Localized functional neurochemical marker abnormalities in dorsolateral prefrontal cortex in pediatric obsessive-compulsive disorder

Obsessive-compulsive disorder (OCD) is associated with increased engagement of frontal brain regions across multiple event-related potentials

BACKGROUND

Obsessive-compulsive disorder (OCD) is a psychiatric condition leading to significant distress and poor quality of life. Successful treatment of OCD is restricted by the limited knowledge about its pathophysiology. This study aimed to investigate the pathophysiology of OCD using electroencephalographic (EEG) event-related potentials (ERPs), elicited from multiple tasks to characterise disorder-related differences in underlying brain activity across multiple neural processes.

METHODS

ERP data were obtained from 25 OCD patients and 27 age- and sex-matched healthy controls (HCs) by recording EEG during flanker and go/nogo tasks. Error-related negativity (ERN) was elicited by the flanker task, while N200 and P300 were generated using the go/nogo task. Primary comparisons of the neural response amplitudes and the topographical distribution of neural activity were conducted using scalp field differences across all time points and electrodes.

RESULTS

Compared to HCs, the OCD group showed altered ERP distributions. Contrasting with the previous literature on ERN and N200 topographies in OCD where fronto-central negative voltages were reported, we detected positive voltages. Additionally, the P300 was found to be less negative in the frontal regions. None of these ERP findings were associated with OCD symptom severity.

CONCLUSIONS

These results indicate that individuals with OCD show altered frontal neural activity across multiple executive function-related processes, supporting the frontal dysfunction theory of OCD. Furthermore, due to the lack of association between altered ERPs and OCD symptom severity, they may be considered potential candidate endophenotypes for OCD.

Proton magnetic resonance spectroscopy-based evaluation of metabolic abnormalities in the right dorsolateral prefrontal cortex and caudate nucleus in treatment-naïve patients with obsessive-compulsive disorder

Background

Obsessive-compulsive disorder (OCD) is a common psychiatric disorder whose underlying pathophysiology is insufficiently understood. The pathophysiology of OCD may be related to abnormalities in the biochemistry of neurotransmitters.

Aim

The aim of the present study was to measure the absolute concentration of various metabolites in the right dorsolateral prefrontal cortex (DLPFC) and caudate nucleus (CN) in treatment-naive patients with OCD and compare it with healthy controls (HCs).

Methods

The present study investigated the metabolic profile of two brain regions, namely right DLPFC and CN, by using single voxel in-vivo proton magnetic resonance spectroscopy (1H MRS) in drug-naive patients with OCD (n = 17, mean age = 30.71 ± 10.104 years) and compared it with healthy controls (n = 13, mean age = 30.77 ± 5.449 years). The patients with OCD were recruited after appropriate psychometric assessments. The 1H-MRS experiments were performed using the 3 Tesla (3T) human MR scanner, and absolute concentrations of metabolites were estimated using the LC model.

Results

Significantly lower concentration of tNAA in the right DLPFC was observed in the patients with OCD compared to the controls, which may be indicative of neurodegeneration in this region. However, no significant differences were observed in the concentrations of the metabolites between the patients and controls in the CN region. The level of tNAA in DLPFC significantly correlated with the disability level (WHO-DAS) of the patients.

Conclusions

The present study demonstrates abnormalities in the metabolic profile of an important region, DLPFC of the CSTC circuit, which is suggestive of neurodegeneration in the region in OCD patients.

The impact of childhood trauma on thalamic functional connectivity in patients with obsessive-compulsive disorder

BACKGROUND

Childhood trauma is a vulnerability factor for the development of obsessive-compulsive disorder (OCD). Empirical findings suggest that trauma-related alterations in brain networks, especially in thalamus-related regions, have been observed in OCD patients. However, the relationship between childhood trauma and thalamic connectivity in patients with OCD remains unclear. The present study aimed to examine the impact of childhood trauma on thalamic functional connectivity in OCD patients.

METHODS

Magnetic resonance imaging resting-state scans were acquired in 79 patients with OCD, including 22 patients with a high level of childhood trauma (OCD_HCT), 57 patients with a low level of childhood trauma (OCD_LCT) and 47 healthy controls. Seven thalamic subdivisions were chosen as regions of interest (ROIs) to examine the group difference in thalamic ROIs and whole-brain resting-state functional connectivity (rsFC).

RESULTS

We found significantly decreased caudate-thalamic rsFC in OCD patients as a whole group and also in OCD_LCT patients, compared with healthy controls. However, OCD_HCT patients exhibited increased thalamic rsFC with the prefrontal cortex when compared with both OCD_LCT patients and healthy controls.

CONCLUSIONS

Taken together, OCD patients with high and low levels of childhood trauma exhibit different pathological alterations in thalamic rsFC, suggesting that childhood trauma may be a predisposing factor for some OCD patients.

Detailed measurements and simulations of electric field distribution of two TMS coils cleared for obsessive compulsive disorder in the brain and in specific regions associated with OCD

The FDA cleared deep transcranial magnetic stimulation (Deep TMS) with the H7 coil for obsessive-compulsive disorder (OCD) treatment, following a double-blinded placebo-controlled multicenter trial. Two years later the FDA cleared TMS with the D-B80 coil on the basis of substantial equivalence. In order to investigate the induced electric field characteristics of the two coils, these were placed at the treatment position for OCD over the prefrontal cortex of a head phantom, and the field distribution was measured. Additionally, numerical simulations were performed in eight Population Head Model repository models with two sets of conductivity values and three Virtual Population anatomical head models and their homogeneous versions. The H7 was found to induce significantly higher maximal electric fields (p<0.0001, t = 11.08) and to stimulate two to five times larger volumes in the brain (p<0.0001, t = 6.71). The rate of decay of electric field with distance is significantly slower for the H7 coil (p < 0.0001, Wilcoxon matched-pairs test). The field at the scalp is 306% of the field at a 3 cm depth with the D-B80, and 155% with the H7 coil. The H7 induces significantly higher intensities in broader volumes within the brain and in specific brain regions known to be implicated in OCD (dorsal anterior cingulate cortex (dACC), dorsolateral prefrontal cortex (dlPFC), inferior frontal gyrus (IFG), orbitofrontal cortex (OFC) and pre-supplementary motor area (pre-SMA)) compared to the D-B80. Significant field ≥ 80 V/m is induced by the H7 (D-B80) in 15% (1%) of the dACC, 78% (29%) of the pre-SMA, 50% (20%) of the dlPFC, 30% (12%) of the OFC and 15% (1%) of the IFG. Considering the substantial differences between the two coils, the clinical efficacy in OCD should be tested and verified separately for each coil.

