Urine metals concentrations and dyslexia among children in China

Association of exposure to phthalates and phthalate alternatives with dyslexia in Chinese primary school children

Previous studies have shown associations between children's exposure to phthalates and neurodevelopmental disorders. Whereas the impact of exposure to phthalate alternatives is understudied. This study aimed to evaluate the association of exposure to phthalates/their alternatives with the risk of dyslexia. We recruited 745 children (355 dyslexia and 390 non-dyslexia) via the Tongji Reading Environment and Dyslexia Research Project, and their urine samples were collected. A total of 26 metabolites of phthalates/their alternatives were measured. Multivariate logistic regression and quantile-based g-computation were used to estimate the associations of exposure to the phthalates/their alternatives with dyslexia. More than 80% of the children had 17 related metabolites detected in their urine samples. After adjustment, the association between mono-2-(propyl-6-hydroxy-heptyl) phthalate (OH-MPHP) with the risk of dyslexia was observed. Compared with the lowest quartile of OH-MPHP levels, the odds of dyslexia for the third quartile was 1.93 (95% CI 1.06, 3.57). Regarding mixture analyses, it was found that OH-MPHP contributed the most to the association. Further analyses stratified by sex revealed that this association was only observed in boys. Our results suggested a significantly adverse association of di-2-propylheptyl phthalate exposure with children's language abilities. It highlights the necessity to prioritize the protection of children's neurodevelopment by minimizing their exposure to endocrine-disrupting chemicals like di-2-propylheptyl phthalate.

Exposure to organophosphate, pyrethroid, and neonicotinoid insecticides and dyslexia: Association with oxidative stress

Organophosphates (OPPs), pyrethroids (PYRs), and neonicotinoids (NNIs) are three major classes of insecticides used worldwide. They might compromise child neurodevelopment. However, few studies have explored the association between exposure to them and dyslexia. The present study aimed to investigate the association between dyslexia and exposure to the three classes of insecticides, as well as explore the potential role of oxidative stress in the association. A total of 355 dyslexic children and 390 controls were included in this study. The exposure biomarkers were determined by liquid chromatography-tandem mass spectrometry. Specifically, the exposure biomarkers included three typical metabolites of OPPs, three of PYRs, and nine of NNIs. Additionally, three typical oxidative stress biomarkers, namely, 8-hydroxy-2'-deoxyguanosine (8-OHdG) for DNA damage, 8-hydroxyguanosine (8-OHG) for RNA damage, and 4-hydroxy-2-nonenal-mercapturic acid (HNEMA) for lipid peroxidation were measured. The detection frequencies of the urinary biomarkers ranged from 83.9% to 100%. Among the target metabolites of the insecticides, a significant association was observed between urinary 3,5,6-trichloro-2-pyridinol (TCPy, the metabolite of chlorpyrifos, an OPP insecticide) and dyslexia. After adjusting for potential confounding variables, children in the highest quartile of TCPy levels had an increased odds of dyslexia (odds ratio [OR], 1.68; 95% confidence interval [CI]: 1.03, 2.75] in comparison to those in the lowest quartile. Among the three oxidative stress biomarkers, urinary HNEMA concentration showed a significant relationship with dyslexia. Children in the highest quartile of HNEMA levels demonstrated an increased dyslexic odds in comparison to those in the lowest quartile after multiple adjustments (OR, 1.64; 95% CI: 1.01, 2.65). Mediation analysis indicated a significant effect of HNEMA in the association between urinary TCPy and dyslexia, with an estimate of 17.2% (P < 0.01). In conclusion, this study suggested the association between urinary TCPy and dyslexia. The association could be attributed to lipid peroxidation partially.

