Formula Feeding as a Risk Factor for Attention-Deficit/Hyperactivity Disorder: Is Bisphenol A Exposure a Smoking Gun?

The research landscape concerning environmental factors in neurodevelopmental disorders: Endocrine disrupters and pesticides-A review

In recent years, environmental epidemiology and toxicology have seen a growing interest in the environmental factors that contribute to the increased prevalence of neurodevelopmental disorders, with the purpose of establishing appropriate prevention strategies. A literature review was performed, and 192 articles covering the topic of endocrine disruptors and neurodevelopmental disorders were found, focusing on polychlorinated biphenyls, polybrominated diphenyl ethers, bisphenol A, and pesticides. This study contributes to analyzing their effect on the molecular mechanism in maternal and infant thyroid function, essential for infant neurodevelopment, and whose alteration has been associated with various neurodevelopmental disorders. The results provide scientific evidence of the association that exists between the environmental neurotoxins and various neurodevelopmental disorders. In addition, other possible molecular mechanisms by which pesticides and endocrine disruptors may be associated with neurodevelopmental disorders are being discussed.

Effect of bisphenol A on the neurological system: a review update

Bisphenol A (BPA) is an endocrine-disrupting chemical (EDC) and one of the most produced synthetic compounds worldwide. BPA can be found in epoxy resins and polycarbonate plastics, which are frequently used in food storage and baby bottles. However, BPA can bind mainly to estrogen receptors, interfering with various neurologic functions, its use is a topic of significant concern. Nonetheless, the neurotoxicity of BPA has not been fully understood despite numerous investigations on its disruptive effects. Therefore, this review aims to highlight the most recent studies on the implications of BPA on the neurologic system. Our findings suggest that BPA exposure impairs various structural and molecular brain changes, promoting oxidative stress, changing expression levels of several crucial genes and proteins, destructive effects on neurotransmitters, excitotoxicity and neuroinflammation, damaged blood-brain barrier function, neuronal damage, apoptosis effects, disruption of intracellular Ca2+ homeostasis, increase in reactive oxygen species, promoted apoptosis and intracellular lactate dehydrogenase release, a decrease of axon length, microglial DNA damage, astrogliosis, and significantly reduced myelination. Moreover, BPA exposure increases the risk of developing neurologic diseases, including neurovascular (e.g. stroke) and neurodegenerative (e.g. Alzheimer's and Parkinson's) diseases. Furthermore, epidemiological studies showed that the adverse effects of BPA on neurodevelopment in children contributed to the emergence of serious neurological diseases like attention-deficit/hyperactivity disorder (ADHD), autism spectrum disorder (ASD), depression, emotional problems, anxiety, and cognitive disorders. In summary, BPA exposure compromises human health, promoting the development and progression of neurologic disorders. More research is required to fully understand how BPA-induced neurotoxicity affects human health.

Dexmedetomidine alleviates host ADHD-like behaviors by reshaping the gut microbiota and reducing gut-brain inflammation

Attention-deficit/hyperactivity disorder (ADHD) is one of the most prevalent psychiatric disorders that affects children and even continues into adulthood. Dexmedetomidine (DEX), a short-term sedative, can selectively activate the α2-adrenoceptor. Treatment with α2-adrenergic agonists in patients with ADHD is becoming increasingly common. However, the therapeutic potential of DEX for the treatment of ADHD is unknown. Here, we evaluated the effect of DEX on ADHD-like behavior in spontaneously hypertensive rats (SHRs), a widely used animal model of ADHD. DEX treatment ameliorated hyperactivity and spatial working memory deficits and normalized θ electroencephalogram (EEG) rhythms in SHRs. We also found that DEX treatment altered the gut microbiota composition and promoted the enrichment of beneficial gut bacterial genera associated with anti-inflammatory effects in SHRs. The gut pathological scores and permeability and the level of inflammation observed in the gut and brain were remarkably improved after DEX administration. Moreover, transplantation of fecal microbiota from DEX-treated SHRs produced effects that mimicked the therapeutic effects of DEX administration. Therefore, DEX is a promising treatment for ADHD that functions by reshaping the composition of the gut microbiota and reducing inflammation in the gut and brain.

The translational genetics of ADHD and related phenotypes in model organisms

Attention-deficit/hyperactivity disorder (ADHD) is a highly prevalent neurodevelopmental disorder resulting from the interaction between genetic and environmental risk factors. It is well known that ADHD co-occurs frequently with other psychiatric disorders due, in part, to shared genetics factors. Although many studies have contributed to delineate the genetic landscape of psychiatric disorders, their specific molecular underpinnings are still not fully understood. The use of animal models can help us to understand the role of specific genes and environmental stimuli-induced epigenetic modifications in the pathogenesis of ADHD and its comorbidities. The aim of this review is to provide an overview on the functional work performed in rodents, zebrafish and fruit fly and highlight the generated insights into the biology of ADHD, with a special focus on genetics and epigenetics. We also describe the behavioral tests that are available to study ADHD-relevant phenotypes and comorbid traits in these models. Furthermore, we have searched for new models to study ADHD and its comorbidities, which can be useful to test potential pharmacological treatments.

