Evaluation of Oxidative Metabolism in Child and Adolescent Patients with Attention Deficit Hyperactivity Disorder

Heavy Metal and Thiol/Disulfide in Children with Attention-Deficit and Hyperactivity Disorder

Background

In the etiology of attention-deficit and hyperactivity disorder (ADHD), oxidative stress and heavy metal exposure are still controversial topics. In this study, our goal was to examine heavy metal levels and oxidative balance in newly diagnosed patients with ADHD and reveal whether heavy metal levels have an effect on the oxidation balance.

Methods

The study included 35 patients with newly diagnosed ADHD and 31 healthy control groups of similar age and gender. Participants' parents or caregivers completed a semi-structured questionnaire regarding their children's breastfeeding and prenatal and postnatal smoking exposures. The levels of heavy metals lead (Pb), mercury (Hg), and cadmium were measured with inductively coupled plasma optical emission spectroscopy, and a unique automated spectrophotometric approach was used to quantify serum total thiol, native thiol, and disulfide quantities and ratios.

Results

The rate of smoking during pregnancy was significantly higher in the ADHD group than in the control group (P = .030). Compared to the control group, the native and total thiol levels of children with ADHD were significantly higher (P < .001). Likewise, the ADHD group had significantly higher Hg levels compared to the control group (P = .002). Cadmium levels were substantially greater in the control group compared to the ADHD group (P < .001). However, there was no significant difference between Pb levels in the ADHD and the control group (P = .844).

Conclusion

Exposure to Hg and prenatal smoking may contribute to the development of ADHD in childhood. In response to oxidative stress, the young brains of children with ADHD may enhance their antioxidant levels.

[Recent research on the role of oxidative stress in the pathogenesis of attention deficit hyperactivity disorder]

Attention deficit hyperactivity disorder (ADHD) is a common neurodevelopmental disorder in children and adolescents, and its etiology and pathogenesis are still unclear. Brain is the organ with the largest oxygen consumption in human body and is easily affected by oxidative imbalance. Oxidative stress has become the key research direction for the pathogenesis of ADHD, but there is still a lack of relevant studies in China. Based on the latest research findings in China and overseas, this article reviews the clinical and experimental studies on oxidative stress in ADHD and explores the association of oxidative stress with neurotransmitter imbalance, neuroinflammation, and cell apoptosis in the pathogenesis of ADHD, so as to provide new research ideas for exploring the pathogenesis of ADHD.

Changes in Cortisol and in Oxidative/Nitrosative Stress Indicators after ADHD Treatment

Although ADHD is one of the most prevalent diseases during childhood, we still do not know its precise origin; oxidative/nitrosative stress and the hypothalamic-pituitary-adrenal axis are suggested contributors. Methylphenidate, among others, is the main drug used in ADHD patients, but its effects on relevant markers and structures remain unclear. This study, involving 59 patients diagnosed with ADHD according to DSM-5 criteria, aimed to assess changes in cortisol levels (using cortisol awakening response, CAR) and oxidative/nitrosative status with the treatment. Blood samples before and 3 months after treatment with methylphenidate were used to measure oxidative and inflammatory markers, as well as the endogenous antioxidant activity, while saliva samples tracked cortisol awakening response (CAR). The results showed a treatment-related improvement in the redox profile, with the reduction in advanced oxidation protein products (AOPP), lipid peroxidation (LPO), and nitrite plus nitrate (NOx) levels, and the increase in the enzymatic activities of glutathione reductase (GRd) and catalase (CAT). Moreover, the area under the curve (AUC) of CAR increased significantly, indicating increased reactivity of the HPA axis. These results support, for the first time, the involvement of the endogenous antioxidant system in the pathophysiology of ADHD.

