, it showed that maternal isolated TPOAb positivity before 20 gestational weeks may be associated with the increased risk of abnormalities in peer problems (odds ratio [OR] = 1.90, 95% confidence interval [CI]: 1.26, 287). Maternal isolated SCH before 20 gestational weeks was observed to be related with increased risk of abnormalities in inhibition (OR = 2.73, 95% CI: 1.37, 5.41), working memory (OR = 1.67, 95% CI: 1.04, 2.70), conduct problems (OR = 1.80, 95% CI: 1.05, 3.09), hyperactivity (OR = 1.94, 95% CI:1.08, 3.49) and total difficulties (OR = 1.94, 95% CI: 1.13, 3.34). Maternal isolated hypothyroxinemia before 20 gestational was observed to be related with increased risk of abnormalities in peer problems (OR = 2.71, 95% CI: 1.17, 6.27).

CONCLUSIONS

Thyroid function test abnormalities before 20 gestational weeks may be associated with children's neurodevelopment at 3-6 years of age.

Maternal thyroid hormone receptor β activation in mice sparks brown fat thermogenesis in the offspring

It is well established that maternal thyroid hormones play an important role for the developing fetus; however, the consequences of maternal hyperthyroidism for the offspring remain poorly understood. Here we show in mice that maternal 3,3',5-triiodothyronine (T3) treatment during pregnancy leads to improved glucose tolerance in the adult male offspring and hyperactivity of brown adipose tissue (BAT) thermogenesis in both sexes starting early after birth. The activated BAT provides advantages upon cold exposure, reducing the strain on other thermogenic organs like muscle. This maternal BAT programming requires intact maternal thyroid hormone receptor β (TRβ) signaling, as offspring of mothers lacking this receptor display the opposite phenotype. On the molecular level, we identify distinct T3 induced alterations in maternal serum metabolites, including choline, a key metabolite for healthy pregnancy. Taken together, our results connect maternal TRβ activation to the fetal programming of a thermoregulatory phenotype in the offspring.

Association of maternal prenatal urinary fluoride levels with ADHD symptoms in childhood

BACKGROUND

Health concerns about the potential impact of exposure to fluoride via drinking water (DW) on neuropsychological development include behavioral outcomes such as ADHD.

OBJECTIVE

We aimed to examine the association between prenatal maternal urinary fluoride and symptoms associated with attention-deficit/hyperactivity disorder (ADHD) at the age of 8 and 11 years.

METHOD

Data from 255 to 236 mother-child pairs from the "Infancia y Medio Ambiente" (INMA) birth cohort (Gipuzkoa; Spain) with maternal urinary F adjusted for creatinine (MUFcr) during pregnancy (first and third trimester) and child assessments of ADHD-like symptoms reported by Conners' Rating Scales-Revised at age of 8 and 11 years was available. Clinical approach was also used: cut off criteria (T > 66). Multiple linear regression models were fitted when outcomes were analyzed as continuous, and logistic regression models when the outcomes were analyzed with a categorical clinical approach. Covariates related to maternal characteristics, birth outcomes, childhood, quality of family context and biomarkers of neuro-toxicants were used.

RESULTS

No association was found between MUFcr levels during pregnancy and cognitive problems-inattention, hyperactivity or ADHD index score of symptoms at 8 or 11 years. When results were analyzed from the perspective of a clinical approach, at the age of 11 years, there were significant inverse association between MUFcr and being categorized as a cognitive problems-inattention case. ORs were also indicative of a lower risk, although not significant, for ADHD index at age 11. Sensitivity analyses, taking into consideration quality of family context or the levels of other toxicants during pregnancy showed similar results.

CONCLUSIONS

Higher levels of MUFcr in pregnant women were associated with a lower risk of cognitive problems-inattention at 11 years. These findings are inconsistent with those from previous studies and indicate the need for other population-based studies to confirm or overturn these results.

Maternal Thyroid Function During Pregnancy and Offspring White Matter Microstructure in Early Adulthood: A Prospective Birth Cohort Study

Background: The fetus is fully dependent on maternal thyroid hormones until mid-gestation and suboptimal maternal thyroid function has been associated with alterations in the neurodevelopment of the offspring. We used maternal free thyroxine (fT4) and thyrotropin (TSH) levels in early gestation to study the association of maternal thyroid function during early pregnancy and offspring brain white matter (WM) integrity in early adulthood. Methods: Our study population consisted of a total of 292 mother-child pairs. Maternal fT4 and TSH were used as predictors and offspring multimodal imaging measures of fractional anisotropy, mean diffusivity, and magnetization transfer ratio (FA, MD, and MTR) as dependent variables. First, as Global analysis, all analyzed 14 WM tracts were studied simultaneously using linear-mixed effect models. Second, if a global effect was detected, a post hoc Tract-wise analysis was carried out using linear models individually in each WM tract. Study population was stratified by sex. Results: We found a positive association between maternal fT4 and offspring Global FA in males when adjusted for all maternal and offspring covariates (n = 114; β = 0.154; confidence interval = 0.045-0.263; p = 0.006). The finding was observed to be driven by multiple WM tracts, of which three projection fiber tracts and the forceps minor survived correcting for multiple comparisons in Tract-wise analysis. Conclusions: Maternal thyroid function in early pregnancy was observed to be associated with WM microstructure in male offspring in early adulthood. Our results suggest that maternal fT4 levels in early pregnancy may modulate axonal characteristics, with a long-term effect on offspring WM development.

Gut microbiota short-chain fatty acids and their impact on the host thyroid function and diseases

Thyroid disorders are clinically characterized by alterations of L-3,5,3',5'-tetraiodothyronine (T4), L-3,5,3'-triiodothyronine (T3), and/or thyroid-stimulating hormone (TSH) levels in the blood. The most frequent thyroid disorders are hypothyroidism, hyperthyroidism, and hypothyroxinemia. These conditions affect cell differentiation, function, and metabolism. It has been reported that 40% of the world's population suffers from some type of thyroid disorder and that several factors increase susceptibility to these diseases. Among them are iodine intake, environmental contamination, smoking, certain drugs, and genetic factors. Recently, the intestinal microbiota, composed of more than trillions of microbes, has emerged as a critical player in human health, and dysbiosis has been linked to thyroid diseases. The intestinal microbiota can affect host physiology by producing metabolites derived from dietary fiber, such as short-chain fatty acids (SCFAs). SCFAs have local actions in the intestine and can affect the central nervous system and immune system. Modulation of SCFAs-producing bacteria has also been connected to metabolic diseases, such as obesity and diabetes. In this review, we discuss how alterations in the production of SCFAs due to dysbiosis in patients could be related to thyroid disorders. The studies reviewed here may be of significant interest to endocrinology researchers and medical practitioners.

Prenatal exposure to polybrominated diphenyl ethers and inattention/hyperactivity symptoms in mid to late adolescents

Introduction

Prenatal exposure to polybrominated diphenyl ethers (PBDEs) has been associated with increased symptoms of attention deficit/hyperactivity disorder (ADHD) in early to middle childhood, as well as early adolescence. However, data are limited for the long-lasting impact of exposure on outcomes assessed across the entire adolescent period and the sex-specificity of such associations.

Methods

We investigated the association between continuous natural-log-transformed cord plasma PBDE concentrations and ADHD rating scale 4th edition (ADHD-RS-IV) score from mid adolescence (approximately 11 years old) to late adolescence (approximately 17 years old). The study sample includes a subset (n = 219) of the African American and Dominican children enrolled in the Columbia Center for Children's Environmental Health Mothers and Newborns birth cohort. We used generalized estimating equations to account for the repeated measure of ADHD-RS scores. We examined interactions between exposure to PBDE and sex using cross-product terms and sex-stratified models. In addition, we used linear regression using an age-stratified sample as a sensitivity analysis.

Results and Discussion

Associations between prenatal exposure and parents' reports of ADHD symptoms varied by sex (p-interaction <0.20), with positive relationships observed among girls but not boys from sex-stratified models. Our finding suggests prenatal exposure to PBDE may affect ADHD symptoms assessed during middle to late adolescence and the sex-specificity of such impact. Our results can be confirmed by future studies with larger and more diverse samples.

Gestational thyroid hormone concentrations and risk of attention-deficit hyperactivity disorder in the Norwegian Mother, Father and Child Cohort Study

BACKGROUND

Maternal thyroid function plays an important role in foetal brain development; however, little consensus exists regarding the relationship between normal variability in thyroid hormones and common neurodevelopmental disorders, such as attention-deficit hyperactivity disorder (ADHD).

OBJECTIVE

We sought to examine the association between mid-pregnancy maternal thyroid function and risk of clinically diagnosed ADHD in offspring.

METHODS

We conducted a nested case-control study in the Norwegian Mother, Father and Child Cohort Study. Among children born 2003 or later, we randomly sampled singleton ADHD cases obtained through linkage with the Norwegian Patient Registry (n = 298) and 554 controls. Concentrations of maternal triiodothyronine (T3), thyroxine (T4), T3-Uptake, thyroid-stimulating hormone (TSH) and thyroid peroxidase antibody (TPO-Ab) were measured in maternal plasma, collected at approximately 17 weeks' gestation. Indices of free T4 (FT4i) and free T3 (FT3i) were calculated. We used multivariable adjusted logistic regression to calculate odds ratios and accounted for missing covariate data using multiple imputation. We used restricted cubic splines to assess non-linear trends and provide flexible representations. We examined effect measure modification by dietary iodine and selenium intake. In sensitivity analyses, we excluded women with clinically significant thyroid disorders (n = 73).

RESULTS

High maternal T3 was associated with increased risk of ADHD (5th vs 1st quintile odds ratio  2.27, 95% confidence interval 1.21, 4.26). For FT4i, both the lowest and highest quintiles were associated with an approximate 1.6-fold increase in risk of ADHD, with similar trends found for T4. The FT4i association was modified by dietary iodine intake such that the highest risk strata were confined to the low intake group.

CONCLUSIONS

Both high and low concentrations of maternal thyroid hormones, although within population reference ranges, increase the risk of ADHD in offspring. Increased susceptibility may be found among women with low dietary intake of iodine and selenium.

