The regional cerebral blood flow changes in major depressive disorder with and without psychotic features

Investigating the association between depression and cerebral haemodynamics-A systematic review and meta-analysis

BACKGROUND

Vascular mechanisms may play a role in depression. The aim of this review is to summarise the evidence on alterations in cerebral haemodynamics in depression.

METHODS

MEDLINE (1946- present), Embase (1947-present), Web of Science (1970-present), PsycINFO (1984-present), CINAHL (1976-present) and CENTRAL were searched using a predefined search strategy. A meta-analysis was conducted in four groups: 1) global cerebral blood flow (CBF) in ml/min/100 g, 2) CBF velocity (CBFv) in cm/s (maximum flow of left middle cerebral artery, 3) combined CBF and CBFv, 4) Ratio of uptake of Tc 99 m HMPAO (region of interest compared to whole brain). Data are presented as mean difference or standardised mean difference and 95% confidence interval (95% CI). A narrative synthesis of the remaining studies was performed.

RESULTS

87 studies were included. CBF was significantly reduced in depressed patients compared to HC [15 studies, 538 patients, 416 HC, MD: -2.24 (95% CI -4.12, -0.36), p = 0.02, I² = 64%]. There were no statistically significant differences in other parameters. The narrative synthesis revealed variable changes in CBF in depressed patients, particularly affecting the anterior cingulate and prefrontal cortices.

LIMITATIONS

There were various sources of heterogeneity including the severity of depression, use of antidepressant medication, imaging modality used and reporting of outcomes. All of these factors made direct comparisons between studies difficult.

CONCLUSIONS

The reduction in CBF in depressed patients compared to HCs may indicate a role for assessment and CBF altering interventions in high-risk groups. However, results were inconsistent across studies, warranting further work to investigate specific subgroups.

Regional Parieto-occipital Hypoperfusion on Arterial Spin Labeling Associates with Major Depressive Disorder

Background:

Reduced cerebral blood flow in parieto-occipital regions has been reported in neurodegenerative disorders using ASL. We aimed to investigate neuropsychiatric and neurodegenerative comorbidities that may associate with parieto-occipital region hypoperfusion.

Methods:

This was a retrospective single-center study. Between March 2017 to May 2018, adult patients who underwent brain MRI with the inclusion of ASL perfusion and who had bilateral reductions of CBF in the parieto-occipital regions were included. ASL was performed using a pseudo-continuous arterial spin labeling (pCASL) technique on 1.5T MR system. Age and gender-matched patients with no perfusion defect were concurrently collected. Comorbidity data was collected from EMR, including major depressive disorder, Alzheimer’s disease, Parkinson’s disease, Schizophrenia, anxiety disorder, hypertension, diabetes mellitus type II, coronary artery disease, and chronic kidney disease. A Pearson’s Chi-Square test was performed to assess for comorbidities associated with hypoperfusion of the parieto-occipital lobes.

Results:

Our patient cohort consisted of 93 patients with bilateral hypoperfusion in the parieto-occipital lobes and 93 age and gender-matched patients without corresponding perfusion defects based on ASL-CBF. Among the comorbidities assessed, there was a statistically significant association between hypoperfusion of the parieto-occipital lobes and major depressive disorder (p=0.004) and Parkinson’s disease (p=0.044). There was no statistically significant association for Alzheimer’s disease, generalized anxiety disorder, diabetes mellitus type II, hypertension, coronary artery disease, or chronic kidney disease.

Conclusion:

Major depressive disorder may be linked to regional parieto-occipital hypoperfusion on ASL.

Efficacy and brain mechanism of transcutaneous auricular vagus nerve stimulation for adolescents with mild to moderate depression: Study protocol for a randomized controlled trial

BACKGROUND

Depression is a common mental illness in childhood and adolescence, with an incidence of 4%-5%; it can lead to impairments in learning and social functioning. Transcutaneous auricular vagus nerve stimulation (taVNS) is a commonly used method of auricular acupuncture point stimulation, which is regarded as an effective treatment for adults with depression. The aim of this study was to investigate the efficacy and mechanism of taVNS for adolescents with mild to moderate depression.

METHODS

This randomized controlled clinical trial will include 120 patients aged 12-16 years, all of whom are diagnosed with mild to moderate depression. Patients will be randomly assigned to a taVNS group and a drug control group (sertraline hydrochloride) at a ratio of 1:1. Patients will be evaluated using the 17-item Hamilton Depression Scale, Hamilton Anxiety Rating Scale, Self-Rating Depression Scale, Self-Rating Anxiety Scale, and Pittsburgh Sleep Quality Index scores at baseline, as well as at the 2nd, 4th, 6th, 8th, and 12th weeks. To investigate the underlying neural mechanisms of taVNS treatment from the perspective of the default mode network, multimodal magnetic resonance imaging (MRI; i.e., structural MRI [sMRI], resting state MRI [rsMRI], and pseudocontinuous arterial spin-labeled [pcASL] MRI) will be used to compare cerebral images among groups. MRI data will also be collected from 40 healthy volunteers to assess whether the participants exhibit normal development of structural and functional components.

DISCUSSION

Depression is the most common mental disorder in adolescence. Drug treatment can improve depression symptoms; however, the side effects of drug treatments are often severe. This study proposes a simple physiotherapy that aims to treat adolescents with mild to moderate depression. The mechanism of taVNS in the treatment of depression will also be investigated. The results of this study will provide evidence to guide the application of taVNS in adolescents with depression.