Comparison of Possible Changes in Oxidative Stress, DNA Damage, and Inflammatory Markers in Children/Adolescents Diagnosed with Sluggish Cognitive Tempo and Children/Adolescents Diagnosed with Attention-Deficit/Hyperactivity Disorder

Background: There has been a debate on whether sluggish cognitive tempo (SCT) differs from attention-deficit/hyperactivity disorder (ADHD). Although there have been many studies on metabolic parameters in relation to ADHD, no similar studies have been conducted on patients with SCT. We investigated whether there are differences between SCT and ADHD in terms of these factors. Subjects and Methods: Sixty-two participants with ages ranging from 11 to 18 who have diagnosis of ADHD (33 subjects) and SCT (29 subjects) were included in this study. The parents of all participants completed the 48-item Conners' Parent Rating Scale (CPRS) and the Barkley Child Attention Scale (BCAS) forms, and all participants' blood was taken to compare metabolic, oxidative stress, and antioxidant status of the SCT and ADHD groups. A child and adolescent psychiatrist interviewed the parents and children to assess the diagnosis of SCT and ADHD using standard diagnostic procedures. Results: In the comparison between the SCT and ADHD groups in terms of metabolic parameters, statistically significant differences were found in terms of total oxidant status, total antioxidant status, Oxidative Stress Index, total thiol, native thiol, disulfide, interleukin (IL)-1β, IL-6, and DNA damage (p < 0.05), but not in terms of tumor necrosis factor-α (p > 0.05). Conclusions: Our data showed that these two disorders may be different, but we believe that the data that indicate their differences remain inconclusive overall, but this study may be a potential pathway for future research.

The Effect of Drug Use, Body Mass Index and Blood Pressure on Oxidative Stress Levels in Children and Adolescents with Attention Deficit and Hyperactivity Disorder

Objective

The aim of this study was to determine the correlation between clinical variables such as body mass index, blood pressure, drug use and oxidative stress level in children and adolescents with attention deficit and hyperactivity disorder (ADHD).

Methods

Total oxidant status (TOS), total antioxidant status (TAS), oxidative stress index (OSI), malondialdehyde (MDA) and superoxide dismutase (SOD) activity were measured in the serum of 51 patients (38 male, 13 female) diagnosed with ADHD according to DSM-5 diagnostic criteria and 32 control subjects (12 male, 20 female). The Kiddie Schedule for Affective Disorders and Schizophrenia Present and Lifetime Version was applied to all participants.

Results

The mean TOS, OSI, MDA values were determined to be significantly higher (p < 0.001) and the mean SOD value was lower in the ADHD group (p < 0.001). Multivariate regression analysis indicated significantly lower SOD and diastolic blood pressure values and significantly higher MDA in the ADHD group compared to the control group (p < 0.01). Low SOD (sensitivity 90.2%, specificity 78.0%) and high MDA (sensitivity 86.3%, specificity 81.2%) were determined to be predictive parameters for diagnosing ADHD. In univariate analysis, the mean TOS, OSI and SOD values were higher in ADHD patients under medication, while the mean TAS was higher in patients not using medication (p < 0.01). Only TOS was significant in multivariate logistic regression analysis (p < 0.01).

Conclusion

The results of this study demonstrate that impaired oxidative balance may play a role in the etiology of ADHD.

ADHD – What Is the Meaning of Sex-dependent Incidence Differences?

There is a clear experience in clinical practice: boys with a diagnosis of ADHD are clearly in greater numbers than girls. It is noteworthy that even in the “older” review articles, the cause of sex-dependent incidence is not mentioned. If we accept the neurodevelopmental hypothesis of such disorder, then the possible genetic predisposition breaks down into two separate groups. On the genome of an individual with ADHD and on the genome of the parents. However, it cannot be overlooked that the incidence of ADHD (3–7%) corresponds to the incidence and sex differences of the number of newborns born at a certain risk (premature birth, immaturity, hypotrophy, hypoxic-ischemic syndrome, low birth weight, etc.). This association of possible genetic predisposition with “external” risks in the genesis of ADHD raises the question of whether a higher incidence of ADHD, as well as higher morbidity and mortality in males, are a) the norm and the female is privileged, or b) the female is the norm and the male is handicapped. The picture of ADHD includes various cognitive dysfunctions with one possible cause in norepinephrine and dopamine insufficiency. Experimental work shows that in response to stress females release more catecholamines in the CNS than males. Since catecholamines stimulate membrane Na+ K+ ATPase activity, this means both the value of the membrane potential and the threshold for activation is increased. Females are more successful in responding to and adapting to a stressful situation due to their higher production of noradrenaline in the CNS.