Association between urinary 2-hydroxyethyl mercapturic acid and dyslexia among school-aged children

Ethylene oxide is commonly used in industrial synthesis and medical disinfection. It is a known human carcinogen and has neurotoxicity. However, the association between ethylene oxide exposure and neurodevelopmental disorders remains unclear. This study aimed to evaluate the association between urinary concentrations of 2-hydroxyethyl mercapturic acid (HEMA; metabolite of ethylene oxide) and dyslexia among school-aged children. A total of 355 dyslexic children and 390 controls from three cities in China were enrolled in this case-control study from November 2017 to December 2020. Urinary HEMA was detected in 100% of the urine samples, suggesting widespread exposure to ethylene oxide in the children. Notably, the children with dyslexia had higher concentrations of urinary HEMA compared to the controls (geometric mean: 2.92 vs. 2.47 ng/mL) (P = 0.004). In the multivariable-adjusted model, urinary concentrations of HEMA were significantly associated with dyslexia risk. The individuals within the highest HEMA concentration demonstrated a 1.97-fold increased odds of dyslexia compared to those within the lowest quartile (95% confidence interval: 1.20-3.23). Thus, these findings suggested the possible link between HEMA levels and the risk of dyslexia. Further studies are warranted to validate this finding and illustrate the underlying mechanism.

Construction of Models To Predict the Effectiveness of E-Waste Control through Capture of Volatile Organic Compounds and Metals/Metalloids Exposure Fingerprints: A Six-Year Longitudinal Study

The significant health implications of e-waste toxicants have triggered the global tightening of regulation on informal e-waste recycling sites (ER) but with disparate governance that requires effective monitoring. Taking advantage of the opportunity to implement e-waste control in the Guiyu ER since 2015, we investigated the temporal variations in levels of oxidative DNA damage, 25 volatile organic compound metabolites (VOCs), and 16 metals/metalloids (MeTs) in urine in 918 children between 2016 and 2021 to demonstrate the effectiveness of e-waste control in reducing population exposure risks. The hazard quotients of most MeTs and levels of 8-hydroxy-2'-deoxyguanosine in children decreased significantly during this time, indicating that e-waste control effectively reduces the noncarcinogenic risks of MeT exposure and levels of oxidative DNA damage. Using mVOC-derived indexes as a feature, a bagging-support vector machine algorithm-based machine learning model was constructed to predict the extent of e-waste pollution (EWP). The model exhibited excellent performance with accuracies >97.0% in differentiating between slight and severe EWP. Five simple functions established using mVOC-derived indexes also had high accuracy in predicting the presence of EWP. These models and functions provide a novel human exposure monitoring-based approach for assessing e-waste governance or the presence of EWP in other ERs.

Association of perchlorate, thiocyanate, and nitrate with dyslexic risk

Perchlorate, thiocyanate, and nitrate are sodium iodide symporter (NIS) inhibitors that disturb iodide uptake into the thyroid and have been implicated in child development. However, no data are available on the association between exposure to/related with them and dyslexia. Here, we examined the association of exposure to/related with the three NIS inhibitors with the risk of dyslexia in a case-control study. The three chemicals were detected in urine samples of 355 children with dyslexia and 390 children without dyslexia from three cities in China. The adjusted odds ratios for dyslexia were examined using logistic regression models. The detection frequencies of all the targeted compounds were 100%. After adjusting for multiple covariates, urinary thiocyanate was significantly associated with the risk of dyslexia (P-trend = 0.02). Compared with the lowest quartile, children within the highest quartile had a 2.66-fold risk of dyslexia (95% confidence interval: 1.32, 5.36]. Stratified analyses showed that the association between urinary thiocyanate level and the risk of dyslexia was more pronounced among boys, children with fixed reading time, and those without maternal depression or anxiety during pregnancy. Urinary perchlorate and nitrate levels were not associated with the risk of dyslexia. This study suggests the possible neurotoxicity of thiocyanate or its parent compounds in dyslexia. Further investigation is warranted to confirm our findings and clarify the potential mechanisms.