Emotional distress, brain functioning, and biobehavioral processes in cancer patients: a neuroimaging review and future directions

Despite emerging evidence that distress and adversity can contribute to negative health outcomes in cancer, little is known about the brain networks, regions, or circuits that can contribute to individual differences in affect/distress states and health outcomes in treated cancer patients. To understand the state-of-the-science in this regard, we reviewed neuroimaging studies with cancer patients that examined the associations between negative affect (distress) and changes in the metabolism or structure of brain regions. Cancer patients showed changes in function and/or structure of key brain regions such as the prefrontal cortex, thalamus, amygdala, hippocampus, cingulate cortex (mainly subgenual area), hypothalamus, basal ganglia (striatum and caudate), and insula, which are associated with greater anxiety, depression, posttraumatic stress disorder (PTSD) symptoms, and distress. These results provide insights for understanding the effects of these psychological and emotional factors on peripheral stress-related biobehavioral pathways known to contribute to cancer progression and long-term health outcomes. This line of work provides leads for understanding the brain-mediated mechanisms that may explain the health effects of psychosocial interventions in cancer patients and survivors. A multilevel and integrated model for distress management intervention effects on psychological adaptation, biobehavioral processes, cancer pathogenesis, and clinical outcomes is proposed for future research.

Cerebellar microstructural abnormalities in bipolar depression and unipolar depression: A diffusion kurtosis and perfusion imaging study

BACKGROUND

Depression in the context of bipolar disorder (BD) is often misdiagnosed as unipolar depression (UD), leading to mistreatment and poor clinical outcomes. However, little is known about the similarities and differences in cerebellum between BD and UD.

METHODS

Patients with BD (n=35) and UD (n=30) during a depressive episode as well as 40 healthy controls underwent diffusional kurtosis imaging (DKI) and three dimensional arterial spin labeling (3D ASL). The DKI parameters including mean kurtosis (MK), axial kurtosis (Ka), radial kurtosis (Kr),fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (Da) and radial diffusivity (Dr) and 3D ASL parameters (i.e. cerebral blood flow) was measured by using regions-of-interest (ROIs) analysis in the superior cerebellar peduncles (SCP), middle cerebellar peduncles (MCP) and dentate nuclei (DN) of cerebellum.

RESULTS

Patients with UD exhibited significant differences from controls for DKI measures in bilateral SCP and MCP and cerebral blood flow (CBF) in bilateral SCP and left DN. Patients with BD exhibited significant differences from controls for DKI measures in the right MCP and left DN and CBF in the left DN. Patients with UD showed significantly lower MD values compared with patients with BD in the right SCP. Correlation analysis showed there were negative correlations between illness duration and MD and Dr values in the right SCP in UD.

LIMITATIONS

This study was cross-sectional and the sample size was not large. Parts of the patients included were under medication prior to MRI scanning.

CONCLUSIONS

Our findings provide new evidence of microstructural changes in cerebellum in BD and UD. The two disorders may have overlaps in microstructural abnormality in MCP and DN during the depressive period. Microstructural abnormality in SCP may be a key neurobiological feature of UD.

A neurocognitive model for understanding treatment action in depression

The way in which emotion is represented and processed in the human brain is an expanding area of research and has key implications for how we understand and potentially treat affective disorders such as depression. Characterizing the effects of pharmacological manipulations of key neurotransmitter systems can also help reveal the neurochemical underpinnings of emotional processing and how common antidepressant drugs may work in the treatment of depression and anxiety. This approach has revealed that depression is associated with both neural and behavioural biases towards negative over positive stimuli. Evidence from pharmacological challenge studies suggests that antidepressant treatment acts to normalize these biases early on in treatment, resulting in patients experiencing the world in a more positive way, improving their mood over time. This model is supported by evidence from both pharmacological and non-pharmacological interventions. The unique perspective on antidepressant treatment offered by this approach provides some insights into individual response to treatment, as well as novel approaches to drug development.

Extrarenal phenotypes of the UT-B knockout mouse

The urea transporter UT-B is expressed in multiple tissues including erythrocytes, kidney, brain, heart, liver, colon, bone marrow, spleen, lung, skeletal muscle, bladder, prostate, and testis in mammals. Phenotype analysis of UT-B-null mice has confirmed that UT-B deletion results in a urea-selective urine-concentrating defect (see Chap. 9 ). The functional significance of UT-B in extrarenal tissues studied in the UT-B-null mouse is discussed in this chapter. UT-B-null mice present depression-like behavior with urea accumulation and nitric oxide reduction in the hippocampus. UT-B deletion causes a cardiac conduction defect, and TNNT2 and ANP expression changes in the aged UT-B-null heart. UT-B also plays a very important role in protecting bladder urothelium from DNA damage and apoptosis by regulating the urea concentration in urothelial cells. UT-B functional deficiency results in urea accumulation in the testis and early maturation of the male reproductive system. These results show that UT-B is an indispensable transporter involved in maintaining physiological functions in different tissues.