Effect of Vitamin D on Paraxonase-1, Total Antioxidant Capacity, and 8-Isoprostan in Children with Attention Deficit Hyperactivity Disorder

METHOD

In this double-blind, randomized, placebo-controlled trial, 75 children (aged 6-12) diagnosed with ADHD were randomly assigned into two groups. The supplementation group received vitamin D3 (2000 IU), and the control group received a placebo for 3 months. Blood samples were collected at baseline and after intervention to analyze the 25(OH)D, paraxonase-1 activity (PON-1), Total Antioxidant Capacity (TAC), and 8-isoprostan levels.

RESULTS

A significant rise in circulating 25(OH)D was observed in the vitamin D group versus the placebo group at the end of the study. There was no reduction in 8-isoprostan levels in the vitamin D group compared to the placebo group. Serum paraxonase-1 and TAC concentration decreased in both groups, but these alterations were not statistically significant in the treatment group versus the placebo group at the end of the intervention.

CONCLUSION

Vitamin D supplementation for 3 months did not have beneficial effects on biomarkers of oxidative stress status. To confirm these findings, further studies on children are suggested.

Elevated Melatonin Levels in Children With Attention Deficit Hyperactivity Disorder: Relationship to Oxidative and Nitrosative Stress

Objective: The aim of this article is to measure serum antioxidant melatonin, the oxidants of nitric oxide, and malondialdehyde levels to calculate the serum oxidant-antioxidant balance based on the nitric oxide/melatonin and malondialdehyde/melatonin ratios in children with ADHD. Method: The serum melatonin, nitric oxide, malondialdehyde, and the nitric oxide/melatonin and malondialdehyde/melatonin ratios were calculated and compared between the children with ADHD (n = 103) and healthy control participants (n = 73). Results: Serum melatonin and nitric oxide levels were higher, and the nitric oxide/melatonin and malondialdehyde/melatonin ratios were lower in ADHD children than the control group. Melatonin was found to be significantly high, and the malondialdehyde/melatonin ratio was found to be significantly low in children with a positive ADHD family history. Conclusion: The serum oxidant-antioxidant balance was impaired in children with ADHD. Within the ADHD group, higher melatonin levels were determined in the children with a positive family history.

Thiols and ceruloplasmin levels in serum of children with attention deficit hyperactivity disorder: A cross-sectional study

Attention deficit hyperactivity disorder (ADHD) is a childhood onset disorder with well-known findings that include impulsivity, hyperactivity, and inattention. This study aims to explore the relationship between the levels of ceruloplasmin, native thiol, total thiol, and disulfide and ADHD by comparing case and control groups. The study case group comprised 50 children aged 6-16 years who had been diagnosed with ADHD. The control group included 47 healthy children. Clinical interviews were conducted and the Schedule for Affective Disorders and Schizophrenia for School-Age Children-Present and Lifetime Version Turkish Adaptation and the Conners Parent Rating Scale were administered. Additionally, blood samples were taken and native thiol, total thiol, disulfide, and ceruloplasmin levels measured. In the ADHD group, the mean native thiol, total thiol, and disulfide levels were significantly lower than the control group. There was no significant difference between the ADHD and control groups in ceruloplasmin levels. Total thiol and native thiol levels were inversely correlated with scores on the Conners Inattention and Hyperactivity subscales; total thiol was negatively correlated with the ADHD index. Thiol-disulfide homeostasis was impaired in ADHD children and was related to symptom severity. Oxidative stress balance may play a role in ADHD.

Role of Oxidative Stress and Neuroinflammation in Attention-Deficit/Hyperactivity Disorder

Attention-deficit/hyperactivity disorder (ADHD) is a neurodevelopmental disorder of childhood. Although abnormalities in several brain regions and disturbances of the catecholaminergic pathway have been demonstrated, the pathophysiology of ADHD is not completely understood, but as a multifactorial disorder, has been associated with an increase in oxidative stress and neuroinflammation. This review presents an overview of factors that increase oxidative stress and neuroinflammation. The imbalance between oxidants and antioxidants and also the treatment with medications are two factors that can increase oxidative damage, whereas the comorbidity between ADHD and inflammatory disorders, altered immune response, genetic and environmental associations, and polymorphisms in inflammatory-related genes can increase neuroinflammation. Evidence of an association with these factors has become valuable for research on ADHD. Such evidence opens up new intervention routes for the use of natural products as antioxidants that could have potential as a treatment against oxidative stress and neuroinflammation in ADHD.

