Striatal neuronal loss or dysfunction and choline rise in children with attention-deficit hyperactivity disorder: a 1H-magnetic resonance spectroscopy study

The Role of Choline in Neurodevelopmental Disorders-A Narrative Review Focusing on ASC, ADHD and Dyslexia

Neurodevelopmental disorders appear to be rising in prevalence, according to the recent Global Burden of Disease Study. This rise is likely to be multi-factorial, but the role of certain nutrients known to facilitate neurodevelopment should be considered. One possible contributing factor could be attributed to deficits in choline intake, particularly during key stages of neurodevelopment, which includes the first 1000 days of life and childhood. Choline, a key micronutrient, is crucial for optimal neurodevelopment and brain functioning of offspring. The present narrative review discusses the main research, describing the effect of choline in neurodevelopmental disorders, to better understand its role in the etiology and management of these disorders. In terms of findings, low choline intakes and reduced or altered choline status have been reported in relevant population subgroups: pregnancy (in utero), children with autism spectrum disorders, people with attention deficit hyperactivity disorder and those with dyslexia. In conclusion, an optimal choline provision may offer some neuronal protection in early life and help to mitigate some cognitive effects in later life attributed to neurodevelopmental conditions. Research indicates that choline may act as a modifiable risk factor for certain neurodevelopmental conditions. Ongoing research is needed to unravel the mechanisms and explanations.

Emerging findings of glutamate-glutamine imbalance in the medial prefrontal cortex in attention deficit/hyperactivity disorder: systematic review and meta-analysis of spectroscopy studies

One of the main challenges in investigating the neurobiology of ADHD is our limited capacity to study its neurochemistry in vivo. Magnetic resonance spectroscopy (MRS) estimates metabolite concentrations within the brain, but approaches and findings have been heterogeneous. To assess differences in brain metabolites between patients with ADHD and healthy controls, we searched 12 databases screening for MRS studies. Studies were divided into 'children and adolescents' and 'adults' and meta-analyses were performed for each brain region with more than five studies. The quality of studies was assessed by the Newcastle-Ottawa Scale. Thirty-three studies met our eligibility criteria, including 874 patients with ADHD. Primary analyses revealed that the right medial frontal area of children with ADHD presented higher concentrations of a composite of glutamate and glutamine (p = 0.02, SMD = 0.53). Glutamate might be implicated in pruning and neurodegenerative processes as an excitotoxin, while glutamine excess might signal a glutamate depletion that could hinder neurotrophic activity. Both neuro metabolites could be implicated in the differential cortical thinning observed in patients with ADHD across all ages. Notably, more homogeneous designs and reporting guidelines are the key factors to determine how suitable MRS is for research and, perhaps, for clinical psychiatry. Results of this meta-analysis provided an overall map of the brain regions evaluated so far, addressed the role of glutamatergic metabolites in the pathophysiology of ADHD, and pointed to new perspectives for consistent use of the tool in the field.

Neuroimaging in Attention-Deficit/Hyperactivity Disorder: Recent Advances

Attention-deficit/hyperactivity disorder (ADHD) is a common neurodevelopmental condition, leading to impaired attention and impulsive behaviors diagnosed in, but not limited to, children. ADHD can cause symptoms throughout life. This article summarizes structural (conventional, volumetric, and diffusion tensor imaging MRI) and functional [task-based functional MRI (fMRI), resting state fMRI, PET, and MR spectroscopy] brain findings in patients with ADHD. Consensus is lacking regarding altered anatomic or functional imaging findings of the brain in children with ADHD, likely because of the disorder's heterogeneity. Most anatomic studies report abnormalities in the frontal lobes, basal ganglia, and corpus callosum; decreased surface area in the left ventral frontal and right prefrontal cortex; thinner medial temporal lobes; and smaller caudate nuclei. Using fMRI, researchers have focused on the prefrontal and temporal regions, reflecting perception-action mapping alterations. Artificial intelligence models evaluating brain anatomy have highlighted changes in cortical thickness and shape of the inferior frontal cortex, bilateral sensorimotor cortex, left temporal lobe, and insula. Early intervention and/or normal brain maturation can alter imaging patterns and convert functional imaging studies to a normal pattern. While the imaging findings provide insight into the disease's neuropathophysiology, no definitive structural or functional pattern defines the disorder from a neuroradiologic perspective.

The role of tryptophan metabolic pathway in children with attention deficit hyperactivity disorder with and without comorbid oppositional defiant disorder and conduct disorder

Accumulating data presented that tryptophan metabolic pathway (TMP) may play a role in attention-deficit/hyperactivity disorder (ADHD). However, no study have investigated potential role of TMP in disruptive behavior disorders coexisting with ADHD. This study compared serum levels of tryptophan, kynurenine, kynurenic acid, 3-hydroxykynurenine and 3-hydroxyantranilic acid in medication-free children with ADHD combined presentation (ADHD-C), with ADHD-C and oppositional defiant disorder (ODD), and with ADHD-C and conduct disorder (CD) versus healthy controls. The study also compared several ratios that are previously suggested to reflect the activities of the KP enzymes (kynurenine/tryptophan, kynurenic acid/kynurenine, 3-hydroxykynurenine/kynurenine) or neuroprotective activity (kynurenic acid/3-hydroxykynurenine) among groups. A total of 122 patients were enrolled: 46 children with ADHD-C alone, 43 children with ADHD-C+ODD, 33 children with ADHD-C+CD and 50 healthy controls. Targeted biochemical molecules were assessed by liquid chromatography-mass spectrometry/mass spectrometry. Compared to control group, serum kynurenine levels were significantly higher in the ADHD-C group, serum 3-hydroxykynurenine levels were significantly lower in the ADHD-C and ADHD-C+ODD groups, the serum kynurenic acid/kynurenine ratio was significantly higher in the ADHD-C, ADHD-C+ODD and ADHD-C+CD groups, and the serum 3-hydroxykynurenine/kynurenine ratio was significantly lower in the ADHD-C group. These findings suggest that TMP may play a role in the pathophysiology of ADHD-C.

Attention-deficit/hyperactivity disorder and brain metabolites from proton magnetic resonance spectroscopy: a systematic review and meta-analysis protocol

Despite major advances in the study of the brain, investigations on neurochemistry in vivo still lack the solid ground of more established methods, such as structural and functional magnetic resonance imaging. Proton magnetic resonance spectroscopy (MRS) is a technique that might potentially fill in this gap. Nevertheless, studies using this approach feature great methodological heterogeneity, such as varying voxel of choice, differences on emphasized metabolites, and absence of a standardized unit. In this study, we present a methodology for creating a systematic review and meta-analysis for this kind of scientific evidence using the prototypical case of attention-deficit/hyperactivity disorder. Systematic review registration: International Prospective Register of Systematic Reviews (PROSPERO), CRD42018112418.

Effects of 12-Week Methylphenidate Treatment on Neurometabolism in Adult Patients with ADHD: The First Double-Blind Placebo-Controlled MR Spectroscopy Study

Attention deficit hyperactivity disorder (ADHD) is a frequent neurodevelopmental disorder that often persists into adulthood. Methylphenidate (MPH) is the first-line treatment for ADHD; however, despite its wide usage, little is known about its neurometabolic effects. Until now, no randomized and blinded clinical trials have been conducted addressing the neurometabolic signals of MPH administration in adults with ADHD. In the current study, the authors investigated how MPH intake and group psychotherapy (GPT) influence brain neurometabolism over the course of three months. The authors hypothesized a decrease in the anterior cingulate cortex (ACC) glutamate concentration following MPH administration. This study was part of a double-blind multicenter trial (Comparison of Methylphenidate and Psychotherapy in Adult ADHD Study (COMPAS)) investigating the effects of MPH and GPT in patients with adult ADHD. Using single-voxel magnetic resonance spectroscopy (MRS) of the pregenual ACC and the left cerebellar hemisphere (CHL), we investigated the concentration of glutamate plus glutamine (Glx), N-acetyl-aspartate, creatine, total choline containing compounds, and myo-inositol in patients before and after 12 weeks of treatment. Neither MPH nor GPT significantly influenced the Glx concentration or any of the other metabolite concentrations in the ACC and CHL after 12 weeks. Therefore, contrary to the hypothesis, no change in the prefrontal Glx signal was detected after MPH treatment. Given that MRS does not differentiate between glutamate in the synaptic cleft and in neuronal tissue, MPH-induced down-regulation of glutamatergic neurotransmission in the ACC might only affect the concentration of glutamate in the synaptic cleft, while the general availability of glutamate in the respective neuronal tissue might be unaffected by MPH intake. The observed lack of any MPH-induced normalization in metabolite concentrations is less surprising, considering that the baseline sample did not significantly differ from a healthy control group. Future studies of other regions, such as the basal ganglia, and the use of novel methods, such as whole brain MRS and multimodal imaging approaches, are necessary.