The development of the gut microbiome and temperament during infancy and early childhood: A systematic review

Temperament in early childhood is a good predictor of later personality, behavior, and risk of psychopathology. Variation in temperament can be explained by environmental and biological factors. One biological mechanism of interest is the gut microbiome (GM), which has been associated with mental and physical health. This review synthesized existing literature evaluating the relationship between GM composition and diversity, and temperament in early life. Web of Science, PsycInfo, PubMed, and Scopus were searched, and data were extracted according to PRISMA guidelines. In total, 1562 studies were identified, of which six remained following application of exclusion/inclusion criteria. The findings suggest that there is an association between higher alpha diversity and temperament: greater Surgency/Extraversion and High-Intensity Pleasure in males, and lower Effortful Control in females. Unique community structures (beta diversity) were found for Surgency/Extraversion in males and Fear in females. An emerging pattern of positive temperament traits being associated with GM communities biased toward short-chain fatty acid production from a metabolism based on dietary fiber and complex carbohydrates was observed and is worthy of further investigation. To gain deeper understanding of the relationship, future research should investigate further the functional aspects of the microbiome and the influence of diet.

Gut metagenomic characteristics of ADHD reveal low Bacteroides ovatus-associated host cognitive impairment

Attention-deficit/hyperactivity disorder (ADHD) is a highly heterogeneous psychiatric disorder that can have three phenotypical presentations: inattentive (I-ADHD), hyperactive-impulsive (HI-ADHD), and combined (C-ADHD). Environmental factors correlated with the gut microbiota community have been implicated in the development of ADHD. However, whether different ADHD symptomatic presentations are associated with distinct microbiota compositions and whether patients could benefit from the correction of aberrant bacterial colonization are still largely unclear. We carried out metagenomic shotgun analysis with 207 human fecal samples to characterize the gut microbial profiles of patients with ADHD grouped according to their phenotypical presentation. Then, we transplanted the candidate low-abundance bacteria identified in patient subgroups into ADHD rats and evaluated ADHD-associated behaviors and neuronal activation in these rats. Patients with C-ADHD had a different gut microbial composition from that of healthy controls (HCs) (p = .02), but not from that of I-ADHD patients. Eight species became progressively attenuated or enriched when comparing the compositions of HCs to those of I-ADHD and C-ADHD; in particular, the abundance of Bacteroides ovatus was depleted in patients with C-ADHD. In turn, Bacteroides ovatus supplementation ameliorated spatial working memory deficits and reversed θ electroencephalogram rhythm alterations in ADHD rats. In addition, Bacteroides ovatus induced enhanced neuronal activation in the hippocampal CA1 subregion. These findings indicate that gut microbial characteristics that are unique to patients with C-ADHD may be masked when considering a more heterogeneous group of patients. We link the gut microbiota to brain function in an ADHD animal model, suggesting the relevance of testing a potential bacteria-based intervention for some aspects of ADHD.

Duration of breast feeding and attention-deficit/hyperactivity disorder in United States preschool-aged children

BACKGROUND

Attention-deficit/hyperactivity disorder (ADHD) is a neurodevelopmental disorder characterized by difficulties sustaining attention and controlling hyperactivity and impulsive behavior. Population-based studies concerning the association between breast-feeding duration and ADHD among preschool-aged children in the United States (U.S.) have been sparse.

AIMS

To determine whether there is an association between the duration of breast feeding and ADHD in U.S. children aged 2-5 years.

METHODS AND PROCEDURES

We used nationally representative data from the 2016, 2017, and 2018 National Survey of Children's Health (NSCH) to examine the association between breast-feeding duration and ADHD in U.S. preschool-aged children. Sample characteristics were compared using Rao-Scott chi-square test, and adjusted prevalence odds ratios and 95 % confidence intervals were estimated using unconditional logistic regression.

OUTCOMES AND RESULTS

Of the 20,453 children eligible for our study, 1.5 % had received a diagnosis of ADHD and 77.5 % were reported to have been fed human milk as infants. Prevalence odds of ADHD were 57 % lower among children fed human milk for 6-12 months compared to children never fed human milk after controlling for potential confounders. Among children with durations of breast feeding lasting less than 6 months or lasting 12 months or longer, prevalence odds of ADHD were not significantly lower than the comparison group, children who were never fed human milk, after controlling for potential confounders.