The Relationship Between Antioxidants and Inflammation in Children With Attention Deficit Hyperactivity Disorder

Introduction

Recent studies have identified Attention Deficit Hyperactivity Disorder (ADHD) as an inflammatory condition associated with immunological and oxidative responses. Therefore, it is necessary to examine these processes in these patients. The present study aimed at investigating the relationship between the dietary intake of antioxidants, Superoxide Dismutase (SOD) activity, and the serum levels of inflammatory factors in ADHD students.

Methods

This retrospective case-control study was conducted on 64 ADHD children aged 6 - 13 years. The demographic questionnaire, Food Frequency Questionnaire, and Baecke Physical Activity Questionnaire were used for data collection. SOD activity and the serum level of inflammatory factors (homocysteine, interleukin-6, and C-reactive Protein (CRP)) were measured in all patients. According to the CRP values, 32 patients were included in the case group (CRP≥1 mg/L) and 32 patients in the control group (0≤CRP<1 mg/L).

Results

There was no significant difference between the two groups in age, sex, weight, height, and body mass index. In the case group, the mean SOD activity (P=0.034), the physical activity (P=0.04), zinc intake (P=0.02), and homocysteine levels were higher than the control group (P=0.001). Of all studied variables, the best predictors were homocysteine (OR: 1.34, 95% CI: 1.082-1.670, P=0.029) and physical activity (OR: 0.85, 95% CI: 0.761-0.952, P=0.022) respectively, whereas other variables were not significant predictors.

Conclusion

The present study showed that the level of inflammatory factors in the case group was significantly higher than the control group. Homocysteine and physical activity can predict the inflammation status induced by CRP.

Oxidative stress and immune aberrancies in attention-deficit/hyperactivity disorder (ADHD): a case-control comparison

The objective of this study is to compare oxidative stress and immune biomarkers between attention-deficit/hyperactivity disorder (ADHD) patients and controls without ADHD. A case-control comparison between 57 paediatric (6-12 years) untreated ADHD patients from the Antwerp University Hospital and 69 controls without ADHD from random schools in Flanders, Belgium, was conducted. Erythrocyte glutathione (GSH) and plasma lipid-soluble antioxidants (retinol, α-tocopherol, γ-tocopherol, retinyl palmitate, β-carotene, and co-enzyme Q10) were determined by HPLC with electrochemical detection, plasma malondialdehyde (MDA) by HPLC with fluorescence detection, plasma cytokines (interleukin (IL)-1β, IL-5, IL-6, IL-8, IL-10, tumour necrosis factor (TNF) and interferon (INF)-γ) and immunoglobulins (IgE, IgG and IgM) by flow cytometry and urinary 8-hydroxy-2'deoxyguanosine (8-OHdG) levels by ELISA assay. Dietary habits were determined by a food frequency questionnaire. Plasma MDA levels were on average 0.031 µM higher in patients than in controls (p < 0.05), and a trend for higher urinary 8-OHdG was observed. Erythrocyte GSH and plasma retinyl palmitate levels, as well as IgG and IgE levels, were higher in patients than in controls as well (on average 93.707 µg/ml, 0.006 µg/ml, 301.555 µg/ml and 125.004 µg/ml, resp., p < 0.05). Finally, a trend for lower plasma IL-5 levels was observed. After Bonferroni correction for multiple testing, the difference in GSH levels remained statistically significant (nominally significant for retinyl palmitate), while significance was lost for MDA, IgG and IgE levels. Dietary habits do not appear to cause the observed differences. These results point at the potential involvement of slight oxidative stress and immune disturbances in ADHD.

Relationship between Antioxidant Status and Attention Deficit Hyperactivity Disorder Among Children

Background:

Attention deficit hyperactivity disorder (ADHD) is one of the prevalent neuropsychiatric disorders in childhood. In general, diagnoses of ADHD include inattention, hyperactivity, and impulsivity. Recent studies have reported increased oxidative stress in psychiatric disorders such as ADHD, but the results are conflicting. This research aimed to study the relationship between antioxidant status and ADHD in children of 6–13 years old.