The role of glutamate receptors in attention-deficit/hyperactivity disorder: From physiology to disease

Attention-deficit hyperactivity disorder (ADHD) is the most common psychiatric disorder in children and adolescents, which is characterized by behavioral problems such as attention deficit, hyperactivity, and impulsivity. As the receptors of the major excitatory neurotransmitter in the mammalian central nervous system (CNS), glutamate receptors (GluRs) are strongly linked to normal brain functioning and pathological processes. Extensive investigations have been made about the structure, function, and regulation of GluR family, describing evidences that support the disruption of these mechanisms in mental disorders, including ADHD. In this review, we briefly described the family and function of GluRs in the CNS, and discussed what is recently known about the role of GluRs in ADHD, that including GluR genes, animal models, and the treatment, which would help us further elucidate the etiology of ADHD.

A functional variant in SLC1A3 influences ADHD risk by disrupting a hsa-miR-3171 binding site: A two-stage association study

Attention-deficit hyperactivity disorder (ADHD) is one of the most common neuropsychiatric disorders in children and adolescents with high heritability. Evidence is accumulating that SLC1A3 may play a role in ADHD etiology. Therefore, a two-stage case-control study was conducted on 752 cases and 774 controls to explore the role of SLC1A3 in ADHD. Bioinformatic annotations and functional experiments were applied to reveal the potential biological mechanisms. Finally, SLC1A3 rs1049522 showed significant association with ADHD risk in two stages with CA genotype vs AA genotype, odds ratio (OR) = 0.694 (95% confidence interval, CI = 0.570-0.844) and dominant model, OR = 0.749 (95% CI = 0.621-0.904) in the combined stage. Besides, rs1049522 was found to be related to ADHD hyperactive/impulsive symptom, and rs1049522-C showed increased SLC1A3 mRNA expression in the cerebellar cortex. Dual-luciferase reporter assay further indicated that rs1049522-C allele enhanced SLC1A3 expression by disrupting the hsa-miR-3171 binding site. In conclusion, SLC1A3 variant rs1049522 was implicated in ADHD susceptibility in a Chinese Han population probably by enhancing the SLC1A3 expression in a miRNA-mediated manner.

Differential neuroimaging indices in prefrontal white matter in prenatal alcohol-associated ADHD versus idiopathic ADHD

BACKGROUND

Attention deficit-hyperactivity disorder (ADHD) is common in fetal alcohol spectrum disorders (FASD) but also in patients without prenatal alcohol exposure (PAE). Many patients diagnosed with idiopathic ADHD may actually have ADHD and covert PAE, a treatment-relevant distinction.

METHODS

We compared proton magnetic resonance spectroscopic imaging (MRSI; N = 44) and diffusion tensor imaging (DTI; N = 46) of the anterior corona radiata (ACR)-a key fiber tract in models of ADHD-at 1.5 T in children with ADHD with PAE (ADHD+PAE), children with ADHD without PAE (ADHD-PAE), children without ADHD with PAE (non-ADHD+PAE), and children with neither ADHD nor PAE (non-ADHD-PAE, i.e., typically developing controls). Levels of choline-compounds (Cho) were the main MRSI endpoint, given interest in dietary choline for FASD; the main DTI endpoint was fractional anisotropy (FA), as ACR FA may reflect ADHD-relevant executive control functions.

RESULTS

For ACR Cho, there was an ADHD-by-PAE interaction (p = 0.038) whereby ACR Cho was 26.7% lower in ADHD+PAE than in ADHD-PAE children (p < 0.0005), but there was no significant ACR Cho difference between non-ADHD+PAE and non-ADHD-PAE children. Voxelwise false-discovery rate (FDR)-corrected analysis of DTI revealed significantly (q ≤ 0.0101-0.05) lower FA in ACR for subjects with PAE (ADHD+PAE or non-ADHD+PAE) than for subjects without PAE (ADHD-PAE or non-ADHD-PAE). There was no significant effect of ADHD on FA. Thus, in overlapping samples, effects of PAE on Cho and FA were observed in the same white-matter tract.

CONCLUSIONS

These findings point to tract focal, white-matter pathology possibly specific for ADHD+PAE subjects. Low Cho may derive from abnormal choline metabolism; low FA suggests suboptimal white-matter integrity in PAE. More advanced MRSI and DTI-and neurocognitive assessments-may better distinguish ADHD+PAE from ADHD-PAE, helping identify covert cases of FASD.

Correlation between attention-deficit/hyperactivity disorder, its pharmacotherapy and thyroid dysfunction: A nationwide population-based study in Taiwan

OBJECTIVE

The aim of this study was to examine the comorbid rates of thyroid dysfunction among patients with attention-deficit/hyperactivity disorder (ADHD) and the general population. We further examined whether pharmacotherapy affects ADHD patients' risk of developing thyroid dysfunction.

DESIGN AND MEASUREMENT

We recruited 75 247 newly diagnosed ADHD patient and 75 247 healthy controls between January 1999 and December 2011 from the National Health Insurance database in Taiwan. We compared hyperthyroidism, hypothyroidism and other common paediatric psychiatric diseases between ADHD patients and controls. We carried out logistic regression analysis to identify an independent factor for predicting thyroid dysfunction. Furthermore, we analysed the time sequence of the diagnosis and the risk of developing a thyroid disorder after receiving pharmacotherapy.

RESULTS

Compared to the control group, the ADHD group had higher comorbidity rates of both hyperthyroidism (1.1% of ADHD vs 0.7% of controls, aOR: 1.72, P < 0.001) and hypothyroidism (0.6% of ADHD vs 0.2% of controls, aOR: 2.23, P < 0.001). Of the ADHD patients with comorbid thyroid dysfunction, about two-thirds and half of patients were diagnosed with ADHD prior to their diagnosis of hyperthyroidism and hypothyroidism, respectively. Furthermore, pharmacotherapy had no significant influence on the risk of developing hyperthyroidism (aHR: 1.09, P = 0.363) or hypothyroidism (aHR: 0.95, P = 0.719) among ADHD patients.

CONCLUSION

Patients with ADHD had greater comorbid rates with thyroid dysfunction than the control subjects, but pharmacotherapy for treating ADHD did not affect thyroid dysfunction later in life. However, these findings should be further verified using a clinical cohort with comprehensive laboratory assessment in future.

