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

Milk Fat Globule Membranes for Mental Health across the Human Lifespan

The milk fat globule membrane (MFGM) contains bioactive proteins, carbohydrates, and lipids. Polar lipids found in the MFGM play a critical role in maintaining cell membrane integrity and neuronal signalling capacity, thereby supporting brain health. This review summarises the literature on the MFGM and its phospholipid constituents for improvement of mental health across three key stages of the human lifespan, i.e., infancy, adulthood, and older age. MFGM supplementation may improve mental health by reducing neuroinflammation and supporting neurotransmitter synthesis through the gut-brain axis. Fortification of infant formula with MFGMs is designed to mimic the composition of breastmilk and optimise early gut and central nervous system development. Early behavioural and emotional development sets the stage for future mental health. In adults, promising results suggest that MFGMs can reduce the negative consequences of situational stress. Preclinical models of age-related cognitive decline suggest a role for the MFGM in supporting brain health in older age and reducing depressive symptoms. While there is preclinical and clinical evidence to support the use of MFGM supplementation for improved mental health, human studies with mental health as the primary target outcome are sparce. Further high-quality clinical trials examining the potential of the MFGM for psychological health improvement are important.

Phosphatidylserine for the Treatment of Pediatric Attention-Deficit/Hyperactivity Disorder: A Systematic Review and Meta-Analysis

Objective: To examine the evidence for efficacy of phosphatidylserine for symptoms of attention-deficit/hyperactivity disorder (ADHD) in children. Methods: Medline, Cochrane Library, and ClinicalTrials.gov were searched from inception through August 2020. Studies of any design that assessed phosphatidylserine supplementation for children aged ≤18 years with a diagnosis of ADHD were included in the systematic review; only randomized clinical trials were included in the meta-analysis. Standardized mean differences and 95% confidence intervals (CIs) were calculated, and the heterogeneity of the studies was estimated using I2. The overall quality of the evidence was assessed using the Grading of Recommendations Assessment, Development and Evaluation tool. Results: Four studies met the inclusion criteria for the narrative review (n = 344) and three for the meta-analysis (n = 216). Results of the meta-analysis showed a statistically significant effect of 200-300 mg/day of phosphatidylserine on symptoms of inattention relative to placebo (effect size [ES] 0.36; 95% CI: 0.07 to 0.64; p = 0.01). The effects of phosphatidylserine on overall symptoms of ADHD (ES 0.76; 95% CI: -0.07 to 1.60; p = 0.07) and hyperactivity-impulsivity (ES 0.24; 95% CI: -0.04 to 0.53; p = 0.09) were not statistically significant. Conclusions: Preliminary evidence suggests that phosphatidylserine may be effective for reducing symptoms of inattention in children with ADHD, although the quality of the evidence is low and additional research in this area is warranted.

31 P T2 s of phosphomonoesters, phosphodiesters, and inorganic phosphate in the human brain at 7T

PURPOSE

To determine the phosphorus-31 T2 s of phosphomonoesters, phosphodiesters, and inorganic phosphate in the healthy human brain at 7T.

METHODS

A 3D chemical shift imaging multi-echo sequence with composite block pulses for refocusing was used to measure one free induction decay (FID) and seven full echoes with an echo spacing of 45 ms on the brain of nine healthy volunteers (age range 22-45 years; average age 27 ± 8 years). Spectral fitting was used to determine the change in metabolic signal amplitude with echo time.

RESULTS

The average apparent T2 s with their standard deviation were 202 ± 6 ms, 129 ± 6 ms, 86 ± 2 ms, 214 ± 10 ms, and 213 ± 11 ms for phosphoethanolamine, phosphocholine, inorganic phosphate, glycerophosphoethanolamine, and glycerophosphocholine, respectively.

