Brain correlates of antidepressant treatment outcome from neuroimaging studies in depression

Brain SPECT as an Imaging Biomarker for Evaluating Effects of Novel Treatments in Psychiatry-A Case Series

The difficulties of evaluating patients with complex neuropsychiatric conditions and prescribing appropriate treatments are well known. Imaging complements clinical assessments and allows a clinician to narrow the differential diagnosis by facilitating accurate and efficient evaluation. This is particularly relevant to neuropsychiatric conditions that are often diagnosed using a trial-and error process of exclusion. Single Photon Emission Computed Tomography (SPECT) is a functional brain imaging procedure that allows practitioners to measure the functional changes of gray matter structures based on regional cerebral blood flow (rCBF). The accurate diagnosis and treatment selection in psychiatry is challenging due to complex cases and frequent comorbidities. However, such complex neuropsychiatric conditions are increasingly benefitting from new treatment approaches, in addition to established medications. Among these are combination transcranial magnetic stimulation with ketamine infusions (CTK), hyperbaric oxygen therapy (HBOT) and perispinal administration of etanercept (PSE). This article provides readers with six case study examples that demonstrate how brain SPECT imaging can be used, both as a diagnostic tool, and as a potential biomarker for monitoring and evaluating novel treatments for patients with complex neuropsychiatric conditions. Six patients were assessed in our clinic and baseline brain SPECT imagesTourettes and a long history of alcohol were visually compared with SPECT images collected after periods of treatment with CTK or HBOT followed by PSE. This retrospective review demonstrates the clinical utility of these novel treatments and describes how SPECT imaging can complement standard diagnostic assessments. A novel display technique for SPECT images is described and we argue that SPECT imaging can be used for monitoring biomarker for clinical change.

Opportunities of connectomic neuromodulation

The process of altering neural activity - neuromodulation - has long been used to treat patients with brain disorders and answer scientific questions. Deep brain stimulation in particular has provided clinical benefit to over 150,000 patients. However, our understanding of how neuromodulation impacts the brain is evolving. Instead of focusing on the local impact at the stimulation site itself, we are considering the remote impact on brain regions connected to the stimulation site. Brain connectivity information derived from advanced magnetic resonance imaging data can be used to identify these connections and better understand clinical and behavioral effects of neuromodulation. In this article, we review studies combining neuromodulation and brain connectomics, highlighting opportunities where this approach may prove particularly valuable. We focus on deep brain stimulation, but show that the same principles can be applied to other forms of neuromodulation, such as transcranial magnetic stimulation and MRI-guided focused ultrasound. We outline future perspectives and provide testable hypotheses for future work.

Standardization and validation of a parallel form of the verbal and non-verbal recognition memory test in an Italian population sample

In the neuropsychological assessment of several neurological conditions, recognition memory evaluation is requested. Recognition seems to be more appropriate than recall to study verbal and non-verbal memory, because interferences of psychological and emotional disorders are less relevant in the recognition than they are in recall memory paradigms. In many neurological disorders, longitudinal repeated assessments are needed to monitor the effectiveness of rehabilitation programs or pharmacological treatments on the recovery of memory. In order to contain the practice effect in repeated neuropsychological evaluations, it is necessary the use of parallel forms of the tests. Having two parallel forms of the same test, that kept administration procedures and scoring constant, is a great advantage in both clinical practice, for the monitoring of memory disorder, and in experimental practice, to allow the repeated evaluation of memory on healthy and neurological subjects. First aim of the present study was to provide normative values in an Italian sample (n = 160) for a parallel form of a verbal and non-verbal recognition memory battery. Multiple regression analysis revealed significant effects of age and education on recognition memory performance, whereas sex did not reach a significant probability level. Inferential cutoffs have been determined and equivalent scores computed. Secondly, the study aimed to validate the equivalence of the two parallel forms of the Recognition Memory Test. The correlations analyses between the total scores of the two versions of the test and correlation between the three subtasks revealed that the two forms are parallel and the subtasks are equivalent for difficulty.