1H NMR-based metabolomics reveals neurochemical alterations in the brain of adolescent rats following acute methylphenidate administration

The psychostimulant methylphenidate (MPH) is increasingly used in the treatment of attention deficit hyperactivity disorder (ADHD). While there is little evidence for common brain pathology in ADHD, some studies suggest a right hemisphere dysfunction among people diagnosed with the condition. However, in spite of the high usage of MPH in children and adolescents, its mechanism of action is poorly understood. Given that MPH blocks the neuronal transporters for dopamine and noradrenaline, most research into the effects of MPH on the brain has largely focused on these two monoamine neurotransmitter systems. Interestingly, recent studies have demonstrated metabolic changes in the brain of ADHD patients, but the impact of MPH on endogenous brain metabolites remains unclear. In this study, a proton nuclear magnetic resonance (¹H NMR)-based metabolomics approach was employed to investigate the effects of MPH on brain biomolecules. Adolescent male Sprague Dawley rats were injected intraperitoneally with MPH (5.0 mg/kg) or saline (1.0 ml/kg), and cerebral extracts from the left and right hemispheres were analysed. A total of 22 variables (representing 13 distinct metabolites) were significantly increased in the MPH-treated samples relative to the saline-treated controls. The upregulated metabolites included: amino acid neurotransmitters such as GABA, glutamate and aspartate; large neutral amino acids (LNAA), including the aromatic amino acids (AAA) tyrosine and phenylalanine, both of which are involved in the metabolism of dopamine and noradrenaline; and metabolites associated with energy and cell membrane dynamics, such as creatine and myo-inositol. No significant differences in metabolite concentrations were found between the left and right cerebral hemispheres. These findings provide new insights into the mechanisms of action of the anti-ADHD drug MPH.

Possible Effects of Copper and Ceruloplasmin Levels on Auditory Event Potentials in Boys with Attention Deficit Hyperactivity Disorder

INTRODUCTION

The aims of the present study were to investigate the relationship between levels of plasma copper (Cu) and ceruloplasmin (Cp) and amplitudes and latencies of P1, N2, and P3 in the parietal and frontal areas of children with attention deficit hyperactivity disorder (ADHD) as well as to compare these Cu levels and event-related potentials (ERPs) indices in controls.

METHODS

Boys (n=41) with ADHD were divided into two subgroups according to a median split of plasma Cu and Cp levels, separately. ERP indices from the parietal and frontal regions were recorded in children with ADHD and 24 normal boys (control group) using an auditory oddball paradigm.

RESULTS

Parietal P3 latency was significantly longer, and parietal P3 amplitude, frontal P3 amplitude, and frontal N2 amplitudes were smaller in children with ADHD than in controls (all p values <0.017). Parietal P1 and frontal P1 latencies were significantly shorter in the higher Cu group than in the lower Cu group (both p values <0.017). Decreased latency of parietal P1 was dependent on plasma levels of Cu (p<0.05). Frontal N2 and parietal N2 amplitudes were significantly lower in the ADHD group with lower Cp levels than in the ADHD group with higher Cp levels (both p values <0.017). Decreased frontal N2 and parietal N2 amplitudes were dependent on plasma levels of Cp (both p values <0.05).

CONCLUSION

Plasma Cu and Cp levels may have an effect on ERPs in ADHD, thus indicating the existence of effects on information processing. Cu levels may have a negative effect on the neuronal encoding of sound, whereas Cp levels may have a positive effect on the processes of cognitive control, conflict monitoring, and stimulus discrimination in children with ADHD.

Neurochemical correlates of internet game play in adolescents with attention deficit hyperactivity disorder: A proton magnetic resonance spectroscopy (MRS) study

Previous studies have examined the relationship of brain metabolic changes in patients with attention deficit hyperactivity disorder (ADHD) and internet gaming disorder (IGD). However, these studies have been limited by a small number of subjects, a large variance in subject age, and different brain regions of interest. The present study assessed the effects of chronic internet game play in ADHD children. Twenty eight ADHD adolescents with IGD (IGD+ADHD), 27 ADHD adolescents without problematic internet game playing (ADHD only) and 42 healthy comparison adolescents (HC) were included in the study. Magnetic resonance spectroscopy (MRS) was performed on a 3T MRI scanner. Our results indicate that the levels of NAA in both ADHD groups were lower than those observed in the HC group. The levels of Glu+Gln in the ADHD only group were increased, compared to those observed in the control group. However, Glu+Gln was not increased in the IGD+ADHD group. In addition, the levels of Glu+Gln in the IGD+ADHD group were positively correlated with K-ARS total and inattention scores. ADHD and IGD subjects were both characterized by decreased NAA levels within the frontal lobe, consistent with hypofrontality.

The Effect of Single Dose Methylphenidate on Neurometabolites according to COMT Gene Val158Met Polymorphism in the Patient with Attention Deficit Hyperactivity Disorder: A Study Using Magnetic Resonance Spectroscopy

OBJECTIVE

Attention deficit/hyperactivity disorder (ADHD) is a common neurodevelopmental disorder. Thus, the present study aimed to determine the effects of a single dose of methylphenidate (Mph) on neurometabolite levels according to polymorphisms of the catechol-O-methyltransferase (COMT) gene.

METHODS

This study evaluated the neurometabolite levels including N-acetylaspartate (NAA), creatine (Cr), and choline (Cho) of ADHD patients, before and after treatment with Mph (10 mg) according to the presence of COMT polymorphisms. The spectra were obtained from the dorsolateral prefrontal cortex (DLPFC), anterior cingulate cortex (ACC), cerebellum, and striatum.

RESULTS

The NAA levels of the val/val and val genotype carriers (val/val and val/met genotypes) increased in the DLPFC and ACC, respectively, following Mph treatment. The NAA/Cr ratio was lower in the DLPFC of val carriers than in the met/met genotype carriers prior to Mph administration. The Cho levels of the val/met genotype and val carriers increased in the striatum following Mph treatment. Following Mph treatment, the Cr levels of the met/met genotype carriers were higher than those of the val/met genotype and val carriers. Additionally, after Mph treatment, there was a significant increase in Cr levels in the DLPFC of the met/met genotype carriers but a significant decrease in such levels in the striatum of val/val genotype carriers.

CONCLUSION

These findings suggest that polymorphisms of the COMT gene can account for individual differences in neurochemical responses to Mph among ADHD patients. Therefore, further studies are needed to fully characterize the effects of the Val158met polymorphism of the COMT gene on treatment outcomes in patients with ADHD.

The impact of synapsin III gene on the neurometabolite level alterations after single-dose methylphenidate in attention-deficit hyperactivity disorder patients

OBJECTIVE

To investigate the neurometabolite level changes according to synapsin III gene rs133945G>A and rs133946C>G polymorphisms by using magnetic resonance spectroscopy (MRS) in patients with attention-deficit hyperactivity disorder (ADHD).

METHODS

Fifty-seven adults diagnosed with ADHD were recruited for the study. The participants were examined by single-voxel (1)H MRS when medication naïve and 30 minutes after oral administration of 10 mg methylphenidate (Mph). Those who had been on a stimulant discontinued the medication 48 hours before MRS imaging. Spectra were taken from the anterior cingulate cortex, dorsolateral prefrontal cortex, striatum, and cerebellum, and N-acetylaspartate (NAA), choline, and creatine levels were examined. For genotyping of the synapsin III gene polymorphisms, DNA was isolated from peripheral blood leukocytes. The effects of age, sex, and ADHD subtypes were controlled in the analyses.

RESULTS

After a single dose of Mph, choline levels increased significantly in the striatum of rs133945G>A polymorphism-GG genotypes (P=0.020) and NAA levels rose in the anterior cingulate cortex of rs133946C>G polymorphism-CG genotypes (P=0.014). Both rs133945G>A and rs133946C>G polymorphisms were found to statistically significantly affect the alteration of NAA levels in response to Mph in dorsolateral prefrontal cortex with two-way repeated measure of analysis of variance. Post hoc comparisons revealed a significant difference between CG and GG genotypes of rs133946C>G polymorphisms after Bonferroni adjustment (P=0.016).

CONCLUSION

Synapsin III gene polymorphisms may be affecting the changes in neurometabolite levels in response to Mph in adult ADHD patients. Future studies are needed to confirm our findings.