Neural primacy of the dorsolateral prefrontal cortex in patients with obsessive-compulsive disorder

The dorsolateral prefrontal cortex (DLPFC), a key structure in the executive system, has consistently emerged as a crucial element in the pathophysiology of obsessive-compulsive disorder (OCD). However, the neural primacy of the DLPFC remains elusive in this disorder. We investigated the causal interaction (measured by effective connectivity) between the DLPFC and the remaining brain areas using bivariate Granger causality analysis of resting-state fMRI collected from 88 medication-free OCD patients and 88 matched healthy controls. Additionally, we conducted seed-based functional connectivity (FC) analyses to identify network-level neural functional alterations using the bilateral DLPFC as seeds. OCD patients demonstrated reduced FC between the right DLPFC and right orbitofrontal cortex (OFC), and activity in the right OFC had an inhibitory effect on the right DLPFC. Additionally, we observed alterations in both feedforward and reciprocal influences between the inferior temporal gyrus (ITG) and the DLPFC in patients. Furthermore, activity in the cerebellum had an excitatory influence on the right DLPFC in OCD patients. These findings may help to elucidate the psychopathology of OCD by detailing the directional connectivity between the DLPFC and the rest of the brain, ultimately helping to identify regions that could serve as treatment targets in OCD.

The right thalamic glutamate level correlates with functional connectivity with right dorsal anterior cingulate cortex/middle occipital gyrus in unmedicated obsessive-compulsive disorder: A combined fMRI and 1H-MRS study

OBJECTIVE

The imbalance in neurotransmitter and neuronal metabolite concentration within cortico-striato-thalamo-cortical (CSTC) circuit contributes to obsessive-compulsive disorder's (OCD) onset. Previous studies showed that glutamate mediated upregulation of resting-state activity in healthy people. However, there have been few studies investigating the correlational features between functional and neurochemical alterations in OCD.

METHODS

We utilize a combined resting-state functional magnetic resonance imaging (rs-fMRI) and proton magnetic resonance spectroscopy (¹H-MRS) approach to investigate the altered functional connectivity (FC) in association with glutamatergic dysfunction in OCD pathophysiology. Three regions of interest are investigated, i.e., medial prefrontal cortex and bilateral thalamus, for seed-based whole-brain FC analysis as well as MRS data acquisition. There are 23 unmedicated adult OCD patients and 23 healthy controls recruited for brain FC analysis. Among them, 12 OCD and 8 controls are performed MRS data acquisition.

RESULTS

Besides abnormal FC within CSTC circuit, we also find altered FCs in large-scale networks outside CSTC circuit, including occipital area and limbic and motor systems. The decreased FC between right thalamus and right middle occipital gyrus (MOG) is correlated with glutamatergic signal within right thalamus in OCD patients. Moreover, the FC between right thalamus and right dorsal anterior cingulate cortex (dACC) is associated with glutamate level in right thalamus, specifically in patient's group. Finally, the FC between right thalamus and right MOG is correlated with patient's Yale-Brown Obsessive Compulsive Scale (YBOCS) compulsion and total scores, while the right thalamic glutamatergic signal is associated with YBOCS-compulsion score.

CONCLUSION

Our findings showed that the coupled intrinsic functional-biochemical alterations existed both within CSTC circuit and from CSTC to occipital lobe in OCD pathophysiology.

Normal Electrical Activity of the Brain in Obsessive-Compulsive Patients After Anodal Stimulation of the Left Dorsolateral Prefrontal Cortex

Introduction:

Transcranial Direct Current Stimulation (tDCS) has been used as a non-invasive method to increase the plasticity of brain. Growing evidence has shown several brain disorders such as depression, anxiety disorders, and chronic pain syndrome are improved following tDCS. In patients with Obsessive-Compulsive Disorder (OCD), increased brain rhythm activity particularly in the frontal lobe has been reported in several studies using Eectroencephalogram (EEG). To our knowledge, no research has been done on the effects of electrical stimulation on brain signals of patients with OCD. We measured the electrical activity of the brain using EEG in patients with OCD before and after tDCS and compared it to normal participants.

Methods:

Eight patients with OCD (3 males) and 8 matched healthy controls were recruited. A 64-channel EEG was used to record a 5-min resting state before and after application of tDCS in both groups. The intervention of tDCS was applied for 15 minutes with 2 mA amplitude where anode was placed on the left Dorsolateral Prefrontal Cortex (DLPFC) and cathode on the right DLPFC.

Results:

In line with previous studies, the results showed that the power of Delta frequency band in OCD patients are significantly higher than the normal group. Following anodal tDCS, hyperactivity in Delta and Theta bands declined in most channels, particularly in DLPFC (F3, F4) and became similar to normal signals pattern. The reduction in Delta band was significantly more than the other bands.

Conclusion:

Anodal tDCS over the left DLPFC significantly decreased the power of frequency bands of Delta and Theta in Patients with OCD. The pattern of EEG activity after tDCS became particularly similar to normal, so tDCS may have potential clinical application in these patients.

Metabolic abnormality in the right dorsolateral prefrontal cortex in patients with obsessive-compulsive disorder: proton magnetic resonance spectroscopy

OBJECTIVE

Proton magnetic resonance spectroscopy (1H-MRS) was used to evaluate metabolic changes in the dorsolateral prefrontal cortex (DLPFC) in patients with obsessive-compulsive disorder (OCD).

METHODS

In total, 14 OCD patients (mean age 28.9±7.2 years) and 14 healthy controls (mean age 32.6±7.1 years) with no history of neurological and psychiatric illness participated in this study. Brain metabolite concentrations were measured from a localised voxel on the right DLPFC using a 3-Tesla 1H-MRS.

RESULTS

The metabolic concentration of myo-inositol in patients with OCD increased significantly by 52% compared with the healthy controls, whereas glutamine/glutamate was decreased by 11%. However, there were no significant differences in N-acetylaspartate, choline, lactate and lipid between the two groups.

CONCLUSION

These findings would be helpful to understand the pathophysiology of OCD associated with the brain metabolic abnormalities in the right DLPFC.

Serum Cytokine Profiles of Children with Obsessive-Compulsive Disorder Shows the Evidence of Autoimmunity

BACKGROUND

Previous reports have described an association between autoimmunity and primary obsessive compulsive disorder. This study aimed to investigate any differences in the levels of T helper 1, 2, and 17 effector cell cytokines between obsessive compulsive disorder patients and the control group.

METHODS

The study included 34 children (23 males, 11 females), aged between 7 and 17 years, with a diagnosis of obsessive compulsive disorder prior to receiving treatment. The control group consisted of age- and gender-matched children. Study participants were assessed using the Kiddie Schedule for Affective Disorders and Schizophrenia, Present and Lifetime version, Children's Yale Brown Obsession Compulsion Scale, and Children's Depression Inventory. Cytokine serum concentrations were measured using the BD Cytometric Bead Array Human Th1/Th2/Th17 Cytokine Kit.

RESULTS

Interleukin-17A, tumor necrosis factor-α, and interleukin-2 levels were significantly higher in obsessive compulsive disorder patients, However, there was no correlation between T helper 1 and 17 cytokine profiles in the obsessive compulsive disorder group. The duration and severity of obsessive compulsive disorder symptoms were not significantly associated with interleukin-17A, interferon-gamma-γ, interleukin-10, interleukin-6, interleukin-4, and interleukin-2 levels. Interestingly, a negative correlation was found between tumor necrosis factor-α levels and Clinical Global Impression scores.

CONCLUSIONS

These findings suggest, in some cases, obsessive compulsive disorder may develop on a background of autoimmunity, and interleukin-2, tumor necrosis factor-α, and interleukin-17A may play a role in these autoimmune processes. Therefore, we believe it is important to investigate for obsessive compulsive disorder symptoms in patients with autoimmune disease and, conversely, autoimmune diseases in obsessive compulsive disorder patients.