White matter integrity in major depressive disorder: Implications of childhood trauma, 5-HTTLPR and BDNF polymorphisms

This study examined the impact of childhood neglect, serotonin transporter (5-HTTLPR) and brain derived neurotrophic factor (BDNF) polymorphisms on white matter (WM) integrity in major depressive disorder (MDD) using diffusion tensor imaging (DTI). Fifty-five medication-free MDD patients and 18 controls underwent diffusion tensor imaging scanning, genotyping and completed the Childhood Trauma Questionnaire. Tract based spatial statistics (TBSS) findings revealed reduced fractional anisotropy (FA) in the MDD group in the anterior internal capsule. 5-HTTLPR-S'L' heterozygotes in the MDD group exhibited reduced FA in the internal capsule relative to S'S' and reduced FA in corona radiata compared to L'L'. Probabilistic tractography revealed higher FA in the uncinate fasciculus (UF) for BDNF val/val genotype relative to met-carriers, particularly in individuals with high depression severity. High depression severity and experiences of childhood physical or emotional neglect predicted higher FA in the UF and superior longitudinal fasciculus. Reductions in FA were identified for subgroups of MDD patients who were 5-HTTLPR heterozygotes and BDNF-met carriers. An association between emotional/physical neglect and FA was observed in subjects with high depressive symptoms. Our findings suggest that WM connectivity within frontal and limbic regions are affected by depression and influenced by experiences of neglect and genetic risk factors.

Comparison of Metabolite Concentrations in the Left Dorsolateral Prefrontal Cortex, the Left Frontal White Matter, and the Left Hippocampus in Patients in Stable Schizophrenia Treated with Antipsychotics with or without Antidepressants. ¹H-NMR Spectroscopy Study

Managing affective, negative, and cognitive symptoms remains the most difficult therapeutic problem in stable phase of schizophrenia. Efforts include administration of antidepressants. Drugs effects on brain metabolic parameters can be evaluated by means of proton nuclear magnetic resonance (¹H-NMR) spectroscopy. We compared spectroscopic parameters in the left prefrontal cortex (DLPFC), the left frontal white matter (WM) and the left hippocampus and assessed the relationship between treatment and the spectroscopic parameters in both groups. We recruited 25 patients diagnosed with schizophrenia (DSM-IV-TR), with dominant negative symptoms and in stable clinical condition, who were treated with antipsychotic and antidepressive medication for minimum of three months. A group of 25 patients with schizophrenia, who were taking antipsychotic drugs but not antidepressants, was matched. We compared metabolic parameters (N-acetylaspartate (NAA), myo-inositol (mI), glutamatergic parameters (Glx), choline (Cho), and creatine (Cr)) between the two groups. All patients were also assessed with the Positive and Negative Syndrome Scale (PANSS) and the Calgary Depression Scale for Schizophrenia (CDSS). In patients receiving antidepressants we observed significantly higher NAA/Cr and NAA/Cho ratios within the DLPFC, as well as significantly higher mI/Cr within the frontal WM. Moreover, we noted significantly lower values of parameters associated with the glutamatergic transmission--Glx/Cr and Glx/Cho in the hippocampus. Doses of antipsychotic drugs in the group treated with antidepressants were also significantly lower in the patients showing similar severity of psychopathology.

A MRS study of metabolic alterations in the frontal white matter of major depressive disorder patients with the treatment of SSRIs

BACKGROUND

Proton magnetic resonance spectroscopy provides a non-invasive technology to study brain metabolite levels in vivo, which can be used to measure biochemical compounds or metabolite concentrations in circumscribed brain regions. Previous research has highlighted the role of glial cells in brain white matter. It has been assumed that antidepressant treatment with SSRIs not only affects neurons, but also activates glial cells. This study focused on the observation of any potential changes in the metabolite levels of the ventral prefrontal white matter in major depressive disorder (MDD) patients who have received antidepressant treatment.

METHODS

17 female patients diagnosed as MDD according to Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) criteria with the scores of 18 and above on the 24-item Hamilton Depression Rating Scale (HDRS) were recruited. MRS studies were performed on a 3.0 T MR system, single voxel PRESS spectroscopy with chemical-shift selective saturation water suppression. The volume of interest was localized at the bilateral ventral prefrontal white matter regions (voxel size: 2 × 2 × 2 mm(3)). The spectral data analysis was performed by using the instrument manufacturer supplied software.

RESULTS

The bilateral ventral prefrontal white matter of MDD patients showed significantly lower Cho/Cr (p < 0.05) before receiving treatment. The HDRS, as the indicator of treatment response, showed a significant decrease in patients who had gone through 12 weeks treatment (p < 0.01). The bilateral Cho/Cr values of post-treatment patients were increased significantly compared to that of pre-treatment (p < 0.05).