Normal Neurochemistry in the Prefrontal and Cerebellar Brain of Adults with Attention-Deficit Hyperactivity Disorder

Attention-deficit hyperactivity disorder (ADHD) is a common neurodevelopmental disorder. In an attempt to extend earlier neurochemical findings, we organized a magnetic resonance spectroscopy (MRS) study as part of a large, government-funded, prospective, randomized, multicenter clinical trial comparing the effectiveness of specific psychotherapy with counseling and stimulant treatment with placebo treatment (Comparison of Methylphenidate and Psychotherapy Study). We report the baseline neurochemical data for the anterior cingulate cortex (ACC) and the cerebellum in a case–control setting. For the trial, 1,480 adult patients were contacted for participation, 518 were assessed for eligibility, 433 were randomized, and 187 were potentially eligible for neuroimaging. The control group included 119 healthy volunteers. Single-voxel proton MRS was performed. In the patient group, 113 ACC and 104 cerebellar spectra fulfilled all quality criteria for inclusion in statistical calculations, as did 82 ACC and 78 cerebellar spectra in the control group. We did not find any significant neurometabolic differences between the ADHD and control group in the ACC (Wilks’ lambda test: p = 0.97) or in the cerebellum (p = 0.62). Thus, we were unable to replicate earlier findings in this methodologically sophisticated study. We discuss our findings in the context of a comprehensive review of other MRS studies on ADHD and a somewhat skeptical neuropsychiatric research perspective. As in other neuropsychiatric disorders, the unclear nosological status of ADHD might be an explanation for false-negative findings.

Association of adult attention deficit hyperactivity disorder subtypes and response to methylphenidate HCL treatment: A magnetic resonance spectroscopy study

The effects of methylphenidate (MPH) treatment on N-acetyl aspartate (NAA), choline and creatine are being examined in individuals with different subtypes of attention deficit hyperactivity disorder (ADHD). Sixty ADHD subjects were included into the study aging between 18 and 60 years. Levels of NAA, creatine and choline in anterior cingulate cortex, cerebellum, striatum and dorsolateral prefrontal cortex were measured with magnetic resonance spectroscopy. Then, 10mg oral MPH was given to the subjects and the same metabolite levels were measured after an interval of 30min. Distribution of the patients according to the ADHD subtypes was as follows: 21 of them (35.0%) were in the inattentive type, 11 of them (18.3%) were in the hyperactive type and 28 of them were (46.7%) in the combined type. Changes of brain metabolite levels after MPH were found not to be statistically significantly different between the subtypes. The increase of choline levels after MPH compared to the levels of choline before MPH in striatum in the combined type patients were statistically significant. No clear association was found between ADHD subtypes and changes of brain metabolites with use of MPH in adult ADHD.

Developmental changes in gamma-aminobutyric acid levels in attention-deficit/hyperactivity disorder

While the neurobiological basis and developmental course of attention-deficit/hyperactivity disorder (ADHD) have not yet been fully established, an imbalance between inhibitory/excitatory neurotransmitters is thought to have an important role in the pathophysiology of ADHD. This study examined the changes in cerebral levels of GABA+, glutamate and glutamine in children and adults with ADHD using edited magnetic resonance spectroscopy. We studied 89 participants (16 children with ADHD, 19 control children, 16 adults with ADHD and 38 control adults) in a subcortical voxel (children and adults) and a frontal voxel (adults only). ADHD adults showed increased GABA+ levels relative to controls (P = 0.048), while ADHD children showed no difference in GABA+ in the subcortical voxel (P > 0.1), resulting in a significant age by disorder interaction (P = 0.026). Co-varying for age in an analysis of covariance model resulted in a nonsignificant age by disorder interaction (P = 0.06). Glutamine levels were increased in children with ADHD (P = 0.041), but there was no significant difference in adults (P > 0.1). Glutamate showed no difference between controls and ADHD patients but demonstrated a strong effect of age across both groups (P < 0.001). In conclusion, patients with ADHD show altered levels of GABA+ in a subcortical voxel which change with development. Further, we found increased glutamine levels in children with ADHD, but this difference normalized in adults. These observed imbalances in neurotransmitter levels are associated with ADHD symptomatology and lend new insight in the developmental trajectory and pathophysiology of ADHD.

The Amygdala's Neurochemical Ratios after 12 Weeks Administration of 20 mg Long-acting Methylphenidate in Children with Attention Deficit and Hyperactivity Disorder: A Pilot Study Using (1)H Magnetic Resonance Spectroscopy

Objective

Recent pediatric studies have suggested a correlation between decreased amygdala volume and attention deficit and hyperactivity disorder (ADHD) symptoms, including the emotional dysregulation. To investigate the hypothesis that medication treatment of ADHD specifically improves amygdala function, we used ¹H magnetic resonance spectroscopy (MRS) to study the effect of 12 weeks of treatment with daily 20 mg long-acting methylphenidate on the Glu/Cr, NAA/Cr, Cho/Cr, and mI/Cr ratios in the amygdala of medication-naïve children with ADHD.

Methods

This was a prospective study, using a pre- and post-test design, on a single group of 21 children (average age 8.52 years, 17 males and 4 females) diagnosed with ADHD. Low Time Echo MRS scans sampled voxels of interest (1.5×1.5×2.0) from both the right and left amygdala.

Results

There was significant clinical improvement after 12 weeks of treatment with 20 mg long-acting methylphenidate. On 1H MRS, there were no statistical significant differences of NAA/Cr ratio, Cho/Cr ratio, mI/Cr ratio before and after 12 weeks administration of 20 mg long-acting methylphenidate both in the right and left amygdala. In addition, Glu/Cr ratio decreased 14.1% in the right amygdala (p=0.029) and 11.4% in the left amygdala (p=0.008). Standardized mean effect sizes ranged from 0.14-0.32.

Conclusion

The findings are consistent with the possibility that hyperglutamatergic processes in the amygdale are related to the hyperactive-impulsive symptoms of ADHD.

Effect of diet on brain metabolites and behavior in spontaneously hypertensive rats

Attention-deficit hyperactivity disorder (ADHD) is a heterogeneous psychiatric disorder affecting 5-10% of children. One of the suggested mechanisms underlying the pathophysiology of ADHD is insufficient energy supply to neurons. Here, we investigated the role of omega 3 fatty acids in altering neural energy metabolism and behavior of spontaneously hypertensive rats (SHR), which is an animal model of ADHD. To this end, we employed Proton Magnetic Resonance Spectroscopy ((1)H MRS) to evaluate changes in brain neurochemistry in the SHR following consumption of one of three experimental diets (starting PND 21): fish oil enriched (FOE), regular (RD) and animal fat enriched (AFE) diet. Behavioral tests were performed to evaluate differences in locomotor activity and risk-taking behavior (starting PND 44). Comparison of frontal lobe metabolites showed that increased amounts of omega 3 fatty acids decreased total Creatine levels (tCr), but did not change Glutamate (Glu), total N-Acetylaspartate (tNAA), Lactate (Lac), Choline (Cho) or Inositol (Ino) levels. Although behavior was not significantly affected by different diets, significant correlations were observed between brain metabolites and behavior in the open field and elevated plus maze. SHR with higher levels of brain tCr and Glu exhibited greater hyperactivity in a familiar environment. On the other hand, risk-taking exploration of the elevated plus maze's open arms correlated negatively with forebrain tNAA and Lac levels. These findings support the possible alteration in energy metabolites in ADHD, correlating with hyperactivity in the animal model. The data also suggest that omega 3 fatty acids alter brain energy and phospholipid metabolism.

The metabotropic glutamate receptor subtype 7 rs3792452 polymorphism is associated with the response to methylphenidate in children with attention-deficit/hyperactivity disorder

OBJECTIVE

The purpose of this study was to investigate the association between the metabotropic glutamate receptor subtype 7 (mGluR7) gene (GRM7) polymorphism and treatment response to methylphenidate in Korean children with attention-deficit/hyperactivity disorder (ADHD).

METHODS

We enrolled 175 medication-naïve children with ADHD in an open-label 8 week trial of methylphenidate. The participants were genotyped and evaluated using the Clinical Global Impressions (CGI) Scale and the parent version of the ADHD Rating Scale-IV (ADHD-RS) before and after treatment.