Methods:

From schools, 32 ADHD students whose diseases were diagnosed by child and adolescence psychiatrist based on Diagnostic and Statistical Manual of Mental Disorders-IV index were recruited; moreover, 32 healthy subjects, which according to the medical history questionnaire of psychiatric disorder had not had chronic disease, were selected. Total antioxidant capacity (TAC), catalase (CAT), glutathione (GSH), and malondiadehyde (MDA) were measured. General information, health history, and medication history were collected. All participants completed a 168-item food frequency questionnaire. Dietary intakes of antioxidants were obtained through this questionnaire.

Results:

There was no significant difference between mean of energy intake and Zn, Se, vitamin E, C, and β-carotene as antioxidants between the two groups. The mean of serum TAC, GSH level, and CAT level in the patients were significantly lower than the healthy group (P < 0.001), but the mean of MDA was not significantly different between the two groups (P = 0.18).

Conclusions:

The result of this study indicates that, in ADHD, the serum levels of GSH, CAT, and TAC decrease; the level of antioxidant in the serum has been compromised to fight oxidative stress. More perspective studies with large sample sizes are essential to confirm these findings.

Prefrontal cortex dysfunction in hypoxic-ischaemic encephalopathy contributes to executive function impairments in rats: Potential contribution for attention-deficit/hyperactivity disorder

OBJECTIVES

The attention-deficit/hyperactivity disorder (ADHD) compromises the quality of life of individuals including adaptation to the social environment. ADHD aetiology includes perinatal conditions such as hypoxic-ischaemic events; preclinical studies have demonstrated attentional deficits and impulsive-hyperactive outcomes after neonatal hypoxic and/or ischaemic intervention, but data are missing to understand this relationship. Thus, the aim of this study was to evaluate executive function (EF) and impulsivity, and tissue integrity and dopaminergic function in the prefrontal cortex (PFC) of rats submitted to hypoxia-ischaemia (HI).

METHODS

At postnatal day (PND) 7, male Wistar rats were divided into control (n = 10) and HI groups (n = 11) and the HI procedure was conducted. At PND60, the animals were tested in the attentional set-shifting (ASS) task to EF and in the tolerance to delay of reward for assessment of impulsivity. After, morphological analysis and the dopaminergic system were evaluated in the PFC.

RESULTS

Animals subjected to HI had impairments in EF evidenced by a behavioural inflexibility that was correlated to PFC atrophy. Moreover, HI animals presented reduced D2 receptors in the ipsilateral side of ischaemia in the PFC.

CONCLUSIONS

Animals submitted to HI presented impaired EF associated with tissue atrophy and dopaminergic disturbance in the PFC.

Oxidative stress contribution to attention deficit hyperactivity disorder in children with epilepsy

Children with epilepsy have a high incidence of attention deficit hyperactivity disorder (ADHD). Oxidation stress and disturbed neurotransmitters are suggested mechanisms; however, their role is not fully explored. This study evaluates the association between circulating malondialdehyde as an oxidation stress marker, apelin neuropeptide, and ADHD in children with epilepsy. Fifty children with epilepsy of unknown etiology, of which 25 have ADHD, as well as 35 healthy children were included. Serum levels of malondialdehyde and apelin were estimated. We investigated the association between seizure severity, response to medications, malondialdehyde, apelin levels, and ADHD in children with epilepsy. Serum malondialdehyde and apelin levels were higher in children with epilepsy, especially those with ADHD. Malondialdehyde and apelin levels have significant positive correlation with the Chalfont Seizure Severity Score. Regression analysis showed that elevated malondialdehyde is an independent risk factor for ADHD in children with epilepsy (OR: 1.401, 95%CI: 1.056-1.859, p= 0.02). No significant association was found between malondialdehyde and apelin levels and the type of epilepsy or ADHD. Longer duration of epilepsy, increased seizure severity, and uncontrolled seizures are associated with increased oxidation stress, which further increased susceptibility for ADHD. In spite of elevated apelin in children with ADHD, the elevation did not increase the risk of ADHD in children with epilepsy.

