Association between heavy metals exposure and risk of attention deficit hyperactivity disorder (ADHD) in children: a systematic review and meta-analysis

Heavy metals can negatively affect children's neurodevelopment, yet the relationship between heavy metals exposure and attention deficit hyperactivity disorder (ADHD) in children remains unclear. We aimed to examine associations between exposure to five common heavy metals (lead, arsenic, mercury, cadmium, and manganese) with neurodevelopmental toxicity and the risk of ADHD in children. Online databases of PubMed, Web of Science, and Embase were searched before February 29, 2024. A total of 31 studies involving 25,258 children were included in the final analysis. Our findings revealed that lead exposure was positively associated with ADHD risk in children (OR = 1.95, 95% CI: 1.57-2.41) overall, while the associations varied among different WHO regions, with the strongest in the Americas. Sensitivity analyses revealed significant associations between arsenic (OR = 1.53, 95% CI: 1.01-2.32) and manganese (OR = 1.79, 95% CI: 1.28-2.49) exposure and ADHD risk after omitting one study. Arsenic exposure was positively associated with ADHD risk in studies conducted in the Americas and adjusted for environmental smoke exposure. Positive associations between manganese exposure and ADHD risk were also found in several subgroup analyses. No significant associations were found for mercury and cadmium exposure. Dose-response meta-analysis suggested that children with higher blood lead levels exhibited a higher probability of ADHD diagnosis. Lead exposure consistently increases the risk of ADHD in children, while arsenic and manganese exposure may be associated with ADHD under different occasions. More research is required to understand heavy metals' impact on ADHD across varying exposure levels, particularly in less contaminated regions.

Vitamins B9 and B12 in children with attention deficit hyperactivity disorder (ADHD)

Background: Attention deficit hyperactivity disorder (ADHD) is a common childhood neurodevelopmental disorder that begins before age 12. Given the role of B group vitamins in cell metabolism, synthesis of nucleotides, and neurotransmitters, the present study systematically investigated the plasma levels of vitamins B9 and B12 in children with ADHD. Methods: We searched electronic databases including Web of Science, MEDLINE, EMBASE, Scopus, Iran MEDEX, Cochran database, and SID from conception to June 2023. Full-text case-control or cross-sectional studies were included in this study. Participants in the case group were children with ADHD aged 6-12 years. Review Manager Software (RevMan 5.4) was used for statistical analyses. Standardized mean differences (SMD) with 95% CIs were used to determine the differences between the two groups. Results: Six studies were included in the present meta-analysis. They included 982 children, of whom, 204 were girls and 744 were boys. The mean age of the children was 8.86±2.03 years. The level of vitamin B9 was significantly different between children with and without ADHD [SMD -0.80, 95% CI (-1.55, -0.04)]. Vitamin B12 was significantly lower in children with ADHD [SMD -0.29, 95% CI (-0.42, -0.16)]. However, due to high heterogeneity (I2 = 93%), sensitivity analysis was used, I2 fell to 21%, and significant difference was observed between the two groups [SMD -0.19, 95% CI (-0.34, -0.04)]. Conclusion: The results of this systematic review showed that the level of vitamins B9 and B12 in children with ADHD was significantly lower than that in healthy children.

The effects of chiropractic adjustment on inattention, hyperactivity, and impulsivity in children with attention deficit hyperactivity disorder: a pilot RCT

Background

Attention deficit hyperactivity disorder (ADHD) is a neurobiological disorder characterized by inattention, hyperactivity, and impulsivity. We hypothesized that chiropractic adjustments could improve these symptoms by enhancing prefrontal cortex function. This pilot study aimed to explore the feasibility and efficacy of 4 weeks of chiropractic adjustment on inattention, hyperactivity, and impulsivity in children with ADHD.

Methods

67 children with ADHD were randomly allocated to receive either chiropractic adjustments plus usual care (Chiro+UC) or sham chiropractic plus usual care (Sham+UC). The Vanderbilt ADHD Diagnostic Teacher Rating Scale (VADTRS), Swanson, Nolan and Pelham Teacher and Parents Rating Scale (SNAP-IV), and ADHD Rating Scale-IV were used to assess outcomes at baseline, 4 weeks, and 8 weeks. Feasibility measures such as recruitment, retention, blinding, safety, and adherence were recorded. Linear mixed regression models were used for data analysis.

Results

56 participants (mean age ± SD: 10.70 ± 3.93 years) were included in the analysis. Both the Chiro+UC and Sham+UC groups showed significant improvements in total and subscale ADHD scores at 4 weeks and 8 weeks. However, there were no significant differences between the two groups.

Conclusion

This pilot study demonstrated that it was feasible to examine the effects of chiropractic adjustment when added to usual care on ADHD outcomes in children. While both groups showed improvements, the lack of significant between-group differences requires caution in interpretation due to the small sample size. Further research with larger samples and longer follow-up periods is needed to conclusively evaluate the effects of chiropractic adjustments on ADHD in children.

The effect of long-term use of methylphenidate on cardiac autonomic functions and ventricular arrhythmogenesis: a prospective case-control study

OBJECTIVE

We aimed to assess cardiac autonomic balance with heart rate variability by using 24-hour Holter electrocardiography and also to assess susceptibility to ventricular arrhythmias by using microvolt T wave alternance in children with attention deficit hyperactivity disorder.

METHOD

This study was conducted with age- and gender-matched groups of 40 patients taking long-acting methylphenidate for more than a year and 55 healthy controls. Heart rate variability analysis for cardiac autonomic functions and microvolt T wave alternance measurements for susceptibility to ventricular arrhythmias were evaluated by 24-hour Holter electrocardiography.

RESULTS

The mean age 10.9 ± 2.7 years, mean duration of therapy 22.76 months, and mean methylphenidate doses were 37.64 mg/day. The study group had considerably higher rMSSD, higher HF, and a lower LF/HF ratio (respectively, p : 0.02, p : 0.001 and p : 0.01). While parasympathetic activity parameters were elevated, sympathetic activity parameters were low during the sleep period. Increase in the microvolt T wave alternance values of the study group was not found to be statistically significant (p > 0.05).