Demyelinating evidences in CMS rat model of depression: a DTI study at 7 T

Depression is among the most debilitating diseases worldwide. Long-term exposure to stressors plays a major role in development of human depression. Chronic mild stress (CMS) seems to be a valid animal model for depression. Diffusion tensor imaging (DTI) is capable of inferring microstructural abnormalities of the white matter and has shown to serve as non-invasive marker of specific pathology. We developed a CMS rat model of depression and validated with behavioral experiments. We measured the diffusion indices (mean diffusivity (MD), fractional anisotropy (FA), axial (λ∥) and radial (λ⊥) diffusivity) to investigate the changes in CMS rat brain during depression onset. Diffusion indices have shown to be useful to discriminate myelin damage from axon loss. DTI was performed in both control and CMS rats (n=10, in each group) and maps of FA, MD, λ∥ and λ⊥ diffusivity values were generated using in-house built software. The diffusion indices were calculated by region of interest (ROI) analysis in different brain regions like the frontal cortex, hippocampus, hypothalamus, cingulum, thalamus, caudate putamen, corpus callosum, cerebral peduncle and sensory motor cortex. The results showed signs of demyelination, reflected by increased MD, decreased FA and increased λ⊥. The results also suggest a possible role of edema or inflammation concerning the brain morphology in CMS rats. The overall finding using DTI suggests there might be a major role of loss of myelin sheath, which leads to disrupted connectivity between the limbic area and the prefrontal cortex during the onset of depression. Our findings indicate that interpretation of these indices may provide crucial information about the type and severity of mood disorders.

Dissociation of regional activity in the default mode network in first-episode, drug-naive major depressive disorder at rest

BACKGROUND

Major depressive disorder (MDD) is associated with altered neural activity in the default mode network (DMN). In the present study, we used a fractional amplitude of low-frequency fluctuations (fALFF) approach to directly investigate the features of spontaneous brain activity of the DMN in patients with the first-episode, drug-naive MDD at rest.

METHODS

Twenty-four first-episode, drug-naive patients with MDD and 24 age-, gender-, and education-matched healthy subjects participated in the study. The fALFF and independent component analysis (ICA) approaches were utilized to analyze the data.

RESULTS

Patients with MDD exhibited a dissociation pattern of resting-state fALFF in the DMN, with increased fALFF in the left dorsal medial prefrontal cortex (MPFC) and decreased fALFF in the left parahippocampal gyrus (PHG). The increased fALFF values of the left dorsal MPFC were positively correlated to the Hamilton Rating Scale for Depression (HRSD) scores.

CONCLUSIONS

Our results first suggested that there was a dissociation pattern of resting-state fALFF in the DMN in patient with MDD, which highlighted the importance of the DMN in the pathogenesis of MDD.

Psychotic versus non-psychotic major depressive disorder: a comparative naturalistic study

OBJECTIVE

Psychotic depressed patients were found to have more severe cognitive deficits, poorer treatment response and higher suicidal risk respect to non-psychotic depressives. Aim of the present research was to compare clinical variables and outcome between psychotic and non-psychotic major depressive patients.

METHOD

A sample of 36 major depressed patients was divided into two groups according to the presence of psychotic symptoms. Structured Clinical Interview for DSM (SCID-I) and Hamilton Depression Rating Scale (HAM-D) were administered to the patients at baseline by trained raters. One-way analysis of variance (ANOVAs) and chi-square tests were performed to compare the two groups. Binary logistic regression was performed to assess the risk of lack of response/remission in patients with psychotic symptoms and the risk of developing psychotic symptoms in major depressives with a family history of schizophrenia or bipolar disorder.

RESULTS

Psychotic major depressives presented more severe illness as showed by HAM-D baseline scores (F=17.20, p<0.001), a longer duration of hospitalization (F=7.64, p=0.009) and they were more frequently treated with clomipramine (χ(2)=16.22, p=0.027). Psychotic symptoms were predictive of lack of remission (OR=4.09, p=0.05) and family history of schizophrenia/psychotic bipolar disorder was associated with psychotic major depression (OR=10.81, p=0.04).

CONCLUSIONS

Patients with psychotic symptoms present a more severe course of illness as showed by long hospitalizations and lower rates of remission. Psychotic depressives show more frequently a family history of "major psychoses" suggesting a continuum in psychotic disorders and a genetic association of major psychotic depression with bipolar disorder and schizophrenia.

Decreased interhemispheric resting-state functional connectivity in first-episode, drug-naive major depressive disorder

BACKGROUND

Major depressive disorder (MDD) is shown to have structural and functional abnormalities in specific brain areas and connections by recent neuroimaging studies. However, little is known about the alterations of the interhemispheric resting-state functional connectivity (FC) in patients with MDD. In the present study, we used a newly developed voxel-mirrored homotopic connectivity (VMHC) method to investigate the interhemispheric FC of the whole brain in patients with MDD at rest.

METHODS

Twenty-four first-episode, drug-naive patients with MDD and 24 age-, gender-, and education-matched healthy subjects underwent a resting-state functional magnetic resonance imaging (fMRI). An automated VMHC approach was used to analyze the data.

RESULTS

Patients with MDD showed lower VMHC than healthy subjects in the medial prefrontal cortex (MPFC) and the posterior cingulate cortex/precuneus (PCC/PCu), two core regions within default mode network (DMN). Both left and right MPFC showed reduced FC with the other frontal areas and with right anterior cingulate gyrus (ACC), while PCC/PCu exhibited abnormal FC with the frontal areas and thalamus in patient group. Significant positive correlation was observed between VMHC in MPFC and persistent error response of Wisconsin Card Sorting Test (WCST-Pre) in patients. Further ROC analysis revealed that VMHC in the MPFC and PCC/PCu could be used to differentiate the patients from healthy subjects with relatively high sensitivity and specificity.

CONCLUSIONS

Our results suggest that decreased VMHC in brain regions within DMN may underlie the pathogenesis of MDD.