Sex-specific neurobehavioral and prefrontal cortex gene expression alterations following developmental acetaminophen exposure in mice

Acetaminophen (N-acetyl-p-aminophenol (APAP), also known as paracetamol) is one of the most common medications used by the general population, including pregnant people. Although many human observational and animal model studies have shown associations between prenatal and early postnatal APAP exposure and attention deficit hyperactivity disorder, autism spectrum disorders, and altered neurodevelopment, the existing literature is limited. In particular, no mouse studies of prenatal APAP exposure have investigated offspring attention deficits in behavioral tasks specifically designed to measure attention, and no prior rodent studies have utilized 'omics' technologies, such as transcriptomics, for an untargeted exploration of potential mechanisms. We randomly assigned pregnant mice (starting embryonic day 4-10) to receive APAP (150 mg/kg/day) or vehicle control through postnatal day 14. We evaluated 111 mouse offspring in a battery of behavioral tests, including pup ultrasonic vocalizations, elevated plus-maze, open field test, CatWalk (gait), pre-pulse inhibition, and the automated 5-choice serial reaction time task. Prefrontal cortex was collected at birth from 24 pups for RNA sequencing. Developmental APAP treatment resulted in increased and hastened separation-induced pup vocalizations between postnatal days 2 and 11, as well as decreased ambulation and vertical rearings in the open field in male but not female adult offspring. APAP treatment was also associated with altered sex-specific prefrontal cortex gene expression relating to glutathione and cytochrome p450 metabolism, DNA damage, and the endocrine and immune systems. This study provides additional evidence for the neurodevelopmental harm of prenatal APAP exposure and generates hypotheses for underlying molecular pathways via RNA sequencing.

Methimazole-induced gestational hypothyroidism affects the offspring development and differently impairs the conditioned fear in male and female adulthood rodents

Gestational hypothyroidism is a prevalent disorder in pregnant women and also impairs fetal development with relevant outcomes. One of the outcomes of greatest interest has been rodent fear- and anxiety-like behavior. However, the relationship between maternal hypothyroidism and onset of conditioned fear-related responses in offspring remains controversial. Here, we used a well-validated methimazole-induced gestational hypothyroidism to investigate the behavioral consequences in offspring. Dams were treated with methimazole at 0.02% in drinking water up to gestational Day 9. Maternal body weights and maternal behavior were evaluated, and the puppies ware analyzed for weight gain and physical/behavioral development and assigned for the open field and fear conditioning test. Methimazole-induced gestational hypothyroidism induced loss in maternal and litter weight, increases in maternal behavior, and impairs in offspring developmental landmarks in both male and female rodents. Only male offspring enhanced responsiveness to conditioned fear-like behavior in adulthood.

Multisensory Stimulation Improves Cognition and Behavior in Adult Male Rats Born to LT4-treated Thyroidectomized Dams

Gestational hypothyroidism can impair development, cognition, and mood. Here, we tested whether multisensory stimulation (MS) improves the phenotype of rats born to surgically thyroidectomized (Tx) dams suboptimally treated with LT4. 8-week-old female Tx Wistar rats were kept on daily LT4 (0.7 µg/100 g body weight) dosed by gavage (serum TSH and T4 levels indicated moderate hypothyroidism) and 3 weeks later placed for breeding. MS of the litter started at age 60 days and lasted for 8 weeks. It consisted of twice per week of physical, cognitive, sensorial, and food stimuli. The offspring were assessed before and after MS for standardized tests of locomotor activity, cognition, and mood. Gestational hypothyroidism resulted in reduced litter size and increased offspring mortality. The pups exhibited delayed physical development, impairment of short- and long-term memory, and anxiety- and depressive-like behaviors. Nonetheless, ambulatory activity, social memory, and social preference were not affected by gestational hypothyroidism. MS restored short-term memory and anxiety while improving depressive like-behaviors. MS did not improve long-term memory. MS also did not modify the performance of control litter born to intact dams. We conclude that cognition and mood impairments caused by moderate gestational hypothyroidism were reversed or minimized in rats through MS. Further studies should define the molecular mechanisms involved.

Developmental exposure to the brominated flame retardant DE-71 reduces serum thyroid hormones in rats without hypothalamic-pituitary-thyroid axis activation or neurobehavioral changes in offspring

Polybrominated diphenyl ethers (PBDEs) are legacy flame retardants for which human exposure remains ubiquitous. This is of concern since these chemicals can perturb development and cause adverse health effects. For instance, DE-71, a technical mixture of PBDEs, can induce liver toxicity as well as reproductive and developmental toxicity. DE-71 can also disrupt the thyroid hormone (TH) system which may induce developmental neurotoxicity indirectly. However, in developmental toxicity studies, it remains unclear how DE-71 exposure affects the offspring’s thyroid hormone system and if this dose-dependently relates to neurodevelopmental effects. To address this, we performed a rat toxicity study by exposing pregnant dams to DE-71 at 0, 40 or 60 mg/kg/day during perinatal development from gestational day 7 to postnatal day 16. We assessed the TH system in both dams and their offspring, as well as potential hearing and neurodevelopmental effects in prepubertal and adult offspring. DE-71 significantly reduced serum T4 and T3 levels in both dams and offspring without a concomitant upregulation of TSH, thus inducing a hypothyroxinemia-like effect. No discernible effects were observed on the offspring’s brain function when assessed in motor activity boxes and in the Morris water maze, or on offspring hearing function. Our results, together with a thorough review of the literature, suggest that DE-71 does not elicit a clear dose-dependent relationship between low serum thyroxine (T4) and effects on the rat brain in standard behavioral assays. However, low serum TH levels are in themselves believed to be detrimental to human brain development, thus we propose that we lack assays to identify developmental neurotoxicity caused by chemicals disrupting the TH system through various mechanisms.

Sex-specific Effect of Maternal Thyroid Hormone Trajectories on Preschoolers' Behavioral Development: A Birth Cohort Study

CONTEXT

Maternal thyroid hormone trajectories are a better predictor of offspring's neurodevelopment than hormone levels in single trimester of pregnancy. Programming effect of uterine hormonal environment on offspring's health is usually sex-specific.

OBJECTIVE

To examine the sex-specific effect of thyroid hormone trajectories on preschoolers' behavioral development.

DESIGN

Based on Ma' anshan Birth Cohort in China, pregnant women were recruited at their first antenatal checkup from May 2013 to September 2014.

SETTING

Ma' anshan Maternal and Child Health Hospital in China.

PATIENTS OR OTHER PARTICIPANTS

1860 mother-child pairs were included in the analysis. Children were followed up at age of 4.

MAIN OUTCOME MEASURES

Maternal thyroid hormones [thyroid-stimulating hormone (TSH), free thyroxine (FT4)] and thyroid peroxidase antibody in the first, second, and third trimesters of pregnancy were retrospectively assayed. Preschoolers' behavioral development was assessed by Achenbach Child Behavior Checklist/1.5~5.

RESULTS

Maternal TSH and FT4 levels were respectively fitted into high, moderate, and low trajectories. In boys, maternal high TSH trajectory was related to withdrawn [odds ratio (OR) = 2.01, 95% CI: 1.16, 3.50) and externalizing problems (OR = 2.69, 95% CI: 1.22, 5.92), and moderate TSH trajectory was associated with aggressive behavior (OR = 3.76, 95% CI: 1.16, 12.23). Maternal high FT4 trajectory was associated with anxious/depressed (OR = 2.22, 95% CI: 1.08, 4.56) and total problems (OR = 1.74, 95% CI: 1.13, 2.66), and low FT4 trajectory was associated with aggressive behavior (OR = 4.17, 95% CI: 1.22, 14.24).

CONCLUSIONS

Maternal thyroid hormone trajectories impact preschool boys' behavioral development.

Maternal Thyroid Anomalies and Attention-Deficit Hyperactivity Disorder in Progeny

Previous epidemiologic investigations suggested that maternal thyroid anomalies are a possible causal factor in attention-deficit hyperactivity disorder (ADHD) in progeny, yet clinical trials indicated that levothyroxine treatment was ineffective in preventing neurodevelopmental impairments. We used an Israeli cohort of 385,542 singleton births from 1999-2012 to explore the interrelated roles of maternal thyroid conditions, laboratory gestational thyroid hormone measurements, use of thyroid medications, and offspring ADHD. Analyses were performed using Cox proportional hazards models. Results indicated that maternal hypothyroidism diagnosis was associated with an elevated progeny ADHD hazard (adjusted hazard ratio = 1.14, 95% confidence interval = 1.10, 1.18). However, this association was unmitigated by gestational use of levothyroxine and was unexplained by maternal gestational thyroid hormone levels. Associations with gestational thyrotropin values and hypothyroxinemia were also observed but were robust only in mothers without other records indicative of a thyroid problem. Results indicated that maternal thyroid hypofunction was associated with progeny ADHD but possibly not due to a direct causal relationship. Instead, maternal thyroid hypofunction may serve as a proxy indicator for other factors that affect neurodevelopment through thyroid hormone independent pathways, which are thus unaffected by pharmaceutical treatments for thyroid hypofunction. Factors known to disrupt thyroid functioning should be examined for their independent ADHD-related effects.

Interrelationships among growth hormone, thyroid function, and endocrine-disrupting chemicals on the susceptibility to attention-deficit/hyperactivity disorder

Abnormal growth hormones and thyroid function may be linked to pathophysiology of attention-deficit/hyperactivity disorder (ADHD). Phthalates and bisphenol-A (BPA), two endocrine-disrupting chemicals (EDCs), may affect the human endocrine system. In this study, we aimed to perform a comprehensive investigation of whether growth hormone, thyroid function, and EDCs exhibited differential levels between ADHD patients and healthy controls. In total, 144 children with ADHD and 70 healthy control subjects were enrolled. Their endocrine systems were evaluated using the serum levels of insulin-like growth factor-1 (IGF-1), IGF-binding protein-3 (IGFBP-3), thyroid-stimulating hormone (TSH), triiodothyronine (T3), thyroxine (T4), and Free T4. The urinary levels of EDCs, including monoethyl phthalate (MEP), mono-methyl phthalate (MMP), monoethylhexyl phthalate (MEHP), mono-n-butyl phthalate (MnBP), monobenzyl phthalate (MBzP), and BPA, were also examined. Patients with ADHD had lower IGF-1 levels than healthy controls (p = 0.003), but we observed no significant difference in IGFBP-3, TSH, T3, T4, or Free T4. Compared to the control group, patients with ADHD demonstrated higher MEHP levels (p = 0.043), MnBP (p = 0.033), and MBzP (p = 0.040). Furthermore, MEHP levels (p < 0.001) and BPA levels (p = 0.041) were negatively correlated with IGF-1 levels, while IGF-1 levels were negatively correlated with principal components consisting of ADHD clinical symptoms and neuropsychological performance variables. We suggest that MEHP exposure may be associated with decreased serum levels of IGF-1 and increased risk of ADHD. The mechanism underlying this association may be important for protecting children from environmental chemicals that adversely affect neurodevelopment.