CONCLUSION

In children taking long-acting methylphenidate, the autonomic balance was shown to be in favour of the parasympathetic system. Determination of the vulnerability to life-threatening ventricular arrhythmias has been evaluated for the first time in children with attention deficit hyperactivity disorder. Accordingly, microvolt T-wave alternance values give the notion that drug use is safe.

Perceived Social Support on the Relationship Between ADD/ADHD and Both Anxious and Depressive Symptoms Among Canadian Adults

OBJECTIVE

The primary goal of the present research was to examine whether the relationships that social support demonstrates with both anxiety and depression varied between adults with and without ADD/ADHD in a Canadian sample.

METHOD

Data were obtained from the 2012 Canadian Community Health Survey-Mental Health (N ≥ 16,354). Presence of social support, diagnosis of generalized anxiety disorder (GAD), and experience of major depressive episodes (MDEs) were estimated in the self-report ADD/ADHD and non-ADD/ADHD groups.

RESULTS

Although social support was negatively associated with having GAD or experiencing an MDE, and self-report ADD/ADHD was positively associated with these outcomes. Presence of self-report ADD/ADHD did not significantly modify the relationships between social support and GAD or MDE.

CONCLUSION

Social support may be a protective factor against symptoms of anxiety and depression in the general Canadian population, for adults with and without ADHD.

Fronto-Cerebellar Neurometabolite Alterations After Methylphenidate in Children and Adolescents With ADHD: A Proton Magnetic Resonance Spectroscopy Study

OBJECTIVE

The fronto-cerebellar circuit is involved in ADHD pathophysiology. Methylphenidate, as a first-line medication for ADHD, affects different brain regions, however, its effect on the fronto-cerebellar circuit is not investigated sufficiently. We aimed to investigate the effect of 8-week treatment with methylphenidate on neurometabolite ratios in the fronto-cerebellar circuit in ADHD participants using magnetic resonance spectroscopy (MRS).

METHODS

Fifteen drug-naïve ADHD children and adolescents were enrolled in the present study. Two single-voxel MR spectra were acquired from the right dorsolateral prefrontal cortex (DLPFC) and left Crus 1, before and after the medication. Also, neuropsychological and behavioral assessments were administered.

RESULTS

After medication, the glutamate/creatine in the DLPFC and the choline/creatine in the Crus 1 decreased in the ADHD participants.

CONCLUSION

These findings propose that methylphenidate-induced metabolite changes in the fronto-cerebellar circuit could be associated with improvement in cognitive/behavioral characteristics in ADHD. Also, results highlighted cerebellar engagement in ADHD pathophysiology.

A Potential Role for Neuroinflammation in ADHD

Attention deficit hyperactivity disorder (ADHD) is a neurobehavioural disorder in children and adolescents. Although increases in oxidative stress and disturbances of neurotransmitter system such as the dopaminergic and abnormalities in several brain regions have been demonstrated, the pathophysiology of ADHD is not fully understood. Nevertheless, ADHD involves several factors that have been associated with an increase in neuroinflammation. This chapter presents an overview of factors that may increase neuroinflammation and play a potential role in the development and pathophysiology of ADHD. The altered immune response, polymorphisms in inflammatory-related genes, ADHD comorbidity with autoimmune and inflammatory disorders and prenatal exposure to inflammation are associated with alterations in offspring brain development and are a risk factor; genetic and environmental risk factors that may increase the risk for ADHD and medications can increase neuroinflammation. Evidence of an association between these factors has been an invaluable tool for research on inflammation in ADHD. Therefore, evidence studies have made it possible to generate alternative therapeutic interventions using natural products as anti-inflammatories that could have great potential against neuroinflammation in ADHD.

Attention-deficit/hyperactive disorder updates

Background

Attention-deficit/hyperactive disorder (ADHD) is a neurodevelopmental disorder that commonly occurs in children with a prevalence ranging from 3.4 to 7.2%. It profoundly affects academic achievement, well-being, and social interactions. As a result, this disorder is of high cost to both individuals and society. Despite the availability of knowledge regarding the mechanisms of ADHD, the pathogenesis is not clear, hence, the existence of many challenges especially in making correct early diagnosis and provision of accurate management.

Objectives

We aimed to review the pathogenic pathways of ADHD in children. The major focus was to provide an update on the reported etiologies in humans, animal models, modulators, therapies, mechanisms, epigenetic changes, and the interaction between genetic and environmental factors.

Methods

References for this review were identified through a systematic search in PubMed by using special keywords for all years until January 2022.

Results

Several genes have been reported to associate with ADHD: DRD1, DRD2, DRD4, DAT1, TPH2, HTR1A, HTR1B, SLC6A4, HTR2A, DBH, NET1, ADRA2A, ADRA2C, CHRNA4, CHRNA7, GAD1, GRM1, GRM5, GRM7, GRM8, TARBP1, ADGRL3, FGF1, MAOA, BDNF, SNAP25, STX1A, ATXN7, and SORCS2. Some of these genes have evidence both from human beings and animal models, while others have evidence in either humans or animal models only. Notably, most of these animal models are knockout and do not generate the genetic alteration of the patients. Besides, some of the gene polymorphisms reported differ according to the ethnic groups. The majority of the available animal models are related to the dopaminergic pathway. Epigenetic changes including SUMOylation, methylation, and acetylation have been reported in genes related to the dopaminergic pathway.

Conclusion

The dopaminergic pathway remains to be crucial in the pathogenesis of ADHD. It can be affected by environmental factors and other pathways. Nevertheless, it is still unclear how environmental factors relate to all neurotransmitter pathways; thus, more studies are needed. Although several genes have been related to ADHD, there are few animal model studies on the majority of the genes, and they do not generate the genetic alteration of the patients. More animal models and epigenetic studies are required.