Seeking a unified framework for cerebellar function and dysfunction: from circuit operations to cognition

Following the fundamental recognition of its involvement in sensory-motor coordination and learning, the cerebellum is now also believed to take part in the processing of cognition and emotion. This hypothesis is recurrent in numerous papers reporting anatomical and functional observations, and it requires an explanation. We argue that a similar circuit structure in all cerebellar areas may carry out various operations using a common computational scheme. On the basis of a broad review of anatomical data, it is conceivable that the different roles of the cerebellum lie in the specific connectivity of the cerebellar modules, with motor, cognitive, and emotional functions (at least partially) segregated into different cerebro-cerebellar loops. We here develop a conceptual and operational framework based on multiple interconnected levels (a meta-levels hypothesis): from cellular/molecular to network mechanisms leading to generation of computational primitives, thence to high-level cognitive/emotional processing, and finally to the sphere of mental function and dysfunction. The main concept explored is that of intimate interplay between timing and learning (reminiscent of the “timing and learning machine” capabilities long attributed to the cerebellum), which reverberates from cellular to circuit mechanisms. Subsequently, integration within large-scale brain loops could generate the disparate cognitive/emotional and mental functions in which the cerebellum has been implicated. We propose, therefore, that the cerebellum operates as a general-purpose co-processor, whose effects depend on the specific brain centers to which individual modules are connected. Abnormal functioning in these loops could eventually contribute to the pathogenesis of major brain pathologies including not just ataxia but also dyslexia, autism, schizophrenia, and depression.

Assessment of cerebral blood flow findings using 99mTc-ECD single-photon emission computed tomography in patients diagnosed with major depressive disorder

BACKGROUND

Single-photon emission computed tomography (SPECT) is used as an ancillary diagnostic tool in clinical psychiatry. A variety of SPECT studies has been conducted on the findings and the factors that affect the findings, and there is a possibility that age has an effect on cerebral blood flow. We used SPECT to verify the cerebral blood flow findings of patients with major depressive disorder (MDD) considering the effect of age on the findings.

METHODS

We conducted a retrospective survey of inpatients who fulfilled the DSM-IV diagnostic criteria for MDD and who had undergone imaging by technetium-99m ethyl cysteinate dimer ((99m)Tc-ECD) SPECT (N=98, 37 males). After excluding organic factors and comorbidities, we established a depression group (N=61, 24 males) and conducted an inter-group comparison with a normal control group by using SPM software considering the effect of age.

RESULTS

The depression group showed the reduction of cerebral blood flow in the prefrontal area bilaterally, predominantly on the left, including the orbitofrontal cortex, anterior portion of the gyrus cinguli, and dorsolateral prefrontal area, in the left temporal lobe, and in the occipital lobe bilaterally, predominantly on the left. The findings were common to all age groups and that age-specific pattern was not detected.

LIMITATIONS

The facts that this was a retrospective study and small sample size in each age group were limitations of this research. Although it also seems important to evaluate the impact of medication on cerebral blood flow and conduct an evaluation according to the subtype of depression, but we couldn't in this study. In the future it will be necessary to accumulate additional cases and conduct additional studies, including a prospective survey.

CONCLUSION

The results of this study may suggest the existence of a common biological background in patients with MDD that is unaffected by age.

Evidence of a dissociation pattern in resting-state default mode network connectivity in first-episode, treatment-naive major depression patients

BACKGROUND

Imaging studies have shown that major depressive disorder (MDD) is associated with altered activity patterns of the default mode network (DMN). However, the neural correlates of the resting-state DMN and MDD-related pathopsychological characteristics, such as depressive rumination and overgeneral autobiographical memory (OGM) phenomena, still remain unclear.

METHODS

Using independent component analysis, we analyzed resting-state functional magnetic resonance imaging data obtained from 35 first-episode, treatment-naive young adults with MDD and from 35 matched healthy control subjects.

RESULTS

Patients with MDD exhibited higher levels of rumination and OGM than did the control subjects. We observed increased functional connectivity in the anterior medial cortex regions (especially the medial prefrontal cortex and anterior cingulate cortex) and decreased functional connectivity in the posterior medial cortex regions (especially the posterior cingulate cortex/precuneus) in MDD patients compared with control subjects. In the depressed group, the increased functional connectivity in the anterior medial cortex correlated positively with rumination score, while the decreased functional connectivity in the posterior medial cortex correlated negatively with OGM score.

CONCLUSIONS

We report dissociation between anterior and posterior functional connectivity in resting-state DMNs of first-episode, treatment-naive young adults with MDD. Increased functional connectivity in anterior medial regions of the resting-state DMN was associated with rumination, whereas decreased functional connectivity in posterior medial regions was associated with OGM. These results provide new evidence for the importance of the DMN in the pathophysiology of MDD and suggest that abnormal DMN activity may be an MDD trait.

Neurodegenerative evidences during early onset of depression in CMS rats as detected by proton magnetic resonance spectroscopy at 7 T

Depression is a complex psychiatric disorder characterized by anhedonia and feeling of sadness and chronic mild stress (CMS) seems to be a valuable animal model of depression. CMS animal model was induced and validated using behavioral studies. In the present study we investigated the neuro-metabolite changes occurring in prefrontal cortex and hippocampus during the onset of depression, in CMS rat model using in vivo proton magnetic resonance spectroscopy ((1)H MRS) at field strength of 7 T. Results showed that CMS caused depression-like behavior in rats, as indicated by the decrease in sucrose consumption and locomotor activity. (1)H MRS was performed in both control and CMS rats (n=10, in each group) and the quantitative assessment of the neurometabolites was done using LC model. Relative concentrations of all the metabolites along with the macromolecules were calculated for analysis. The results revealed a significant decrease of glutamate (Glu), glutamine (Gln), NAA+NAAG, Glx and GABA levels in both hippocampus and prefrontal cortex of CMS animals and an elevated level of myo-ionisitol (mI) and taurine (Tau) was observed only in hippocampus. These metabolite fluctuations revealed by proton MRS indicate that there might be change in the neuronal integrity of the glial cells and neurons within prefrontal cortex and hippocampus in CMS model of depression. The present study also suggests that there may be a degenerative process concerning the brain morphology in the CMS rats. The overall finding using (1)H MRS suggests that, there might be a major role of the glia and neuron in the onset of depression.