Urinary Levels of 14 Metal Elements in General Population: A Region-Based Exploratory Study in China

Metal pollution may lead to a variety of diseases; for this reason, it has become a matter of public concern worldwide. However, it is necessary to use biomonitoring approaches to assess the risks posed to human health by metals. In this study, the concentrations of 14 metal elements in 181 urine samples obtained from the general population of Gansu Province, China, were analyzed using inductively coupled plasma mass spectrometry. Eleven out of fourteen target elements had detection frequencies above 85%, namely, Cr, Ni, As, Se, Cd, Al, Fe, Cu and Rb. The concentrations of most metal elements in the urine of our subjects corresponded to the medium levels of subjects in other regional studies. Gender exerted a significant influence (p < 0.05) on the concentrations of Tl, Rb and Zn. The concentrations of Ni, As, Pb, Sr, Tl, Zn, Cu and Se showed significant differences among different age groups and the age-related concentration trends varied among these elements. There were significant differences in the urine concentrations of Zn and Sr between those subjects in the group who were frequently exposed to soil (exposed soil > 20 min/day) and those in the group who were not, indicating that people in regular contact with soil may be more exposed to metals. This study provides useful information for evaluating the levels of metal exposure among general populations.

Volatile organic compounds and metals/metalloids exposure in children after e-waste control: Implications for priority control pollutants and exposure mitigation measures

The decade-long effort to control e-waste in China has made significant progress from haphazard disposal to organized recycling, but environmental research suggests that exposure to volatile organic compounds (VOCs) and metals/metalloids (MeTs) still poses plausible health risks. To investigate the exposure risk faced by children and identify corresponding priority control chemicals, we evaluated the carcinogenic risk (CR), non-CR, and oxidative DNA damage risks of VOCs and MeTs exposure in 673 children from an e-waste recycling area (ER) by measuring urinary exposure biomarker levels. The ER children were generally exposed to high levels of VOCs and MeTs. We observed distinctive VOCs exposure profiles in ER children. In particular, the 1,2-dichloroethane/ethylbenzene ratio and 1,2-dichloroethane were promising diagnostic indexes for identifying e-waste pollution due to their high accuracy (91.4%) in predicting e-waste exposure. Exposure to acrolein, benzene, 1,3-butadiene, 1,2-dichloroethane, acrylamide, acrylonitrile, arsenic, vanadium, copper, and lead posed considerable CR or/and non-CR and oxidative DNA damage risks to children, while changing personal lifestyles, especially enhancing daily physical exercise, may facilitate mitigating these chemical exposure risks. These findings highlight that the exposure risk of some VOCs and MeTs is still non-negligible in regulated ER, and these hazardous chemicals should be controlled as priorities.

Associations between dyslexia and children's mental health: Findings from a follow-up study in China

Dyslexia is a common learning difficulty that can lead to adverse health outcomes and socioeconomic difficulties. Evidence from longitudinal studies on the association between dyslexia and psychological symptoms in children is limited. Moreover, the psychological trends of children with dyslexia are unclear. In this study, we enrolled 2,056 students in Grades 2 to 5, including 61 dyslexic children, who participated in three mental health surveys and dyslexia screening. All the children were surveyed for symptoms of stress, anxiety and depression. We used generalized estimating equation models to estimate changes in psychological symptoms of children with dyslexia over time and the association between dyslexia and psychological symptoms. The results showed that dyslexia was associated with stress and depressive symptoms in children in both crude (β = 3.27, 95% confidence interval [CI] [1.89∼4.65], β=1.20, 95%CI: [0.45∼1.94], respectively) and adjusted models (β = 3.32, 95%CI: [1.87∼4.77], β=1.31, 95%CI: [0.52∼2.10], respectively). In addition, we found no significant differences in the emotional status of dyslexic children in either survey. Dyslexic children are at risk for mental health issues, and persistent emotional symptoms. Therefore, interventions regarding not only reading ability but also psychological conditions should be pursued.