Association between Individual Norepinephrine Transporter (NET) Availability and Response to Pharmacological Therapy in Adults with Attention-Deficit/Hyperactivity Disorder (ADHD)

Background: The role of the norepinephrine transporter (NET) has received increased focus in recent studies on the pathogenesis of attention-deficit/hyperactivity disorder (ADHD). The predictive value for pharmacological treatment and its link to other health or social limitations has been little-studied. This follow-up research on adult patients with ADHD aimed to explore whether the therapy response and health and social impairments depend on baseline individual NET availability. Methods: Data were collected from 10 patients on personal, family and professional situations, mental and physical health and treatments received after baseline via online and telephone surveys and were compared to baseline data to evaluate treatment-related changes. Results: The majority of our ADHD patients did not show therapy responses but showed improvements due to pharmacological treatment. There was no evidence of relationships between pre-treatment NET availability and therapy response or health/social limitations. Conclusions: Pharmacological monotherapy was insufficient to promote symptom remission, especially for participants with extreme insufficiency in NET availability, but improved outcomes in academic and social functioning. Psychotherapy should be considered as an add-on to the standard treatment approach due to its positive outcome in reducing social limitations. The prognostic value of individual NET availability in predicting the response to therapy needs further studies with large sample sizes.

Monitoring medication response in ADHD: what can continuous performance tests tell us?

Documenting effectiveness of ADHD medication is essential throughout the course of treatment. A rating scale and a continuous performance test (CPT) with motion tracking were used to study the effect of ADHD medication including compliance during one year. Children (N = 78, age 6-18 years) with ADHD were tested with the QbTest at baseline, visit 1 (1 month after baseline) and visit 5 (12 months after baseline). The ADHD-Rating scale was rated by investigator interview at the same visits. QbTest results and ADHD-RS ratings showed reductions in symptoms on all cardinal parameters of the QbTest and on all ADHD-RS subscales between baseline and 1 month and between baseline and 12 months. There was a weak but significant correlation between the total change scores on the two measures from baseline to 1 month. Eighteen participants dropped out of the study before visit 5; at baseline, these children showed significantly lower results on the inattention parameter of the QbTest, with faster reaction time and lower variation in reaction time, suggesting they suffered less problems with inattention. Both the QbTest and the ADHD-RS showed robust ADHD symptom improvements indicative of medication effect, and the QbTest results might also predict non-compliance of medication. Further research is warranted to increase knowledge about reliable monitoring of long-term medication and compliance.

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.

Maternal and cord plasma branched-chain amino acids and child risk of attention-deficit hyperactivity disorder: a prospective birth cohort study

BACKGROUND

Branched-chain amino acids (BCAA: leucine, isoleucine, and valine) are essential amino acids involved in biological functions of brain development and recently linked with autism. However, their role in attention-deficit hyperactivity disorder (ADHD) is not well-studied. We investigated individual and combined relationships of maternal plasma and newborn cord plasma BCAAs with childhood development of ADHD.

METHODS

We utilized the Boston Birth Cohort, a predominantly urban, low-income, US minority population. Child developmental outcomes were defined in three mutually exclusive groups - ADHD, neurotypical (NT), or other developmental disabilities based on physician diagnoses per ICD-9 or 10 in medical records. The final sample included 626 children (299 ADHD, 327 NT) excluding other developmental disabilities. BCAAs were measured by liquid chromatography-tandem mass spectrometry. We used factor analysis to create composite scores of maternal and cord BCAA, which we divided into tertiles. Logistic regressions analyzed relationships between maternal or cord BCAA tertiles with child ADHD risk, controlling for maternal race, age, parity, smoking, education, low birth weight, preterm birth, and child sex. Additionally, we analyzed maternal and cord plasma BCAAs jointly on child ADHD risk.

RESULTS

Adjusted logistic regression found significantly increased odds of child ADHD diagnosis for the second (OR 1.63, 95% CI: 1.04, 2.54, p = .032) and third tertiles (OR 2.01, 95% CI: 1.28, 3.15, p = .002) of cord BCAA scores compared to the first tertile. This finding held for the third tertile when further adjusting for maternal BCAA score. There was no significant association between maternal BCAA score and child ADHD risk, nor a significant interaction between maternal and cord BCAA scores.

CONCLUSIONS

In this prospective US birth cohort, higher cord BCAA levels were associated with a greater risk of developing ADHD in childhood. These results have implications for further research into mechanisms of ADHD development and possible early life screening and interventions.

Novel Potent Dopamine-Norepinephrine and Triple Reuptake Uptake Inhibitors Based on Asymmetric Pyran Template and Their Molecular Interactions with Monoamine Transporters

We have carried out a structural exploration of (2S,4R,5R)-2-(bis(4-fluorophenyl)methyl)-5-((4-methoxybenzyl)amino)tetrahydro-2H-pyran-4-ol (D-473) to investigate the influence of various functional groups on its aromatic ring, the introduction of heterocyclic aromatic rings, and the alteration of the stereochemistry of functional group on the pyran ring. The novel compounds were tested for their affinities for the dopamine transporter (DAT), serotonin transporter (SERT), and norepinephrine transporter (NET) in the brain by measuring their potency in inhibiting monoamine neurotransmitter uptake. Our studies identified some of the most potent dopamine-norepinephrine reuptake inhibitors known to-date like D-528 and D-529. The studies also led to development of potent triple reuptake inhibitors such as compounds D-544 and D-595. A significant influence from the alteration of the stereochemistry of the hydroxyl group on the pyran ring of D-473 on transporters affinities was observed indicating stereospecific preference for interaction. The inhibitory profiles and structure-activity relationship of lead compounds were further corroborated by molecular docking studies at the primary binding sites of monoamine transporters. The nature of interactions found computationally correlated well with their affinities for the transporters.