Rationale for Dietary Antioxidant Treatment of ADHD

Increasing understanding arises regarding disadvantages of stimulant medication in children with ADHD (Attention-Deficit Hyperactivity Disorder). This review presents scientific findings supporting dietary antioxidant treatment of ADHD and describes substantial alterations in the immune system, epigenetic regulation of gene expression, and oxidative stress regulation in ADHD. As a result, chronic inflammation and oxidative stress could develop, which can lead to ADHD symptoms, for example by chronic T-cell-mediated neuroinflammation, as well as by neuronal oxidative damage and loss of normal cerebral functions. Therefore, modulation of immune system activity and oxidant-antioxidant balance using nutritional approaches might have potential in ADHD treatment. The use of natural antioxidants against oxidative conditions is an emerging field in the management of neurodegenerative diseases. Dietary polyphenols, for example, have antioxidant capacities as well as immunoregulatory effects and, therefore, appear appropriate in ADHD therapy. This review can stimulate the development and investigation of dietary antioxidant treatment in ADHD, which is highly desired.

Peripheral iron levels in children with attention-deficit hyperactivity disorder: a systematic review and meta-analysis

There is growing recognition that the risk of attention-deficit hyperactivity disorder (ADHD) in children may be influenced by micronutrient deficiencies, including iron. We conducted this meta-analysis to examine the association between ADHD and iron levels/iron deficiency (ID). We searched for the databases of the PubMed, ScienceDirect, Cochrane CENTRAL, and ClinicalTrials.gov up to August 9^th, 2017. Primary outcomes were differences in peripheral iron levels in children with ADHD versus healthy controls (HCs) and the severity of ADHD symptoms in children with/without ID (Hedges' g) and the pooled adjusted odds ratio (OR) of the association between ADHD and ID. Overall, seventeen articles met the inclusion criteria. Peripheral serum ferritin levels were significantly lower in ADHD children (children with ADHD = 1560, HCs = 4691, Hedges' g = -0.246, p = 0.013), but no significant difference in serum iron or transferrin levels. In addition, the severity of ADHD was significantly higher in the children with ID than those without ID (with ID = 79, without ID = 76, Hedges' g = 0.888, p = 0.002), and there was a significant association between ADHD and ID (OR = 1.636, p = 0.031). Our results suggest that ADHD is associated with lower serum ferritin levels and ID. Future longitudinal studies are required to confirm these associations and to elucidate potential mechanisms.

The interactions among organophosphate pesticide exposure, oxidative stress, and genetic polymorphisms of dopamine receptor D4 increase the risk of attention deficit/hyperactivity disorder in children

OBJECTIVE

The aim of this study was to clarify the association between organophosphate pesticides (OPs) and attention-deficit/hyperactivity disorder (ADHD) related to oxidative stress and genetic polymorphisms.

METHODS

This case-control study enrolled 93 children with ADHD and 112 control children in north Taiwan. Six dialkyl phosphate (DAP) metabolites of OPs and oxidative stress biomarkers were analyzed. Polymorphisms of the dopamine receptor D4 gene (DRD4) were identified.

RESULTS

Children with ADHD had significantly higher dimethylphosphate (DMP, 236.69nmol/g cre. vs. 186.84nmol/g cre., p value = 0.01) and 4-hydroxy-2-nonenal-mercapturic acid (HNE-MA, 28.95µg/g cre. vs. 16.55µg/g cre., p value<0.01) concentrations than control children. Children who carried DRD4 GA/AA genotypes (rs752306) were less likely than those who carried the DRD4 GG genotype to have ADHD (odds ratio [OR]: 0.45, 95% CI: 0.24-0.84). The estimated value of the AP (attributable proportion due to interaction) was 0.59 (95% CI: 0.13-1.05), indicating that 59% of ADHD cases in DMP-exposed children with the DRD4 GG genotype were due to the gene-environment interaction. After adjustment for other covariates, children who carried the DRD4 GG genotype, had been exposed to high DMP levels (more than the median), and had high HNE-MA levels had a significantly increased risk for developing ADHD (OR = 11.74, 95% CI: 2.12-65.04).

CONCLUSION

This study indicated a gene-environment interaction in the risk of ADHD in children. The association between DMP and ADHD in children might relate to the mechanism of lipid peroxidation. Dose-response relationships and the combined effects of OPs, oxidative stress, and genetic polymorphism on ADHD should not be neglected.