CONCLUSION

The alteration of ventral prefrontal white matter metabolite levels are likely involved in MDD pathophysiology and imply a crucial role of white matter in MDD.

Neural correlates during working memory processing in major depressive disorder

BACKGROUND

Functional magnetic resonance imaging (fMRI) studies in major depressive disorder (MDD) have revealed cortical-limbic-subcortical dysfunctions during working memory (WM) processing, but the results are inconsistent and it is unclear to what extent these findings are influenced by demographic, clinical characteristics and task performance of patients. The present study conducted a quantitative coordinate-based meta-analysis of fMRI data to investigate the hypothesized dysfunction in the neural correlates during WM processing in MDD.

METHODS

A systematic research was conducted for fMRI studies during WM processing comparing MDD patients with healthy controls (HC). Meta-analysis was performed using effect size signed differential mapping (ES-SDM). Meta-regression analyses with age, sex and medication as factors were performed in MDD group.

RESULTS

Functional MRI data of 160 MDD patients and 203 HC from 13 WM experiments across 11 studies were included in this meta-analysis. In the pooled meta-analysis of all included studies, significant increased activation during WM in the left lateral prefrontal cortex, left precentral gyrus, left insula, right superior temporal and right supramarginal areas, and significant decreased activity in the right precentral gyrus, right precuneus and right insula were observed in MDD compared with controls. In the subgroup analysis of the studies with matched task performance, MDD subgroup showed hyperactivation only in the left prefrontal cortex and hypoactivation in the regions similar to the pooled analysis. The meta-regression with age, sex and medication showed no significance in MDD group.

CONCLUSIONS

Regardless of differences in task performance between groups, patients with MDD showed consistent functional abnormalities in the cortical-limbic-subcortical circuitry during WM processing. Distinct patterns of neural engagement may reflect compensatory neural strategies to potential dysfunction in MDD.

Resting-state brain activation correlates with short-time antidepressant treatment outcome in drug-naïve patients with major depressive disorder

OBJECTIVE

A resting-state functional magnetic resonance imaging study (fMRI) to investigate pretreatment regional differences in brain function, in patients with early treatment responsive (ERD) and early treatment nonresponsive (END) major depressive disorder (MDD).

METHODS

Patients with MDD and healthy control subjects underwent fMRI. Intrinsic neural activity at baseline was evaluated via amplitude of low-frequency fluctuations (ALFF). Antidepressant treatment was initiated after MRI. All patients received selective serotonin reuptake inhibitor type antidepressants at the minimum effective dose.

RESULTS

There were significant differences in brain activity between patients (n = 56) and control subjects (n = 33). Brain activity in patients with ERD (n = 26) differed from those with END (n = 30) in the lingual gyrus and cerebellum. There was a significantly correlation between activity in these regions and disease duration in patients with ERD, and with amelioration of depressive symptoms in patients with END.

CONCLUSIONS

Brain regions related to the neural mechanism of MDD early treatment outcome were identified. These regions may have important implications for the treatment of MDD.

Increased prefrontal cortex activity during negative emotion regulation as a predictor of depression symptom severity trajectory over 6 months

IMPORTANCE

Emotion regulation is critically disrupted in depression, and the use of paradigms that tap into these processes may uncover essential changes in neurobiology during treatment. In addition, because neuroimaging outcome studies of depression commonly use only baseline and end-point data-which are more prone to week-to-week noise in symptomatology-we sought to use all data points over the course of a 6-month trial.

OBJECTIVE

To examine changes in neurobiology resulting from successful treatment.

DESIGN, SETTING, AND PARTICIPANTS

Double-blind trial examining changes in the neural circuits involved in emotion regulation resulting from 1 of 2 antidepressant treatments during a 6-month trial. Twenty-one patients with major depressive disorder and without other Axis I or Axis II diagnoses were scanned before treatment and 2 and 6 months into treatment at the university's functional magnetic resonance imaging facility.

INTERVENTIONS

Venlafaxine hydrochloride extended release (with doses of up to 300 mg) or fluoxetine hydrochloride (with doses of up to 80 mg).

MAIN OUTCOMES AND MEASURES

Neural activity, as measured using functional magnetic resonance imaging during performance of an emotion regulation paradigm, as well as regular assessments of symptom severity using the Hamilton Depression Rating Scale. For use of all data points, slope trajectories were calculated for rate of change in depression severity and for rate of change in neural engagement.