Predicting the Adult Clinical and Academic Outcomes in Boys With ADHD: A 7- to 10-Year Follow-Up Study in China

Background: Attention-deficit/hyperactivity disorder (ADHD) often persists into adulthood and causes adverse effects on social functioning. The present study aimed to widely investigate the predictors, particularly childhood intelligence quotient (IQ) and family environment factors, on adult clinical and academic outcomes in boys with ADHD. Methods: A total of 101 boys with ADHD in a Chinese Han ADHD cohort were followed up 7-10 years later. Baseline ADHD symptoms were evaluated using the parent version of the ADHD Rating Scale-IV (ADHD-RS-IV) and the Chinese version of the Conners' Parent Rating Scale-Revised (CPRS-48). The intelligence of the child was tested by the China-Wechsler Intelligence Scale for Children (C-WISC), and family function was assessed by the Family Environment Scale-Chinese Edition (FES-CV). Adult ADHD persistence was defined using DSM-IV criteria for ADHD, and academic outcome fell into two categories: higher academic level group (studying in senior middle school or above) and lower academic level group (studying in vocational secondary schools or below). Results: Stepwise multiple logistic regression analysis revealed that the father's character, impulsive-hyperactive index as measured by the CPRS-48, and intellectual-cultural index as measured by the FES-CV independently predicted clinical outcomes in adults, with an AUC of 0.770 (p < 0.001, 95% CI = 0.678-0.863). The corresponding sensitivity and specificity were 0.743 and 0.727, respectively. The father's education level, family economic level, and verbal IQ (VIQ) on the C-WISC independently predicted adult academic outcomes, with an AUC of 0.870 (p < 0.001, 95% CI = 0.796-0.944). The corresponding sensitivity and specificity were 0.813 and 0.783, respectively. Conclusion: Initial ADHD symptom severity and IQ, father's character and education level, and family atmosphere and function affect adult clinical and academic outcomes. Addressing these areas early may help to improve the prognosis of ADHD into adulthood.

Efficacy and safety of tipepidine as adjunctive therapy in children with attention-deficit/hyperactivity disorder: Randomized, double-blind, placebo-controlled clinical trial

AIM

This study evaluated the efficacy and safety of tipepidine as an add-on to methylphenidate in the drug treatment of attention-deficit/hyperactivity disorder (ADHD).

METHODS

This study was an 8-week, randomized, parallel group, double-blind, placebo-controlled trial recruiting 53 ADHD-diagnosed children. Patients were randomly divided to receive methylphenidate + tipepidine or methylphenidate + placebo for 8 weeks. Participants were assessed using the parent version of ADHD Rating Scale-IV and the Clinical Global Impression scale at baseline, at week 4, and at the end of the trial. Moreover, the safety and tolerability of the treatment strategies were compared.

RESULTS

On general linear model repeated measures analysis a significant effect was seen for time × treatment interaction on the total and hyperactivity-impulsivity subscales of the Parent ADHD Rating Scale-IV during the trial period (Greenhouse-Geisser corrected: F = 3.45, d.f. = 1.52, P = 0.049, and F = 5.17, d.f. = 1.52, P = 0.014, respectively). The effect for time × treatment interaction, however, was not significant on Clinical Global Impression-Severity scale (Greenhouse-Geisser corrected: F = 1.79, d.f. = 1.43, P = 0.182). The frequencies of adverse events were similar between the two groups.

CONCLUSION

Eight weeks of treatment with tipepidine, as a supplementary medication, resulted in satisfactory efficacy and safety of the adjuvant therapy in management of patients with ADHD. Rigorous investigations, however, involving larger sample sizes, more extended treatment periods, and dose responses should be considered.

Association of ADHD medications with the risk of cardiovascular diseases: a meta-analysis

This meta-analysis was conducted to evaluate the association between Attention deficit hyperactivity disorder (ADHD) medications and risk of sudden death/arrhythmia, stroke, myocardial infarction as well as all-cause death. We searched PubMed, Web of Science and China National Knowledge Infrastructure from 1950 to May 2018. All observational studies that the exposure of interest was ADHD medications, the outcome of interest was sudden death/arrhythmia, stroke, myocardial infarction as well as all-cause death, and the study reported relative risks (RRs) with 95% confidence intervals (95% CIs) were included. Pooled RRs were estimated by random-effects model. Subgroup analyses were conducted to examine the effects of study design, population, Country, follow-up duration, female proportion, covariates adjustment on the risk of sudden death/arrhythmia. Eight articles with ten studies (4,221,929 participants) were included in this meta-analysis about the association between ADHD medications and risk of sudden death/arrhythmia. The pooled RRs with 95% CIs of sudden death/arrhythmia for ADHD medications were 1.39 (1.06, 1.83). The result of the cohort study was 1.24 (0.84, 1.83). The pooled RRs between ADHD medications and stroke, myocardial infarction, all-cause death were 1.00 (0.74, 1.35), 0.91 (0.79, 1.05), 0.89 (0.54, 1.45), respectively. As for methylphenidate, the pooled RRs between methylphenidate and sudden death/arrhythmia, stroke, myocardial infarction, all-cause death were 1.46 (1.03, 2.07), 0.92 (0.70, 1.21), 0.97 (0.77, 1.23), 1.00 (0.49, 2.04), respectively. Based on the results of cohort studies, there was no correlation between ADHD medications and sudden death/arrhythmia, stroke, myocardial infarction and all-cause death. However, some of the confidence intervals do not exclude modest elevated risks, e.g., for sudden death/arrhythmia.

QuilliChew extended-release chewable tablets for the treatment of ADHD in patients ages 6 years old and above

INTRODUCTION

Attention-deficit/hyperactivity disorder (ADHD) is a common neurobehavioral disorder affecting as many as 6.4 million children and adolescents in the United States. Since amphetamine (AMPH) and methylphenidate (MPH) were found to be effective more than 60 years ago, numerous formulations of these compounds have been developed. New preparations have focused on convenience, with extended-release (ER) drugs allowing once-daily dosing. Multiple ER formulations do not require patients to swallow a tablet or capsule. Recent ER preparations include liquids, oral disintegrating tablets, and chewable tablets. Several new formulations use ion exchange technology containing both immediate-release and ER components. Areas covered: Quillichew ER^TM (MPH-ERCT) is an ER methylphenidate designed to be chewed before swallowing. The technology and pharmacokinetics, along with efficacy and safety data, are presented. Expert opinion: Extensive safety and efficacy data exist for MPH. ER formulations can be distinguished by preparation (tablet, capsule, liquid) and onset and duration of effect, but efficacy is similar for all ER MPH products. Each formulation has attributes, such as ease of titration, portability, and taste, that make it more acceptable for certain patients. Because AMPH and MPH are so effective, current technology research is focused on improving safety, convenience, and onset and duration of effect.