Four-year population exposure study: Implications for the effectiveness of e-waste control and biomarkers of e-waste pollution

E-waste pollution has emerged as a significant environmental concern. To assess the impact of e-waste control on human pollutant exposure risk and identify appropriate biomarkers to classify e-waste pollution levels, we performed longitudinal population exposure monitoring research in an e-waste recycling area in China after e-waste control. The urinary levels of oxidative stress markers and typical pollutants emitted during e-waste recycling, including heavy metals, polycyclic aromatic hydrocarbons (PAHs), and volatile organic compounds (VOCs), were continuously monitored in the surrounding population (including 275 children and 485 adults) from 2016 to 2019 using high-performance liquid chromatography-tandem mass spectrometry and inductively coupled plasma-mass spectrometry. The results showed that exposure to PAHs, VOCs and heavy metals was significantly associated with oxidative stress levels in urine. After e-waste control, the exposure levels of most PAHs and VOCs and a few heavy metals in the population significantly decreased. Interestingly, the level of 8-hydroxy-2'-deoxyguanosine (a biomarker of oxidative DNA damage) in children significantly decreased by 17.6 %, from 9.45 μg/g CRE in 2017 to 7.79 μg/g CRE in 2019 (p < 0.01). Thus, implementing e-waste control measures effectively reduced the human exposure risk to e-waste pollutants. Urinary tin (Sn), s-phenylmercapturic acid (PMA), 2-&3-hydroxyfluorene (2-&3-OHF), 3-hydroxyphenanthrene (3-OHPhe), and 1-hydroxypyrene (1-OHP) levels decreased significantly and monotonically over time (p < 0.01). The levels of urinary Sn and PMA in combination with 1-OHP, 2-&3-OHF, or 3-OHPhe as biomarkers demonstrated an excellent ability to classify e-waste pollution. These biomarkers will facilitate evaluations of the effectiveness of the governmental pollution regulations and policy measures. Additionally, children were generally exposed to higher levels of heavy metals and VOCs and suffered higher levels of oxidative stress damage than adults, suggesting that children are more vulnerable to e-waste pollution. This work will provide a reference for e-waste management and control.

The combined effect between BDNF genetic polymorphisms and exposure to metals on the risk of Chinese dyslexia

BDNF gene has been implicated in the development of cognition and language. Meanwhile, exposure to metals might interact with BDNF gene to increase the risk of neurodevelopmental disorders. The present study aimed to explore the association between BDNF genetic polymorphisms and dyslexic risk and examine whether BDNF polymorphisms would interact with metal exposures, jointly contributing to dyslexia. Among a case-control study composed of 238 children with dyslexia and 228 healthy controls, the BDNF genetic polymorphisms were genotyped by the Sequenom MassARRAY system, and the exposure to eight metals, such as lead (Pb), mercury (Hg) and copper (Cu), were measured using an inductively coupled plasma-mass spectrometer (ICP-MS). Multivariable logistic regression models were used to assess the adjusted odds ratios (ORs) and 95% confidence interval (CI) of dyslexia. After multivariate adjustment, significant associations of dyslexic risk with rs6265 polymorphisms of the BDNF gene were observed (OR = 1.99; 95% CI: 1.15-3.44). Furthermore, exposure to Cu could interact with rs6265 to increase the risk of dyslexia (P interaction = 0.045). High-Cu children with the rs6265 TT genotype were more likely to have dyslexia compared with low-Cu children carrying CC + CT genotypes (OR = 3.19; 95% CI: 1.38-7.39). The findings of this study suggested that the polymorphism of rs6265 in BDNF gene could interact with Cu exposure to increase the occurrence of dyslexia.