RESULTS

The depressed individuals who showed the steepest decrease in depression severity over the 6-month period were the same individuals who showed the most rapid increases in activity in Brodmann area 10 and the right dorsolateral prefrontal cortex activity when regulating negative affect over the same time frame. This relationship was more robust when using only the baseline and end-point data.

CONCLUSIONS AND RELEVANCE

Changes in prefrontal cortex engagement when regulating negative affect correlate with changes in depression severity over 6 months. These results are buttressed by calculating these statistics, which are more reliable and robust to week-to-week variation than are difference scores.

Failure to segregate emotional processing from cognitive and sensorimotor processing in major depression

Most functional neuroimaging studies of major depressive disorder (MDD) employ univariate methods of statistical analysis to localize abnormalities of neural activity. Less has been done to investigate functional relations between these regions, or with regions not usually implicated in depression. Examination of intraneuronal and interneural network relations is important for the advancement of emerging network models for MDD. Principal component analysis (PCA), a multivariate statistical method, was used to examine differences in functional connectivity between 10 unmedicated patients with MDD and 12 healthy subjects engaged in a positive word viewing task. In healthy subjects, principal component (PC) 1 (33% variance) revealed functional connectivity of task-specific sensory, linguistic, and motor regions, along with functional anticorrelations in the default mode network; PC2 (10% variance) displayed functional connectivity of areas involved in emotional processing. This segregation of functions did not occur in the depressed group, where regions involved in emotional functions appeared in PC1 (34% variance) co-varying with those involved in linguistic, motor, and default mode network processing. The lack of segregation of emotional processing from cognitive and sensorimotor functions may represent a systems level neural substrate for a core phenomenon of depression: the interconnection of affective disturbance with experience, cognition, and behavior.

The use of the EEG in measuring therapeutic drug action: focus on depression and antidepressants

A major issue in proof of concept studies and early clinical trials of novel therapeutic agents is that the active drugs can often have a relatively small additional effect compared with placebo. This is especially the case in psychiatry when we usually have no direct method of measuring the pathology underlying the disorder being studied but, rather, have to rely on the subjective assessment of psychiatric symptoms. The use of the electroencephalogram (EEG) offers two potential major means of addressing this problem. First it is able to provide direct data relating to neural activity that may be abnormal in certain disorders. As such there are opportunities for utilizing the EEG in a variety of ways as an objective outcome measure. Second there is growing evidence that in certain circumstances the EEG can be used to predict which patients are likely to respond to treatment, thus potentially increasing the power of studies by decreasing non-response rates and increasing mean changes in outcome measure. Both of these uses of the EEG are illustrated in reference to the study of mood disorders and in particular depression and its treatment with antidepressants.

Chronic vagus nerve stimulation for treatment-resistant depression increases regional cerebral blood flow in the dorsolateral prefrontal cortex

The purpose of the present study was to assess the effects of vagus nerve stimulation (VNS) therapy on regional cerebral blood flow (rCBF) in depressed patients. Regional cerebral blood flow (rCBF) was assessed by [(99m)Tc]-HMPAO-single photon emission computed tomography (SPECT) before and after 10weeks of VNS in patients participating in an open, uncontrolled European multi-center study investigating efficacy and safety of VNS. Patients suffered from major depression, with a baseline score of≥20 on the 24-item Hamilton Depression Rating Scale (HDRS) and had been unsuccessfully treated with at least two adequately prescribed antidepressant drugs. Data of 15 patients could be analyzed using SPM 2. After 10weeks of VNS (20Hz, 500μs pulse width, stimulation during 30s every 5min at the maximal comfortable level) rCBF was increased in the left dorsolateral/ventrolateral prefrontal cortex (Brodmann areas 46 and 47) and decreased in the right posterior cingulate area, the lingual gyrus and the left insula. Our findings are in line with earlier results which showed that VNS increases rCBF in the left dorsolateral prefrontal cortex. The modulation of the activity in this region could be associated with the antidepressant efficacy of VNS.