Relative Bioavailability of Methylphenidate Extended-release Chewable Tablets Chewed Versus Swallowed Whole

PURPOSE

Methylphenidate hydrochloride extended-release chewable tablet (MPH ERCT) is approved for treatment of attention deficit hyperactivity disorder in patients aged 6 years and older. This article evaluates the pharmacokinetic parameters and relative bioavailability of MPH ERCT when chewed versus swallowed whole.

METHODS

In this open-label, single-dose, 3-period, 3-treatment crossover study, 12 healthy adult volunteers were randomly assigned to treatment sequence. In each period, subjects received a single 40-mg dose of the assigned treatment (MPH ERCT chewed, MPH ERCT swallowed whole, or methylphenidate extended-release oral suspension [MEROS]). Blood samples for pharmacokinetic analysis were collected for 24 hours postdose. Key pharmacokinetic parameters included C_max, AUC_0-t, and AUC_0-∞.

FINDINGS

The geometric mean values for AUC_0-t, AUC_0-∞, and C_max were similar for MPH ERCT chewed, MPH ERCT swallowed whole, and MEROS. In all pairwise between-treatment comparisons, the 90% CIs of the geometric mean ratios for AUC_0-t, AUC_0-∞, and C_max were fully contained within the bioequivalence range of 80% to 125%. Early exposure over the first 4 hours after dosing (AUC_0-4) was similar for MPH ERCT chewed versus swallowed whole; AUC_0-4 was approximately 15% lower for MPH ERCT, either chewed or swallowed, compared with MEROS. Each treatment was generally well tolerated.

IMPLICATIONS

There was no difference in overall rate or extent of exposure of methylphenidate when MPH ERCT was chewed versus swallowed whole by healthy volunteers.

A Prospective Birth Cohort Study on Maternal Cholesterol Levels and Offspring Attention Deficit Hyperactivity Disorder: New Insight on Sex Differences

Growing evidence suggests that maternal cholesterol levels are important in the offspring’s brain growth and development. Previous studies on cholesterols and brain functions were mostly in adults. We sought to examine the prospective association between maternal cholesterol levels and the risk of attention deficit hyperactivity disorder (ADHD) in the offspring. We analyzed data from the Boston Birth Cohort, enrolled at birth and followed from birth up to age 15 years. The final analyses included 1479 mother-infant pairs: 303 children with ADHD, and 1176 neurotypical children without clinician-diagnosed neurodevelopmental disorders. The median age of the first diagnosis of ADHD was seven years. The multiple logistic regression results showed that a low maternal high-density lipoprotein level (≤60 mg/dL) was associated with an increased risk of ADHD, compared to a higher maternal high-density lipoprotein level, after adjusting for pertinent covariables. A “J” shaped relationship was observed between triglycerides and ADHD risk. The associations with ADHD for maternal high-density lipoprotein and triglycerides were more pronounced among boys. The findings based on this predominantly urban low-income minority birth cohort raise a new mechanistic perspective for understanding the origins of ADHD and the gender differences and future targets in the prevention of ADHD.

Diagnosis and treatment of attention deficit hyperactivity disorder

Attention-deficit hyperactivity disorder (ADHD) is a neurobehavioral disorder characterized by signs and symptoms of inattention, hyperactivity, and impulsivity that typically begin in childhood. ADHD can persist into adulthood, causing impairments in occupational performance and peer and family relationships. This article reviews the epidemiology, diagnosis, and treatment of ADHD.

Pure Autonomic Failure

Pure autonomic failure (PAF) is a rare sporadic neurodegenerative autonomic disorder characterized by slowly progressive pan autonomic failure without other features of neurologic dysfunctions. The main clinical symptoms result from neurogenic orthostatic hypotension and urinary and gastrointestinal autonomic dysfunctions. Autonomic failure in PAF is caused by neuronal degeneration of pre- and postganglionic sympathetic and parasympathetic neurons in the thoracic spinal cord and paravertebral autonomic ganglia. The presence of Lewy bodies and α-synuclein deposits in these neural structures suggests that PAF is one of Lewy body synucleinopathies, examples of which include multiple system atrophy, Parkinson disease, and Lewy body disease. There is currently no specific treatment to stop progression in PAF. Management of autonomic symptoms is the mainstay of treatment and includes management of orthostatic hypotension and supine hypertension. The prognosis for survival of PAF is better than for the other synucleinopathies.

Association of Attention Deficit Hyperactivity Disorder and Autism Spectrum Disorders with Mean Platelet Volume and Vitamin D

BACKGROUND The purpose of this study was to assess the values of the mean platelet volume (MPV) in children with attention deficit hyperactivity disorder (ADHD) and with autism spectrum disorders (ASDs) to determine the risk of cardiovascular disease in these 2 disorder groups. MATERIAL AND METHODS The study included a total of 79 patients with ADHD or ASDs and controls in the Van region of Turkey. The control group included subjects of matching age and sex with no ADHD, ASDs, or chronic disease and taking no vitamins. The hematological parameters of the patients, including MPV, vitamin B12, and vitamin D, were assessed. RESULTS The study included a total of 79 children and adolescents aged 2-18 years (32 females and 47 males). Of the patients, 36 were in the ADHD group, 18 in the ASDs group, and 25 in the control group. There was no statistically significant difference in hematological parameters between the groups, but there were significant differences in terms of vitamin D and vitamin B12. The patient groups showed lower levels of vitamin B12 and vitamin D. In the ADHD group, there was a negative correlation between both vitamins and MPV (p<0.05). Partial correlation analysis of the ADHD group showed that MPV in particular was negatively correlated to vitamin D, and not to vitamin B12 (p: 0.03). CONCLUSIONS Both ADHD and ASDs may accompany increased risk for cardiovascular disease due to the presence of vitamin B12 and D deficiency and their own characteristics. Therefore, these disorders should be closely followed up.