Exposure to multiple metals and the risk of dyslexia - A case control study in Shantou, China

Environmental heavy metal exposure has been considered to be the risk factor for neurodevelopmental disorders in children. However, the available data on the associations between multiple metals exposure and the risk of dyslexia in China are limited. The purpose of our study was to examine the associations between urinary metal concentrations and Chinese dyslexia risk. A total of 56 Chinese dyslexics and 60 typically developing children were recruited. The urinary concentration of 13 metals were measured by inductively coupled plasma-mass spectrometer (ICP-MS). Binary logistic regression and the Probit extension of Bayesian kernel machine regression (BKMR-P) were used to explore the associations between multiple metal exposure and the risk of Chinese dyslexia. Our results indicated that Co, Zn and Pb were significantly associated with Chinese dyslexia in the multiple-metal exposure model. After adjusting the covariates, a positive association was observed between Pb and the risk of Chinese dyslexia, with the odds ratio (OR) in the highest quartiles of 6.81 (95%CI: 1.07-43.19; p-trend = 0.024). Co and Zn were negatively associated with the risk of Chinese dyslexia. Compared to the lowest quartile, the ORs of Co and Zn in the highest quartile are 0.13 (95%CI: 0.02-0.72; p-trend = 0.026) and 0.18 (95%CI: 0.04-0.88; p-trend = 0.038), respectively. In addition, BKMR-P analysis indicated that with the cumulative level across Co, Zn and Pb increased, the risk of Chinese dyslexia gradually declined and then rebounded, albeit non-significantly, and Pb was the major contributor in this association. In general, the urinary concentrations of Co, Zn and Pb were significantly associated with Chinese dyslexia. More prospective studies are needed to confirm the health effects of multiple metals exposure in children with Chinese dyslexia.

Effects of co-exposure to multiple metals on children's behavior problems in China

Exposure to single metals have been linked to childhood behavior problems, But little is known about the effects of metals mixtures on children. We aimed to evaluate associations of multiple metals exposures in urine with childhood behavior in China. For this population-based study, the children eligible for inclusion provided urine samples and their parents agreed to take in-person interview. A total of 831 children were remained from three cities for the final analysis. Urinary metals concentrations were measured by inductively coupled plasma mass spectrometry (ICP-MS). The childhood behavior scores was calculated by the Conners' Parent Rating Scale (CPRS). Variable selection was achieved by the least absolute shrinkage and selection operator (LASSO) regularization and stepwise regression to for all metals in the study. Linear regression models and Bayesian kernel machine regression (BKMR) were applied to estimate the associations of urinary metals concentrations with children's behavior. In BKMR models, the overall effect of mixture was significantly associated with conduct problems, learning problems and hyperactive index when urinary metals concentrations were all above the 50th percentile compared to all of them at their medians. The models also suggested marginally significant interaction effects of Se and Fe as well as Se and Sb (P_Se∗Fe = 0.063; P_Se∗Sb = 0.061), with a decline in estimate of Se on learning problems when Sb/Fe levels were relatively high. The concentrations of 22 metals in boys were higher than girls. In summary, multiple metals are associated with an increased risk of childhood behavioral problems in China. Potential interaction effects of Se and Fe as well as Se and Sb on childhood behavior should be taken into consideration.

Association between urinary dialkylphosphate metabolites and dyslexia among children from three cities of China: The READ program

Exposure to organophosphate (OP) insecticides has been found to be related to neurodevelopmental disorders in children. However, no study has examined the association between OP insecticide exposure and the risk of dyslexia among children. We aimed to explore the association between OP insecticide exposure, indicated by urinary dialkylphosphate metabolites (DAPs), and the risk of dyslexia among Chinese Han children from three cities. A total of 845 children (422 dyslexics and 423 non-dyslexics) from Tongji Reading Environment and Dyslexia research program were included in the current case-control study. We measured six DAPs in urine samples, collected from November 2017 to December 2020. Logistic regression models were used to estimate odds ratios (ORs) for the association between DAPs and dyslexia risk, adjusting for potential confounders. The detection frequencies of DAPs were above 97.5%, except for diethyldithiophosphate and dimethyldithiophosphate. Diethyl phosphate metabolites (DEs) were significantly associated with the risk of dyslexia. Compared with the lowest quartile, the adjusted ORs of dyslexia risk for the highest quartile of urinary diethylthiophosphate (DETP) and diethylphosphate (DEP) were 1.82 (1.04, 3.20) and 1.85 (1.08, 3.17), respectively. In addition, the adjusted ORs for dyslexia per 10-fold of urinary DEP, DETP, and ∑DEs concentration were 1.87 (1.12, 3.13), 1.55 (1.03, 2.35), and 1.91 (1.13, 3.21), respectively. Analyses stratified by gender indicated that such associations were more significant among boys. This study suggested that exposure to OP insecticides may be related to dyslexia among Chinese Han children from the three studied cities. However, our results should be interpreted with caution because of the case-control design and the fact that only one-spot urine sample was collected from the children. More studies with children living in China are necessary concerning the relatively high levels of urinary OP metabolites in our study.