RESULTS

After the 8 week course of methylphenidate, children with the GRM7 rs37952452 polymorphism G/A genotype had a more pronounced response rate to the treatment than did children with the G/G genotype according to the ADHD-RS scores (72.2% vs. 55.4%, respectively; p=0.011) and the more stringent standard of combined ADHD-RS and CGI-Improvement (CGI-I) scores (50.0% vs. 35.3%, respectively; p=0.044).

CONCLUSIONS

The present study suggests that the GRM7 rs37952452 polymorphism may play a role in the treatment response to methylphenidate in children with ADHD. Further studies to evaluate the association between glutamate genes and treatment response to methylphenidate in children with ADHD, including a replication of our findings using a control or comparative group in a larger sample, are warranted.

Prefrontal grey and white matter neurometabolite changes after atomoxetine and methylphenidate in children with attention deficit/hyperactivity disorder: a (1)H magnetic resonance spectroscopy study

Attention deficit/hyperactivity disorder (ADHD) is the most common neurobehavioral childhood disorder. Dysfunction of prefrontal neural circuits which are responsible for executive and attentional functions has been previously shown in ADHD. We investigated the neurometablite changes in areas included in dorsolateral prefrontal neural circuits after 2 months of long-acting methylphenidate or atomoxetine medication in children with ADHD who were responders to treatment. Twenty-one ADHD children were examined by single voxel (1)H-magnetic resonance spectroscopy (MRS) before and after 2 months of medication with OROS methylphenidate (n=10) or atomoxetine (n=11). The spectra were taken from the dorsolateral prefrontal cortex (DLPFC, 8ml) and white matter behind the DLPFC (anterior semioval center, 7.5ml), bilaterally. NAA and NAA/Cr (N-acetylaspartate/creatine) decreased in the left DLPFC and Cho/Cr (choline/creatine) increased in the right DLPFC after atomoxetine medication. Glu+Gln and Glu+Gln/Cr (glutamate/glutamine) increased in the left white matter after methylphenidate medication. We hypothesize that atomoxetine could decrease hyperactivation of DLPFC neurons and methylphenidate could lead to increased activation of cortical glutamatergic projections with the consequences of increased tonic dopamine release in the mesocortical system.

Age-related change of neurochemical abnormality in attention-deficit hyperactivity disorder: a meta-analysis

Prevalence and symptoms of attention-deficit hyperactivity disorder (ADHD) change with advancing age. However, neurochemical background of such age-related change is yet to be elucidated. We therefore conducted a meta-analysis of 16 proton magnetic resonance spectroscopy studies comprising 270 individuals with ADHD and 235 controls. Standardized mean differences were calculated and used as an effect size. Sensitivity analyses and meta-regression to explore the effect of age on neurochemical abnormality were performed. A random effects model identified a significantly higher-than-normal N-acetylaspartate (NAA) in the medial prefrontal cortex (mPFC), but no significant differences of other metabolites in that area. No significant difference in metabolite levels was demonstrated in any other region. Sensitivity analysis of children with ADHD revealed significantly higher-than-normal NAA, whereas no significant difference was found in adults with ADHD. Meta-regression revealed significant correlation between advanced age and normal levels of NAA in the mPFC, suggesting that age-dependent abnormality of NAA level in the mPFC is a potential neural basis of age-related change of symptoms of ADHD.

Association between the GRM7 rs3792452 polymorphism and attention deficit hyperacitiveity disorder in a Korean sample

Background

The purpose of this study was to investigate the association between the ionotropic and glutamate receptors, N-methyl D-asparate 2A (GRIN2A) and 2B (GRIN2B), and the metabotropic glutamate receptor mGluR7 (GRM7) gene polymorphisms and attention-deficit hyperactivity disorder (ADHD) in Korean population.

Methods

We conducted a case–control analysis of 202 ADHD subjects and 159 controls, performed a transmission disequilibrium test (TDT) on 149 trios, and compared scores from the continuous performance test (CPT), the Children’s Depression Inventory (CDI), and the State-Trait Anxiety Inventory for Children (STAIC) according to the genotype of the glutamate receptor genes.

Results

There were no significant differences in the genotype or allele frequencies of the GRIN2A rs8049651, GRIN2B rs2284411, or GRM7 rs37952452 polymorphisms between the ADHD and control groups. For 148 ADHD trios, the TDT analysis also showed no preferential transmission of the GRIN2A rs8049651 or GRIN2B rs2284411 polymorphisms. However, the TDT analysis of the GRM7 rs3792452 polymorphism showed biased transmission of the G allele (χ2 = 4.67, p = 0.031). In the ADHD probands, the subjects with GG genotype in the GRM7 rs37952452 polymorphism had higher mean T-scores for omission errors on the CPT than did those with the GA or AA genotype (t = 3.38, p = 0.001). In addition, the ADHD subjects who were homozygous for the G allele in the GRM7 rs37952452 polymorphism had higher STAIC-T (t = 5.52, p < 0.001) and STAIC-S (t = 2.74, p = 0.007) scores than did those with the GA or AA genotype.

Conclusions

These results provide preliminary evidence of an association between the GRM7 rs37952452 polymorphism and selective attention deficit and anxiety found within the Korean ADHD population.

Genome-wide copy number variation study associates metabotropic glutamate receptor gene networks with attention deficit hyperactivity disorder

Attention deficit hyperactivity disorder (ADHD) is a common, heritable neuropsychiatric disorder of unknown etiology. We performed a whole-genome copy number variation (CNV) study on 1,013 cases with ADHD and 4,105 healthy children of European ancestry using 550,000 SNPs. We evaluated statistically significant findings in multiple independent cohorts, with a total of 2,493 cases with ADHD and 9,222 controls of European ancestry, using matched platforms. CNVs affecting metabotropic glutamate receptor genes were enriched across all cohorts (P = 2.1 × 10(-9)). We saw GRM5 (encoding glutamate receptor, metabotropic 5) deletions in ten cases and one control (P = 1.36 × 10(-6)). We saw GRM7 deletions in six cases, and we saw GRM8 deletions in eight cases and no controls. GRM1 was duplicated in eight cases. We experimentally validated the observed variants using quantitative RT-PCR. A gene network analysis showed that genes interacting with the genes in the GRM family are enriched for CNVs in ∼10% of the cases (P = 4.38 × 10(-10)) after correction for occurrence in the controls. We identified rare recurrent CNVs affecting glutamatergic neurotransmission genes that were overrepresented in multiple ADHD cohorts.

The link between perinatal glucocorticoids exposure and psychiatric disorders

The perinatal period is particularly sensitive to a variety of insults during which stress-regulating systems can be permanently altered and psychopathologies ensue. The programming of physiological, endocrinological, and behavioral functions by perinatal adversities is mediated by altered levels of glucocorticoids or the hypothalamic-pituitary-adrenal axis activity in either the mother or offspring. In this article, I review the integrated data from human studies and from animal models that suggest the programming effects of perinatal glucocorticoids exposure. Finally, the concept of developmental origins of psychiatric disorders is discussed.

A common variant of the latrophilin 3 gene, LPHN3, confers susceptibility to ADHD and predicts effectiveness of stimulant medication

Attention-Deficit/Hyperactivity Disorder (ADHD) has a very high heritability (0.8), suggesting that about 80% of phenotypic variance is due to genetic factors. We used the integration of statistical and functional approaches to discover a novel gene that contributes to ADHD. For our statistical approach, we started with a linkage study based on large multigenerational families in a population isolate, followed by fine mapping of targeted regions using a family-based design. Family- and population-based association studies in five samples from disparate regions of the world were used for replication. Brain imaging studies were performed to evaluate gene function. The linkage study discovered a genome region harbored in the Latrophilin 3 gene (LPHN3). In the world-wide samples (total n=6360, with 2627 ADHD cases and 2531 controls) statistical association of LPHN3 and ADHD was confirmed. Functional studies revealed that LPHN3 variants are expressed in key brain regions related to attention and activity, affect metabolism in neural circuits implicated in ADHD, and are associated with response to stimulant medication. Linkage and replicated association of ADHD with a novel non-candidate gene (LPHN3) provide new insights into the genetics, neurobiology, and treatment of ADHD.