Exposure-response analyses of blood pressure and heart rate changes for methylphenidate in healthy adults

The aim of the study was to evaluate the exposure-response (E-R) relationships of blood pressure (BP) and heart rate (HR) changes in healthy adults taking methylphenidate (MPH). Intensive time profiles of BP and HR from healthy adults in placebo and MPH treatment arms of seven clinical trials from the FDA internal database were utilized for this analysis. The analysis model contains a circadian component for placebo effect and an E-R component to describe drug effect. Internal validation was performed using goodness-of-fit plots and visual predictive check. A meta-database based on a systemic literature search was constructed and used for external validation of the developed models. We found that circadian models could quantify the time profiles of BP/HR in placebo arms. Linear models could describe the correlations between MPH concentrations, and BP/HR changes. The BP and HR changes were highly dependent on the shapes of MPH pharmacokinetic (PK) profiles without an apparent time delay. MPH has the greatest effect on HR, followed by systolic BP, and diastolic BP. Internal validation revealed that the developed models could adequately describe the circadian rhythms of HR and BP in placebo arms and the E-R relationships of MPH. External validation showed the models had good predictive capability of the literature data. In conclusion, the developed models adequately characterized the circadian rhythm and the MPH induced effects on BP and HR. The changes in BP and HR were highly correlated with MPH blood levels with no apparent delay. The time courses of BP and HR are similar to the MPH PK profiles. As a result, the immediate-release formulation may yield larger maximum BP and HR effect than the extended-release formulation under similar dose.

Differential roles for cortical versus sub-cortical noradrenaline and modulation of impulsivity in the rat

RATIONALE

Atomoxetine is a noradrenaline re-uptake inhibitor licensed for the treatment of adult and childhood attention deficit hyperactivity disorder. Although atomoxetine has established efficacy, the mechanisms which mediate its effects are not well understood.

OBJECTIVES

In this study, we investigated the role of cortical versus sub-cortical noradrenaline by using focal dopamine beta hydroxylase-saporin-induced lesions, to the prefrontal cortex (n = 16) or nucleus accumbens shell (n = 18).

METHODS

Healthy animals were tested by using the forced-choice serial reaction time task to assess the impact of the lesion on baseline performance and the response to atomoxetine and the psychostimulant amphetamine.

RESULTS

We observed attenuation in the efficacy of atomoxetine in animals with lesions to the nucleus accumbens shell, but not the prefrontal cortex. Amphetamine-induced increases in premature responses were potentiated in animals with lesions to the prefrontal cortex, but not the nucleus accumbens shell.

CONCLUSIONS

These data suggest that noradrenaline in the nucleus accumbens shell plays an important role in the effects of atomoxetine. Under these conditions, prefrontal cortex noradrenaline did not appear to contribute to atomoxetine's effects suggesting a lack of cortical-mediated "top-down" modulation. Noradrenaline in the prefrontal cortex appears to contribute to the modulation of impulsive responding in amphetamine-treated animals, with a loss of noradrenaline associated with potentiation of its effects. These data demonstrate a potential dissociation between cortical and sub-cortical noradrenergic mechanisms and impulse control in terms of the actions of atomoxetine and amphetamine.

Hormone disorder and vitamin deficiency in attention deficit hyperactivity disorder (ADHD) and autism spectrum disorders (ASDs)

BACKGROUND

The aim of this study was to analyze thyroid hormones and antibodies, ferritin, vitamins B12 and D, adrenal and gonadal steroid levels, and celiac antibodies in children diagnosed with attention deficit hyperactivity disorder (ADHD) and autism spectrum disorder (ASD).

METHODS

Between February 2014 and July 2014, a total of 77 children and adolescents (31 girls, 46 boys) who were admitted to the Van Training and Research Hospital were included in the study. The study population was divided into three groups including ADHD (n=34), ASD (n=16), and age- and sex-matched healthy controls (n=27). The diagnosis of ADHD was made on the basis of Diagnostic and Statistical Manual of Mental Disorders - Fifth Edition (DSM-5) and DSM-4 Turkish version with the diagnostic interview and Disruptive Behavior Disorder Rating Scale (DBDRS). The diagnosis of ASD was based on the DSM-4 and DSM-5 Turkish version with the diagnostic interview and the Childhood Autism Rating Scale (CARS). The blood samples were obtained between 8:00 and 9:00 A.M.

RESULTS

There was a statistically significant difference in vitamin B12 and D levels and ferritin values among the three groups. The ASD group had the highest ferritin and the lowest vitamins B12 and D levels. Vitamin D levels of the ADHD group were significantly lower compared to the healthy controls.

CONCLUSIONS

Our study results highlight the importance of supplementation of vitamins B12 and D in the ASD and ADHD patients.

Single-dose Pharmacokinetic Properties and Relative Bioavailability of a Novel Methylphenidate Extended-release Chewable Tablet Compared With Immediate-release Methylphenidate Chewable Tablet

PURPOSE

A novel methylphenidate hydrochloride extended-release chewable tablet (MPH ERCT) was developed to potentially address an unmet need for patients with attention-deficit/hyperactivity disorder, especially children, who cannot or will not swallow tablets or would prefer the convenience of a chewable tablet. This randomized, open-label, crossover trial compared the pharmacokinetic properties and relative bioavailability of MPH ERCT with an MPH chewable immediate-release tablet (IR MPH) formulation in healthy adults.

METHODS

Healthy men and women 18 to 55 years of age were randomly assigned to MPH ERCT 40 mg or 40 mg IR MPH administered in 2 equal doses of 20 mg 6 hours apart with a 7-day washout period. Plasma concentrations of MPH at selected time points up to 24 hours were measured, and pharmacokinetic parameters were determined using a noncompartmental approach in the SAS (Version 9.2) PROC general linear model procedure.