Higher frequency of Congenital Hypothyroidism among Newborns, District Dera Ghazi Khan-Punjab, Pakistan: A case control study

OBJECTIVES

The study objective was to establish serum TSH cut off value for diagnosis of new case of congenital hypothyroidism and to estimate frequency of Congenital Neonatal Hypothyroidism.

METHODS

A case control study was conducted at DHQ Teaching Hospital of DG Khan Medical College, Dera Ghazi Khan during 2020 to establish reference values of TSH and T4 for study population. Sample size was calculated by classical sample size calculation formula Cochran WG 1977 sampling technique. A group of 30 neonates of normal, healthy, euthyroid mothers was taken as Neonatal Control Group to estimate levels of TSH and total T4 in normal neonates. Neonatal Study Group was neonates of hypothyroid mothers (n=75). Simple random sampling technique was applied.

RESULTS

Mean (mean ± SD) Serum TSH levels of Neonatal Control Group were found to be 3.58 ± 03.09 mIU/l. Mean Serum TSH levels among Neonatal Study Group were found to be 6.88 ±12.95 mIU/l and serum total T4 were found to be 16.78 ± 6.96ug/dl on 3-7 days of life. Serum total T4 (mean ± SD) levels of Neonatal Control Group were 9.73 ± 03.39 ug/dl. Neonatal serum TSH more than 15mIU/l was taken as cut off value to diagnose a case of CNH. So, frequency of CNH was 8% among neonates of study group.

CONCLUSIONS

The TSH cut off value of >15mIU/l was established for case detection of CNH. Our findings of CNH in district Dera Ghazi Khan (8%) are the highest frequency of CNH reported so far in Pakistan.

Pregnancy exposure to organophosphate esters and the risk of attention-deficit hyperactivity disorder in the Norwegian mother, father and child cohort study

BACKGROUND

Organophosphate esters (OPEs) are a class of flame retardants in common use. OPEs can easily leach from materials, resulting in human exposure. Increasing concentrations have been reported in human populations over the past decade. Recent studies have linked prenatal OPE exposure to hyperactivity and attention problems in children. Such behaviors are often found among children with attention-deficit hyperactivity disorder (ADHD), however, no study has investigated OPEs in relation to clinically assessed ADHD.

OBJECTIVE

To evaluate prenatal exposure to OPEs as risk factors for clinically assessed ADHD using a case-cohort study nested within the Norwegian Mother, Father, and Child Cohort Study (MoBa).

METHODS

We included in the case group 295 ADHD cases obtained via linkage with the Norwegian Patient Registry, and the sub-cohort group 555 children sampled at baseline, irrespective of their ADHD case status. Prenatal concentrations of OPE metabolites were measured in maternal urine collected at 17 weeks of gestation, and included diphenyl phosphate (DPHP), di-n-butyl phosphate (DNBP), bis(2-butoxyethyl) hydrogen phosphate (BBOEP), and bis(1,3-dichloro-2-propyl) phosphate (BDCIPP). We estimated risk ratios and the corresponding 95% confidence intervals [95% CI] using logistic regression, adjusting for season of urine collection, child sex, birth year, and maternal depression, education, and sum of urinary di(2-ethylhexyl) phthalate metabolites (∑DEHP) concentration during pregnancy. To assess the overall impact of simultaneously decreasing exposure to all chemical constituents of an OPE-phthalate mixture, quantile based g-computation was implemented. The mixture constituents included OPE and phthalate metabolites commonly detected in our study. In all models, we considered effect measure modification by child sex and polymorphisms in genes encoding paraoxonase 1 (PON1) and cytochrome P450 (P450) enzymes. Mediation analysis was conducted using thyroid function biomarkers estimated from maternal blood collected at 17 weeks of gestation.

RESULTS

DPHP was detected in nearly all samples (97.2%), with a higher geometric mean among the case group (0.70 µg/L) as compared to the sub-cohort (0.52 µg/L). DNBP was commonly detected as well (93.8%), while BBOEP (52.9%) and BDCIPP (22.9%) were detected less frequently. A higher risk of ADHD was observed in children with greater than median exposure to DPHP during pregnancy (risk ratio: 1.38 [95% CI: 0.96, 1.99]), which was slightly higher among girls (2.04 [1.03, 4.02]) and children of mothers with PON1 Q192R genotype QR (1.69 [0.89, 3.19]) or PON1 Q192R genotype RR (4.59 [1.38, 15.29]). The relationship between DPHP and ADHD (total risk ratio: 1.34 [0.90, 2.02]) was partially mediated through total triiodothyronine to total thyroxine ratio (natural direct effect: 1.29 [0.87, 1.94]; natural indirect effect: 1.04 [1.00, 1.10]; 12.48% mediated). We also observed an elevated risk of ADHD in relation to BDCIPP detection during pregnancy (1.50 [0.98, 2.28]). We did not observe notable differences in ADHD by DNBP (0.88 [0.62, 1.26]) or BBOEP (1.03 [0.73, 1.46]) during pregnancy. Simultaneously decreasing all constituents of common-detect OPE-phthalate mixture, specifically DPHP, DNBP, and 6 phthalate metabolites, by a quartile resulted in an ADHD risk ratio of 0.68 [0.64, 0.72].

CONCLUSION

Prenatal exposure to DPHP and BDCIPP may increase the risk of ADHD. For DPHP, we observed potential modification by child sex and maternal PON1 Q192R genotype and partial mediation through maternal thyroid hormone imbalance at 17 weeks gestation.

Pregnancy exposure to common-detect organophosphate esters and phthalates and maternal thyroid function

BACKGROUND

Contemporary human populations are exposed to elevated concentrations of organophosphate esters (OPEs) and phthalates. Some metabolites have been linked with altered thyroid function, however, inconsistencies exist across thyroid function biomarkers. Research on OPEs is sparse, particularly during pregnancy, when maintaining normal thyroid function is critical to maternal and fetal health. In this paper, we aimed to characterize relationships between OPEs and phthalates exposure and maternal thyroid function during pregnancy, using a cross-sectional investigation of pregnant women nested within the Norwegian Mother, Father, and Child Cohort (MoBa).

METHODS

We included 473 pregnant women, who were euthyroid and provided bio-samples at 17 weeks' gestation (2004-2008). Four OPE and six phthalate metabolites were measured from urine; six thyroid function biomarkers were estimated from blood. Relationships between thyroid function biomarkers and log-transformed concentrations of OPE and phthalate metabolites were characterized using two approaches that both accounted for confounding by co-exposures: co-pollutant adjusted general linear model (GLM) and Bayesian Kernal Machine Regression (BKMR).

RESULTS

We restricted our analysis to common-detect OPE and phthalate metabolites (>94%): diphenyl phosphate (DPHP), di-n-butyl phosphate (DNBP), and all phthalate metabolites. In GLM, pregnant women with summed di-isononyl phthalate metabolites (∑DiNP) concentrations in the 75th percentile had a 0.37 ng/μg lower total triiodothyronine (TT3): total thyroxine (TT4) ratio (95% credible interval: [-0.59, -0.15]) as compared to those in the 25th percentile, possibly due to small but diverging influences on TT3 (-1.99 ng/dL [-4.52, 0.53]) and TT4 (0.13 μg/dL [-0.01, 0.26]). Similar trends were observed for DNBP and inverse associations were observed for DPHP, monoethyl phthalate, mono-isobutyl phthalate, and mono-n-butyl phthalate. Most associations observed in co-pollutants adjusted GLMs were attenuated towards the null in BKMR, except for the case of ∑DiNP and TT3:TT4 ratio (-0.48 [-0.96, 0.003]).

CONCLUSIONS

Maternal thyroid function varied modestly with ∑DiNP, whereas results for DPHP varied by the type of statistical models.

Increased Risk of ADHD at Short and Long Interpregnancy Intervals in a National Birth Cohort

BACKGROUND

Short or long interpregnancy interval (IPI) may adversely impact conditions for foetal development. Whether attention deficit hyperactivity disorder (ADHD) is related to IPI has been largely unexplored.

OBJECTIVES

To examine the association between IPI and ADHD in a large, population-based Finnish study.

METHODS

All children born in Finland between 1991 and 2005 and diagnosed with ADHD (ICD-9 314x or ICD-10 F90.x) from 1995 to 2011 were identified using data from linked national registers. Each subject with ADHD was matched to 4 controls based on sex, date of birth, and place of birth. A total of 9564 subjects with ADHD and 34,479 matched controls were included in analyses. IPI was calculated as the time interval between sibling birth dates minus the gestational age of the second sibling. The association between IPI and ADHD was determined using conditional logistic regression and adjusted for potential confounders.

RESULTS

Relative to births with an IPI of 24 to 59 months, those with the shortest IPI (<6 months) had an increased risk of ADHD (odds ratio [OR] 1.30, 95% confidence interval (CI) 1.12, 1.51) and the ORs for the longer IPI births (60-119 months and ≥120 months) were 1.12 (95% CI 1.02, 1.24) and 1.25 (95% CI 1.08, 1.45), respectively. The association of longer IPI with ADHD was attenuated by adjustment for maternal age at the preceding birth, and comorbid autism spectrum disorders did not explain the associations with ADHD.

CONCLUSIONS

The risk of ADHD is higher among children born following short or long IPIs although further studies are needed to explain this association.