Risk of neurodegeneration among residents of electronic waste recycling areas

The abnormal disposal process of electronic waste (e-waste) always emits a variety of toxic substances that enter the human body through various environmental media and can have many adverse health effects. Metals are thought to be inextricably linked to neurodegeneration. In the present study, we tried to explore the neurodegenerative status of subjects exposed to e-waste and the association between metal intake and neurodegeneration. We recruited the residents near the e-waste recycling area (the exposed group) and the residents without any e-waste contact history (the reference group) for a comparative study with detection and analysis of metals, biomarkers associated with neurodegeneration or oxidative stress (OS). The results showed that the metals between the reference and exposed group were significantly different. The concentrations of Brain-derived neurotrophic factor (BDNF) and β-amyloid protein 42 (Aβ42) in the exposed groups were significantly lower, while the levels of Euchromatic Histone lysine Methyltransferase 1 (EHMT1), Bromodomain Adjacent to Zinc finger domain 2B (BAZ2B) and Malondialdehyde (MDA) were significantly higher than in the reference groups. Although the ratio of Aβ42/Aβ40 had no statistical significance in the two groups, the medians of the ratio in the exposed group was lower than in the reference group. The linear regression and mediating effect analysis showed that MDA (OS) might mediate the effects of metals on EHMT1(pAg-MDA <0.001, pMDA-EHMT1 <0.05, pAg-EHMT1 <0.001). It could be inferred from the results of the present investigation that e-waste exposure had a high risk of neurodegeneration, especially Sliver (Ag) and Nickel (Ni).

Association between developmental dyslexia and anxiety/depressive symptoms among children in China: The chain mediating of time spent on homework and stress

BACKGROUND

The relationship between dyslexia and anxiety/depressive symptoms among children in China is unclear. Besides, the pathways to explain the risks are also undefined.

METHODS

3993 primary school students from grade 2 to 6 were recruited in this study. The Dyslexia Checklist for Chinese Children and the Pupil Rating Scale-Revised Screening for Learning Disabilities were used to filter the dyslexic children. The Chinese perceived stress scale, the Screen for Child Anxiety Related Emotional Disorders, and the Children's Depression Inventory-Short Form were used separately to assess stress, anxiety symptoms, and depressive symptoms of the children. Time spent on homework was obtained by asking their parents: "How long does it take the children to complete the homework every day?". The chain mediation models were examined using SPSS PROCESS macro 3.3 software.

RESULTS

Dyslexic children spend more time on homework (2.61±1.15), and have higher scores for depression (4.75±3.60) and stress (26.55±7.40) compared to normal children (1.87±0.77, 3.25±3.32, and 23.20±8.43, respectively). The differences are statistically significant (all P<0.01). There is no direct association between dyslexia and anxiety symptoms, while dyslexia has a direct link with depressive symptoms. Dyslexia could affect anxiety/depressive symptoms via the independent mediating effect of stress and the chain mediating effect of time spent on homework and stress. The total indirect effect is 0.21 and 0.25, respectively.

LIMITATIONS

The data used in our study is self-reported and this is a cross-sectional study.

CONCLUSIONS

Time spent on homework and stress could mediate the association between dyslexia and anxiety/depressive symptoms.