Functional connectivity of brain structures correlates with treatment outcome in major depressive disorder

Identifying biosignatures to assess the probability of response to an antidepressant for patients with major depressive disorder (MDD) is critically needed. Functional connectivity MRI (fcMRI) offers the promise to provide such a measure. Previous work with fcMRI demonstrated that the correlation in signal from one region to another is a measure of functional connectivity. In this pilot work, a baseline non-task fcMRI was acquired in 14 adults with MDD who were free of all medications. Participants were then treated for 8 weeks with an antidepressant and then clinically re-evaluated. Probabilistic anatomic regions of interest (ROI) were defined for 16 brain regions (eight for each hemisphere) previously identified as being important in mood disorders. These ROIs were used to determine mean time courses for each individual's baseline non-task fcMRI. The correlations in time courses between 16 brain regions were calculated. These calculated correlations were considered to signify measures of functional connectivity. The degree of connectivity for each participant was correlated with treatment outcome. Among 13 participants with 8 weeks follow-up data, connectivity measures in several regions, especially the subcallosal cortex, were highly correlated with treatment outcome. These connectivity measures could provide a means to evaluate how likely a patient is to respond to an antidepressant treatment. Further work using larger samples is required to confirm these findings and to assess if measures of functional connectivity can be used to predict differential outcomes between antidepressant treatments.

Functional connectivity between ventral prefrontal cortex and amygdala at low frequency in the resting state in bipolar disorder

Trait abnormalities in bipolar disorder (BD) within the ventral prefrontal cortex (vPFC) and the amygdala suggest dysfunction in their connectivity. This study employed low frequency resting state functional magnetic resonance imaging (LFRS-fMRI) to analyze functional connectivity between the vPFC and the amygdala in BD. LFRS-fMRI identified a negative correlation in vPFC-amygdala activity, and the magnitude of this correlation was greater in healthy participants than in subjects with BD. Additionally, whole-brain analysis revealed higher correlations between left and right vPFC in BD, as well as with ventral striatum.

Sigma receptors: potential targets for a new class of antidepressant drug

Despite the widespread and devastating impact of depression on society, our current understanding of its pathogenesis is limited. Likewise, existing treatments are inadequate, providing relief to only a subset of people suffering from depression. The search for more effective antidepressant drugs includes the investigation of new molecular targets. Among them, current data suggests that sigma receptors are involved in multiple processes effecting antidepressant-like actions in vivo and in vitro. This review summarizes accumulated evidence supporting a role for sigma receptors in antidepressant effects and provides a conceptual framework for delineating their potential roles over the course of antidepressant treatment.

Does physical anhedonia play a role in depression? A 20-year longitudinal study

BACKGROUND

Anhedonia towards physical or sensory experiences (i.e., physical anhedonia) has most often been examined as a differentia of schizophrenia and not depression, despite the fact that general anhedonia is a core feature of many models of Major Depressive Disorder (MDD).

METHODS

Forty-nine participants with non-psychotic MDD were recruited from inpatient settings and followed-up six times over 20 years. The three aims of the study was to assess a) the stability of physical anhedonia over time, b) whether physical anhedonia relates to the course of depressive symptoms over time, and c) whether physical anhedonia relates to three domains of functioning - work, social functioning, or re-hospitalizations.

RESULTS

We found that over time physical anhedonia was relatively stable and related to depressive symptoms (both between and within person). Physical anhedonia was also related to certain aspects of functioning, though less robustly than depressive symptoms.

LIMITATIONS

Because depressive symptoms, functioning, and physical anhedonia were measured concurrently at each follow-up, the direction of causality among these variables could not be assessed. Additionally, because our sample was recruited from inpatient settings, our findings may not generalize to individuals with less severe depression.

CONCLUSIONS

A trait tendency to experience decreased pleasure to positive physical stimuli is a clinically meaningful variable for those with MDD and may be a behavioral endophenotype for a more severe form of depression.

Identifying phronotypes in psychiatry

Refinements in the methods of diagnosis for psychiatric disorders are critically needed. These new methods should be based on objectively measured brain characteristics that provide clinically useful information. Studying the brain with respect to psychiatric disorders, however, faces numerous challenges. Utilizing techniques learned in other areas of medicine to deal with symptoms that lead to complex disorders can provide insight into improving diagnostic models in psychiatry. Specifically, many areas of medicine use objective measures of an organ's function or characteristic to guide clinical management of particular subjective complaints. In psychiatry, an objectively measured brain characteristic that provides clinically useful information is proposed to be that person's "phronotype." Important requirements to developing phronotypes are discussed. Identifying phronotypes in psychiatry will require a specific investigative approach that must be grounded in rigorous scientific methodology. Successfully developing such markers will have a profound impact on clinical care, clinical research, basic science research, and most importantly the lives of those suffering from these illnesses.