CONCLUSION

The determined apparent T2 for phosphoethanolamine, glycerophosphocholine, and glycerophosphoethanolamine is approximately 200 ms. The lower apparent T2 value for phosphocholine is attributed to the overlap of this resonance with the 3-phosphorous resonance of 2,3-diphosphoglycerate from blood, with an apparent shorter T2 . Omitting the FID signal and the first echo of phosphocholine leads to a T2 of 182 ± 7 ms, whereas a biexponential analysis leads to 203 ± 4 ms. These values are more in line with phosphoethanolamine and the phosphodiesters. The short T2 of inorganic phosphate is subscribed to the fast reversible exchange with γ-adenosine triphosphate, which is mediated by glyceraldehyde-3-phosphate dehydrogenase and phosphoglycerate kinase within the glycolytic pathway. Magn Reson Med 80:29-35, 2018. © 2017 The Authors Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine. This is an open access article under the terms of the Creative Commons Attribution NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.

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.

MR imaging-detectable metabolic alterations in attention deficit/hyperactivity disorder: from preclinical to clinical studies

MR spectroscopy represents one of the most suitable in vivo tool to assess neurochemical dysfunction in several brain disorders, including attention deficit/hyperactivity disorder. This is the most common neuropsychiatric disorder in childhood and adolescence, which persists into adulthood (in approximately 30%-50% of cases). In past years, many studies have applied different MR spectroscopy techniques to investigate the pathogenesis and effect of conventional treatments. In this article, we review the most recent clinical and preclinical MR spectroscopy results on subjects with attention deficit/hyperactivity disorder and animal models, from childhood to adulthood. We found that the most investigated brain regions were the (pre)frontal lobes and striatum, both involved in the frontostriatal circuits and networks that are known to be impaired in this pathology. Neurometabolite alterations were detected in several regions: the NAA, choline, and glutamatergic compounds. The creatine pool was also altered when an absolute quantitative protocol was adopted. In particular, glutamate was increased in children with attention deficit/hyperactivity disorder, and this can apparently be reversed by methylphenidate treatment. The main difficulties in reviewing MR spectroscopy studies were in the nonhomogeneity of the analyzed subjects, the variety of the investigated brain regions, and also the use of different MR spectroscopy techniques. As for possible improvements in future studies, we recommend the use of standardized protocols and the analysis of other brain regions of particular interest for attention deficit hyperactivity disorder, like the hippocampus, limbic structures, thalamus, and cerebellum.

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.

Proton magnetic resonance spectroscopy of prefrontal white matter in psychotropic naïve children and adolescents with obsessive-compulsive disorder

Obsessive-compulsive disorder (OCD) has a typical onset during childhood or adolescence. Although recent in-vivo proton magnetic resonance spectroscopy ((1)H-MRS) studies report gray matter metabolite abnormalities in children and adolescents with OCD, there are no existing (1)H-MRS studies that measure white matter (WM) metabolite levels in this population. In the present study, we measured metabolite levels in the left and right prefrontal WM (LPFWM and RPFWM, respectively) of psychotropic-naïve children and adolescents with OCD (LPFWM: N=15, mean age 13.3±2.4 years; right RPFWM: N=14, mean age 13.0±2.3 years) and healthy controls (LPFWM: N=17, mean age 11.8±2.7 years; RPFWM: N=18, mean age 12.2±2.8 years). Spectra were acquired using a 3T single voxel PRESS sequence (1.5×2.0×2.0cm(3)). When age and sex effects were controlled, OCD patients had higher levels of RPFWM choline and N-acetyl-aspartate (NAA). In addition, RPFWM levels of NAA, creatine and myo-inositol were positively and significantly correlated with severity of OCD symptoms. In summary, this is the first published study of WM metabolite levels in children and adolescents with OCD. Our preliminary findings lend further support to the previous findings of WM abnormalities in OCD.

Glutamate levels in the associative striatum before and after 4 weeks of antipsychotic treatment in first-episode psychosis: a longitudinal proton magnetic resonance spectroscopy study

IMPORTANCE

Increased glutamate levels in the right associative striatum have been described in patients during a first episode of psychosis. Whether this increase would persist after effective antipsychotic treatment is unknown.

OBJECTIVES

To compare the glutamate levels in antipsychotic-naive patients with first-episode psychosis in the right associative striatum and right cerebellar cortex using proton magnetic resonance spectroscopy before and 4 weeks after antipsychotic treatment and to compare these results with normative data from sex-matched healthy control subjects.

DESIGN, SETTING, AND PARTICIPANTS

Before-after trial in an inpatient psychiatric research unit among 24 antipsychotic-naive patients with first-episode psychosis and 18 healthy controls matched for age, sex, handedness, and cigarette smoking.