Gut microbiota and attention deficit hyperactivity disorder: new perspectives for a challenging condition

A bidirectional communication between the gut and the brain (gut-brain axis) is well recognized with the gut microbiota viewed as a key regulator of this cross-talk. Currently, a body of preclinical and to a lesser extent epidemiological evidence supports the notion that host-microbe interactions play a key role in brain development and function and in the etiology of neurodevelopmental disorders. Early life events and shifts away from traditional lifestyles are known to impact gut microbiota composition and function and, thereby, may increase the risk of developing neurodevelopmental disorders. Attention deficit hyperactivity disorder (ADHD) is nowadays the most prevalent neurodevelopmental disorder. Despite many years of research its etiology is unclear and its diagnosis and treatment are still challenging. Different factors reported to be associated with the risk of developing ADHD and/or linked to different ADHD manifestations have also been linked to shifts in gut microbiota composition, suggesting a link between the microbiota and the disorder. Evidence from preliminary human studies also suggests that dietary components that modulate gut microbiota may also influence ADHD development or symptoms, although further studies are warranted to confirm this hypothesis. Here, we firstly review the potential mechanisms by which the gut microbiota may regulate the brain-gut axis and influence behavior and neurodevelopmental disorders. Secondly, we discuss the current knowledge about the different factors and dietary components reported to be associated with the risk of developing ADHD or its manifestations and with shifts in gut microbiota composition. Finally, we briefly highlight the need to progress our understanding regarding the role of the gut microbiota in ADHD, since this could open new avenues for early intervention and improved management of the disease.

Dynamic thiol/disulfide homeostasis in children with attention deficit hyperactivity disorder and its relation with disease subtypes

BACKGROUND

The aim of this study was to evaluate a novel oxidative stress marker (thiol/disulfide homeostasis) in attention deficit hyperactivity disorder (ADHD) children for the first time in literature.

METHODS

Ninety children with ADHD diagnosed according to DSM-V and as control group, 65 healthy children were included to the study. Native thiol, total thiol, disulfide, disulfide/native thiol, disulfide/total thiol were compared between the groups.

RESULTS

Total and native thiol levels were significantly higher whereas the disulfide/native thiol ratios were significantly lower in children with ADHD. ADHD combined type appeared to have higher disulfide, disulfide/native thiol and disulfide/total thiol ratios compared to other subtypes. Disulfide levels of the males with ADHD were significantly higher than those of the females with ADHD.

CONCLUSION

This study suggests that thiol/disulfide homeostasis is abnormal in children with ADHD. It may be used as a novel OS marker in ADHD children because it is easy, practical, fully automated and relatively inexpensive.

Attention deficit-hyperactivity disorder suffers from mitochondrial dysfunction

Background

Pathophysiology of attention-deficit hyperactivity disorder (ADHD) is not known, and therefore the present study investigated mitochondrial defects, if any in cybrids created from patients and control population.

Methods

To investigate mitochondrial pathology in ADHD, cybrids cell lines were created from ADHD probands and controls by fusing their platelets with ρ⁰-cells prepared from SH-SY5Y neuroblastoma cell line. Cellular respiration, oxidative stress, mitochondrial membrane potential and morphology were evaluated employing oxygraph, mitochondria-specific fluorescence staining and evaluation by FACS, and immunocytochemistry. HPLC-electrochemical detection, quantitative RT-PCR and Blue Native PAGE were employed respectively for assays of serotonin, mitochondrial ATPase 6/8 subunits levels and complex V activity.

Results

Significantly low cellular and mitochondrial respiration, ATPase6/8 transcripts levels, mitochondrial complex V activity and loss of mitochondrial membrane potential and elevated oxidative stress were observed in ADHD cybrids. Expression of monoamine oxidizing mitochondrial enzymes, MAO-A and MAO-B levels remained unaffected. Two-fold increase in serotonin level was noted in differentiated cybrid-neurons.

Conclusions

Since cybrids are shown to replicate mitochondrial defects seen in post-mortem brains, these observed defects in ADHD cybrids strongly suggest mitochondrial pathology in this disorder.

General significance

Mitochondrial defects are detected in ADHD cybrids created from patients' platelets, implying bioenergetics crisis in the mitochondria could be a contributory factor for ADHD pathology and/or phenotypes.