Decreased thalamic glutamate level in unmedicated adult obsessive-compulsive disorder patients detected by proton magnetic resonance spectroscopy

BACKGROUND

Previous neuroimaging studies implied that the dysfunction of cortico-striato-thalamo-cortical (CSTC) circuit served as the neural basis for the pathophysiology of obsessive-compulsive disorder (OCD). The imbalances in neuronal metabolite and neurotransmitter within CSTC circuit have been shown as the leading reasons of the OCD onset. The aim of this study is to investigate the metabolic alterations, especially the glutamatergic signal dysfunction within CSTC circuit, and the relationships between neural metabolites and the symptom severity of OCD patients.

METHODS

Single voxel magnetic resonance spectroscopy (MRS) was conducted in medial prefrontal cortex (mPFC) and bilateral thalamus areas for thirteen unmedicated adult OCD patients with age-, gender-, and education-matched healthy controls. Quantification and multivariate analysis were performed to identify vital metabolic biomarkers for patients and healthy controls group differentiation. Moreover, we performed Spearman׳s rank correlation analysis for OCD patients to examine the relationship between the metabolite concentration level and OCD symptomatology.

RESULTS

Patients with OCD showed significantly decreased glutamate level in mPFC (p=0.021) and right thalamus (p=0.039), and significantly increased choline compounds in left thalamus (p=0.044).The glutamate in right thalamus was shown as the most important metabolite for group separation from multivariate analysis (Q(2)=0.134) and was significantly correlated with the patients׳ compulsion scores (Spearman r=-0.674, p=0.016).

LIMITATIONS

Limited sample size, the use of creatine and phosphocreatine (Cr) ratios rather than absolute concentrations and unresolved glutamine (Gln) are limitations of the present study.

CONCLUSION

Our study results consolidated the hypothesis about glutamatergic signaling dysfunction in OCD. To our knowledge, it is the first finding about a reduced thalamic glutamate level in adult unmedicated OCD patients. The dysregulation of glutamate serves as a potential target for the OCD pharmacotherapy and the detailed mechanisms underlying the glutamate alterations within CSTC circuits merit further investigations.

Body checking as a behavioral link: a preliminary study assessing inhibition and its association to idiosyncratic body checking in anorexia nervosa

Body checking (BC) is a behavioral feature of anorexia nervosa (AN), which is also present in obsessive-compulsive (OC) disorders. This study assessed whether increased body checking in AN patients correlated with deficits in cognitive inhibition. A battery of neuropsychological tests (the Ravello Profile), OC disorder measures, and the Body Checking Questionnaire (BCQ) were administered to nine adolescent females being treated for AN at an in-patient hospital in Scotland, UK. Neuropsychological measures were assessed using composite variables. Body Checking prevalence was split into high and low category to compare across groups. A negative relationship between cognitive inhibition and idiosyncratic body checking was evident. Clinically, increased body-checking symptoms were related to OC symptoms. These findings provide preliminary evidence that idiosyncratic body checking in AN patients may indicate a similar neuropsychological profile found in those with checking behaviors in OCD patients.

Neural Correlates of Boredom in Music Perception

INTRODUCTION

Music can elicit powerful emotional responses, the neural correlates of which have not been properly understood. An important aspect about the quality of any musical piece is its ability to elicit a sense of excitement in the listeners. In this study, we investigated the neural correlates of boredom evoked by music in human subjects.

METHODS

We used EEG recording in nine subjects while they were listening to total number of 10 short-length (83 sec) musical pieces with various boredom indices. Subjects evaluated boringness of musical pieces while their EEG was recording.

RESULTS

Using short time Fourier analysis, we found that beta 2 rhythm was (16-20 Hz) significantly lower whenever the subjects rated the music as boring in comparison to non-boring.

DISCUSSION

The results demonstrate that the music modulates neural activity of various parts of the brain and can be measured using EEG.

Combining diffusion tensor imaging and magnetic resonance spectroscopy to study reduced frontal white matter integrity in youths with family histories of substance use disorders

Individuals with a family history of substance use disorder (FH+) show impaired frontal white matter as indicated by diffusion tensor imaging (DTI). This impairment may be due to impaired or delayed development of myelin in frontal regions, potentially contributing to this population's increased risk for developing substance use disorders. In this study, we examined high angular resolution DTI and proton magnetic resonance spectroscopy data from the anterior corona radiata were collected in 80 FH+ and 34 FH- youths (12.9 ± 1.0 years old). White matter integrity indices included fractional anisotropy (FA), N-acetylaspartate (NAA), and total choline (tCho). Lower FA suggests decreased myelination. Decreased NAA coupled with higher tCho suggests impaired build-up and maintenance of cerebral myelin and consequently greater breakdown of cellular membranes. We found FH+ youths had lower FA (P < 0.0001) and NAA (P = 0.017) and higher tCho (P = 0.04). FH density (number of parents and grandparents with substance use disorders) was negatively correlated with FA (P < 0.0001) and NAA (P = 0.011) and positively correlated with tCho (P = 0.001). FA was independently predicted by both FH density (P = 0.006) and NAA (P = 0.002), and NAA and tCho were both independent predictors of FH density (P < 0.001). Our finding of lower frontal FA in FH+ youths corresponding to lower NAA and increased tCho is consistent with delayed or impaired development of frontal white matter in FH+ youths. Longitudinal studies are needed to determine how these differences relate to substance use outcomes.

Independent component analysis of resting state activity in pediatric obsessive-compulsive disorder

Obsessive-compulsive disorder (OCD) is an often severely disabling illness with onset generally in childhood or adolescence. Little is known, however, regarding the pattern of brain resting state activity in OCD early in the course of illness. We therefore examined differences in brain resting state activity in patients with pediatric OCD compared with healthy volunteers and their clinical correlates. Twenty-three pediatric OCD patients and 23 healthy volunteers (age range 9-17), matched for sex, age, handedness, and IQ completed a resting state functional magnetic resonance imaging exam at 3T. Patients completed the Children's Yale Brown Obsessive Scale. Data were decomposed into 36 functional networks using spatial group independent component analysis (ICA) and logistic regression was used to identify the components that yielded maximum group separation. Using ICA we identified three components that maximally separated the groups: a middle frontal/dorsal anterior cingulate network, an anterior/posterior cingulate network, and a visual network yielding an overall group classification of 76.1% (sensitivity = 78.3% and specificity = 73.9%). Independent component expression scores were significantly higher in patients compared with healthy volunteers in the middle frontal/dorsal anterior cingulate and the anterior/posterior cingulate networks, but lower in patients within the visual network. Higher expression scores in the anterior/posterior cingulate network correlated with greater severity of compulsions among patients. These findings implicate resting state fMRI abnormalities within the cingulate cortex and related control regions in the pathogenesis and phenomenology of OCD early in the course of the disorder and prior to extensive pharmacologic intervention.

Obsessive compulsive disorder networks: positron emission tomography and neuropsychology provide new insights

BACKGROUND

Deep brain stimulation has shed new light on the central role of the prefrontal cortex (PFC) in obsessive compulsive disorder (OCD). We explored this structure from a functional perspective, synchronizing neuroimaging and cognitive measures.