Functional anatomy of autobiographical memory recall deficits in depression

BACKGROUND

Major depressive disorder (MDD) is associated with deficits in recalling specific autobiographical memories (AMs). Extensive research has examined the functional anatomical correlates of AM in healthy humans, but no studies have examined the neurophysiological underpinnings of AM deficits in MDD. The goal of the present study was to examine the differences in the hemodynamic response between patients with MDD and controls while they engage in AM recall.

METHOD

Participants (12 unmedicated MDD patients; 14 controls) underwent functional magnetic resonance imaging (fMRI) scanning while recalling AMs in response to positive, negative and neutral cue words. The hemodynamic response during memory recall versus performing subtraction problems was compared between MDD patients and controls. Additionally, a parametric linear analysis examined which regions correlated with increasing arousal ratings.

RESULTS

Behavioral results showed that relative to controls, the patients with MDD had fewer specific (p=0.013), positive (p=0.030), highly arousing (p=0.036) and recent (p=0.020) AMs, and more categorical (p<0.001) AMs. The blood oxygen level-dependent (BOLD) response in the parahippocampus and hippocampus was higher for memory recall versus subtraction in controls and lower in those with MDD. Activity in the anterior insula was lower for specific AM recall versus subtraction, with the magnitude of the decrement greater in MDD patients. Activity in the anterior cingulate cortex was positively correlated with arousal ratings in controls but not in patients with MDD.

CONCLUSIONS

We replicated previous findings of fewer specific and more categorical AMs in patients with MDD versus controls. We found differential activity in medial temporal and prefrontal lobe structures involved in AM retrieval between MDD patients and controls as they engaged in AM recall. These neurophysiological deficits may underlie AM recall impairments seen in MDD.

Frontal regional homogeneity increased and temporal regional homogeneity decreased after remission of first-episode drug-naïve major depressive disorder with panic disorder patients under duloxetine therapy for 6 weeks

OBJECTIVE

We designed this study to investigate the changes of regional homogeneity (ReHo) after a 6-week duloxetine therapy in first-episode drug-naïve major depressive disorder with panic disorder (FEMDDPD) patients.

METHOD

3T magnetic resonance imaging (MRI) scanning and ReHo functional MRI analysis were performed on 15 patients (male: 5; female: 10; age: 35.87±9.59 years old) at baseline and remitted status (sixth week) compared with 15 healthy control subjects (male: 4; female: 11; age: 34.30±9.87 years old) which were scanned twice within 6 weeks. The ReHo was analyzed by the REST toolbox (resting-state functional MRI data analysis toolbox). The ReHos of different time-points were compared by using paired t test function of REST.

RESULTS

ReHo increased in right superior frontal cortex, right medial frontal cortex and decreased in right superior temporal cortex (uncorrected p<0.00005, cluster threshold>20, surface connected theory) after remission of symptoms in these FEMDDPD patients within 6 weeks (improvements of clinician rating and self rating scale scores; post-hoc corrected p<0.001). No significant changes of ReHo were observed in the controls within 6 weeks (uncorrected p<0.1, no cluster threshold setting, surface connected theory). The changes of ReHo value were mildly correlated with improvements of clinical rating scales with age, gender, depression and anxiety severity as covariates.

CONCLUSION

Our study suggested that differential modulations inside the default mode network probably were associated with remission of FEMDDPD symptoms after duloxetine therapy.

Bimodal effects of fluoxetine on cerebral nitrergic neurogenic vasodilation in porcine large cerebral arteries

Fluoxetine-induced relaxation of the smooth muscle of small cerebral arteries is thought beneficial in treating mental disorders. The present study was designed to examine effect of fluoxetine on neurogenic nitrergic vasodilation in large cerebral arteries, using in vitro tissue myography, techniques of electrophysiology, calcium imaging and biochemistry. In isolated porcine endothelium-denuded basilar arteries in the presence of U-46619-induced active muscle tone, fluoxetine in low concentration (<0.03 μM) significantly enhanced nicotine- and choline-induced relaxations. The vasorelaxation, however, was blocked by higher concentration of fluoxetine (>0.3 μM) with maximum inhibition at 3 μM. At this concentration, fluoxetine did not affect the basal tone or vasorelaxations induced by transmural nerve stimulation, sodium nitroprusside, or isoproterenol. Furthermore, fluoxetine exclusively blocked nicotine-induced inward currents and calcium influx in cultured neurons of rat superior cervical ganglion and Xenopus oocytes expressing human α7-, α3β2-, or α4β2-nicotinic acetylcholine receptors (nAChRs). In addition, fluoxetine at 0.03 μM and 3 μM significantly enhanced and blocked, respectively, nicotine-induced norepinephrine (NE) release from cerebral perivascular sympathetic nerves. These results indicate that fluoxetine via axo-axonal interaction mechanism exhibits bimodal effects on nAChR-mediated neurogenic nitrergic dilation of basilar arteries. Fluoxetine in high concentrations decreases while in low concentrations it increases neurogenic vasodilation. These results from in vitro experimentation suggest that optimal concentrations of fluoxetine which increase or minimally affect neurogenic vasodilation indicative of regional cerebral blood flow may be important consideration in treating mental disorders.