CONCLUSIONS AND IMPLICATIONS

We noted an inverse association between breast feeding durations of 6-12 months and parent-reported diagnosis of ADHD in preschool-aged children in the U.S. Future studies should use longitudinal designs to examine ADHD and duration of breast-feeding measures.

Breastfeeding Is Associated with a Reduced Risk of Attention-Deficit/Hyperactivity Disorder Among Preschool Children

BACKGROUND

Breastfeeding has been associated with a lower risk of attention-deficit/hyperactivity disorder (ADHD). However, most studies examining this association have focused on small samples outside the United States or were likely subject to substantial residual confounding. Our objectives were to investigate, in a nationally representative sample of preschool children in the United States, the associations between ADHD and both age of breastfeeding cessation and age of formula introduction, as well as associations between ADHD and exclusive breastfeeding duration.

METHODS

Analysis of data from children aged 3 to 5 years in the 2011/12 National Survey of Children's Health (n = 12,793). Logistic regressions were used to model current medical diagnosis of preschool ADHD as a function of breastfeeding duration, breastfeeding exclusivity, and the timing of formula introduction with adjustment for 12 potential confounders using propensity scores, including sex, age, race, household income, prematurity, insurance, and medical home.

RESULTS

After adjustment for potential confounders, exclusive breastfeeding for at least 6 months was associated with substantially reduced odds of ADHD (adjusted prevalence odds ratio [aPOR] = 0.38; 95% confidence interval [CI], 0.15-0.99). Breastfeeding duration was also associated with ADHD, with 8% reduced odds of ADHD for each additional month of breastfeeding (aPOR = 0.92; 95% CI, 0.86-0.99). The results for exclusive breastfeeding duration were similar, but the confidence interval included the null (aPOR = 0.92; 95% CI, 0.85-1.00). The age of formula introduction was not associated with ADHD (aPOR = 0.92; 95% CI, 0.81-1.05).

CONCLUSION

In a nationally representative sample of preschool children, breastfeeding was associated with a lower prevalence of ADHD. These findings provide evidence in support of the neurodevelopmental benefits of breastfeeding.

Breastfeeding for 3 Months or Longer but Not Probiotics Is Associated with Reduced Risk for Inattention/Hyperactivity and Conduct Problems in Very-Low-Birth-Weight Children at Early Primary School Age

(1) Background: We aimed to evaluate the effect of proposed “microbiome-stabilising interventions”, i.e., breastfeeding for ≥3 months and prophylactic use of Lactobacillus acidophilus/ Bifidobacterium infantis probiotics on neurocognitive and behavioral outcomes of very-low-birthweight (VLBW) children aged 5–6 years. (2) Methods: We performed a 5-year-follow-up assessment including a strength and difficulties questionnaire (SDQ) and an intelligence quotient (IQ) assessment using the Wechsler Preschool and Primary Scale of Intelligence (WPPSI)-III test in preterm children previously enrolled in the German Neonatal Network (GNN). The analysis was restricted to children exposed to antenatal corticosteroids and postnatal antibiotics. (3) Results: 2467 primary school-aged children fulfilled the inclusion criteria. In multivariable linear regression models breastfeeding ≥3 months was associated with lower conduct disorders (B (95% confidence intervals (CI)): −0.25 (−0.47 to −0.03)) and inattention/hyperactivity (−0.46 (−0.81 to −0.10)) as measured by SDQ. Probiotic treatment during the neonatal period had no effect on SDQ scores or intelligence. (4) Conclusions: Prolonged breastfeeding of highly vulnerable infants may promote their mental health later in childhood, particularly by reducing risk for inattention/hyperactivity and conduct disorders. Future studies need to disentangle the underlying mechanisms during a critical time frame of development.

The Potential Influence of the Bacterial Microbiome on the Development and Progression of ADHD

The latest research cumulates staggering information about the correlation between the microbiota-gut-brain axis and neurodevelopmental disorders. This review aims to shed light on the potential influence of the microbiome on the development of the most prevalent neurodevelopmental disease, attention-deficit-hyperactive disorder (ADHD). As the etiology and pathophysiology of ADHD are still unclear, finding viable biomarkers and effective treatment still represent a challenge. Therefore, we focused on factors that have been associated with a higher risk of developing ADHD, while simultaneously influencing the microbial composition. We reviewed the effect of a differing microbial makeup on neurotransmitter concentrations important in the pathophysiology of ADHD. Additionally, we deduced factors that correlate with a high prevalence of ADHD, while simultaneously affecting the gut microbiome, such as emergency c-sections, and premature birth as the former leads to a decrease of the gut microbial diversity and the latter causes neuroprotective Lactobacillus levels to be reduced. Also, we assessed nutritional influences, such as breastfeeding, ingestion of short-chain fatty acids (SCFAs) and polyunsaturated fatty acids (PUFAs) on the host′s microbiome and development of ADHD. Finally, we discussed the potential significance of Bifidobacterium as a biomarker for ADHD, the importance of preventing premature birth as prophylaxis and nutrition as a prospective therapeutic measurement against ADHD.