METHODS AND FINDINGS

This case-control cross-sectional study compared 15 OCD patients without comorbidities and not currently on serotonin reuptake inhibitors or cognitive behavioural therapy with 15 healthy controls (matched for age, sex and education level) on resting-state (18)FDG-PET scans and a neuropsychological battery assessing executive functions. We looked for correlations between metabolic modifications and impaired neuropsychological scores. Modifications in glucose metabolism were found in frontal regions (orbitofrontal cortex and dorsolateral cortices), the cingulate gyrus, insula and parietal gyrus. Neuropsychological differences between patients and controls, which were subtle, were correlated with the metabolism of the prefrontal, parietal, and temporal cortices.

CONCLUSION

As expected, we confirmed previous reports of a PFC dysfunction in OCD patients, and established a correlation with cognitive deficits. Other regions outside the prefrontal cortex, including the dorsoparietal cortex and the insula, also appeared to be implicated in the pathophysiology of OCD, providing fresh insights on the complexity of OCD syndromes.

A critical review of magnetic resonance spectroscopy studies of obsessive-compulsive disorder

Functional neuroimaging studies have converged to suggest that cortico-striatal-thalamo-cortical (CSTC) circuit dysfunction is a core pathophysiologic feature of obsessive-compulsive disorder (OCD). Now, complementary approaches examining regional neurochemistry are beginning to yield additional insights with regard to the neurobiology of aberrant CSTC circuitry in OCD. In particular, proton magnetic resonance spectroscopy, which allows for the in vivo quantification of various neurochemicals in the CSTC circuit and other brain regions, has recently been used extensively in studies of OCD patients. In this review, we summarize the diverse and often seemingly inconsistent findings of these studies, consider methodological factors that might help to explain these inconsistencies, and discuss several convergent findings that tentatively seem to be emerging. We conclude with suggestions for possible future proton magnetic resonance spectroscopy studies in OCD.

Proton magnetic resonance spectroscopy in pediatric obsessive-compulsive disorder: longitudinal study before and after treatment

Abnormalities in neurochemical compounds in obsessive-compulsive disorder (OCD) may help increase our knowledge of neurobiological abnormalities in the fronto-subcortical circuits. The aims of this exploratory study were to identify with in vivo magnetic resonance spectroscopy ((1)H-MRS) the possible alterations in neurometabolites in a group of drug naïve children and adolescents with OCD in comparison with a control group and to determine whether there was any effect of treatment on the metabolite levels. Eleven OCD children and adolescents (age range 9-17 years; 6 male, 5 female) and twelve healthy subjects with similar age, sex and estimated intellectual quotient were studied. Proton magnetic resonance spectroscopy at 1.5 T was used. We placed 3 voxels, one bilaterally located involving anterior cingulate-medial frontal regions, and one in each striatal region involving the caudate and putaminal regions. Concentrations of creatine (Cr), myo-inositol (mI), total Cho (glycerophosphocholine+phosphocholine), total NAA (N-acetyl aspartate+N-acetyl aspartylglutamate), and total Glx (glutamate+glutamine) were calculated. We found significantly lower concentrations of total Cho in left striatum in OCD patients compared with healthy subjects. The difference in Cho concentrations in left striatum between the two groups did not change over time and persisted at follow-up assessment. Like the control subjects, OCD patients undergoing pharmacological treatment and clinical recovery showed no significant changes in neurometabolic activity between the first and second evaluations.

A voxel-based morphometric MRI study of stabilized obsessive-compulsive adolescent patients

BACKGROUND

The aim of this study was to determine whether treated stabilized adolescents with obsessive-compulsive disorder (OCD) present brain structure differences in comparison with healthy control subjects.

METHODS

Twenty-seven adolescents with already-treated OCD and 27 healthy controls matched by age, sex and estimated intellectual level were assessed by means of psychopathological scales and magnetic resonance imaging (MRI). Axial three-dimensional T1-weighted images were obtained in a 1.5 T scanner and analyzed using optimized voxel-based morphometry (VBM).

RESULTS

Compared with controls, stabilized patients with OCD did not present any statistical differences in the whole brain. However, a small volume correction analysis yielded significant results that survived correction for multiple comparisons, showing decreased white matter (WM) volume in a small area of the parietal cortex (t=3.39, p=0.045 FWE (family wise error)-corrected) of OCD patients in comparison with healthy controls. There was no significant correlation between decreased WM volume in the parietal cortex and obsessive-compulsive symptomatology.

CONCLUSION

There were no global significant differences in either gray matter (GM) or WM. Small differences were found between adolescent patients with stabilized OCD and healthy controls as regards in WM volume in right parietal areas. The parietal lobe may play a role in the pathophysiology of OCD, even in clinically stabilized patients.

Ion channels and schizophrenia: a gene set-based analytic approach to GWAS data for biological hypothesis testing

Schizophrenia is a complex genetic disorder. Gene set-based analytic (GSA) methods have been widely applied for exploratory analyses of large, high-throughput datasets, but less commonly employed for biological hypothesis testing. Our primary hypothesis is that variation in ion channel genes contribute to the genetic susceptibility to schizophrenia. We applied Exploratory Visual Analysis (EVA), one GSA application, to analyze European-American (EA) and African-American (AA) schizophrenia genome-wide association study datasets for statistical enrichment of ion channel gene sets, comparing GSA results derived under three SNP-to-gene mapping strategies: (1) GENIC; (2) 500-Kb; (3) 2.5-Mb and three complimentary SNP-to-gene statistical reduction methods: (1) minimum p value (pMIN); (2) a novel method, proportion of SNPs per Gene with p values below a pre-defined α-threshold (PROP); and (3) the truncated product method (TPM). In the EA analyses, ion channel gene set(s) were enriched under all mapping and statistical approaches. In the AA analysis, ion channel gene set(s) were significantly enriched under pMIN for all mapping strategies and under PROP for broader mapping strategies. Less extensive enrichment in the AA sample may reflect true ethnic differences in susceptibility, sampling or case ascertainment differences, or higher dimensionality relative to sample size of the AA data. More consistent findings under broader mapping strategies may reflect enhanced power due to increased SNP inclusion, enhanced capture of effects over extended haplotypes or significant contributions from regulatory regions. While extensive pMIN findings may reflect gene size bias, the extent and significance of PROP and TPM findings suggest that common variation at ion channel genes may capture some of the heritability of schizophrenia.

Brain magnetic resonance spectroscopy in obsessive-compulsive disorder: the importance of considering subclinical symptoms of anxiety and depression

Brain metabolite concentrations have recently been assessed in different cerebral regions presumably targeted in patients with obsessive-compulsive disorder (OCD) using magnetic resonance spectroscopy (MRS). However, results have been divergent. Possible confounding variables, such as the cerebral localisation of investigated regions and metabolites considered, as well as subclinical symptoms of anxiety and depression, could have affected these MRS profiles. The main goal of this study was to assess MRS metabolite differences between 13 individuals with OCD and 12 matched healthy controls in seven brain regions potentially involved in OCD. The secondary objective was to assess the relationships between levels of anxiety and depression and brain metabolite concentrations. No difference was found for N-acetylaspartate, glutamate-glutamine, myo-inositol (mI) and choline relative to creatine (Cr) concentration in either the left or right orbitofrontal area, left or right median temporal lobe, left or right thalamus or the anterior cingulate cortex. A significant negative correlation between the mI/Cr in the left orbitofrontal area and the severity of OCD symptomatology was observed while subclinical anxiety and depression were closely related to brain metabolite ratios. Thus, these subclinical symptoms, commonly associated with OCD, should be considered in assessing brain metabolite concentrations and may be central to the comprehension of this disorder.