Longitudinal MRI study of cortical thickness, perfusion, and metabolite levels in major depressive disorder

OBJECTIVE

To determine whether patients with major depressive disorder (MDD) display morphologic, functional, and metabolic brain abnormalities in limbic-cortical regions at a baseline magnetic resonance (MR) scan and whether these changes are normalized in MDD patients in remission at a follow-up scan.

METHOD

A longitudinal 3.0-Tesla (T) magnetic resonance imaging (MRI) study was carried out with cortical thickness measurements with a surface-based approach, perfusion measurements with three-dimensional (3D) pseudo-continuous arterial spin labeling (pCASL), and spectroscopy (1H-MRS) measurements in the anterior cingulate cortex (ACC) with water as an internal reference adjusted for cerebrospinal fluid content. We examined 23 MDD patients and 26 healthy controls. MDD patients underwent a baseline MRI at inclusion and were invited to a follow-up scan when they were in remission or after a 6-month follow-up period.

RESULTS

Major findings were a significantly thinner posterior cingulate cortex in non-remitters than in remitters, a significant decrease in perfusion in the frontal lobes and the ACC in non-remitters compared with healthy controls at baseline and significantly reduced N-acetylaspartate, myo-inositol, and glutamate levels in MDD patients compared with healthy controls at baseline.

CONCLUSION

Using novel MRI techniques, we have found abnormalities in cerebral regions related to cortical-limbic pathways in MDD patients.

Mice lacking urea transporter UT-B display depression-like behavior

Urea transporter B is one of urea transporters that selectively transport urea driven by urea gradient across membrane and expressed abundantly in brain. To determine the physiological role of UT-B in brain, UT-B localization, urea concentration, tissue morphology of brain, and behavioral phenotypes were studied in UT-B heterozygous mice via UT-B null mice. UT-B mRNA was expressed in olfactory bulb, cortex, caudate nucleus, hippocampus and hypothalamus of UT-B heterozygous mice. UT-B null mice exhibited depression-like behavior, with urea accumulation, nitric oxide reduction, and selective neuronal nitric oxide synthase level increase in hippocampus. After acute urea loading, the urea level increased, NO production decreased in hippocampus from both types of mice. Moreover, urea level was higher, and NO concentration was lower consistently in UT-B null hippocampus than that in heterozygous hippocampus. In vitro, 25 mM urea inhibited NO production too. Furthermore, UT-B knockout induced a long-lasting notable decrease in regional cerebral blood flow and altered morphology, such as loss of neurons in CA3 region, swelling, and membranous myelin-like structure formation within myelinated and unmyelinated fibers in hippocampus. These results suggest that urea accumulation in the hippocampus induced by UT-B deletion can cause depression-like behavior, which possibly attribute to disturbance in NOS/NO system.

Investigating neural primacy in Major Depressive Disorder: multivariate Granger causality analysis of resting-state fMRI time-series data

Major Depressive Disorder (MDD) has been conceptualized as a neural network-level disease. Few studies of the neural bases of depression, however, have used analytical techniques that are capable of testing network-level hypotheses of neural dysfunction in this disorder. Moreover, of those that have, fewer still have attempted to determine the directionality of influence within functionally abnormal networks of structures. We used multivariate GC analysis, a technique that estimates the extent to which preceding neural activity in one or more seed regions predicts subsequent activity in target brain regions, to analyze blood-oxygen-level-dependent (BOLD) data collected during eyes-closed rest from depressed and never-depressed persons. We found that activation in the hippocampus predicted subsequent increases in ventral anterior cingulate cortex (vACC) activity in depression, and that activity in the medial prefrontal cortex and vACC were mutually reinforcing in MDD. Hippocampal and vACC activation in depressed participants predicted subsequent decreases in dorsal cortical activity. This study shows that, on a moment-by-moment basis, there is increased excitatory activity among limbic and paralimbic structures, as well as increased inhibition in the activity of dorsal cortical structures, by limbic structures in depression; these aberrant patterns of effective connectivity implicate disturbances in the mesostriatal dopamine system in depression. These findings advance the neural theory of depression by detailing specific patterns of limbic excitation in MDD, by making explicit the primary role of limbic inhibition of dorsal cortex in the cortico-limbic relation posited to underlie depression, and by presenting an integrated neurofunctional account of altered dopamine function in this disorder.

Effects of antidepressant treatment on N-acetyl aspartate and choline levels in the hippocampus and thalami of post-stroke depression patients: a study using (1)H magnetic resonance spectroscopy

Previous studies in patients with a major depressive disorder show functional abnormalities in the medial frontal cortex. Functional and structural abnormalities in patients with post-stroke depression (PSD) are not well studied. The major goals of this study were to determine the biochemical abnormalities that occur in PSD and to assess the effect of antidepressants in patients with PSD at the biochemical level. We used magnetic resonance imaging to detect structural or functional abnormalities in PSD patients. In a prospective study, we included 30 patients with PSD and 20 age-matched subjects as controls. Magnetic resonance spectroscopy (MRS) of the brain was conducted in all subjects at the beginning of the study. Patients with PSD were treated with the antidepressant paroxetine (20-40mg/days) for 6 months. After the 6-month period, all PSD subjects underwent MRS again. PSD patients were evaluated with the Hamilton Depression Scale (HAMD) both before and after treatment with the antidepressant. The mean age of the PSD patients was 70.0+/-4.2 years and that of the controls was 67.2+/-5.4 years. Before treatment, N-acetyl aspartate/creatine (NAA/Cr) ratios in the bilateral hippocampus and thalami were significantly lower in PSD patients than in controls. Choline/creatine (Cho/Cr) ratios were significantly higher in the bilateral hippocampus and left thalamus in PSD patients than in controls. The Cho/Cr ratios were significantly higher in the left thalamus than in the right in PSD patients. The HAMD scores were significantly correlated with the Cho/Cr ratios in the left and right hippocampus. Compared with PSD patients before antidepressant treatment, the PSD subjects after treatment had significantly higher NAA/Cr ratios in the left hippocampus and bilateral thalami. They had significantly lower Cho/Cr ratios in bilateral hippocampus and left thalamus. Our study suggests that metabolic abnormalities in the hippocampus and thalamus are implicated in PSD. Antidepressants may alter the local metabolic abnormalities in these areas.