Association between circulating zinc/ferritin levels and parent Conner's scores in children with attention deficit hyperactivity disorder

ADHD is one of the most common neurobehavioral disorders among children and adolescents. In this prospective study, we aimed to measure circulating zinc and ferritin levels in children with ADHD, pick up the deficient ones to give zinc and iron supplements then compare before and after treatment according to their Conner's scores and Wecsler IQ test. Current study included fifty children diagnosed as having ADHD by DSMV criteria, their zinc and ferritin levels were measured by Colorimetric method and enzyme-linked immunosorbent assay (ELISA) respectively. They were divided into: group I (zinc only deficient),group II (zinc and ferritin deficient),group III (non-deficient), cases with mineral deficiency received zinc (55 mg/day) and/or iron (6 mg/kg/day) for 6 months then reassessed by parent Conner's rating scale. In group 1, there was no significant difference between the Wecsler verbal and non-verbal IQ scores and oppositional and cognitive problems in Conner's scores before and after zinc supplements, although there was significant improvement in attention, hyperactivity, emotional liability and impulsivity. In group II, there was significant improvement in verbal and total IQ but not in performance IQ, also there was significant improvement in hyperactivity, emotional liability and impulsivity with no significant difference in oppositional, cognitive problems and inattention before and after zinc/ iron supplements. In Conclusion, Zinc supplements in adjuvant to the main treatment significantly improved symptoms of ADHD children. However, a combined zinc and iron supplements was superior to zinc alone in alleviating ADHD symptoms as well as IQ improvement.

Early-life intake of major trace elements, bisphenol A, tetrabromobisphenol A and fatty acids: Comparing human milk and commercial infant formulas

In the present study, the presence of a wide spectrum of major and trace elements (As, Ag, Al, Ba, Cd, Co, Cr, Cu, Hg, Mn, Ni, Sr, Sb, Se, Sn, Pb, V, and Zn), fatty acids, as well as some pollutants like free and total BPA and tetrabromobisphenol A (TBBPA), was analysed in human milk (n = 53) and infant formula (n = 50) samples. In addition, the infant exposure to these chemicals was assessed. The content of free BPA and several elements (Al, Ca, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, Sn, Sr, and Zn) was higher (p < 0.01) in infant formula samples. Furthermore, human milk contained levels of BPA and elements that, in almost all cases, were well below their respective EFSA and/or WHO thresholds, being also independent of the maternal characteristics (e.g., age, BMI or breastfeeding period). The fatty acid profiling also revealed major differences between human milk and infant formulas, which should be taken in account in the development of new formulas as well as in specific recommendations for the diet of breastfeeding mothers. Anyway, the results of this study reinforce that breastfeeding should be always the first feeding option in early life.

Association between the different duration of breastfeeding and attention deficit/hyperactivity disorder in children: a systematic review and meta-analysis

Objectives: To summarize the current evidence on the association between maternal breastfeeding and the occurrence of attention deficit/hyperactivity disorder (ADHD) in offspring. Methods: We searched for studies published in English before May 2018 using the PubMed, EMBASE, Cochrane, and Web of Science databases. We included cohort studies, case-control studies, and cross-sectional studies, that focused on the association between maternal breastfeeding and the occurrence of ADHD in offspring. Random effects models were used for combined analyses. Results: Two cohort studies, 7 case-control studies and 3 cross-sectional studies, with 3,686 cases and 106,907 participants, were included. Children with any maternal breastfeeding had a lower incidence of ADHD than children who were never breastfed (odds ratio [OR]: 0.70; 95% confidence interval [CI]:0.52-0.93). Further analyses also showed associations between reduced ADHD incidence and duration of breastfeeding. Children breastfed for over 1 month, over 3 months, over 6 months, and over 12 months had a lower incidence of ADHD than children breastfed for less than 1 month (OR: 0.20; 95% CI: 0.11-0.38), less than 3 months (OR: 0.33; 95% CI: 0.23-0.47), less than 6 months (OR: 0.50; 95% CI: 0.41-0.61), and less than 12 months (OR: 0.55; 95% CI: 0.37-0.81), respectively. These results were stable in the 1-month, 3-month, and 6-month breastfeeding groups. Conclusion: With our meta-analysis, we provide evidence that maternal breastfeeding may reduce the risk of ADHD in children. The causality of this relationship and underlying mechanisms need to be explored in future prospective studies.