Regional gray and white matter volume abnormalities in obsessive-compulsive disorder: a voxel-based morphometry study

Previous studies have demonstrated both functional and structural abnormalities in the frontal-striatal-thalamic circuits in obsessive-compulsive disorder (OCD). The purpose of this study was to assess volume abnormalities not only of gray matter (GM), but also of white matter (WM) in patients with OCD using voxel-based morphometry (VBM). Subjects consisted of 23 patients with OCD and 26 normal control subjects. All patients were drug-free for at least 2 weeks before the study. Three-dimensional T1-weighed MR images were obtained in all subjects. Optimized voxel-based morphometry was performed to detect structural difference between the two groups. The patients with OCD demonstrated a significant reduction of GM volume in the bilateral medial prefrontal cortex, right premotor area, right orbitofrontal cortex (OFC), right dorsolateral prefrontal cortex, and bilateral temporal and occipital regions. The OCD patients also showed a significant WM volume increase in the right anterior limb of the internal capsule, right orbitofrontal region, and a significant WM volume reduction in the left anterior cingulate gyrus. Our findings are consistent with previous studies implicating dysfunction of the frontal cortex including the OFC. The results suggested that WM volume abnormalities in the orbitofrontal region, anterior limb of the internal capsule, and anterior cingulate gyrus would imply abnormalities in the pathways of frontal-striatal circuits.

Increased N-Acetylaspartate/creatine ratio in the medial prefrontal cortex among unmedicated obsessive-compulsive disorder patients

AIMS

Changes in the fronto-striato-thalamo-cortical-circuit loop have been suggested in the pathogenesis of obsessive-compulsive disorder (OCD), and have been studied using (1)H magnetic resonance spectroscopy ((1)H MRS) with interesting findings. However, whether neural metabolites are abnormal in the medial prefrontal cortex in patients with OCD is unknown. The purpose of the present study was to investigate neural metabolites in this brain region in a sample of patients with OCD.

METHODS

Subjects were 21 unmedicated OCD patients, including 10 who were drug-naïve, and 19 healthy controls. Single-voxel (1)H MRS was used to study the medial prefrontal cortex for each subject. Levels of N-acetylaspartate (NAA), choline-containing compounds and myoinositol were measured in terms of their ratios with creatine (Cr).

RESULTS

The NAA/Cr ratio was significantly higher among OCD patients than among healthy controls (F = 4.76, P = 0.037). However, it did not correlate with patients' symptoms or with their illness durations. The NAA/Cr ratio also did not differ between drug-naïve and previously medicated patients. No significant group differences were found between OCD patients and normal controls for the choline-containing compounds/Cr or myoinositol/Cr ratios. In addition, a significant correlation between the NAA/Cr ratio and trait anxiety scores on the State-Trait Anxiety Inventory was found among the controls (r = 0.639, P = 0.010).

CONCLUSIONS

The N-Acetylaspartate level relative to creatine in the medial prefrontal cortex was increased among unmedicated OCD patients. This cannot be attributed to the effect of medications. The possible significance of this finding in the pathophysiology of OCD is discussed.

Neurochemistry of the hippocampus in patients with obsessive-compulsive disorder

AIM

To date, despite possible neuroanatomical importance, no magnetic resonance spectroscopy (MRS) study on hippocampus has been performed in obsessive-compulsive disorder (OCD). The purpose of the present study was therefore to compare hippocampal chemicals in patients with OCD with those in healthy subjects with no psychopathology.

METHODS

Eighteen patients meeting DSM-IV criteria for OCD and 18 healthy controls were studied. The patients and controls underwent proton magnetic resonance spectroscopy ((1)H-MRS), and measures of N-acetyl-l-aspartate (NAA), choline (CHO), and creatine (CRE) in hippocampal regions were obtained.

RESULTS

Both NAA/CRE and NAA/CHO ratios in the hippocampus in patients with OCD were reduced relative to healthy controls. The anova showed a near-significant effect of diagnosis for NAA/CRE and a significant effect for NAA/CHO, but the anova did not show any significant effect even at a trend level for CHO/CRE. No main effect of hemisphere was found for any metabolite ratio.

CONCLUSIONS

The presence of neuronal degeneration is suggested in OCD. Future longitudinal neuroimaging and neuropsychological studies with larger patient samples are warranted in order to confirm these preliminary findings to better characterize the relevance of neurochemical abnormalities in hippocampus in the pathophysiology of OCD.

Low expression of catecholamine-O-methyl-transferase gene in obsessive-compulsive disorder

This study examined peripheral catecholamine-O-methyl-transferase (COMT) gene expression in obsessive-compulsive disorder (OCD) patients and healthy controls. Participants included 35 first episode OCD patients and 31 age- and sex-matched healthy controls. Relative COMT gene expression levels were examined by real-time quantitative reverse transcription polymerase chain reaction (RT-PCR) in peripheral blood of all the subjects. COMT gene expression levels, normalized by glyceraldehyde-3-phosphate dehydrogenase (GAPDH), were significantly decreased in the OCD group compared with healthy controls (F=6.244, p=0.015). OCD patients showed a 32% down-regulation. We also found lower COMT gene expression levels in female in comparison to male participants (F=5.366, p=0.024) in the sample as a whole. COMT gene expression down-regulation of male OCD patients relative to male controls is 38%, and that of female OCD patients relative to female controls is 27%. These results suggest that COMT gene expression down-regulation might play an important role in the development of OCD and that there may be gender differences in this alteration.

Neuroimaging in obsessive-compulsive disorder

Many neuroimaging studies have investigated the pathophysiology of obsessive-compulsive disorder. These studies have contributed greatly to the development of contemporary neurocircuitry models of obsessive-compulsive disorder, which emphasize the dysfunction of fronto-striato-thalamocortical circuitry in obsessive-compulsive disorder patients. Specifically, dysfunctions of the orbitofrontal cortex, anterior cingulate cortex, thalamus and caudate nucleus have been revealed through resting state or symptom provocation studies. In addition, dysfunctional activations in the dorsolateral prefrontal cortex and parietal regions have been reported. Recently, these findings have led to the suggestion that the pathogenesis of obsessive-compulsive disorder involves an imbalance between dorsal and ventral fronto-striatal circuits. In this review, we provide updated findings on structural and functional neuroimaging studies performed with obsessive-compulsive disorder patients. The limitations of traditional imaging techniques and recent developments to overcome them will also be discussed.