Comorbidity of ADHD and Substance Use Disorder (SUD): a neuroimaging perspective

INTRODUCTION

ADHD has a high comorbidity with substance use disorders (SUD). Both diseases have profound social, psychological, and economic consequences and are therefore highly relevant for health systems. The high comorbidity indicates some shared underlying neurobiological substrates. Knowing these substrates may increase the understanding of the disease and help identify therapeutic processes.

METHOD

Neuroimaging studies of ADHD were reviewed and similarities with SUD identified. For this a PubMed research was conducted with the search terms ADHD, SUD, MRI or positron emission tomography (PET) or spectroscopy or imaging.

RESULTS

Similarities were found, in both PET and fMRI studies, between patients with ADHD and those with addiction-related craving. Results from structural MRI and MR spectroscopy do not support a common pathophysiological background, probably because of the lack of studies on craving.

DISCUSSION

ADHD and SUD-related craving share some neurobiological similarities. One reason may be that patients with addiction show more craving when they also suffer from ADHD. The present review thus supports the conclusion from an earlier meta-analysis of clinical studies which found that adequate treatment of ADHD reduces craving and relapse into substance use.

Short-TE proton magnetic resonance spectroscopy investigation in adolescents with attention-deficit hyperactivity disorder

In this study, short echo time (1)H-magnetic resonance spectroscopy (MRS) was applied for quantification of neurometabolites using the LC Model algorithm in Taiwanese adolescents with attention-deficit hyperactivity disorder (ADHD). Proton magnetic resonance spectra were acquired bilaterally on the prefrontal area (part of the anterior cingulate gyrus and part of the medial frontal gyrus) in 15 adolescents with ADHD (average age of 13.88years) and 22 controls (average age of 14.85years). Absolute metabolite levels and ratios relative to creatine plus phosphocreatine (Cr+PCr) were obtained to be compared between groups. Results showed that adolescents with ADHD had significantly lower mean right prefrontal levels of Cr+PCr as compared with the controls. No significant differences between groups were noted in the remainder of the prefrontal metabolites. As for the group comparison of relative ratios, the N-acetylaspartate/Cr+PCr ratio was significantly higher in the right prefrontal regions of ADHD adolescents. This finding provides evidence of a right prefrontal neurochemical alteration in ADHD adolescents, which is consistent with current ADHD theory of prefrontal neuropathology with developmental mechanism. In addition, it highlights the importance of the method in interpretation of MRS findings in the context of ADHD.

Spectroscopic findings in attention-deficit/hyperactivity disorder: review and meta-analysis

OBJECTIVES

The last decade has seen an increasing interest in the method of magnet resonance spectroscopy (MRS) since this is the only research tool that allows a non-invasive in vivo assessment of neurochemical aspects of ADHD without employing ionising radiation. In this paper we review published MRS results with respect to childhood, adolescence and adult ADHD.

METHOD

We searched the Medline (Pub Med) database using the key words ADHD, attention-deficit/hyperactivity disorder, magnet resonance spectroscopy, MRS and spectroscopy. Citations of identified articles were also searched for relevant studies. Meta-analyses were performed for the measured metabolites and regions of assessment.

RESULTS

Sixteen studies could be identified that used MRS to investigate the neurobiology of ADHD. Two regions could be identified as the focus of spectroscopic investigations--the frontal lobe including anterior cingulate cortex and parts of prefrontal cortex and the basal ganglia, mostly striatum, alongside the fronto-striato-thalamo-frontal circuits. As for metabolites, in the majority of studies the ratios to creatine and not absolute concentrations of metabolites were estimated. Choline compounds, N-acetyl-aspartate and glutamate/glutamine (to creatine ratios) could be identified as being altered in several studies in ADHD. The meta-analysis showed increased choline compounds in several researched regions.

DISCUSSION

MRS is a promising tool for the non-invasive in vivo assessment of the cerebral neurochemistry in ADHD. More regions of interest (ROI) like amygdala, hippocampus, thalamus and cerebellum should be assessed in future studies. Further methodological improvements of MRS are desirable in order to assess the absolute metabolite concentration of several ROIs at the same time. Such developments will open novel perspectives in spectroscopic investigations of ADHD.

Attention-deficit/hyperactivity disorder and attention networks

Research attempting to elucidate the neuropathophysiology of attention-deficit/hyperactivity disorder (ADHD) has not only shed light on the disorder itself, it has simultaneously provided new insights into the mechanisms of normal cognition and attention. This review will highlight and integrate this bidirectional flow of information. Following a brief overview of ADHD clinical phenomenology, ADHD studies will be placed into a wider historical perspective by providing illustrative examples of how major models of attention have influenced the development of neurocircuitry models of ADHD. The review will then identify major components of neural systems potentially relevant to ADHD, including attention networks, reward/feedback-based processing systems, as well as a 'default mode' resting state network. Further, it will suggest ways in which these systems may interact and be influenced by neuromodulatory factors. Recent ADHD imaging data will be selectively provided to both illustrate the field's current level of knowledge and to show how such data can inform our understanding of normal brain functions. The review will conclude by suggesting possible avenues for future research.

Cerebellar neurometabolite abnormalities in pediatric attention/deficit hyperactivity disorder: a proton MR spectroscopic study

We designed a case-control proton magnetic resonance spectroscopic study comparing the cerebellar and prefrontal regions of a group of 17 ADHD (attention deficit/hyperactivity disorder) medicated children and a group of 17 control children matched for laterality, gender and age. As we had found decreased gray matter volume in the right prefrontal region and the left cerebellar hemisphere in a previous voxel-based morphometry study conducted on an independent ADHD sample, we tested the hypothesis that these regions should show neurometabolite abnormalities. MRI (magnetic resonance imaging) was performed with a 1.5 T system; spectral acquisition was performed with a single-voxel technique and a PRESS sequence. Two volumes of interest were selected in the right prefrontal region and the left cerebellar hemisphere. NAA (N-acetylaspartate), Cre (creatine), Cho (choline), MI (myo-inositol) and Glx (glutamate-glutamine) resonance intensities were absolutely quantified. In the left cerebellar hemisphere, ADHD children showed significant decreased MI and NAA absolute concentrations with high effect sizes (p=0.004, ES=1.184; p=0.001, ES=1.083). The diminished absolute concentration of the NAA could be related to a gray matter volume decrease in the same cerebellar region found in the previous voxel-based morphometry MRI study, while the reduced MI absolute concentration could express a decreased glial density. This is the first proton MR spectroscopic study examining the cerebellum and it provides additional support for the role of cerebellum in the ADHD neurobiology.

Lithium and valproate protect against dextro-amphetamine induced brain choline concentration changes in bipolar disorder patients

BACKGROUND

Lithium may affect brain choline concentrations, and this effect has been proposed to potentially explain its clinical efficacy. Since dextro-amphetamine is a useful human model of mania, we were interested in determining firstly whether dextro-amphetamine would alter brain choline concentrations, and secondly to determine if lithium would protect against any such changes in bipolar patients. In addition, we wanted to determine if valproate would also have any effects upon choline levels.

METHODS

Healthy controls (n=18) were compared with euthymic Bipolar Disorder patients (Type I and Type II) who were taking lithium (n=14) or valproate (n=11). We utilized (1)H-magnetic resonance spectroscopy ((1)H-MRS) in a 3.0T scanner to examine brain choline/phosphocholine+creatine (Cho/Cr) ratios. Changes in this ratio were measured to determine any changes in choline concentrations in the temporal lobe.

RESULTS

The results showed that administration of dextro-amphetamine decreased the Cho/Cr ratios. In contrast, in both the lithium-treated and valproate-treated patients this decrease was not seen; this attenuation in the change in Cho/Cr ratio changes was statistically significant. It should be noted that Cho/Cr ratios were significantly higher at baseline in the controls compared to both groups of patients, which may have influenced the results.