FINDINGS

A total of 33 participants were enrolled in the study; 31 participants were included in the pharmacokinetic analysis. The exposure ratios for MPH ERCT and IR MPH (MPH ERCT/IR MPH) for area under the analyte concentration versus time curves (AUC) from time zero to the last measurable analyte concentration (AUC0-last) (87.64%; 95% CI, 84.96-90.41) and AUC0-∞ (89.11%; 95% CI, 86.57-91.73) were within the standard 80% to 125% bioequivalence acceptance criteria. Mean Cmax for MPH ERCT and IR MPH was 12.51 ng/mL and 15.57 ng/mL, respectively; mean time to Cmax was 4.16 hours and 6.43 hours, respectively. The mean Cmax of MPH ERCT was 80% of the Cmax of IR MPH due to a higher peak concentration that occurs after the second dose of IR MPH. All adverse events were mild in severity.

IMPLICATIONS

The relative bioavailability of MPH ERCT 40 mg, based on the exposure (AUC), was comparable to that of IR MPH 40 mg administered in 2 equal doses of 20 mg 6 hours apart. Both formulations were generally well tolerated.

The impact of a model-based clinical regional registry for attention-deficit hyperactivity disorder

This article describes the development and clinical impact of the Italian Regional ADHD Registry, aimed at collecting and monitoring diagnostic and therapeutic pathways of care for attention-deficit hyperactivity disorder children and adolescents, launched by the Italian Lombardy Region in June 2011. In particular, the model-based software used to run the registry and manage clinical care data acquisition and monitoring, is described. This software was developed using the PROSAFE programme, which is already used for data collection in many Italian intensive care units, as a stand-alone interface case report form. The use of the attention-deficit hyperactivity disorder regional registry led to an increase in the appropriateness of the clinical management of all patients included in the registry, proving to be an important instrument in ensuring an appropriate healthcare strategy for children and adolescents with attention-deficit/hyperactivity disorder.

The Association of SNAP25 Gene Polymorphisms in Attention Deficit/Hyperactivity Disorder: a Systematic Review and Meta-Analysis

Attention deficit/hyperactivity disorder (ADHD) is one of the most highly heritable psychiatric disorders in childhood. The risk gene mutation accounts for about 60 to 90 % cases. Synaptosomal-associated protein of 25 kDa (SNAP-25) is a presynaptic plasma membrane protein which is expressed highly and specifically in the neuronal cells. A number of evidences have suggested the role of SNAP-25 in the etiology of ADHD. Notably, the animal model of coloboma mouse mutant bears a ∼2-cM deletion encompassing genes including SNAP25 and displays spontaneous hyperkinetic behavior. Previous investigators have reported association between SNPs in SNAP25 and ADHD, and controversial results were observed. In this study, we analyzed the possible association between six polymorphisms (rs3746544, rs363006, rs1051312, rs8636, rs362549, and rs362998) of SNAP25 and ADHD in a pooled sample of ten family-based studies and four case-control studies by using meta-analysis. The combined analysis results were significant only for rs3746544 (P = 0.010) with mild association (odds ratio (OR) = 1.14). And, the meta-analysis data for rs8636, rs362549, and rs362998 are the first time to be reported; however, no positive association was detected. In conclusion, we report some evidence supporting the association of SNAP25 to ADHD. Future research should emphasize genome-wide association studies in more specific subgroups and larger independent samples.

Stress weakens prefrontal networks: molecular insults to higher cognition

A variety of cognitive disorders are worsened by stress exposure and involve dysfunction of the newly evolved prefrontal cortex (PFC). Exposure to acute, uncontrollable stress increases catecholamine release in PFC, reducing neuronal firing and impairing cognitive abilities. High levels of noradrenergic α1-adrenoceptor and dopaminergic D1 receptor stimulation activate feedforward calcium-protein kinase C and cyclic AMP-protein kinase A signaling, which open potassium channels to weaken synaptic efficacy in spines. In contrast, high levels of catecholamines strengthen the primary sensory cortices, amygdala and striatum, rapidly flipping the brain from reflective to reflexive control of behavior. These mechanisms are exaggerated by chronic stress exposure, where architectural changes lead to persistent loss of PFC function. Understanding these mechanisms has led to the successful translation of prazosin and guanfacine for treating stress-related disorders. Dysregulation of stress signaling pathways by genetic insults likely contributes to PFC deficits in schizophrenia, while age-related insults initiate interacting vicious cycles that increase vulnerability to Alzheimer's degeneration.

Systematic review of the epidemiology of attention deficit hyperactivity disorder in Arab countries

Objective:

To assess the epidemiology of attention deficit hyperactivity disorder (ADHD) in Arab countries, and identify gaps for future research.

Methods:

We searched PubMed from July 1978 to July 2014 and reviewed local journals with cross-referencing. The keywords we used were ADHD, diagnosis, prevalence, incidence, factor, diagnosis, rate, risk, and each of the names of the 22 Arab countries (Jordan, Egypt, Lebanon, Saudi Arabia, and so on). Studies were eligible for inclusion if they investigated the epidemiology of ADHD in any Arab country, and were published in English. The search was conducted from 2nd to 5th August 2014 in King Saud Bin Abdulaziz University for Health Sciences, Riyadh, Saudi Arabia.

Results:

A total of 22 articles were included in the review. Twenty studies were cross-sectional and found the prevalence of ADHD ranged between 1.3-16%, prevalence of hyperactive type ADHD between 1.4-7.8%, and the prevalence of inattention type between 2.1-2.7%. Only 2 case-control studies investigated potential risk factors. Evidence extracted from these studies shows a significant association between ADHD and male gender, previous psychiatric illness in the family, vitamin D deficiency, poor school performance, sleep problems, and nocturnal enuresis.

Conclusion:

The prevalence of ADHD in Arab countries is comparable to reports in North America, Africa, and other countries of the Middle East. Longitudinal studies are needed to investigate the prognosis and determinants of this condition in the Arab world.