A non-targeted metabolite profiling pilot study suggests that tryptophan and lipid metabolisms are linked with ADHD-like behaviours in dogs

BACKGROUND

Attention deficit hyperactivity disorder (ADHD) is a prevalent and multifactorial neuropsychiatric disorder in the human population worldwide. Complex etiology and clinical heterogeneity have challenged the research, diagnostics and treatment of the disease. Hyperactive and impulsive behaviour has also been observed in dogs, and they could offer a physiologically relevant model for human ADHD. As a part of our ongoing study to understand the molecular etiology of canine anxiety traits, this study was aimed to pilot an approach to identify metabolic biomarkers in canine ADHD-like behaviours for research, diagnostics and treatment purposes.

METHODS

We collected fresh plasma samples from 22 German Shepherds with varying ADHD-like behaviours. All dogs were on the same controlled diet for 2 weeks prior to sampling. A liquid chromatography combined with mass spectrometry (LC-MS)-based non-targeted metabolite profiling was performed to identify plasma metabolites correlating with the ADHD-like behaviour of the dogs.

RESULTS

649 molecular features correlated with ADHD-like behavioural scores (p_raw < 0.05), and three of them [sn-1 LysoPC(18:3), PC(18:3/18:2) and sn-1 LysoPE(18:2)] had significant correlations also after FDR correction (pFDR < 0.05). Phospholipids were found to negatively correlate with ADHD-like behavioural scores, whereas tryptophan metabolites 3-indolepropionic acid (IPA) and kynurenic acid (KYNA) had negative and positive correlations with ADHD-like behavioural scores, respectively.

CONCLUSIONS

Our study identified associations between canine ADHD-like behaviours and metabolites that are involved in lipid and tryptophan metabolisms. The identified metabolites share similarity with earlier findings in human and rodent ADHD models. However, a larger replication study is warranted to validate the discoveries prior to further studies to understand the biological role of the identified metabolites in canine ADHD-like behaviours.

Association of glutathione S-transferases M1, T1 and P1 gene polymorphisms with attention deficit and hyperactivity disorder in Korean children

Attention deficit and hyperactivity disorder (ADHD) is highly heritable disorder and common in school-age children characterized by inattention, hyperactivity and impulsivity. Although its heritability was estimated at 80-90% from family, adoption and twin studies, the molecular etiology of this disorder has not elucidated. Meanwhile, an impaired balance of oxidant-antioxidant status and increased oxidative stress is observed in ADHD, and it may imply a possible relationship between oxidative stress and etiology of ADHD. Glutathione S-transferase (GST) is antioxidant enzymes that play a key role in the cellular detoxification. In the present study, we examined the association between the genetic polymorphisms of GSTM1, GSTP1 and GSTT1, and ADHD in Korean children. Case-control study was conducted with 243 ADHD children and 327 controls. There were no significant associations between the polymorphisms and the incidence of ADHD (p>0.05). However, significant associations were observed in the stratified analyses. The frequency of GSTP1 Ile/Ile genotype is reached to the significant level in the hyperactivity subtype (88.2%) compared to controls (64.8%) (p=0.035) and the frequency of GSTT1-null genotype is significantly higher in the inattentive boys (p=0.005). Similarly, GSTT1-null genotype showed significant associations in combined subtype (p=0.016) and hyperactivity subtype (p=0.036) of the ADHD girls. Thus our result imply that the polymorphisms in the GST genes may affect ADHD, however, replication study for larger sample set and functional studies are crucial to confirm these findings.

Evaluation of oxidant, antioxidant, and S100B levels in patients with conversion disorder

INTRODUCTION

Various psychodynamic, neurobiological, genetic, and sociocultural factors are believed to be involved in the etiology of conversion disorder (CD). Oxidative metabolism has been shown to deteriorate in association with many health problems and psychiatric disorders. We evaluated oxidative metabolism and S100B levels in the context of this multifactorial disease.

METHODS

Thirty-seven patients with CD (25 females and 12 males) and 42 healthy volunteers (21 females and 21 males), all matched for age and sex, were included in this study. The total oxidant status, total antioxidant status, oxidative stress index, and S100B levels were compared between the two groups.

RESULTS

The total oxidant status, oxidative stress index, and S100B levels were significantly higher in patients with CD than in the control group, whereas the total antioxidant status was significantly lower.

CONCLUSION

CD is associated with deterioration of oxidative metabolism and increased neuronal damage.