The neural bases of obsessive-compulsive disorder in children and adults

Functional imaging studies have reported with remarkable consistency hyperactivity in the orbitofrontal cortex (OFC), anterior cingulate cortex (ACC), and caudate nucleus of patients with obsessive-compulsive disorder (OCD). These findings have often been interpreted as evidence that abnormalities in cortico-basal ganglia-thalamo-cortical loops involving the OFC and ACC are causally related to OCD. This interpretation remains controversial, however, because such hyperactivity may represent either a cause or a consequence of the symptoms. This article analyzes the evidence for a causal role of these loops in producing OCD in children and adults. The article first reviews the strong evidence for anatomical abnormalities in these loops in patients with OCD. These findings are not sufficient to establish causality, however, because anatomical alterations may themselves be a consequence rather than a cause of the symptoms. The article then reviews three lines of evidence that, despite their own limitations, permit stronger causal inferences: the development of OCD following brain injury, pediatric autoimmune neuropsychiatric disorders associated with streptococcal infection, and neurosurgical lesions that attenuate OCD. Converging evidence from these various lines of research supports a causal role for the cortico-basal ganglia-thalamo-cortical loops that involve the OFC and ACC in the pathogenesis of OCD in children and adults.

Paediatric obsessive-compulsive disorder, a neurodevelopmental disorder? Evidence from neuroimaging

OBJECTIVE

To present an overview of neuroimaging data on paediatric obsessive-compulsive disorder (OCD) and discuss implications for further research.

METHOD

Medline PsycINFO databases and reference lists were searched for relevant articles. All neuroimaging studies up to October 1, 2008 involving children and adolescents with obsessive-compulsive disorder were included.

RESULTS

Twenty-eight neuroimaging studies using various neuroimaging techniques (CT (2) MRI (15) MRS (8) and SPECT (2) fMRI (2) but no PET or DTI) including a total of 462 paediatric patients were identified. A number of findings indicate a dysfunction of the prefrontal-striatal-thalamic circuit with the involvement of other basal ganglia structures (putamen globus pallidus) and the thalamus in contrast to adult studies which report mainly involvement of the caudate nucleus and orbitofrontal cortex. Several findings point at an aberrant development of the brain in paediatric OCD, patients when compared with healthy controls.

CONCLUSION

Neuroimaging studies have contributed to our understanding of the neurobiological basis of paediatric OCD. This review provides an agenda for further theory driven research in particular aimed at identifying a critical window of abnormal maturation of prefrontal-striatal-thalamic and limbic circuitry in paediatric OCD patients.

Gray matter structural alterations in obsessive-compulsive disorder: relationship to neuropsychological functions

Numerous magnetic resonance (MR) studies have examined gray matter structural alterations in patients with obsessive-compulsive disorder (OCD). Few, however, have used automated, highly reliable techniques such as voxel-based morphometry (VBM) to examine the entire brain in contrast to selected regions of interest. Moreover, few studies have examined the functional correlates of gray matter abnormalities in OCD. We used VBM to evaluate regional gray matter differences between 21 OCD patients and 21 age- and sex-matched healthy volunteers. All patients had comprehensive neuropsychological assessments. MR images were normalized to a customized template and segmented using optimized VBM. OCD patients had significantly more gray matter in the left thalamus compared with healthy volunteers. OCD patients without major depression had significantly more gray matter in the thalamus (bilaterally) and left orbitofrontal cortex as well as an unpredicted region of more right dorsolateral prefrontal gray matter, which remained significant after correction for multiple comparisons, compared with healthy volunteers. In the subgroup of patients without depression, greater right hemisphere thalamic and dorsolateral prefrontal gray matter correlated significantly with worse motor functioning and processing speed, respectively. In this subgroup there was also a tendency for more gray matter in the left orbitofrontal cortex and right dorsolateral prefrontal cortex to be associated with greater symptom severity. Our findings provide additional support for the involvement of cortical-striatal-thalamic circuits in the pathophysiology of OCD and preliminary evidence that a defect involving the dorsolateral prefrontal cortex may also be implicated. Moreover, our data suggest that gray matter structural alterations in OCD have neuropsychological correlates, which may be useful in further characterizing structure-function relations in this disorder.

Brain imaging in pediatric obsessive-compulsive disorder

OBJECTIVE

To review progress in understanding pediatric obsessive-compulsive disorder (OCD). The focus is on the frontal-striatal-thalamic model of OCD, neurobiological and genetic studies of the disorder, and their influence on recent advances in treatment.

METHOD

Computerized literature searches were conducted with the key words "obsessive-compulsive disorder" in conjunction with "pediatric," "genetics," and "imaging."

RESULTS

Neuroimaging studies find evidence to support the frontal-striatal-thalamic model. Genetic and neurochemical studies also implicate glutamate in the pathological finding of OCD. This has led to the application of glutamate-modulating agents to treat OCD.

CONCLUSIONS

Studies of pediatric OCD have led to a refined frontal-striatal-thalamic model of pathogenesis and are having an evidence-based impact on treatment. Despite this progress, fully explanatory models are still needed that would allow for accurate prognosis and the development of targeted and efficacious treatments.

Anterior cingulate glutamate-glutamine levels predict symptom severity in women with obsessive-compulsive disorder

OBJECTIVE

Abnormalities of the anterior cingulate cortex (ACC) have consistently been identified in obsessive-compulsive disorder (OCD), but very few studies have examined the biochemical basis of such changes. The purpose of the present study was to investigate how ACC biochemistry in OCD varies as a function of gender, hemisphere, subregion, and symptomatology.

METHOD

3 T proton-magnetic resonance spectroscopy (MRS) was used to probe ACC biochemistry in 20 OCD patients (10 male, 10 female) and a comparable group of 26 healthy comparison subjects. Data were acquired from the left and right dorsal and rostral subregions of the ACC. Metabolites assessed included N-acetylaspartate (NAA), glutamate-glutamine (Glx), choline-containing compounds (Cho), creatine/phosphocreatine (Cr), and myoinositol-containing compounds (mI).

RESULTS

Female OCD patients had significantly reduced levels of Glx in all but one subregion of the ACC when compared to matched controls. Levels of Glx were correlated with clinical measures of symptom severity in female but not male patients. State levels of anxiety and depression did not explain this association. In addition, both male and female OCD patients had relatively higher concentrations of mI in their right ACC (rostral and dorsal) compared with healthy controls. No other compounds had any statistically significant group differences, nor were the concentrations of any other compounds correlated with symptom measures.

CONCLUSIONS

To the authors' knowledge this is the first study to demonstrate gender-specific neurochemical changes in OCD. Although these findings are tentative and require replication, they raise the possibility that MRS techniques may be of use in objectively monitoring patient progress and assessing the effectiveness of various treatments.

Integrating evidence from neuroimaging and neuropsychological studies of obsessive-compulsive disorder: the orbitofronto-striatal model revisited

Obsessive-compulsive disorder (OCD) is a common, heritable and disabling neuropsychiatric disorder. Theoretical models suggest that OCD is underpinned by functional and structural abnormalities in orbitofronto-striatal circuits. Evidence from cognitive and neuroimaging studies (functional and structural magnetic resonance imaging (MRI) and positron emission tomography (PET)) have generally been taken to be supportive of these theoretical models; however, results from these studies have not been entirely congruent with each other. With the advent of whole brain-based structural imaging techniques, such as voxel-based morphometry and multivoxel analyses, we consider it timely to assess neuroimaging findings to date, and to examine their compatibility with cognitive studies and orbitofronto-striatal models. As part of this assessment, we performed a quantitative, voxel-level meta-analysis of functional MRI findings, which revealed consistent abnormalities in orbitofronto-striatal and other additional areas in OCD. This review also considers the evidence for involvement of other brain areas outside orbitofronto-striatal regions in OCD, the limitations of current imaging techniques, and how future developments in imaging may aid our understanding of OCD.