INTERVENTIONS

Participants underwent 2 proton magnetic resonance spectroscopy studies: patients were imaged at baseline and after 4 weeks of antipsychotic treatment, while controls were imaged at baseline and at 4 weeks after the baseline measurement. Patients were treated with oral risperidone (open label) for 4 weeks with dosages that were titrated on the basis of clinical judgment.

MAIN OUTCOMES AND MEASURES

Glutamate levels were estimated using LCModel (version 6.2-1T) and were corrected for the cerebrospinal fluid proportion within the voxel.

RESULTS

Patients with first-episode psychosis had higher levels of glutamate in the associative striatum and the cerebellum during the antipsychotic-naive condition compared with controls. After clinically effective antipsychotic treatment, glutamate levels significantly decreased in the associative striatum, with no significant change in the cerebellum. No differences in glutamate levels were observed between groups at 4 weeks.

CONCLUSIONS AND RELEVANCE

Increased glutamate levels observed at baseline in patients with first-episode psychosis normalized after 4 weeks of clinically effective antipsychotic treatment. These results provide support for the hypothesis that improvement in clinical symptoms might be related to a decrease in glutamate levels.

Brain changes in long-term zen meditators using proton magnetic resonance spectroscopy and diffusion tensor imaging: a controlled study

Introduction

This work aimed to determine whether ¹H magnetic resonance imaging (MRI), magnetic resonance spectroscopy (MRS), diffusion-weighted imaging (DWI) and diffusion tensor imaging (DTI) are correlated with years of meditation and psychological variables in long-term Zen meditators compared to healthy non-meditator controls.

Materials and Methods

Design. Controlled, cross-sectional study. Sample. Meditators were recruited from a Zen Buddhist monastery. The control group was recruited from hospital staff. Meditators were administered questionnaires on anxiety, depression, cognitive impairment and mindfulness. ¹H-MRS (1.5 T) of the brain was carried out by exploring four areas: both thalami, both hippocampi, the posterior superior parietal lobule (PSPL) and posterior cingulate gyrus. Predefined areas of the brain were measured for diffusivity (ADC) and fractional anisotropy (FA) by MR-DTI.

Results

Myo-inositol (mI) was increased in the posterior cingulate gyrus and Glutamate (Glu), N-acetyl-aspartate (NAA) and N-acetyl-aspartate/Creatine (NAA/Cr) was reduced in the left thalamus in meditators. We found a significant positive correlation between mI in the posterior cingulate and years of meditation (r = 0.518; p = .019). We also found significant negative correlations between Glu (r = −0.452; p = .045), NAA (r = −0.617; p = .003) and NAA/Cr (r = −0.448; P = .047) in the left thalamus and years of meditation. Meditators showed a lower Apparent Diffusion Coefficient (ADC) in the left posterior parietal white matter than did controls, and the ADC was negatively correlated with years of meditation (r = −0.4850, p = .0066).

Conclusions

The results are consistent with the view that mI, Glu and NAA are the most important altered metabolites. This study provides evidence of subtle abnormalities in neuronal function in regions of the white matter in meditators.

Higher levels of glutamate in the associative-striatum of subjects with prodromal symptoms of schizophrenia and patients with first-episode psychosis

The glutamatergic and dopaminergic systems are thought to be involved in the pathophysiology of schizophrenia. Their interaction has been widely documented and may have a role in the neurobiological basis of the disease. The aim of this study was to compare, using proton magnetic resonance spectroscopy ((1)H-MRS), glutamate levels in the precommissural dorsal-caudate (a dopamine-rich region) and the cerebellar cortex (negligible for dopamine) in the following: (1) 18 antipsychotic-naïve subjects with prodromal symptoms and considered to be at ultra high-risk for schizophrenia (UHR), (2) 18 antipsychotic-naïve first- episode psychosis patients (FEP), and (3) 40 age- and sex- matched healthy controls. All subjects underwent a (1)H-MRS study using a 3Tesla scanner. Glutamate levels were quantified and corrected for the proportion of cerebrospinal fluid and percentage of gray matter in the voxel. The UHR and FEP groups showed higher levels of glutamate than controls, without differences between UHR and FEP. In the cerebellum, no differences were seen between the three groups. The higher glutamate level in the precommissural dorsal-caudate and not in the cerebellum of UHR and FEP suggests that a high glutamate level (a) precedes the onset of schizophrenia, and (b) is present in a dopamine-rich region previously implicated in the pathophysiology of schizophrenia.