A single photon emission computerized tomography (SPECT) study of regional cerebral blood flow in bipolar disorder

Data on functional imaging of bipolar disorder (BD) utilizing single photon emission computerized tomography (SPECT) is limited. This study assessed regional cerebral blood flow (rCBF), using (99m)Tc-ECD SPECT, among patients with BD, with mania (N=10) or depression (N=10), compared with 10 patients with unipolar depression and 10 normal controls. Regions of interest were analysed using a semi-automatic brain quantification programme. Compared to controls, patients with mania had significantly reduced perfusion mainly in the left frontal area, also in the left anterior cingulate and parietal cortices; those with bipolar depression had significantly lowered rCBF principally in the anterior temporal regions bilaterally, as well as the left parietal area. Patients with unipolar depression had significantly lowered perfusion than controls in most of the regions examined, chiefly in the anterior temporal and frontal cortices bilaterally; they also had lowered perfusion in the right anterior temporal and frontal areas, as well as the right middle temporal area and the right thalamus, compared to patients with mania. Increased severity of psychotic symptoms was associated with reduced rCBF in patients. These results indicate that altered blood flow in the frontal-subcortical systems characterises patients with BD, as well as those with unipolar depression.

A preliminary investigation on the relationship between color-word Stroop task performance and delusion-proneness in nonpsychiatric adults

The current study examined whether there is a relationship between the dimension of delusion-proneness and performance on the color-word Stroop task. As dysfunction in the anterior cingulate cortex (ACC) has been related to both Stroop task performance and the presence of delusions in various psychiatric populations, we hypothesized that impaired Stroop performance would relate to increased delusion-proneness in a nonpsychiatric sample. A total of 36 college students, representing a wide range of scores on a measure of delusion-proneness (Peters et al. Delusions Inventory-PDI-21), completed a computerized version of the classic color-word Stroop task. Results revealed a statistically significant positive correlation between the PDI-21 score and the Stroop effect. The pattern of results suggests that reduced efficiency of Stroop performance is related to increasing levels of delusion-proneness. This study appears to be the first to report this relationship across a continuum of delusion-proneness in a nonpsychiatric sample. This finding contributes to the cognitive neurobiological understanding of delusions and adds further support for the dimensional construct of propensity for delusions.

Response suppression deficits in treatment-naïve first-episode patients with schizophrenia, psychotic bipolar disorder and psychotic major depression

Recent evidence indicates common genetic, neurobiological, and psychopharmacological aspects of schizophrenia and psychotic affective disorders. Some similarities in neurocognitive deficits associated with these disorders have also been reported. We investigated performance on antisaccade and visually-guided saccade tasks in treatment-naïve first-episode psychosis patients (schizophrenia n=59, major depression n=15, bipolar disorder n=9), matched non-psychotic major depression patients (n=40), and matched healthy individuals (n=106). All psychosis groups displayed elevated antisaccade error rates relative to healthy individuals. Antisaccade latencies were elevated in schizophrenia, but no significant error rate or latency differences were observed among psychosis groups. For schizophrenia only, shorter visually guided saccade latencies were associated with higher antisaccade error rates. Schizophrenia was also the only group without a significant relationship between visually guided and antisaccade latencies. Reflexive saccades were unimpaired except in psychotic unipolar depression, where saccades were hypometric. As in schizophrenia, antisaccade abnormalities are present in affective psychoses, even early in the course of illness and prior to treatment. Disturbances in frontostriatal systems are believed to occur in both affective psychoses and schizophrenia, potentially causing some similar cognitive abnormalities across psychotic disorders. However, the distinct pattern of dysfunction in schizophrenia across oculomotor paradigms suggests possible unique causes of their observed oculomotor performance deficits.

Resting state default-mode network connectivity in early depression using a seed region-of-interest analysis: decreased connectivity with caudate nucleus

AIM

Reports on resting brain activity in healthy controls have described a default-mode network (DMN) and important differences in DMN connectivity have emerged for several psychiatric conditions. No study to date, however, has investigated resting-state DMN in relatively early depression before years of medication treatment. The objective of the present study was, therefore, to investigate the DMN in patients seeking help from specialized mental health services for the first time for symptoms of depression.

METHODS

Fourteen depressed subjects and 15 matched controls were scanned using 4-T functional magnetic resonance imaging while resting with eyes closed. All but one subject was medication free. A precuneus/posterior cingulate cortex (P/PCC) seed-region connectivity analysis was used to identify the DMN and compare study groups in regions of relevance to depression.

RESULTS

The P/PCC analysis identified the DMN well in both study groups, consistent with prior literature. Direct comparison showed significantly reduced correlation between the P/PCC and the bilateral caudate in depression compared with controls and no areas of increased connectivity in the depressed group.