Proton MR spectroscopy: higher right anterior cingulate N-acetylaspartate/choline ratio in Asperger syndrome compared with healthy controls

BACKGROUND AND PURPOSE

One former study reported higher prefrontal N-acetylaspartate (NAA) levels in patients with Asperger syndrome (AS). The objective of the current study was to test the hypothesis that patients with AS would have higher dorsolateral prefrontal and anterior cingulate cortex NAA/creatine (Cr) and that NAA/Cr would be correlated with symptom severity.

MATERIALS AND METHODS

NAA/choline (Cho), NAA/Cr, and Cho/Cr values revealed by (1)H-MR spectroscopy in 14 right-handed male patients with AS (6 medicated with risperidone), 17-38 years of age, diagnosed by the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, criteria were compared with those of 21 right-handed male controls frequency-matched by age and intelligence quotient scores.

RESULTS

Patients with AS had significantly higher anterior cingulate NAA/Cho levels (z = -2.18, P = .028); there was a statistical trend for higher anterior cingulate NAA/Cr (z = -1.81, P = .069) that was significant when only the unmedicated patients with AS were taken into account (z = -1.95, P = .050). There were no significant differences in dorsolateral prefrontal MR spectroscopy values.

CONCLUSIONS

Our findings show that individuals with AS had higher NAA/Cho levels in the right anterior cingulate compared with healthy controls and that higher anterior cingulate NAA/Cho levels were correlated with higher Yale-Brown Obsessive Compulsive Scale total scores.

Relationship between obsessive-compulsive symptoms and smoking habits amongst schizophrenic patients

The rate of smoking is especially high among patients with schizophrenia (SCH) and schizoaffective disorder (SCHAFF). Patients with obsessive-compulsive disorder (OCD) smoke less than the general population. OCD symptoms are more frequent among patients with SCH or SCHAFF than in the general population, but it is still unclear whether schizophrenia patients with OC symptoms suffer from SCH and comorbid OCD, or whether they represent a unique subgroup of SCH with presenting OC symptoms. In our study we hypothetised that the current smoking rate of schizophrenia patients with OC symptoms is lower than in schizophrenia patients without OC symptoms. We assessed OC symptoms with the Yale-Brown Obsessive Compulsive Scale (Y-BOCS), general state with the Brief Psychiatric Rating Scale (BPRS) and smoking habits with a questionnaire among 66 patients with SCH or SCHAFF. We formed two groups by dividing patients according to their Y-BOCS score. Group I consisted of patients with Y-BOCS scores under 16, while group II consisted of patients with Y-BOCS scores above 16, and we compared the current smoking rates of the two groups. We found that the rates did not differ significantly, so we came to the conclusion that OC symptoms are not in a tight relationship with smoking habits among patients with SCH/SCHAFF.

Bildgebungsbefunde bei Kindern und Jugendlichen mit ADHS, Tic-Störungen und Zwangserkrankungen

Zusammenfassung: ADHS, Tic-Störung, Tourette-Syndrom und Zwangsstörung sind gekennzeichnet durch Defizite in der Handlungskontrolle und treten überzufällig häufig komorbid auf. Es bestehen Hinweise auf eine gemeinsame neurobiologische Basis. Der folgende Übersichtsartikel fasst Ergebnisse aus Bildgebungsstudien zu diesen Störungen im Kindes- und Jugendalter zusammen, wobei strukturelle und funktionelle Befunde durch Magnetresonanztomographie einen Schwerpunkt einnehmen. Übereinstimmend zeigen sich im Vergleich zu gesunden Kontrollen morphologische Veränderungen im Bereich von Basalganglien und präfrontalem Kortex sowie abnorme Aktivierungen in fronto-striatalen Systemen. Vor allem beim ADHS und Tourette-Syndrom werden präfrontale Abweichungen gefunden, die beim letzteren milder ausgeprägt sind und unter Umständen auf Kompensationsmechanismen zurückzuführen sein könnten. Beim ADHS finden sich zusätzlich kleine, globale morphologische Veränderungen im gesamten Kortex und im Zerebellum, beim Tourette-Syndrom werden zudem Auffälligkeiten im okzipitalen Kortex beschrieben. Bei der Zwangserkrankung bestehen weitere strukturelle und funktionelle Aberrationen im Bereich von Amygdala und Thalamus und zudem orbito-frontale Funktionsveränderungen, die beim ADHS eher im ventralen präfrontalen Kortex zu finden sind. Diese Befunde scheinen insgesamt mit Störungen in kortiko-striato-thalamiko-kortikalen Regelkreisen assoziiert zu sein und u. a. in Verbindung mit Dysfunktionen im Bereich der Inhibition von motorischen Reaktionen, impulsiven Handlungen und unerwünschten Gedanken zu stehen. Generell wird die Aussagekraft und Vergleichbarkeit vieler Studien durch kleine und heterogene Gruppen sowie methodische Unterschiede eingeschränkt.

Magnetic resonance and spectroscopic imaging in prenatal alcohol-exposed children: preliminary findings in the caudate nucleus

Magnetic resonance imaging (MRI) and magnetic resonance spectroscopic imaging (MRSI) offer unique, noninvasive methods of measuring, respectively, in vivo quantitative neuroanatomy and neurochemistry. The main purpose of the present study was to identify and compare the neuroanatomical and neurochemical abnormalities that are associated with prenatal exposure to alcohol in both fetal alcohol syndrome (FAS)-diagnosed children and those diagnosed with fetal alcohol effects (FAE). MR data of three age-, gender- and race-balanced groups of children, FAS-diagnosed, FAE-diagnosed and non-exposed controls, were compared. Effects of prenatal alcohol exposure, regardless of diagnosis, were found in the caudate nucleus. Specifically, a significantly smaller caudate nucleus was found for the FAS and FAE participants compared to the controls. In addition, the metabolite ratio of N-acetyl-aspartate to creatine (NAA/Cr), an indicator of neuronal function, in left caudate nucleus of both the FAS and FAE participants was elevated compared to the control group. Analysis of absolute concentrations revealed that the increase in the ratio of NAA/Cr was due to an increase in NAA alone. Although its exact function in the CNS is unknown, NAA is believed to be a neuronal marker due to its exclusive localization to neurons. Some also speculate a role for NAA in myelination. Elevated NAA in the prenatal alcohol-exposed participants could indicate a lack of normal program cell death, dendritic pruning and/or myelination during development. The present study demonstrates that prenatal alcohol-exposed children, with or without facial dysmorphology, have abnormal brain anatomy and chemistry.