Associations Between Maternal Prenatal C-Reactive Protein and Risk Factors for Psychosis in Adolescent Offspring: Findings From the Northern Finland Birth Cohort 1986

Prenatal infection is associated with brain structural and functional abnormalities and may increase the risk for psychosis through a direct effect on neurodevelopment. Various infections may exert their effect through a proinflammatory immune response but studies of prenatal maternal inflammatory markers and offspring neurodevelopment are scarce. Using the longitudinal Northern Finland Birth Cohort 1986 study, we examined the associations of maternal prenatal C-reactive protein (CRP) levels with psychosis risk factors in adolescent offspring. CRP was measured in maternal sera collected in pregnancy. In offspring, school performance was measured at age 7 years, while school performance, psychotic experiences, and cannabis use were measured at age 16 years. We tested associations of CRP with offspring measures using regression analysis controlling for offspring sex, maternal education level, and prenatal maternal body mass index, smoking and alcohol use in pregnancy, place of birth, maternal psychiatric admission, paternal psychiatric admission, mothers age at birth, and gestational week of CRP sample. We also tested if adolescent cannabis use mediated the associations between maternal CRP and offspring outcomes. Controlling for covariates, maternal CRP was associated with academic performance at age 16 years (beta = .062, 95% CI = 0.036-0.088), but not with possible psychotic experiences at 16 years (odds ratio [OR] = 1.09, 95% CI = 0.96-1.24). Maternal CRP was also associated with adolescent cannabis use (OR = 1.24, 95% CI = 1.07-1.43). These findings suggest that prenatal inflammation may influence later mental illness risk by affecting neurodevelopment and also indirectly by increasing the risk of exposure to cannabis.

Maternal spontaneous abortion and the risk of attention-deficit/hyperactivity disorder in offspring: a population-based cohort study

STUDY QUESTION

Is a maternal history of spontaneous abortion (SA) associated with an increased risk of attention-deficit/hyperactivity disorder (ADHD) in offspring?

SUMMARY ANSWER

Our results suggest an association between maternal history of SA and ADHD in offspring, with the risk increasing with the number of maternal SA and highest in the firstborn children whose mothers had had recurrent SAs after adjusting for a number of potential confounders.

WHAT IS KNOWN ALREADY

A history of SA has been associated with more complications in next pregnancies and adverse childbirth outcomes, which are risk factors for ADHD in the offspring. However, no previous study has investigated whether maternal SA increases risk of ADHD in the offspring.

STUDY DESIGN, SIZE, DURATION

This population-based study included all live-born children in Denmark from 1 January 1995 to 31 December 2012 (n = 1 062 667). All children were followed from 3 years of age until the day of ADHD diagnosis, death, emigration or 31 December 2016, whichever came first.

PARTICIPANTS/MATERIALS, SETTING, METHODS

There were 130 206 (12.2%) children born to mothers who had at least one SA. Cox proportional hazards regression models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs).

MAIN RESULTS AND THE ROLE OF CHANCE

During a median follow-up of 9.4 years (interquartile range, 5.4-14.3), 25 747 children were diagnosed with ADHD. Overall, children of mothers with a history of SA had an increased rate of ADHD (HR, 1.11; 95% CI, 1.07 to 1.15). The HRs increased with the number of maternal SA, 1.09 (95% CI, 1.05 to 1.13) for one SA and 1.22 (95% CI, 1.12 to 1.33) for at least two SAs, respectively. These findings were consistent when we took into consideration a number of factors, such as maternal socioeconomic status, type of SA, birth order, parental history of psychiatric disorders, pregnancy characteristics and adverse birth outcomes.

LIMITATIONS, REASONS FOR CAUTION

Misclassification of SA was possible as we used population-based register data to capture maternal history of SA. However, any misclassification of maternal history of SA would be non-differential with regard to the diagnosis of ADHD in offspring, which generally leads to underestimation of the associations. Furthermore, probabilistic sensitivity analysis suggested that only 1% of change in the estimate may have been due to misclassification of SA.

WIDER IMPLICATIONS OF THE FINDINGS

SA is quite frequent (varying from 15 to 20%), and a small increase of neurodevelopmental problems in offspring could have major public health implications.

STUDY FUNDING/COMPETING INTEREST(S)

This work was supported by grants from the National Natural Science Foundation of China (No. 81703237, No. 81530086 and No. 81761128035), National Key Research and Development Program (2018YFC1002801, 2016YFC1000505), Shanghai Municipal Commission of Health and Family Planning (No. 2017ZZ02026, No. 2017EKHWYX-02), the Novo Nordisk Foundation (NNF18OC0052029), the Danish Council for Independent Research (DFF-6110-00019), the Nordic Cancer Union (176673, 186200 and R217-A13234-18-S65), Karen Elise Jensens Fond (2016) and Xinhua Hospital of Shanghai Jiao Tong University School of Medicine (2018YJRC03). All authors report no conflict of interest.

TRIAL REGISTRATION NUMBER

NA.

Intermediate lengths of the C9ORF72 hexanucleotide repeat expansion may synergistically contribute to attention deficit hyperactivity disorder in child and his father: case report

We have summarized the abstract section as follows: "We report a son and his father affected by Attention Deficit Hyperactivity Disorder (ADHD). They belonged to a larger cohort (116 ADHD children, 20 related parents, 77 controls) wholly genotyped forC9ORF72 expansion. Ten ADHD susceptibility genes were further investigated in the family. We revealed that son and father shared an intermediateC9ORF72 expansion and common variants inCDH23, ITGAE and MTRR. Bioinformatics highlighted aC9ORF72-MTRR interaction. This case-report underlines that in relatives with ADHD, carrying variants in ADHD susceptibility genes, the intermediateC9ORF72 repeats might have a potentially pathogenetic synergistic effect, supporting the multifactorial polygenic aetiopathogenetic profile of disease".

Early Levothyroxine Treatment for Subclinical Hypothyroidism or Hypothyroxinemia in Pregnancy: The St Carlos Gestational and Thyroid Protocol

The optimal maternal levels of thyroid hormones (TH) during the first trimester of gestation have not been established, nor has the ideal moment to initiate levothyroxine treatment (LT) to improve the evolution of gestation and fetal development. Cut-off points for Thyroid-stimulating hormone (TSH) <2.5 µIU/mL and free thyroxine (FT4)>7.5 pg/mL have been recommended. There are no data on whether initiation of LT <9th Gestational Week (GW) can have a favourable impact.

OBJECTIVE

To define the TSH/FT4 percentiles corresponding with 2.5 µIU/mL and 7.5 pg/mL levels, respectively, at GW8 (Study 1), and evaluate the effects of protocol-based LT before GW9 on gestation evolution, in women with TSH ≥2.5 µIU/mL and/or FT4≤ 7.5 pg/mL (study 2).

SUBJECTS

2768 consecutive pregnant women attending the first gestational visit from 2013-2014 and 3026 from 2015-2016 were eligible for Study I and 2 respectively. A final 2043 (study 1) and 2069 (study 2) women were assessed in these studies.

RESULTS

Study 1: The FT4 level of 7.5 pg/mL corresponds with the 17.9th percentile, a TSH level of 2.5 µIU/mL with the 75.8^th. Women with TSH ≥2.5 µIU/mL had a history of fetal losses more frequently than those <2.5 (OR 2.33 (95%CI): 1.58-3.12), as did those with FT4 ≤7.5 pg/ml compared to those >7.5 (OR 4.81; 3.25-8.89). Study 2: A total of 1259 women had optimal TSH/FT4 levels (Group 1), 672 (32.4%, Group 2) had suboptimal TSH or T4l, and 138 (6.7%, Group 3) had suboptimal values of both. 393 (58.5%) in Group 2 and 88 (63.8%) in Group 3 started LT before GW9. Mean (SD) GW24 levels were TSH: 1.96 ± 1.22 µIU/mL and FT4: 7.07 ± 1.25 pg/mL. The highest FT4 value was 12.84 pg/mL. The adjusted risk for an adverse event if LT was started early was 0.71 (0.43-0.91) for Group 2 and 0.80 (0.66-0.94) for Group 3.

CONCLUSIONS

Early LT in women with suboptimum levels of TSH/FT4 (≥2.5µIU/mL/≤7.5 pg/ml) at or before GW9 is safe and improves gestation progression. These data support the recommendation to adopt these cut-off points for LT initiation, which should be started as early as possible.

Maternal Hypothyroidism Increases the Risk of Attention-Deficit Hyperactivity Disorder in the Offspring

OBJECTIVE

This study aimed to determine if hypothyroidism prior to, or during, pregnancy increases the risk of attention-deficit hyperactivity disorder (ADHD) in the child and how the association may be modified by preterm birth, sex of the child, and race-ethnicity.

STUDY DESIGN

Data were abstracted from linked maternal-child medical records. Incidence rate differences (IRDs), adjusted hazard ratios (aHRs), and their 95% confidence intervals (CIs) were estimated to evaluate the association of maternal hypothyroidism with childhood ADHD risk. Stratified analyses were used to evaluate whether the association is affected by timing of first diagnosis, gestational age at birth (term vs. preterm), sex, and race-ethnicity.

RESULTS

Hypothyroidism diagnosed prior to (IRD = 1.30), or during (IRD = 0.59) pregnancy increases the risk of ADHD in the children (aHR = 1.27; 95% CI: 1.15, 1.41, and 1.17; 95% CI: 1.00, 1.38). The association was strongest when diagnosed during the first trimester (IRD = 0.97 and aHR = 1.28; 95% CI: 1.04, 1.58). For children born preterm, there was significantly increased risk of ADHD if their mothers were diagnosed prior to (IRD = 3.06 and aHR = 1.43; 95% CI: 1.09, 1.88), but not during pregnancy. The effect of maternal hypothyroidism on increased risk of ADHD was stronger for boys (IRD = 1.84 and aHR = 1.26; 95% CI: 1.14, 1.40) than it was for girls (IRD = 0.48 and aHR = 1.19; 95% CI: 1.01, 1.40) and for Hispanic children (IRD = 1.60 and aHR = 1.45; 95% CI: 1.25, 1.68) compared with other race ethnicities.

CONCLUSION

Exposure to maternal hypothyroidism during the periconceptual period significantly increases the risk of ADHD and that the association varies with gestational age at delivery, child sex, and race-ethnicity.

KEY POINTS

· Maternal hypothyroidism increases the risk of ADHD diagnosis in the offspring.. · The association of maternal hypothyroidism with childhood ADHD was influenced by timing of diagnosis.. · Strength of the association was strongest in preterm born infants, boys, and Hispanic children..