Association between urinary propylene oxide metabolite and the risk of dyslexia

Although it is a probable human carcinogen, propylene oxide is widely applied in industry and daily life. However, data on neurodevelopmental effects of propylene oxide exposure among children are extremely limited. We aimed to determine the urinary concentrations of propylene oxide metabolite among school-aged children and evaluate the potential association of propylene oxide exposure with risk of dyslexia. A total of 355 dyslexic children and 390 controls were recruited from three cities (Jining, Wuhan, and Hangzhou) in China, between 2017 and 2020. Urinary N-acetyl-S-(2-hydroxypropyl)-L-cysteine (i.e., 2-hydroxypropyl mercapturic acid; 2-HPMA) was measured as the biomarker of propylene oxide exposure. The detection frequency of 2-HPMA was 100%. After adjusting for potential confounders, the odds ratio (OR) for dyslexia per 2-fold increase in urinary 2-HPMA was 1.19 [95% confidence interval (95% CI): 1.01, 1.40, P = 0.042]. Compared with the lowest quartile of urinary 2-HPMA concentrations, children with the highest quartile of 2-HPMA had a 1.63-fold (95% CI: 1.03, 2.56, P = 0.036) significantly increased risk of dyslexia, with a dose-response relationship (P-trend = 0.047). This study provides epidemiological data on the potential association between propylene oxide exposure and the risk of dyslexia in children. Further studies are warranted to confirm the findings and reveal the underlying biological mechanisms.

Self-Concept in Primary School Student with Dyslexia: The Relationship to Parental Rearing Styles

Dyslexic children may be more likely to form a negative self-concept, especially with poor educational experiences and negative parenting. The purpose of the present study was to investigate the self-concept of Chinese dyslexic children in primary school, and explore the influence factors of self-concept as well as its relationship with parenting style. A total of 50 children with dyslexia and 50 non-dyslexics matched for age, grade and gender participated in the study. We used the Piers-Harris children's self-concept scale (PHCSS) and the Chinese version of Egna Minnen Beträffande Uppfostran for Children (EMBU-C) to evaluate the self-concept and parenting styles of the study population. Our results indicated that the academic competence, popularity and general self-concept in the dyslexic group were significantly lower than those in the control group (p < 0.05). Based on the multivariate linear regression, we also found that residence (β = -0.32, p < 0.05) and physical activity (β = 0.36, p < 0.01) may influence factors self-concept in dyslexic children. In addition, a moderate and positive correlation was found between the self-concept of physical appearance and maternal emotional warmth (r = 0.36, p < 0.05) by using the Spearman correlation analysis. Our outcomes suggested that children with dyslexia have a poorer self-concept than typical developing children. The self-concept of dyslexic children should be improved in order to achieve better physical and mental development.

The associations of zinc and GRIN2B genetic polymorphisms with the risk of dyslexia

BACKGROUND

Zinc is an essential trace element and a number of studies have identified the importance of zinc in neurodevelopment in children. However, epidemiologic data on the associations of zinc and genetic susceptibility with the risk of dyslexia are limited. We aimed to investigate whether genetic polymorphisms in GRIN2B genes modify the association between zinc levels and dyslexia risk.

METHODS

A case-control study of 240 dyslexic children and 230 healthy controls was conducted in Wuhan, Hangzhou and Jining city in China from April 2017 to April 2018. Zinc concentrations in urine samples were measured with inductively coupled plasma-mass spectrometry (ICPMS). Multiple imputation was used to impute missing values of covariates. We applied multivariable logistic regression models to evaluate the effect in the study.

RESULTS

After adjustment for potential confounders, we observed the associations of urinary zinc with dyslexia risk were modified by rs1805502 (P_interaction = 0.048) in gene GRIN2B. About 2-fold increase in creatinine-corrected zinc levels was significantly related to a reduced risk of dyslexia [odds ratio (OR) = 0.53, 95% confidence interval (CI): 0.29, 0.95 in rs1805502 mutation carriers].

CONCLUSIONS

The associations between zinc levels and dyslexia risk were modified by polymorphism of rs1805502 in gene GRIN2B.