Decreased choline and creatine concentrations in centrum semiovale in patients with generalized anxiety disorder: relationship to IQ and early trauma

We have demonstrated, using proton magnetic resonance spectroscopy imaging ((1)H-MRSI), elevations of N-acetyl-aspartate/creatine (NAA/CR) in right dorsolateral prefrontal cortex (DLPFC) in patients with generalized anxiety disorder (GAD) in comparison to healthy volunteers. A recent study indicates that the volume of prefrontal cortical white matter may be disproportionately increased in man in comparison to other primate species, with evolutionary implications. We therefore re-analyzed the identical scans with a specific focus on the centrum semiovale (CSO) as a representative region of interest of cerebral white matter. The central hypothesis was, in accordance with our gray matter findings, that patients with GAD, in comparison to healthy controls, would exhibit either an increase in NAA in CSO, or alternatively demonstrate reductions in concentrations of choline (CHO)-containing compounds and/or creatine+phosphocreatine (CR). MRSI scans that were obtained from an earlier [Mathew, S.J., Mao, X., Coplan, J.D., Smith, E.L., Sackeim, H.A., Gorman, J.M., Shungu, D.C., 2004. Dorsolateral prefrontal cortical pathology in generalized anxiety disorder: a proton magnetic resonance spectroscopic imaging study. American Journal of Psychiatry 161, 1119-1121] sample of 15 patients with GAD [6 with early trauma (ET)] and 15 healthy age- and sex-matched volunteers were analyzed further for CSO metabolite alterations. Self-reported worry was scored using the Penn State Worry Questionnaire (PSWQ) and intelligence was assessed using the Wechsler Abbreviated Scale of Intelligence (WASI). Serial multislice/multivoxel MRSI scans had been performed on a 1.5-T MRI. Using absolute quantification methods for metabolite concentrations, we examined NAA, CHO and CR. GAD patients without ET exhibited bilaterally decreased concentrations of CHO and CR in CSO in comparison to healthy volunteers, whereas GAD patients with ET were indistinguishable from controls. In patients with GAD, high IQ was paired with greater worry, whereas in healthy volunteers, high IQ was associated with less worry. In all subjects, IQ inversely predicted left and right CSO CHO concentrations, independent of age, sex, group assignment and PSWQ scores. The CSO may therefore represent a neural substrate that exhibits reductions in CHO and CR metabolite concentrations that are inversely associated with GAD symptomatology and, in the case of CHO, with intelligence. These conclusions are deemed preliminary due to small sample size, with further study of cerebral WM in anxiety disorders suggested.

A magnetic resonance spectroscopy investigation of obsessive-compulsive disorder and anxiety

The aim of the current study was to use proton magnetic resonance spectroscopy (MRS) to investigate potential irregularities in neurochemical compounds in obsessive-compulsive disorder (OCD) and the extent to which these irregularities are related to state anxiety. Single voxel MRS was used to image the head of the caudate nucleus (HOC) and orbitofrontal white matter (OFWM) bilaterally in adult patients with OCD and a control group. The results indicated that patients with OCD had increased levels of a combined measure of glutamate and glutamine (Glx/Cr) and N-acetyl-l-aspartic acid (NAA/Cr) relative to creatine in the right OFWM and reduced levels of myo-inositol relative to creatine (mI/Cr) in the HOC bilaterally. Correlational analyses indicated that Glx/Cr in the OFWM was related to OCD symptoms, while mI/Cr in the HOC was related to trait and/or state anxiety. Reanalysis of the significant group differences controlling for state anxiety symptoms erased three of the four group differences. These results are discussed in context of the methodological difficulties facing this area of research.

Increased medial thalamic creatine-phosphocreatine found by proton magnetic resonance spectroscopy in children with obsessive-compulsive disorder versus major depression and healthy controls

Altered brain creatine-phosphocreatine levels might reflect changes in brain energy use and have been implicated in the pathogenesis of obsessive-compulsive disorder and major depressive disorder. We used proton magnetic resonance spectroscopy to measure absolute concentrations of creatine-phosphocreatine in the right and left medial thalami in 18 pediatric patients with major depressive disorder 9 to 17 years of age, 18 case-matched healthy controls, and 27 patients with obsessive-compulsive disorder 7 to 16 years old. The two patient groups were psychotropic drug naive and were not comorbid for the diagnosis of the comparison group. We found significantly increased left and right medial thalamic creatine-phosphocreatine concentrations in patients with obsessive-compulsive disorder compared with both healthy controls and patients with major depression. Creatine-phosphocreatine concentrations did not differ significantly between patients with major depression and healthy controls. Our data suggest that increased medial thalamic creatine-phosphocreatine concentrations in patients with untreated obsessive-compulsive disorder reflect altered energy use in the medial thalamus and might differentiate patients with obsessive-compulsive disorder from healthy controls and patients with major depression. Although these results must be considered preliminary, further study of the diagnostic specificity of creatine-phosphocreatine in obsessive-compulsive disorder is indicated.

Single photon emission computed tomography (SPECT) in obsessive-compulsive disorder before and after treatment with inositol

Inositol, a glucose isomer and second messenger precursor, regulates numerous cellular functions and has demonstrated efficacy in obsessive-compulsive disorder (OCD) through mechanisms that remain unclear. The effect of inositol treatment on brain function in OCD has not been studied to date. Fourteen OCD subjects underwent single photon emission computed tomography (SPECT) with Tc-99m HMPAO before and after 12 weeks of treatment with inositol. Whole brain voxel-wise SPM was used to assess differences in perfusion between responders and nonresponders before and after treatment as well as the effect of treatment for the group as a whole. There was 1) deactivation in OCD responders relative to nonresponders following treatment with inositol in the left superior temporal gyrus, middle frontal gyrus and precuneus, and the right paramedian post-central gyrus; 2) no significant regions of deactivation for the group as a whole posttreatment; and 3) a single cluster of higher perfusion in the left medial prefrontal region in responders compared to nonresponders at baseline. Significant reductions in the YBOCS and CGI-severity scores followed treatment. These data are only partly consistent with previous functional imaging work on OCD. They may support the idea that inositol effects a clinical response through alternate neuronal circuitry to the SSRIs and may complement animal work proposing an overlapping but distinct mechanism of action.

Increased medial thalamic choline found in pediatric patients with obsessive-compulsive disorder versus major depression or healthy control subjects: a magnetic resonance spectroscopy study

BACKGROUND

Neurobiologic abnormalities in medial thalamus have been implicated in the pathogenesis of obsessive-compulsive disorder (OCD). We previously used multislice proton magnetic resonance spectroscopic imaging (1-H MRSI) to identify localized functional neurochemical marker alterations in choline (Cho) in medial but not lateral thalamus in treatment-naïve pediatric patients with OCD compared with matched control subjects. Altered brain Cho levels have also been implicated in the pathogenesis of mood disorders.

METHODS

We used 1-H MRSI to study absolute Cho concentrations in 18 psychotropic-naïve pediatric patients with major depressive disorder (MDD) not suffering from OCD, 9-17 years of age, 18 case-matched healthy control subjects, and 27 nondepressed, psychotropic-naïve pediatric patients with OCD, 7-16 years of age.

RESULTS

Significantly increased left and right medial thalamic Cho concentrations were observed in OCD patients compared with both healthy control subjects and patients with MDD. Medial thalamic Cho concentrations did not differ significantly between patients with MDD and control subjects.

CONCLUSIONS

These results suggest that localized functional neurochemical marker alterations in medial thalamic Cho differentiate patients with OCD from healthy control subjects and patients with MDD. Although these results must be considered preliminary, further study of the diagnostic specificity of Cho as a relevant biomarker in OCD is clearly warranted.