Sex-specific neurotoxic effects of early-life exposure to fluoride: A review of the epidemiologic and animal literature

PURPOSE OF REVIEW

A growing body of evidence suggests adverse neurodevelopmental effects of early-life exposure to fluoride that may differ depending on timing of exposure and sex of the exposed. We conducted a literature search to identify the animal and human epidemiologic studies that examined sex-specific neurodevelopmental differences in response to prenatal and postnatal exposure to fluoride.

RECENT FINDINGS

Six of 138 animal studies and 15 of 106 human epidemiologic studies tested for sex-specific effects. Prenatal exposure to fluoride was associated with a male susceptibility to adverse behavioural effects in four of six animal studies and lower IQ in one of three prospective cohort studies. The body of evidence examining sex-effects associated with postnatal fluoride exposure was scarce, and many animal and cross-sectional human studies were considered to have a high risk of bias.

SUMMARY

Compared to females, male offspring appear to be more sensitive to prenatal, but not postnatal, exposure to fluoride. We discuss several sex-specific mechanisms and emphasize the need for future research.

Maternal Thyroid Dysfunction During Pregnancy and the Risk of Adverse Outcomes in the Offspring: A Systematic Review and Meta-Analysis

CONTEXT

Previous studies suggested a potential link of maternal thyroid dysfunction with adverse neurocognitive outcomes and impaired development of internal organs in offspring.

OBJECTIVE

To review the association between maternal thyroid dysfunction and the risk of adverse outcomes in offspring.

DATA SOURCES

PubMed, EMBASE, and Cochrane Library.

STUDY SELECTIONS

Eligible studies reported the association between maternal thyroid hormone function and the risk of adverse outcomes in their children.

DATA EXTRACTION

Reviewers extracted data on study characteristics and results independently.

DATA SYNTHESIS

Estimates were pooled and reported as odds ratio (OR) with 95% confidence interval (CI). I2 tests were applied to assess the heterogeneity across studies.

RESULTS

We identified 29 eligible articles and found an association between maternal hyperthyroidism and attention deficit hyperactivity disorder (ADHD) (OR: 1.18, 95% CI: 1.04-1.34, I2 = 0%) and epilepsy (OR: 1.19, 95% CI: 1.08-1.31, I2 = 0%) in offspring; as well as an association of maternal hypothyroidism with increased risk of ADHD (OR: 1.14, 95% CI: 1.03-1.26, I2 = 25%), autism spectrum disorder (OR: 1.41, 95% CI: 1.05-1.90, I2 = 63%), and epilepsy (OR: 1.21, 95% CI: 1.06-1.39, I2 = 0%) in offspring.

CONCLUSION

Routine measurement and timely treatment on thyroid function should be considered for pregnant women.

The association between thyroid function biomarkers and attention deficit hyperactivity disorder

The relation between thyroid function biomarkers and attention deficit hyperactivity disorder (ADHD) in children and adolescents is currently unclear. Cross-sectional data from the German Health Interview and Examination Survey for Children and Adolescents (KiGGS Baseline) was analyzed to assess the association between thyroid function biomarkers and ADHD in a population-based, nationally representative sample. The study cohort included 11,588 children and adolescents with 572 and 559 having an ADHD diagnosis or symptoms, respectively. ADHD symptoms were assessed through the Inattention/Hyperactivity subscale of the Strength and Difficulties Questionnaire. ADHD diagnosis was determined by a physician or psychologist. Serum thyroid stimulating hormone (TSH), free triiodothyronine (fT3), and free thyroxine (fT4) concentrations were determined enzymatically. Adjusted regression models were used to relate serum TSH, fT3, and fT4 with risk for ADHD diagnosis or symptoms. In children, a 1 mIU/l higher TSH was related to a 10% lower risk (odds ratio [OR] 0.90; 95% confidence interval [CI] 0.81-1.00) of ADHD diagnosis. We found a significant positive association between fT3 and continuously assessed ADHD symptoms in children (β 0.08; 95% CI 0.03-0.14). Our results suggest that physical maturity may influence the association between thyroid function biomarkers and risk for ADHD.

Neonatal thyroid-stimulating hormone and association with attention-deficit/hyperactivity disorder

BACKGROUND

Normal brain development is dependent on maternal, fetal and neonatal thyroid function. Measuring neonatal thyroid-stimulating hormone (TSH) 48-72 hours after birth screens for congenital hypothyroidism, allowing early treatment to avoid serious impairment. However, even within sub-clinical ranges, disrupted thyroid homeostasis during brain development has been linked to adverse neurodevelopmental outcomes, including attention-deficit/hyperactivity disorder (ADHD).

OBJECTIVES

To estimate the association between neonatal TSH below threshold for potential congenital hypothyroidism and subsequent ADHD diagnosis using a population-based birth cohort.

METHODS

Children with a diagnosis of ADHD in the Norwegian Mother, Father and Child Cohort Study (MoBa) were identified through linkage with the Norwegian Patient Registry using ICD-10 codes for hyperkinetic disorders. The study included 405 ADHD cases and 1,092 controls (born 2003-2008) with available neonatal TSH concentrations below 10 mU/L (cut-off for potential congenital hypothyroidism) measured in dried blood spots sampled 48-72 hours after birth.

RESULTS

In multivariable, quintile models the relationship appeared to follow a U-shaped pattern with elevated odds ratios (OR) at lower and higher TSH levels. Among children with TSH in the lowest quintile, odds of ADHD was approximately 1.5-fold higher than children in the middle quintile (OR 1.60, 95% CI 1.09, 2.34), which was driven by substantially elevated risk among girls, with no association among boys (P_interaction = 0.02; girls OR 3.10, 95% CI 1.53, 6.30; boys OR 1.16, 95% CI 0.73, 1.84).

CONCLUSIONS

ADHD risk appeared to be elevated among newborns with low TSH levels (i.e. with hyperthyroid status), and this association was mainly found among girls. Because our findings are suggestive of increased risk at very low TSH concentrations, where analytical accuracy is low, future studies should employ highly sensitive assays capable of accurate quantitation at very low concentrations. Also, larger studies are needed to investigate these associations at higher neonatal TSH concentrations where data are more widely distributed.

CATS II Long-term Anthropometric and Metabolic Effects of Maternal Sub-optimal Thyroid Function in Offspring and Mothers

CONTEXT AND OBJECTIVES

The Controlled Antenatal Thyroid Screening Study I (CATS-I) was a randomized controlled trial investigating the effects of levothyroxine therapy for suboptimal gestational thyroid function (SGTF), comparing outcomes in children of treated (SGTF-T) with untreated (SGTF-U) women during pregnancy. This follow-up study, CATS-II, reports the long-term effects on anthropometric, bone, and cardiometabolic outcomes in mothers and offspring and includes a group with normal gestational thyroid function (NGTF).

DESIGN & PARTICIPANTS

332 mothers (197 NGTF, 56 SGTF-U, 79 SGTF-T) aged 41.2±5.3 years (mean±SD) and 326 paired children assessed 9.3±1.0 years after birth for (i) body mass index (BMI); (ii) lean, fat, and bone mass by dual-energy X-ray absorptiometry; (iii) blood pressure, augmentation index, and aortic pulse-wave-velocity; and (iv) thyroid function, lipids, insulin, and adiponectin. The difference between group means was compared using linear regression.

RESULTS

Offspring's measurements were similar between groups. Although maternal BMI was similar between groups at CATS-I, after 9 years (at CATS-II) SGTF-U mothers showed higher BMI (median [interquartile ratio] 28.3 [24.6-32.6] kg/m2) compared with NGTF (25.8 [22.9-30.0] kg/m2; P = 0.029), driven by fat mass increase. At CATS-II SGTF-U mothers also had higher thyroid-stimulating hormone (TSH) values (2.45 [1.43-3.50] mU/L) than NGTF (1.54 [1.12-2.07] mU/L; P = 0.015), since 64% had never received levothyroxine. At CATS-II, SGTF-T mothers had BMI (25.8 [23.1-29.8] kg/m2, P = 0.672) and TSH (1.68 [0.89-2.96] mU/L; P = 0.474) values similar to NGTF mothers.

CONCLUSIONS

Levothyroxine supplementation of women with SGTF did not affect long-term offspring anthropometric, bone, and cardiometabolic measurements. However, absence of treatment was associated with sustained long-term increase in BMI and fat mass in women with SGTF.

Maternal prenatal thyroid function and trajectories of offspring emotional and behavioural problems: findings from the ALSPAC cohort

Maternal thyroid hormone may have impact on fetal brain development and consequently lead to offspring mental health problems. This study examined the role of maternal prenatal thyroid function on trajectories of offspring emotional and behavioural problems. Data were taken from the Avon Longitudinal Study of Parents and Children. A total of 4839 mother-child pairs were included. Thyroid-stimulating hormone (TSH) levels, free thyroxine (FT4), and thyroid peroxidase antibodies (TPO-Ab) were assessed during the first trimester of pregnancy. Childhood emotional and behavioural problems were assessed using the Strengths and difficulties questionnaire. A group-based modelling approach was used to identify the different trajectories of offspring emotional and behavioural problems reported by parents over four waves of measurement at age 3.5 (42 months), 6.75 (81 months), 9 and 11 years. Multinomial logistic regression was then used to test for an association between hormone levels and class membership. We identified four trajectories of offspring emotional and behavioural problems; normative-decreasing (49.7%), moderate-decreasing (35.7%), moderate-static (8.4%), and high-decreasing (6.2%) trajectory. There were no significant differences in the mean values of mother's FT4, TSH, and the proportion of mothers with positive TPO-Ab between trajectories. Univariable and multivariable multinomial logistic models showed no association between maternal thyroid function (FT4, TSH, and TPO-Ab) and the trajectories of offspring emotional and behavioural problems. The results of our study show that maternal thyroid parameters in a community population are not associated with trajectories of offspring emotional and behavioural problems.

Maternal Iodine Status During Pregnancy Is Not Consistently Associated with Attention-Deficit Hyperactivity Disorder or Autistic Traits in Children

BACKGROUND

Severe iodine deficiency during pregnancy can cause intellectual disability, presumably through inadequate placental transfer of maternal thyroid hormone to the fetus. The association between mild-to-moderate iodine deficiency and child neurodevelopmental problems is not well understood.