A new experimental approach and signal processing scheme for the detection and quantitation of ³¹P brain neurochemicals from in vivo MRS studies using dual tuned (¹H/³¹P) head coil

Brain (31)P-neurometabolites play an important role in energy and membrane metabolism. Unambiguous identification and quantification of these neurochemicals in different brain regions would be a great aid in advancing the understanding of metabolic processes in the nervous system. Phosphomonoester (PME), consisting of phosphoethanolamine (PE) and phosphocholine (PC), is the "building block" for membranes, while phosphodiesters (PDE), consisting of glycerophosphocholine (GPC) and glycerophosphoethanolamine (GPE) metabolites are involved in the membrane breakdown process. In the clinical setting, generating well-resolved spectra for PC, PE, GPC, and GPE could be crucial phospholipids in providing information regarding membrane metabolism. We present here a new experimental approach for generating well-resolved (31)P spectra for PC and PE as well as for GPC, GPE, and other (31)P metabolites. Our results (based on uni-dimensional (1D) and multi-voxel (31)P studies) indicate that an intermediate excitation pulse angle (35°) is best suited to obtain well-resolved PC/PE and GPC/GPE resonance peaks. Our novel signal processing scheme allows generating metabolite maps of different phospholipids include PC/PE and GPC/GPE using the 'time-domain-frequency-domain' method as referred to in the MATLAB programming language.

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.

Activation of a PARACEST agent for MRI through selective outersphere interactions with phosphate diesters

Ln(S-THP)(3+) complexes are paramagnetic chemical exchange saturation transfer (PARACEST) agents for magnetic resonance imaging (MRI; S-THP = (1S,4S,7S,10S)-1,4,7,10-tetrakis(2-hydroxypropyl)-1,4,7,10-tetraazacyclododecane, Ln(III) = Ce(III), Eu(III), Yb(III)). CEST spectra at 11.7 T show that the PARACEST effect of these complexes is enhanced at neutral pH in buffered solutions containing 100 mM NaCl upon the addition of 1-2 equiv of diethylphosphate (DEP). CEST images of phantoms at 4.7 T confirm that DEP enhances the properties of Yb(S-THP)(3+) as a PARACEST MRI agent in buffered solutions at neutral pH and 100 mM NaCl. Studies using (1)H NMR, direct excitation Eu(III) luminescence spectroscopy, and UV-visible spectroscopy show that DEP is an outersphere ligand. Dissociation constants for [Ln(S-THP)(OH(2))](DEP) are 1.9 mM and 2.8 mM for Ln(III) = Yb(III) at pH 7.0 and Eu(III) at pH 7.4. Related ligands including phosphorothioic acid, O,O-diethylester, ethyl methylphosphonate, O-(4-nitrophenylphosphoryl)choline, and cyclic 3,5-adenosine monophosphate do not activate PARACEST. BNPP (bis(4-nitrophenyl phosphate) activates PARACEST of Ln(S-THP)(3+) (Ln(III) = Eu(III), Yb(III)), albeit less effectively than does DEP. These data show that binding through second coordination sphere interactions is selective for phosphate diesters with two terminal oxygens and two identical ester groups. A crystal structure of [Eu(S-THP)(OH(2))]((O(2)NPhO)(2)PO(2))(2)(CF(3)SO(3)) x 2 H(2)O x iPrOH has two outersphere BNPP anions that form hydrogen bonds to the alcohol groups of the macrocycle and the bound water ligand. This structure supports (1)H NMR spectroscopy studies showing that outersphere interactions of the phosphate diester with the alcohol protons modulate the rate of alcohol proton exchange to influence the PARACEST properties of the complex. Further, DEP interacts only with the nonionized form of the complex, Ln(S-THP)(OH(2))(3+) contributing to the pH dependence of the PARACEST effect.

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.