Working-memory fMRI reveals cingulate hyperactivation in euthymic major depression

While cognitive impairments are well documented for the acute episode of major depressive disorder (MDD), less is known about cognitive functioning in the euthymic state. For working memory, dysfunctional activation of lateral prefrontal and cingulate cortex has been reported in the acute episode. This study investigates working-memory function and its neurobiological correlate in euthymic MDD patients, particularly whether dysfunctional activation persists when depressive symptoms improve. We investigated 56 subjects with functional magnetic resonance imaging (fMRI) at 3 Tesla. To challenge working-memory function, a classical verbal n-back task (0-, 1-, and 2-back) was used in 28 well-characterized, euthymic, unipolar MDD patients and 28 healthy control subjects matched according to age, sex, and educational level. Data were analyzed using SPM5. In the absence of significant behavioral differences, we observed comparable overall patterns of brain activation in both groups. As expected, both groups showed stronger activation of the typical working-memory network with increasing memory load. However, significant hyperactivation of the cingulate cortex was observed in euthymic patients, while lateral prefrontal activation was comparable between patients and controls. Working-memory challenge in the euthymic state of MDD revealed a dissociation of lateral prefrontal and cingulate brain function. Cingulate function, which is important for both emotional and cognitive processing and their integration, is still abnormal when mood is restored. This could reflect a different speed of normalization in prefrontal and limbic cortices, persistent systematic changes in neuronal networks after an episode of MDD, or a compensatory mechanism to maintain working-memory performance.

HF-rTMS treatment in medication-resistant melancholic depression: results from 18FDG-PET brain imaging

INTRODUCTION

High frequency repetitive transcranial magnetic stimulation (HF-rTMS) of the left dorsolateral prefrontal cortex (DLPFC) might be a promising strategy to treat depression, but not all patients show a positive outcome.

OBJECTIVE

In this open study, we evaluate whether a favorable HF-rTMS treatment outcome could be predicted by baseline prefrontal brain glucose metabolism (CMRglc), measured by 18fluorodeoxyglucose positron emission tomography (18FDG-PET).

METHODS

A sample of 21 antidepressant-free, treatment-resistant depression (TRD) patients of the melancholic subtype received 10 sessions of HF-rTMS delivered on the left DLPFC. Patients underwent a static 18FDG-PET before and after HF-rTMS treatment.

RESULTS

Forty-three percent of the patients showed a reduction of at least 50% on their Hamilton Rating Scale for Depression scores. Higher baseline metabolic activities in the DLPFC and the anterior cingulate cortex (ACC) were associated with better clinical outcome. Successful HF-rTMS treatment was related to metabolic changes in subdivisions of the ACC (Brodmann areas 24 and 32).

CONCLUSION

This biological impact of HF-rTMS on regional brain CMRglc explains to some extent how HF-rTMS may improve moods in TRD patients. Larger sham-controlled HF-rTMS treatment studies are needed to confirm these results.

A tractography analysis of two deep brain stimulation white matter targets for depression

BACKGROUND

Deep brain stimulation (DBS) of the subcallosal cingulate white matter (SCCwm) or anterior limb of the internal capsule (ALIC) may be effective in treating depression. Connectivity patterns of these regions may inform on mechanisms of action for DBS of these targets.

METHODS

Diffusion tensor imaging (DTI) and probabilistic tractography were performed in 13 nondepressed subjects to determine connectivity patterns of SCCwm and ALIC. Tract maps were generated for each target in each subject, and tract voxels were coded as being unique to either target or shared. Group level tract maps were generated by including only those voxels common to at least 10 of 13 (>75%) subjects.

RESULTS

The two targets have distinct patterns of connectivity with regions of overlap. The SCCwm showed consistent ipsilateral connections to the medial frontal cortex, the full extent of the anterior and posterior cingulate, medial temporal lobe, dorsal medial thalamus, hypothalamus, nucleus accumbens, and the dorsal brainstem. The ALIC seed, in contrast, demonstrated widespread projections to frontal pole, medial temporal lobe, cerebellum, nucleus accumbens, thalamus, hypothalamus, and brainstem. Common to both targets, albeit through distinct white matter bundles, were connections to frontal pole, medial temporal lobe, nucleus accumbens, dorsal thalamus, and hypothalamus.