OBJECTIVES

We investigated the association of maternal iodine status during pregnancy with child attention-deficit hyperactivity disorder (ADHD) and autistic traits.

METHODS

This was a collaborative study of 3 population-based birth cohorts: Generation R (n = 1634), INfancia y Medio Ambiente (n = 1293), and the Avon Longitudinal Study of Parents and Children (n = 2619). Exclusion criteria were multiple fetuses, fertility treatment, thyroid-interfering medication use, and pre-existing thyroid disease. The mean age of assessment in the cohorts was between 4.4 and 7.7 y for ADHD symptoms and 4.5 and 7.6 y for autistic traits. We studied the association of the urinary iodine-to-creatinine ratio (UI/Creat) <150 μg/g-in all mother-child pairs, and in those with a urinary-iodine measurement at ≤18 weeks and ≤14 weeks of gestation-with the risk of ADHD or a high autistic-trait score (≥93rd percentile cutoff), using logistic regression. The cohort-specific effect estimates were combined by random-effects meta-analyses. We also investigated whether UI/Creat modified the associations of maternal free thyroxine (FT4) or thyroid-stimulating hormone concentrations with ADHD or autistic traits.

RESULTS

UI/Creat <150 μg/g was not associated with ADHD (OR: 1.2; 95% CI: 0.7, 2.2; P = 0.56) or with a high autistic-trait score (OR: 0.8; 95% CI: 0.6, 1.1; P = 0.22). UI/Creat <150 μg/g in early pregnancy (i.e., ≤18 weeks or ≤14 weeks of gestation) was not associated with a higher risk of behavioral problems. The association between a higher FT4 and a greater risk of ADHD (OR: 1.3; 95% CI: 1.0, 1.6; P = 0.017) was not modified by iodine status.

CONCLUSIONS

There is no consistent evidence to support an association of mild-to-moderate iodine deficiency during pregnancy with child ADHD or autistic traits.

Methylparaben in meconium and risk of maternal thyroid dysfunction, adverse birth outcomes, and Attention-Deficit Hyperactivity Disorder (ADHD)

BACKGROUND

Parabens, which are used as a preservative in foods and personal care products, are detected in nearly 100% of human urine samples. Exposure to parabens is associated with DNA damage, male infertility, and endocrine disruption in adults, but the effects of prenatal exposure are unclear. In part, this is due to inadequate assessment of exposure in maternal urine, which may only reflect maternal rather than fetal exposure. To address this gap, we examined the association of prenatal methylparaben measured in meconium with preterm birth, gestational age, birthweight, maternal thyroid hormones, and child Attention-Deficit Hyperactivity Disorder (ADHD) at 6-7 years.

DESIGN

Data come from the GESTation and the Environment (GESTE) prospective observational pregnancy cohort in Sherbrooke, Quebec, Canada. Participants were 345 children with data on ADHD among 394 eligible pregnancies in women age ≥18 years with no known thyroid disease before pregnancy and meconium collected at delivery. Methylparaben was measured in meconium. Birthweight, gestational age, and maternal thyroid hormones at <20 weeks gestation were measured at the Centre Hospitalier Universitaire de Sherbrooke. Preterm birth was defined as vaginal birth before the 37th week of gestation. Physician diagnosis of ADHD was determined at a scheduled cohort follow-up when children were 6-7 years old or from medical records. Associations between meconium methylparaben and outcomes were estimated with logistic and linear regressions weighted on the inverse probability of exposure to account for potential confounders, including child sex, familial income, maternal education, pre-pregnancy body mass index, age, and smoking and alcohol consumption during pregnancy.

RESULTS

Methylparaben was detected in 65 meconium samples (19%), 33 children were diagnosed with ADHD (10%), and 13 children were born preterm (4%). Meconium methylparaben was associated with preterm birth (odds ratio [OR] = 4.81; 95% CI [2.29, 10.10]), decreased gestational age (beta [β] = -0.61 weeks; 95% CI [-0.93, -0.29]) and birthweight (β = -0.12 kg; 95% CI [-0.21, -0.03]), altered maternal TSH (relative concentration [RC] = 0.76; 95% CI [0.58, 0.99]), total T3 (RC = 0.84; 95% CI [0.75, 0.96]) and total T4 (RC = 1.10; 95% CI [1.01, 1.19]), maternal hypothyroxinemia (OR = 2.50, 95% CI [1.01, 6.22]), and child ADHD at age of 6-7 (OR = 2.33, 95% CI [1.45, 3.76]). The effect of meconium methylparaben on ADHD was partially mediated by preterm birth (20% mediation) and birthweight (13% mediation).

CONCLUSIONS

Meconium methylparaben was associated with preterm birth, decreased gestational age and birthweight, maternal thyroid hormone dysfunction, and child ADHD. Parabens are a substantial health concern if causally related to these adverse outcomes.

Psychiatric Disorders in the Adolescent Offspring of Mothers with Thyroid Problems During Pregnancy

Maternal thyroid problems during pregnancy have been linked to neurocognitive impairments in children. While studies suggest that disorders of maternal thyroid function during pregnancy are associated with symptoms of mental health problems in children, little is known about the risk of clinically significant psychiatric disorders in adolescence. A sample of 2451 Canadian adolescents enrolled in the Ontario Child Health Study completed the Mini International Neuropsychiatric Interview for Children and Adolescents at 12-17 years of age. Their mothers self-reported thyroid problems during pregnancy. Gestational thyroid problems were associated with offspring oppositional defiant disorder (ODD; OR 3.73; 95% CI 1.69-8.24), conduct disorder (CD; OR 12.95; 95% CI 5.12-32.75), and social anxiety disorder (SAD; OR 6.25; 95% CI 2.53-15.47). Neither sex nor gestational age moderated associations between prenatal thyroid dysfunction and the majority of outcomes. School performance mediated 8% of the association between thyroid problems and SAD, 21% for CD and 53% for ODD.

The Impact of Thyroid Function and TPOAb in the First Trimester on Pregnancy Outcomes: A Retrospective Study in Peking

CONTEXT

The impact of mild TSH elevation (2.5-4.08 mIU/L) on pregnancy outcomes is unclear. The treatment strategy for mild TSH elevation is dependent on thyroid peroxidase antibody (TPOAb) status according to the guidelines.

OBJECTIVE

To assess the effects of mild thyroid dysfunction combined with TPOAb status in the first trimester on pregnancy outcomes and the impact of levothyroxine (L-T4) treatment on pregnancy outcomes.

DESIGN

The study retrospectively evaluated 3562 pregnant women. A total of 3296 untreated women were divided into 4 subgroups: group A: 4.08 < TSH <10 mIU/L, TPOAb+/-; group B: 2.5 < TSH ≤ 4.08 mIU/L, TPOAb+; group C: 2.5 < TSH ≤ 4.08 mIU/L, TPOAb-; and group D: 0.23 ≤ TSH ≤ 2.5 mIU/L, TPOAb+/-. The other 266 women with L-T4 treatment were divided into TSH 4.08 to 10 mIU/L and 2.5 to 4.08 mIU/L subgroups.

SETTING

The study was conducted at Peking University First Hospital in China.

PATIENTS

A total of 3562 pregnant women were evaluated.

MAIN OUTCOME MEASURES

The incidence of pregnancy outcomes in the untreated subgroups (groups A-D) and treated subgroups were measured.

RESULTS

Miscarriage and maternal composite outcome risks were 3.53 (1.85-6.75) and 2.19 (1.26-3.81) times greater in group A; 1.58 (1.17-2.13) and 1.27 (1.04-1.54) times greater in group C than in group D. L-T4 improved the miscarriage risk in the TSH 4.08 to 10 and 2.5 to 4.08 mIU/L groups but doubled the risk of gestational diabetes mellitus in the TSH 2.5 to 4.08 mIU/L treated group compared with the untreated group.

CONCLUSIONS

TSH 2.5 to 4.08 mIU/L combined with TPOAb- during early pregnancy was associated with miscarriages and maternal composite outcomes. The advantages and disadvantages of L-T4 administration in TSH 2.5 to 4.08 mIU/L pregnant women remain uncertain.

Controlled Antenatal Thyroid Screening II: Effect of Treating Maternal Suboptimal Thyroid Function on Child Behavior

CONTEXT & OBJECTIVES

The Controlled Antenatal Thyroid Screening (CATS) study was the first randomized controlled trial to investigate effects of treating suboptimal gestational thyroid function (SGTF) on child cognition. Since observational studies indicated that SGTF may also increase symptoms of autism and attention-deficit/hyperactivity disorder (ADHD), the CATS cohort was used to investigate whether treatment of mothers affected their children's behavior.

DESIGN & PARTICIPANTS

Mothers (N = 475) completed 3 questionnaires: the Strengths and Difficulties Questionnaire (SDQ), the Child ADHD Questionnaire, and the Social Communication Questionnaire (SCQ, used as a screen for autism spectrum disorder [ASD]), about their children (mean age 9.5 years). Group comparisons of total scores, numbers of children above clinical thresholds, and association between high maternal free thyroxine (FT4) (> 97.5th percentile of the UK cohort, "overtreated") and child neurodevelopment were reported.

RESULTS

There were no differences in total scores between normal gestational thyroid function (GTF) (n = 246), treated (n = 125), and untreated (n = 104) SGTF groups. More children of treated mothers scored above clinical thresholds, particularly the overtreated. Scores were above thresholds in SDQ conduct (22% vs 7%), SCQ total scores (7% vs 1%), and ADHD hyperactivity (17% vs 5%) when comparing overtreated (n = 40) and untreated (N = 100), respectively. We identified significantly higher mean scores for SDQ conduct (adjusted mean difference [AMD] 0.74; 95% confidence interval [CI], 0.021-1.431; P = 0.040, effect size 0.018) and ADHD hyperactivity (AMD 1.60, 95% CI, 0.361-2.633; P = 0.003, effect size 0.028) comparing overtreated with normal-GTF children.

CONCLUSIONS

There was no overall association between SGTF and offspring ADHD, ASD, or behavior questionnaire scores. However, children of "overtreated" mothers displayed significantly more ADHD symptoms and behavioral difficulties than those of normal-GTF mothers. Thyroxine supplementation during pregnancy requires monitoring to avoid overtreatment.