Longitudinal 4.0 Tesla (31)P magnetic resonance spectroscopy changes in the anterior cingulate and left thalamus in first episode schizophrenia

Progressive volumetric losses in schizophrenia may be preceded by abnormal cell membrane metabolism. Longitudinal changes in membrane metabolites were quantified with (31)P MRS in the anterior cingulate and left thalamus of 13 first episode schizophrenic patients and 13 healthy volunteers at baseline and 30 months. Glycerophosphocholine was higher in patients at baseline in the anterior cingulate and glycerophosphoethanolamine was lower in the left thalamus at 30 months compared with patients at baseline and volunteers at 30 months. These observations suggest longitudinal changes in membrane metabolites consistent with a neurodegenerative process in certain cases of schizophrenia.

Efficient 1H to 31P polarization transfer on a clinical 3T MR system

31P MR spectroscopy (MRS) in the detection of phosphocholine (PC), glycerolphosphocholine (GPC), phosphorylelthanolamine (PE), and glycerolphosphoethanolamine (GPE) compounds has shown clinical potential at 1.5T for several human diseases. The use of (1)H to (31)P polarization transfer can improve the sensitivity using a refocused INEPT method with a potential enhancement of 2.4 (gamma(1H)/gamma(31P)). However, in this method the (31)P signals of PE, PC, GPE, and GPC are strongly attenuated (50% or more) due to J-coupling between (31)P and (1)H that have similar magnitudes for homonuclear J-coupling constants in those metabolites. A method to cancel the homonuclear J-coupling effects in polarization transfer experiments is to apply frequency-selective refocusing pulses, which becomes feasible at 3T due to the increased chemical shift dispersion as compared to 1.5T. In this study, full (1)H to (31)P polarization transfer was realized using chemical shift selective refocusing pulses at 3T. T(1) and T(2) values for (1)H and (31)P spins of PE, PC, GPE, and GPC were measured in the human brain. A more than 2-fold signal-to-noise ratio (SNR) improvement was obtained compared to an optimized direct (31)P MRS method. As shifted RF pulses were used, this method can be applied on a broadband clinical MR system with a single RF system.

Evidence of developmental alterations in cortical and subcortical regions of children with attention-deficit/hyperactivity disorder: a multivoxel in vivo phosphorus 31 spectroscopy study

CONTEXT

There is mounting evidence of neurodevelopmental alterations implicating the prefrontal cortex (PFC) and basal ganglia in children with attention-deficit/hyperactivity disorder (ADHD). The brain undergoes substantive structural and functional changes with a differential timing between brain regions during development from childhood to adolescence. In vivo phosphorus 31 magnetic resonance spectroscopy ((31)P MRS) is a noninvasive neuroimaging approach that is sensitive in assessing developmental changes of overproducing/pruning of synapses.

OBJECTIVE

To provide support for a developmental mechanism targeting a bottom-up dysfunction of the basal ganglia impairing the fine-tuning of prefrontal functions in ADHD.

DESIGN

Cross-sectional study.

SETTING

Pittsburgh, Pennsylvania, and the surrounding areas.

PARTICIPANTS

Thirty-one psychostimulant-naive children with ADHD (mean [SD] age, 8.1 [1.2] years; range, 6.1-10.0 years) and 36 healthy control subjects (mean [SD] age, 8.1 [1.3] years; range, 6.1-10.4 years).

MAIN OUTCOME MEASURE

Membrane phospholipid (MPL) precursor levels (ie, phosphomonoesters that are anabolic metabolites of MPL) were assessed in the PFC and basal ganglia as well as in 4 other brain regions using in vivo (31)P MRS.

RESULTS

Lower bilateral MPL precursor levels in the basal ganglia and higher MPL precursor levels in the inferior parietal region (primarily right side) were noted in the children with ADHD as compared with healthy control children. There was a group x age interaction in the PFC and inferior parietal region, with relatively older psychostimulant-naive children with ADHD showing significantly lower PFC and higher inferior parietal MPL precursor levels. No differences between groups were noted in the superior temporal, posterior white matter, or occipital regions.

CONCLUSION

Though based on cross-sectional data, these results are suggestive of possible progressive, nonlinear, and sequential alterations implicating a bottom-up developmental dysfunction in parts of the cortico-striato-thalamo-cortical network in ADHD.

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.