CONCLUSIONS

These findings are the first to examine the effects of dextro-amphetamine on brain choline concentrations. They show that while in controls dextro-amphetamine decreases choline concentrations, lithium and valproate both appear to protect against this effect in bipolar patients. However, as brain ratios were measured rather than the absolute concentration of choline, and these ratios were lowered in patients at baseline, these results must be regarded as preliminary and require replication in future studies.

Differentiating attention-deficit/hyperactivity disorder inattentive and combined types: a (1)H-magnetic resonance spectroscopy study of fronto-striato-thalamic regions

Despite the implication of fronto-striatal circuits in attention-deficit/hyperactivity disorder (ADHD), there is a lack of information on the role of these regions, especially the thalamus, in the heterogeneity of ADHD. We assessed the (1)H-magnetic resonance spectroscopy profile in ventromedial prefrontal cortex (VMPFC)-thalamic-striatal regions bilaterally in three groups of subjects (age range 18-24 years old): ADHD inattentive type (ADHD-I; n = 9), ADHD combined type (ADHD-C; n = 10) and non-ADHD controls (n = 12). The peaks of N-acetylaspartate, Choline (Cho), myo-inositol (mI), creatine (Cr) and glutamate-glutamine-GABA (Glx) to Cr were calculated. Subjects with ADHD-C showed lower mI/Cr ratio in the right VMPFC than controls, higher Cho/Cr ratio in the left thalamus-pulvinar than the ADHD-I group and higher Glx/Cr ratio in left putamen than individuals with ADHD-I and controls. This metabolic profile suggests a disruption of fronto-striato-thalamic structures in the ADHD-C as a result of lower neuronal energetic metabolism.

Structural brain change in Attention Deficit Hyperactivity Disorder identified by meta-analysis

BACKGROUND

The authors sought to map gray matter changes in Attention Deficit Hyperactivity Disorder (ADHD) using a novel technique incorporating neuro-imaging and genetic meta-analysis methods.

METHODS

A systematic search was conducted for voxel-based structural magnetic resonance imaging studies of patients with ADHD (or with related disorders) in relation to comparison groups. The authors carried out meta-analyses of the co-ordinates of gray matter differences. For the meta-analyses they hybridised the standard method of Activation Likelihood Estimation (ALE) with the rank approach used in Genome Scan Meta-Analysis (GSMA). This system detects three-dimensional conjunctions of co-ordinates from multiple studies and permits the weighting of studies in relation to sample size.

RESULTS

For gray matter decreases, there were 7 studies including a total of 114 patients with ADHD (or related disorders) and 143 comparison subjects. Meta-analysis of these studies identified a significant regional gray matter reduction in ADHD in the right putamen/globus pallidus region. Four studies reported gray matter increases in ADHD but no regional increase was identified by meta-analysis.

CONCLUSION

In ADHD there is gray matter reduction in the right putamen/globus pallidus region. This may be an anatomical marker for dysfunction in frontostriatal circuits mediating cognitive control. Right putamen lesions have been specifically associated with ADHD symptoms after closed head injuries in children.

Cognitive MR spectroscopy of anterior cingulate cortex in ADHD: elevated choline signal correlates with slowed hit reaction times

The anterior cingulate cortex (ACC) plays a major role in modulating executive control of attention. Here, 15 medication-nai ve patients with attention deficit/hyperactivity disorder (ADHD) and 10 carefully matched healthy controls were studied with 2D (1)H-magnetic resonance spectroscopic imaging (MRSI) of the ACC [Brodmann areas 24b'-c' and 32']. Attentional skills were assessed using the identical pairs version of the continuous performance task (CPT-IP). Analysis of regional brain spectra revealed a significantly increased signal of choline-containing compounds (Ch) in the ACC of ADHD patients (p<0.05). Across and within groups, the Ch signal showed high correlations with slowed hit reaction times on the CPT-IP. No group differences in N-acetyl-aspartate (NAA) and creatine (tCr) were detectable. The combination of performance deficits and elevated Ch levels in the ACC supports the hypothesis that subtle structural abnormalities underlie the functional alterations in ACC activation previously observed in ADHD patients.

Poststreptococcal dystonia with bilateral striatal enlargement: MR imaging and spectroscopic findings

Isolated bilateral striatal necrosis is an abnormality of the basal ganglia associated with acute dystonia in children. This report describes the development of dystonic movements in a 7-year-old male patient 2 weeks after streptococcal pharyngitis.

Neuroimaging of attention deficit hyperactivity disorder: can new imaging findings be integrated in clinical practice?

Recent advances in neuroimaging research have helped elucidate the neurobiology of attention deficit hyperactivity disorder (ADHD) and the mechanisms by which medications used to treat ADHD exert their effects. The complex nature and array of imaging techniques, however, present challenges for the busy clinician in assessing possible clinical uses of brain imaging. Even though currently there are no accepted uses for imaging in diagnosing ADHD (other than ruling out identifiable medical or neurologic conditions that may mimic ADHD), this review introduces the main imaging techniques used to study ADHD, identifies relevant complexities facing psychiatric researchers in implementing neuroimaging techniques for clinical purposes, and provides benchmarks to help determine when imaging modalities have advanced to a point that they are deemed clinically useful.

Evidence of brain dysfunction in attention deficit-hyperactivity disorder: a controlled study with proton magnetic resonance spectroscopy

RATIONALE AND OBJECTIVES

Attention deficit-hyperactivity disorder (ADHD) is a socially disabling condition whose pathophysiology is mostly unknown. Previous magnetic resonance imaging (MRI)-based reports have shown structural abnormalities in the prefrontal region and the striatum, but with inconsistencies across the studies with regard to right/left specificity of changes. Our study is aimed at finding evidence of dysfunction with more refined MRI techniques such as diffusion-weighted MRI and spectroscopy.

MATERIALS AND METHODS

We enrolled 22 ADHD children (mean age 9; SD 2.91) and 8 healthy children (mean age 7.5; SD 3). All of them underwent diffusion-weighted MRI in several areas of the brain bilaterally: prefrontal, lentiform nucleus, posterior cingulate, and centrum semiovale; and single-voxel proton magnetic resonance spectroscopy in the left centrum semiovale and right prefrontal region.

RESULTS

We did not see either apparent structural abnormalities of the brain in conventional MRI or differences in the apparent-diffusion coefficients in any of the areas studied. However, we observed significant differences in the N-acetyl-aspartate/creatine ratios in relation to controls in the right prefrontal corticosubcortical region: 1.58 (SD 0.09) versus 1.47 (0.08), P = .01); and in the left centrum semiovale: 2.02 (0.13) versus 1.79 (0.13), P = .0003. This finding is consistent with a published report on eight ADHD children in whom N-acetyl-aspartate/creatine ratios were also elevated.

CONCLUSIONS

Given these results, we hypothesize that a biochemical dysfunction might underlie in the brain of ADHD children. The N-acetyl-aspartate/creatine ratio may be regarded as a potential marker of the disease.