Clinical and subclinical maternal hypothyroidism and their effects on neurodevelopment, behavior and cognition

Clinical and subclinical hypothyroidism are the most common hormonal dysfunctions during pregnancy. Insufficient maternal thyroid hormones (THs) in the early stages of pregnancy can lead to severe impairments in the development of the central nervous system because THs are critical to central nervous system development. In the fetus and after birth, THs participate in neurogenic processes, cell differentiation, neuronal activation, axonal growth, dendritic arborization, synaptogenesis and myelination. Although treatment is simple and effective, approximately 30% of pregnant women in Brazil with access to prenatal care have their first consultation after the first trimester of pregnancy, and any delay in diagnosis and resulting treatment delay may lead to cognitive impairment in children. This review summarizes the effects of clinical and subclinical hypothyroidism on fetal neurodevelopment, behavior and cognition in humans and rodents. Arch Endocrinol Metab. 2020;64(1):89-95.

Association of water fluoride and urinary fluoride concentrations with attention deficit hyperactivity disorder in Canadian youth

BACKGROUND

Exposure to fluoride has been linked with increased prevalence of attention deficit hyperactivity disorder (ADHD) in the United States and symptoms of inattention in Mexican children. We examined the association between fluoride exposure and attention outcomes among youth living in Canada.

METHOD

We used cross-sectional data collected from youth 6 to 17 years of age from the Canadian Health Measures Survey (Cycles 2 and 3). Urinary fluoride concentration adjusted for specific gravity (UFSG) was available for 1877 participants. Water fluoride concentration measured in tap water samples was available for 980 participants. Community water fluoridation (CWF) status was determined by viewing reports on each city's website or contacting the water treatment plant. We used logistic regression to test the association between the three measures of fluoride exposure and ADHD diagnosis. Linear regression was used to examine the relationship between the three measures of fluoride exposure and the hyperactivity/inattention score on the Strengths and Difficulties Questionnaire (SDQ).

RESULTS

UFSG did not significantly predict ADHD diagnosis or hyperactive/inattentive symptoms. A 1 mg/L increase in tap water fluoride level was associated with a 6.1 times higher odds of an ADHD diagnosis (95% CI = 1.60, 22.8). A significant interaction between age and tap water fluoride level (p = .03) indicated a stronger association between tap water fluoride and hyperactivity/inattention symptoms among older youth. A 1 mg/L increase in water fluoride level was associated with a 1.5 SDQ score increase (95% CI: 0.23, 2.68, p = .02) for youth at the 75th percentile of age (14 years old). Similarly, there was a significant interaction between age and CWF. At the 75th percentile of age (14 years old), those living in a fluoridated region had a 0.7-point higher SDQ score (95% CI = 0.34, 1.06, p < .01) and the predicted odds of an ADHD diagnosis was 2.8 times greater compared with youth in a non-fluoridated region (aOR = 2.84, 95% CI: 1.40, 5.76, p < .01).

DISCUSSION

Exposure to higher levels of fluoride in tap water is associated with an increased risk of ADHD symptoms and diagnosis of ADHD among Canadian youth, particularly among adolescents. Prospective studies are needed to confirm these results.

Systemic endocrinopathies (thyroid conditions and diabetes): impact on postnatal life of the offspring

Fetal programming may influence childhood and adult life, determining the risk of specific diseases. During earlier stages of pregnancy, the transfer of maternal thyroid hormones to the fetus is vital for adequate neurologic development. The presence of severe maternal thyroid dysfunction, particularly severe iodine deficiency, is devastating, leading to irreversible neurologic sequelae. Moreover, mild maternal thyroid conditions, such as a mild-to-moderate iodine deficiency, may also lead to milder neurologic and behavioral conditions later during the life of the offspring. Maternal dysglycemia due to pregestational or gestational diabetes mellitus is another common situation in which fetal development encounters a hostile environment. Hyperglycemia in utero may trigger metabolic conditions in the offspring, including abnormalities of glucose tolerance and weight excess. Physicians assisting pregnant women have to be aware about these conditions, because they may go unnoticed if not properly screened. Because an early diagnosis and appropriate management may prevent most of the possible negative consequences for the progeny, the prevention, early diagnosis, and proper management of these endocrine conditions should be offered to all women undergoing pregnancy. Here, we comprehensively review the current evidence about the effects of maternal thyroid dysfunction and maternal dysglycemia on the cognitive function and carbohydrate metabolism in the offspring, two prevalent conditions of utmost importance for the child's health and development.

Maternal Thyroid Function in Early Pregnancy and Child Attention-Deficit Hyperactivity Disorder: An Individual-Participant Meta-Analysis

Background: Thyroid hormone is essential for optimal fetal brain development. Evidence suggests that both low and high maternal thyroid hormone availability may have adverse effects on child neurodevelopmental outcomes, but the effect on behavioral problems remains unclear. We studied the association of maternal thyrotropin (TSH) and free thyroxine (fT4) concentrations during the first 18 weeks of pregnancy with child attention-deficit hyperactivity disorder (ADHD). Methods: A total of 7669 mother-child pairs with data on maternal thyroid function and child ADHD were selected from three prospective population-based birth cohorts: INfancia y Medio Ambiente (INMA; N = 1073, Spain), Generation R (N = 3812, The Netherlands), and Avon Longitudinal Study of Parents and Children (ALSPAC; N = 2784, United Kingdom). Exclusion criteria were multiple pregnancy, fertility treatment, usage of medication affecting the thyroid, and pre-existing thyroid disease. We used logistic regression models to study the association of maternal thyroid function with the primary outcome, ADHD, assessed via the Diagnostic and Statistical Manual of Mental Disorders, fourth edition (DSM-IV) criteria by parents and/or teachers at a median child age of 4.5 to 7.6 years, and with the secondary outcome, an ADHD symptom score above the 90th percentile. Effect modification by gestational age and sex was tested with interaction terms and stratified analyses. Results: Overall, 233 (3%) children met the criteria for ADHD. When analyzed continuously, neither fT4 nor TSH was associated with a higher risk of ADHD (odds ratio [OR] 1.1, 95% confidence interval [CI 1.0-1.3], p = 0.060 and OR 0.9 [CI 0.9-1.1], p = 0.385, respectively) or with high symptom scores. When investigating effect modification by gestational age, a higher fT4 was associated with symptoms above the 90th percentile but only in the first trimester (for fT4 per 1 SD: OR 1.2 [CI 1.0-1.4], p = 0.027). However, these differential effects by gestational age were not consistent. No significant effect modification by sex was observed. Conclusions: We found no clear evidence of an association between maternal thyroid function and child ADHD.

Prenatal exposure to organophosphate esters and behavioral development in young children in the Pregnancy, Infection, and Nutrition Study

Organophosphate esters (OPEs) are commonly used as plasticizers and flame retardants in consumer products, and exposure is relatively ubiquitous in most populations studied. This may be of concern as some OPEs may be neurotoxic, endocrine-disrupting, and interfere with behavioral development; however, observational evidence is limited. We used data from the Pregnancy, Infection, and Nutrition Study, a prospective birth cohort study, to investigate associations between maternal OPE metabolite concentrations during pregnancy and behavioral development in offspring. Women provided a urine sample during pregnancy that was analyzed for concentrations of OPE metabolites, including diphenyl phosphate (DPHP), bis(1,3-dichloro-2-propyl phosphate) (BDCIPP), isopropyl-phenyl phenyl phosphate (ip-PPP), and 1-hydroxyl-2-propyl bis(1-chloro-2-propyl) phosphate (BCIPHIPP). Offspring's behavioral development was assessed by the Behavioral Assessment System for Children (2nd Edition) (BASC-2) at approximately 36 months. Linear regression was used to estimate associations between tertiles in specific gravity-corrected OPE metabolite concentrations and children's scores on the BASC-2, adjusted for maternal age, maternal BMI, maternal race, maternal education, familial income, maternal depression, quality of the home environment, and sex. Higher BDCIPP concentrations were associated with higher scores on the Behavioral Symptoms Index (1st vs. 3rd tertile: β = 3.03; 95% CI = 0.40, 5.67) and Externalizing Problems (1st vs. 3rd tertile: β = 2.49; 95% CI: -0.12, 5.10) composites. Among BASC-2 scales, BDCIPP was most strongly associated with Withdrawal, Attention Problems, Depression, Hyperactivity, and Aggression. DPHP concentrations were also associated with higher scores on the Externalizing Problems and Behavioral Symptoms Index composites, but not as strongly as BDCIPP. Conversely, higher concentrations of ip-PPP were associated with fewer adverse behavioral symptoms, including an inverse association with the Internalizing Problems composite (1st vs. 3rd tertile: β = -3.74; 95% CI = -6.75, -0.74) and constituent scales. BCIPHIPP was not strongly associated with any measured behavioral outcomes. Our results suggest that greater maternal exposure to tris(1,3-dichloro-2-propyl phosphate) (TDCIPP, parent compound of BDCIPP) and, to a lesser degree, triphenyl phosphate (TPHP, parent compound of DPHP) during pregnancy is associated with adverse behavioral development in children. Our study contributes to the growing body of evidence pertaining to adverse developmental effects of prenatal OPE exposure and highlights the need for further research to characterize risks associated with this ubiquitous family of chemicals.

Association of attention deficit hyperactivity disorder with recurrent hypoglycemia in type 1 diabetes mellitus

OBJECTIVE

Data regarding the association between hypoglycemia and attention deficit hyperactivity disorder (ADHD) in children and adolescents with type 1 diabetes mellitus (T1DM) are limited. This study investigated whether hypoglycemia was associated with the risk of ADHD in young people with T1DM.

METHODS

Children and adolescents with a diagnosis of T1DM were identified from the Longitudinal National Health Insurance Database in Taiwan from 1998 to 2011. Among them who were newly diagnosed with hypoglycemia during 2000 to 2007 were selected for the hypoglycemia cohort. The hypoglycemia diagnosis date was defined as the index date. Those who were diagnosed with ADHD before the index date were excluded. The main outcome was the development of ADHD. In total, 726 participants with hypoglycemia and 2852 participants without hypoglycemia were included in this study.