Association between mobile phone use and inattention in 7102 Chinese adolescents: a population-based cross-sectional study

BACKGROUND

The dramatic growth of mobile phone (MP) use among young people has increased interest in its possible health hazards in this age group. The aim of this cross-sectional study was to investigate the association between MP use and inattention in adolescents.

METHODS

A total of 7720 middle school students were involved in this cross-sectional study. Inattention was assessed as defined for the Attention Deficit component of Attention deficit/Hyperactivity disorder (ADHD) by the Diagnostic and Statistical Manual of Mental Disorders (4th ed., text rev. [DSM-IV-TR]). The demographic characteristics and information on MP use were included in the questionnaire. Chi-square tests and logistic regression models were used to analyze the data.

RESULTS

In total, 7102 (91.99%) valid questionnaires were obtained. After adjusted for confounders, inattention in adolescents was significantly associated with MP ownership, the time spent on entertainment on MP per day, the position of the MP during the day and the mode of the MP at night. The strongest association between inattention and the time spent on the MP was among students who spent more than 60 minutes per day playing on their MP.

CONCLUSIONS

Our study shows some associations between MP use and inattention in Chinese adolescents. Decreasing MP usage to less than 60 minutes per day may help adolescents to stay focused and centered.

Is high prevalence of vitamin D deficiency a correlate for attention deficit hyperactivity disorder?

The aim of the study was to determine the association between vitamin D and attention deficit hyperactivity disorder (ADHD), and difference in the level of vitamin D in ADHD children and control. This a case-control study carried out in school health and primary health care clinics. A total of 1,331 children and adolescents who were diagnosed with ADHD based on clinical criteria and standardized questionnaires were enrolled in this study and were matched with 1,331 controls, aged 5-18 years old. Data on body mass index (BMI), clinical biochemistry variables including serum 25-hydroxyvitamin D were collected. The study found significant association between ADHD and vitamin D deficiency after adjusting for BMI and sex (adj. OR 1.54; 95 % CI 1.32-1.81; P < 0.001). Majority of the ADHD children were in the age group 5-10 years (40.7 %), followed by 11-13 years (38.4 %). The proportion of BMI <85th percentile was significantly over represented in ADHD group as compared to healthy control (87.8 vs. 83 %; P < 0.001, respectively), while on the other hand, BMI >95th percentile was over represented in the control than ADHD group (7.6 vs. 4.6 %; P < 0.001, respectively). Mean values of vitamin D (ng/mL) were significantly lower in ADHD children (16.6 ± 7.8) than in healthy children (23.5 ± 9.0) (P < 0.001). There was significant correlation between vitamin D deficiency and age (r = -0.191, P = 0.001); calcium (r = 0.272, P = 0.001); phosphorous (r = 0.284, P = 0.001); magnesium (r = 0.292, P = 0.001); and BMI (r = 0.498, P = 0.001) in ADHD children. The vitamin D deficiency was higher in ADHD children compared to healthy children.

A Review of the Pathophysiology, Etiology, and Treatment of Attention-Deficit Hyperactivity Disorder (ADHD)

Objective: To review the pathophysiology, etiology, and treatment of attention-deficit hyperactivity disorder (ADHD). Data Sources and Data Extraction: A literature search was conducted in PubMed and EMBASE using the terms attention deficit hyperactive disorder, ADHD, pathophysiology, etiology, and neurobiology. Limits applied were the following: published in the past 10 years (January 2003 to August 2013), humans, review, meta-analysis, and English language. These yielded 63 articles in PubMed and 74 in EMBASE. After removing duplicate/irrelevant articles, 86 articles and their relevant reference citations were reviewed. Data Synthesis: ADHD is a neurological disorder that affects children, but symptoms may persist into adulthood. Individuals suffering from this disorder exhibit hyperactivity, inattention, impulsivity, and problems in social interaction and academic performance. Medications used to treat ADHD such as methylphenidate, amphetamine, and atomoxetine indicate a dopamine/norepinephrine deficit as the neurochemical basis of ADHD, but the etiology is more complex. Moreover, these agents have poor adverse effect profiles and a multitude of drug interactions. Because these drugs are also dispensed to adults who may have concomitant conditions or medications, a pharmacist needs to be aware of these adverse events and drug interactions. This review, therefore, focuses on the pathophysiology, etiology, and treatment of ADHD and details the adverse effects and drug interaction profiles of the drugs used to treat it. Conclusions: Published research shows the benefit of drug therapy for ADHD in children, but given the poor adverse effect and drug interaction profiles, these must be dispensed with caution.

Effects of norepinephrine reuptake inhibition on postural tachycardia syndrome

Background

Postural tachycardia syndrome (POTS) is a disorder of chronic orthostatic intolerance accompanied by excessive orthostatic tachycardia. Patients with POTS commonly have comorbid conditions such as attention deficit hyperactivity disorder, depression, or fibromyalgia that are treated with medications that inhibit the norepinephrine reuptake transporter (NRI). NRI medications can increase sympathetic nervous system tone, which may increase heart rate (HR) and worsen symptoms in POTS patients. We sought to determine whether NRI with atomoxetine increases standing tachycardia or worsens the symptom burden in POTS patients.

Methods and Results

Patients with POTS (n=27) underwent an acute drug trial of atomoxetine 40 mg and placebo on separate mornings in a randomized, crossover design. Blood pressure (BP), HR, and symptoms were assessed while seated and after standing prior to and hourly for 4 hours following study drug administration. Atomoxetine significantly increased standing HR compared with placebo (121±17 beats per minute versus 105±15 beats per minute; P=0.001) in POTS patients, with a trend toward higher standing systolic BP (P=0.072). Symptom scores worsened with atomoxetine compared to placebo (+4.2 au versus −3.5 au; P=0.028) from baseline to 2 hours after study drug administration.

Conclusion

Norepinephrine reuptake inhibition with atomoxetine acutely increased standing HR and symptom burden in patients with POTS.

Clinical Trials Registration

URL: http://clinicaltrials.gov. Unique identifier: NCT00262470.