Etiologic subtypes of attention-deficit/hyperactivity disorder: brain imaging, molecular genetic and environmental factors and the dopamine hypothesis

Multiple theories of Attention-Deficit/Hyper-activity Disorder (ADHD) have been proposed, but one that has stood the test of time is the dopamine deficit theory. We review the narrow literature from recent brain imaging and molecular genetic studies that has improved our understanding of the role of dopamine in manifestation of symptoms of ADHD, performance deficits on neuropsychological tasks, and response to stimulant medication that constitutes the most common treatment of this disorder. First, we consider evidence of the presence of dopamine deficits based on the recent literature that (1) confirms abnormalities in dopamine-modulated frontal-striatal circuits, reflected by size (smaller-than-average components) and function (hypoactivation); (2) clarifies the agonist effects of stimulant medication on dopaminergic mechanisms at the synaptic and circuit level of analysis; and (3) challenges the most-widely accepted ADHD-related neural abnormality in the dopamine system (higher-than-normal dopamine transporter [DAT] density). Second, we discuss possible genetic etiologies of dopamine deficits based on recent molecular genetic literature, including (1) multiple replications that confirm the association of ADHD with candidate genes related to the dopamine receptor D4 (DRD4) and the DAT; (2) replication of differences in performance of neuropsychological tasks as a function of the DRD4 genotype; and (3) multiple genome-wide linkage scans that demonstrate the limitations of this method when applied to complex disorders but implicate additional genes that may contribute to the genetic basis of ADHD. Third, we review possible environmental etiologies of dopamine deficits based on recent studies of (1) toxic substances that may affect the dopamine system in early development and contribute substantially to the etiology of ADHD; (2) fetal adaptations in dopamine systems in response to stress that may alter early development with lasting effects, as proposed by the developmental origins of health and disease hypothesis; and (3) gene-environment interactions that may moderate selective damage or adaptation of dopamine neurons. Based on these reviews, we identify critical issues about etiologic subtypes of ADHD that may involve dopamine, discuss methods that could be used to address these issues, and review old and new theories that may direct research in this area in the future.

Proton magnetic resonance spectroscopy study of bilateral thalamus in juvenile myoclonic epilepsy

PURPOSE

To investigate neuronal dysfunction in the thalami of juvenile myoclonic epilepsy (JME) by using proton magnetic resonance spectroscopy (MRS).

METHODS

We performed single-voxel proton MRS over the right and the left thalami of 15 consecutive patients (10 women, 5 men) with JME (mean age 20.3 years) and 16 healthy volunteers (10 women, 6 men) (mean age 24.5 years). All patients had seizure onset in late childhood-teenage, normal neurologic examination, typical electroencephalogram (EEG) of JME and normal magnetic resonance imaging (MRI). We determined N-acetylaspartate (NAA) values and NAA over creatine-phosphocreatine (Cr) values. Mann-Whitney U-test was used to evaluate group differences.

RESULTS

Group analysis showed that echo time (TE) 270 integral value of NAA over left thalamus were significantly decreased in JME patients as compared with controls (34.6033+/-15.8386; 48.0362+/-22.2407, respectively, P=0.019). Also group analysis showed that thalami NAA/Cr ratios were significantly decreased in JME patients (right side, 2.21+/-1.07; left side 2.00+/-0.72) as compared with controls (right side, 3.45+/-1.50; left side, 3.08+/-1.60; P=0.011 and P=0.030, respectively).

CONCLUSION

In the previous studies, NAA values in patients with JME found that they were not statistically lower in thalami than control group. But, in our study, NAA value was found low as well. It has been known that NAA is a neuronal marker and hence it is a valuable metabolite in the neuron physiopathology. As a result, in the patients with JME we tried to support the theory that the underlying mechanism of the generalized seizures was the abnormal thalamocortical circuity, determining the thalamic neuronal dysfunction in MRS statistically.

Evidence for cortical dysfunction in autism: a proton magnetic resonance spectroscopic imaging study

BACKGROUND

Although brain imaging studies have reported neurobiological abnormalities in autism, the nature and distribution of the underlying neurochemical irregularities are unknown. The purpose of this study was to examine cerebral gray and white matter cellular neurochemistry in autism with proton magnetic resonance spectroscopic imaging (MRSI).

METHODS

Proton MRSI examinations were conducted in 26 males with autism (age 9.8 +/- 3.2 years) and 29 male comparison subjects (age 11.1 +/- 2.4 years). Estimates of cerebral gray and white matter concentrations of N-acetylaspartate (NAA), creatine + phosphocreatine, choline-containing compounds, myo-inositol, and glutamate + glutamine (Glx) were made by linear regression analysis of multi-slice MRSI data and compared between groups. Regional estimates of metabolite concentration were also made with multivariate linear regression, allowing for comparisons of frontal, temporal, and occipital gray matter, cerebral white matter, and the cerebellum.

RESULTS

Patients with autism exhibited significantly lower levels of gray matter NAA and Glx than control subjects. Deficits were widespread, affecting most cerebral lobes and the cerebellum. No significant differences were detected in cerebral white matter or cerebellar metabolite levels.

CONCLUSIONS

These results suggest widespread reductions in gray matter neuronal integrity and dysfunction of cortical and cerebellar glutamatergic neurons in patients with autism.

Striatal creatine and glutamate/glutamine in attention-deficit/hyperactivity disorder

OBJECTIVE

The glutamatergic prefrontal-striatal pathway has been implicated previously in the neurobiology of attention-deficit/hyperactivity disorder (ADHD). We used short echo proton magnetic resonance spectroscopy (1H-MRS) to examine glutamate in the prefrontal cortex, left striatum, and, as a control area, the occipital lobe.

METHOD

Thirteen treatment-naïve ADHD children and 10 healthy comparison subjects participated. All were males between the ages of 6 to 11 years of age. Twelve ADHD subjects were scanned after 8 weeks of treatment.

RESULTS

Striatal glutamate, glutamate/glutamine (Glx) and creatine concentrations were greater in the ADHD subjects at baseline as compared to controls. Only striatal creatine, not glutamate or Glx, was reduced after stimulant treatment in the ADHD patients. No significant differences between groups were noted in the remainder of the striatal metabolites or any of the occipital lobe or prefrontal cortex metabolites.

CONCLUSIONS

These findings provide initial evidence of a striatal creatine/glutamatergic dysregulation in ADHD.

1H MRS-detectable metabolic brain changes and reduced impulsive behavior in adult rats exposed to methylphenidate during adolescence

Administration of methylphenidate (MPH, Ritalin) to children affected by attention deficit hyperactivity disorder (ADHD) is an elective therapy, which however raises concerns for public health, due to possible persistent neuro-behavioral alterations. We investigated potential long-term consequences at adulthood of MPH exposure during adolescence, by means of behavioral and brain MRS assessment in drug-free state. Wistar adolescent rats (30- to 44-day-old) were treated with MPH (0 or 2 mg/kg once/day for 14 days) and then left undisturbed until adulthood. Levels of impulsive behavior were assessed in the intolerance-to-delay task: Food-restricted rats were tested in operant chambers with two nose-poking holes, delivering one food pellet immediately, or five pellets after a delay whose length was increased over days. MPH-exposed animals showed a less marked shifting profile from the large/late to the small/soon reward, suggesting reduced basal levels of impulsivity, compared to controls. In vivo MRI-guided 1H MRS examinations at 4.7 T in anaesthetised animals revealed long-term biochemical changes in the dorsal striatum (STR), nucleus accumbens (NAcc), and prefrontal cortex (PFC) of MPH-exposed rats. Notably, total creatine and taurine, metabolites respectively involved in bioenergetics and synaptic efficiency, were up-regulated in the STR and conversely down-regulated in the NAcc of MPH-exposed rats. A strong correlation was evident between non-phosphorylated creatine in the STR and behavioral impulsivity. Moreover, unaltered total creatine and increased phospho-creatine/creatine ratio were detected in the PFC, suggesting improved cortical energetic performance. Because of this enduring rearrangement in the forebrain function, MPH-exposed animals may be more efficient when faced with delay of reinforcement. In summary, MPH exposure during adolescence produced enduring MRS-detectable biochemical modifications in brain reward-related circuits, which may account for increased self-control capacity of adult rats.

Regionally specific alterations in membrane phospholipids in children with ADHD: An in vivo 31P spectroscopy study

This multi-voxel, phosphorus magnetic resonance spectroscopy ((31)P MRS) study examined the prefrontal cortex (PFC), basal ganglia (BG) and superior temporal (ST) region in 10 children with attention-deficit/hyperactivity disorder (ADHD) and 15 healthy controls. ADHD patients had lower PFC and BG phosphomonoester (PME) levels compared to healthy children. No differences were noted in the ST. These deficits in membrane phospholipid (MPL) precursor levels suggest reduced mass of cellular MPLs due to a possible underdevelopment of neuronal processes and synapses in ADHD.