CONCLUSIONS

Connectivity patterns of these two DBS white matter targets suggest distinct neural networks with areas of overlap in regions implicated in depression and antidepressant response.

Improving the prediction of treatment response in depression: integration of clinical, cognitive, psychophysiological, neuroimaging, and genetic measures

Antidepressants are important in the treatment of depression, and selective serotonin reuptake inhibitors are first-line pharmacologic options. However, only 50% to 70% of patients respond to first treatment and <40% remit. Since depression is associated with substantial morbidity, mortality, and family burden, it is unfortunate and demanding on health resources that patients must remain on their prescribed medications for at least 4 weeks without knowing whether the particular antidepressant will be effective. Studies have suggested a number of predictors of treatment response, including clinical, psychophysiological, neuroimaging, and genetics, each with varying degrees of success and nearly all with poor prognostic sensitivity and specificity. Studies are yet to be conducted that use multiple measures from these different domains to determine whether sensitivity and specificity can be improved to predict individual treatment response. It is proposed that a focus on standardized testing methodologies across multiple testing modalities and their integration will be crucial for translation of research findings into clinical practice.

Mourning and melancholia revisited: correspondences between principles of Freudian metapsychology and empirical findings in neuropsychiatry

Freud began his career as a neurologist studying the anatomy and physiology of the nervous system, but it was his later work in psychology that would secure his place in history. This paper draws attention to consistencies between physiological processes identified by modern clinical research and psychological processes described by Freud, with a special emphasis on his famous paper on depression entitled 'Mourning and melancholia'. Inspired by neuroimaging findings in depression and deep brain stimulation for treatment resistant depression, some preliminary physiological correlates are proposed for a number of key psychoanalytic processes. Specifically, activation of the subgenual cingulate is discussed in relation to repression and the default mode network is discussed in relation to the ego. If these correlates are found to be reliable, this may have implications for the manner in which psychoanalysis is viewed by the wider psychological and psychiatric communities.

Transcriptional profiling of the rat frontal cortex following administration of the mGlu5 receptor antagonists MPEP and MTEP

The development of selective type 5 metabotropic glutamate receptor (mGlu5) antagonists, such as 2-methyl-6-(phenylethynyl)-pyridine (MPEP) and 3-[(2-methyl-1,3-thiazol-4-yl)ethynyl]-pyridine (MTEP), has revealed an important role for these receptors in various disorders of the nervous system including depression, anxiety, epilepsy, Parkinson's disease, drug addiction, and alcoholism. In this study, we used microarray technology to examine changes in gene expression induced by repeated administration of the mGlu5 antagonists MPEP and MTEP. Male Wistar rats (n=5 per treatment group) were administered MPEP (10 mg/kg), MTEP (10 mg/kg) or vehicle intraperitoneally twice daily for 5 days. Approximately 30 min following the final drug administration, rats were sacrificed and frontal cortices were then dissected and examined for changes in gene expression by cDNA microarray analysis. Changes in gene expression with p-values less than 0.01 were considered to be statistically significant. The expression of 63 genes was changed by both MPEP and MTEP, with 58 genes down-regulated and 5 genes up-regulated. Quantitative PCR verified the magnitude and direction of change in expression of 9 of these genes (r2=0.556, p=0.017). Pathway analysis revealed that many of the biological processes altered by repeated MPEP and MTEP treatment were related to ATP synthesis, hydrolase activity, and signaling pathways associated with mitogen-activated protein kinase (MAPK). Our results demonstrate diverse effects of MPEP and MTEP gene expression in the frontal cortex, and these results may help elucidate the mechanisms by which these compounds produce beneficial effects in animal models of various disorders of the central nervous system.

Developing a neuropsychiatric functional brain imaging test

A number of critical issues must be addressed in order to develop and properly apply a functional brain imaging test. Diagnostic tests involve making a judgment for a single person. As a result, functional brain imaging tests must also be evaluated at the individual level. The population examined in determining the evidence for the accuracy of the test and the specific question being tested should be clearly described so that the test can be applied appropriately. The accuracy of the test must also be established in order to know the degree of confidence to accord a result. Incorporating what has been learned with medical diagnostic test development will enable legitimate and significant neuropsychiatric functional brain imaging tests to be developed in the future.