RESULTS

The overall incidence density of ADHD was markedly increased among cohort with hypoglycemia compared with cohort without hypoglycemia (4.74 vs 1.65 per 1000 person-years), with an adjusted hazard ratio (aHR) of 2.73 (95% confidence interval [CI] = 1.50-4.98). Cohort with hypoglycemia who had experienced a hypoglycemic coma had a significantly higher risk of ADHD (aHR = 6.54, 95% CI = 1.89-22.7) compared with cohort without hypoglycemia.

CONCLUSIONS

Hypoglycemia, especially hypoglycemic coma, is significantly associated with a subsequent risk of ADHD in young people with T1DM.

Psychiatric research in the Northern Finland Birth Cohort 1986 - a systematic review

The Northern Finland Birth Cohort 1986 is a large population-based birth cohort, which aims to promote health and wellbeing of the population. In this paper, we systematically review the psychiatric research performed in the cohort until today, i.e. at the age of 32 years of the cohort (2018). We conducted a systematic literature search using the databases of PubMed and Scopus and complemented it with a manual search. We found a total of 94 articles, which were classified as examining ADHD, emotional and behavioural problems, psychosis risk or other studies relating to psychiatric subjects. The articles are mainly based on two large comprehensive follow-up studies of the cohort and several substudies. The studies have often used also nationwide register data. The studies have found several early predictors for the aforementioned psychiatric outcomes, such as problems at pregnancy and birth, family factors in childhood, physical inactivity and substance use in adolescence. There are also novel findings relating to brain imaging and cognition, for instance regarding familial risk of psychosis in relation to resting state functional MRI. The Northern Finland Birth Cohort 1986 has been utilised frequently in psychiatric research and future data collections are likely to lead to new scientifically important findings.

Abbreviations: attention deficit hyperactivity disorder (ADHD); magnetic resonance imaging (MRI)

Frequency and outcomes of maternal thyroid function abnormalities in early pregnancy

Thyroid function in pregnant women is of clinical importance considering the crucial role of thyroid hormones during fetal brain development, but the current level of evidence is insufficient to recommend for or against the routine testing of thyroid function in pregnant women. As part of this debate, it is important to evaluate the frequency of undiagnosed and untreated thyroid function abnormalities in pregnant women and to address challenges related to the biochemical assessment of maternal thyroid function in early pregnancy. A hypothesis of fetal programming by maternal thyroid disease has been proposed, but more evidence in humans is needed to extend the hypothesis and to evaluate child neurodevelopmental outcomes after in utero exposure to different abnormalities in maternal thyroid function. The nationwide registers in the Nordic countries provide unique opportunities within reproductive epidemiology to study the impact of various in utero exposures, and stored blood samples from pregnant women in nationwide birth cohorts provide a valuable source for the establishment of pregnancy specific reference ranges. This review addresses the frequency and outcomes of thyroid function abnormalities in pregnant women mainly focusing on observational studies that combine data from the Danish nationwide registers and biological specimens from the Danish National Birth Cohort. Dynamic changes in the reference range of maternal TSH and free T4 during the first trimester of pregnancy are described and discussed. A high frequency of unidentified maternal thyroid function abnormalities is illustrated, and outcomes of child neurodevelopment are evaluated according to subtypes and severity of maternal thyroid dysfunction.

Maternal Thyroid Function During Pregnancy or Neonatal Thyroid Function and Attention Deficit Hyperactivity Disorder: A Systematic Review

BACKGROUND

Attention deficit hyperactivity disorder (ADHD) is the most common neurobehavioral disorder in children, yet its etiology is poorly understood. Early thyroid hormone disruption may contribute to the development of ADHD. Disrupted maternal thyroid hormone function has been associated with adverse neurodevelopmental outcomes in children. Among newborns, early-treated congenital hypothyroidism has been consistently associated with later cognitive deficits.

METHODS

We systematically reviewed literature on the association between maternal or neonatal thyroid hormones and ADHD diagnosis or symptoms. We searched Embase, Pubmed, Cinahl, PsycInfo, ERIC, Medline, Scopus, and Web of Science for articles published or available ahead of print as of April 2018.

RESULTS

We identified 28 eligible articles: 16 studies of maternal thyroid hormones, seven studies of early-treated congenital hypothyroidism, and five studies of neonatal thyroid hormones. The studies provide moderate evidence for an association between maternal thyroid hormone levels and offspring ADHD, some evidence for an association between early-treated congenital hypothyroidism and ADHD, and little evidence for an association between neonatal thyroid hormone levels and later ADHD.

CONCLUSIONS

The reviewed articles suggest an association between maternal thyroid function and ADHD, and possibly between early-treated congenital hypothyroidism and ADHD. Study limitations, however, weaken the conclusions in our systematic review, underlining the need for more research. Importantly, there was much variation in the measurement of thyroid hormone function and of ADHD symptoms. Recommendations for future research include using population-based designs, attending to measurement issues for thyroid hormones and ADHD, considering biologically relevant covariates (e.g., iodine intake), and assessing nonlinear dose-responses.

Prenatal fluoride exposure and attention deficit hyperactivity disorder (ADHD) symptoms in children at 6-12 years of age in Mexico City

BACKGROUND

Epidemiologic and animal-based studies have raised concern over the potential impact of fluoride exposure on neurobehavioral development as manifested by lower IQ and deficits in attention. To date, no prospective epidemiologic studies have examined the effects of prenatal fluoride exposure on behavioral outcomes using fluoride biomarkers and sensitive measures of attention.

OBJECTIVE

We aimed to examine the association between prenatal fluoride exposure and symptoms associated with attention-deficit/hyperactivity disorder (ADHD).

METHOD

213 Mexican mother-children pairs of the Early Life Exposures to Environmental Toxicants (ELEMENT) birth cohort study had available maternal urinary samples during pregnancy and child assessments of ADHD-like behaviors at age 6-12. We measured urinary fluoride levels adjusted for creatinine (MUF_cr) in spot urine samples collected during pregnancy. The Conners' Rating Scales-Revised (CRS-R) was completed by mothers, and the Conners' Continuous Performance Test (CPT-II) was administered to the children.

RESULTS

Mean MUF_cr was 0.85 mg/L (SD = 0.33) and the Interquartile Range (IQR) was 0.46 mg/L. In multivariable adjusted models using gamma regression, a 0.5 mg/L higher MUF_cr (approximately one IQR higher) corresponded with significantly higher scores on the CRS-R for DSM-IV Inattention (2.84 points, 95% CI: 0.84, 4.84) and DSM-IV ADHD Total Index (2.38 points, 95% CI: 0.42, 4.34), as well as the following symptom scales: Cognitive Problems and Inattention (2.54 points, 95% CI: 0.44, 4.63) and ADHD Index (2.47 points; 95% CI: 0.43, 4.50). The shape of the associations suggested a possible celling effect of the exposure. No significant associations were found with outcomes on the CPT-II or on symptom scales assessing hyperactivity.

CONCLUSION

Higher levels of fluoride exposure during pregnancy were associated with global measures of ADHD and more symptoms of inattention as measured by the CRS-R in the offspring.

Maternal Prenatal Thyroid Function and Offspring ADHD: Findings From the ALSPAC Cohort

Thyroid hormone plays a pivotal role in the developing brain and may affect the development of attention deficit hyperactivity disorder (ADHD). This study aimed to examine the role of maternal thyroid function during pregnancy on offspring ADHD. A total of 2912 mother-child pairs were included from the Avon Longitudinal Study of Parents and Children. Thyroid parameters were assessed during the first trimester of pregnancy. Offspring ADHD was assessed using the Development and Well-Being Assessment at the ages of 7.5 and 15 years. The odds of presenting with ADHD were estimated using generalized estimating equations. Levels of thyroid-stimulating hormone (odds ratio [OR], 0.92; 95% confidence interval [CI], 0.48-1.75), free thyroxine (OR, 1.07; 95% CI, 0.87-1.32), and thyroid peroxidase antibodies (OR, 1.00; 95% CI, 0.80-1.25) were not associated with ADHD in children aged 7.5 and 15 years. This study showed no association between maternal thyroid function and offspring ADHD.

Association of Maternal Exposure to Childhood Abuse With Elevated Risk for Attention Deficit Hyperactivity Disorder in Offspring

Children whose mothers experienced childhood abuse are more likely to suffer various neurodevelopmental deficits. Whether an association exists specifically for attention deficit hyperactivity disorder (ADHD) is unknown. We examined the association of maternal experience of childhood abuse with ADHD in offspring, assessed by maternal report of diagnosis and validated with the ADHD Rating Scale-IV in a subsample, in the Nurses' Health Study II (n = 49,497 mothers; n = 7,607 case offspring; n = 102,151 control offspring). We examined whether 10 adverse perinatal circumstances (e.g., prematurity, smoking) or socioeconomic factors accounted for a possible association. Exposure to abuse was associated with greater prevalence of ADHD in offspring (8.7% of offspring of women exposed to severe abuse vs. 5.5% of offspring of women not abused, P = 0.0001) and with greater risk for ADHD when the model was adjusted for demographic factors (male offspring, risk ratio (RR) = 1.6, 95% confidence interval (CI): 1.3, 1.9; female offspring, RR = 2.3, 95% CI: 1.7, 3.0). After adjustment for perinatal factors, the association of maternal childhood abuse with ADHD in offspring was slightly attenuated (male offspring, RR = 1.5, 95% CI: 1.2, 1.8; female offspring, RR = 2.1, 95% CI: 1.6, 2.8). We identified an association between maternal experience of childhood abuse and risk for ADHD in offspring, which was not explained by several important perinatal risk factors or socioeconomic status.

Clinical associations of maternal thyroid function with foetal brain development: Epidemiological interpretation and overview of available evidence

Thyroid hormone is an important regulator of early brain development, particularly during early stages of gestation during which foetal thyroid hormone availability depends on the maternal transfer of thyroid hormones. There is a wide range of experimental studies showing that low maternal thyroid hormone availability is associated with suboptimal brain development parameters. While few clinical studies have shown that overt maternal hypothyroidism is associated with lower child IQ, the question whether more subclinical changes in maternal thyroid function could also lead to suboptimal foetal brain development. In this review, we put the latter studies in perspective and discuss their interpretation from an epidemiological and clinical perspective. Furthermore, we extend this discussion to also include future perspective and identify important knowledge gaps in the field.