CONCLUSIONS

The present study is the first to investigate resting-state DMN in the early stages of treatment-seeking for depression. Depressed subjects had decreased connectivity between the P/PCC and the bilateral caudate, regions known to be involved in motivation and reward processing. Deficits in DMN connectivity with the caudate may be an early manifestation of major depressive disorder.

Neuroimaging and Depression

Major depression is among the most debilitating, prevalent, and recurrent of all psychiatric disorders. Over the past decade, investigators have examined the neural mechanisms associated with this disorder. In this article we present an overview of neuroimaging research that has assessed the structure and functioning of the amygdala, subgenual anterior cingulate cortex, and dorsolateral prefrontal cortex in major depression. We then describe results of studies that have attempted to elucidate the nature of the relations among these brain structures. The picture that emerges from these investigations is one in which heightened activity in limbic structures that underlie the experience and expression of emotion dampens activation in dorsal cortical structures that are involved in affect regulation, reducing their ability to influence limbic activation. We conclude by highlighting unresolved issues concerning the roles of these structures in depression and their relation to specific symptoms of this disorder.

Psychomotor slowing in older patients with major depression: Relationships with blood flow in the caudate nucleus and white matter lesions

[corrected] Selected structural and functional neuroimaging correlates of psychomotor slowing were examined [corrected] in older persons with depression. Clinical, neuropsychological, magnetic resonance imaging (MRI) and single photon emission computerized tomography (SPECT) data were obtained for 32 persons with depression (mean age=55.5) and 17 controls (mean age = 55.4). Psychomotor slowing was measured by simple (SRT) and choice (CRT) reaction times. White matter lesions (WMLs) were visually rated and caudate nucleus regional cerebral blood flow (rCBF) was obtained through the co-registration of MRI and SPECT data. Two SPECT scans were performed (corresponding to the SRT and CRT tasks) and a percentage change score in rCBF (%rCBF) due to the increasing complexity of the second task was calculated. Persons with depression and controls did not differ with respect to %rCBF or frequency of WMLs. In persons with depression, reduced %rCBF was associated with slower CRT. For all subjects, WMLs predicted 14% of the variance in %rCBF. Although CRT was predicted by a combination of older age, WMLs and %rCBF, the diagnosis of depression still predicted a further 25% of the variance. Reduced %rCBF is associated with demonstrable psychomotor slowing and presence of WMLs. While psychomotor slowing is determined in part by subcortical changes, other cortical and illness-dependent factors are likely to be relevant.

A delusion assessment scale for psychotic major depression: Reliability, validity, and utility

BACKGROUND

Although delusions are the hallmark of major depression with psychotic features, a scale to measure the intensity of beliefs across multiple delusional domains in this condition has been unavailable. The development and assessment of the Delusional Assessment Scale (DAS) are described.

METHODS

Scale items were selected initially based on previous studies of delusional ideation in schizophrenia. A three-point item to assess mood congruence was added. A 15-item scale was assessed in 92 subjects participating in the four-site collaborative study of the pharmacotherapy of major depression with psychotic features. Maximum likelihood method was used to determine scale factors. The internal consistency of these factors was determined. Comparisons between scale scores and ratings from the Brief Psychiatric Rating Scale (BPRS) (Overall and Gorham 1962) were used to assess convergent and discriminant validity.

RESULTS

The data were fit by a five-factors model (impact, conviction, disorganization, bizarreness, and extension). Inter-rater reliability of the five factors ranged from .77 for conviction and .74 for impact to .37 for disorganization. Internal consistency for each of the five factors was > or =.72. Scores on specific domains were significantly correlated with the BPRS unusual thought content item and positive symptom subscale scores.

CONCLUSIONS

The DAS is a reliable measure of 5 delusional domains.

Forced swimming test increases superoxide anion positive cells and angiotensin II positive cells in the cerebrum and cerebellum of the rat

Situations of stress are capable of inducing depression and oxidative stress in the brain. Previous reports have shown that angiotensin II (Ang II) induces the production of superoxide anion (O(2)(-)), and impairment of endothelial function in cerebral microvessels in vivo. Substances that reduce angiotensin functions may be important in the treatment of depression. These data suggest a role for both Ang II and O(2)(-) in depression; thus, the aim of this study was to determine the effect of forced swimming test (FST), a model of stress/depression, on the cellular expression of Ang II and O(2)(-) in the central nervous system. To induce stress/depression, rats were subjected to FST daily (30 min) for 15 days. Unstressed animals were used as controls. Motor activity was automatically analyzed daily before swimming. Cerebrum and cerebellum frozen sections were studied for O(2)(-) by a histochemical method and for Ang II producing cells by a polyclonal antibody. In the FST group, struggle time, total horizontal activity, ambulatory movements, and vertical movements, were significantly decreased when the data from the 1st and 15th day were compared. Food intake and body weight gain also decreased when unstressed and FST rats were compared at the 15th day. Increased number of cerebrum and cerebellum O(2)(-), and Ang II positive cells, were observed in FST rats. Significant correlation was found between O(2)(-) positive cells and Ang II positive cell in the cerebrum. These results suggest that stress/depression situations could be involved in the increase of Ang II and oxidative stress in the central nervous system, with possible implications in the depressive condition.

The effect of antidepressant treatment on N-acetyl aspartate levels of medial frontal cortex in drug-free depressed patients

The medial frontal cortex has been shown to modulate emotional behavior and stress responses, suggesting that the dysfunction of this region may be involved in the pathogenesis of depressive symptoms. The present study was performed to determine whether there was any effect of antidepressant treatment on the metabolite levels in the left medial frontal cortex as measured by proton magnetic resonance spectroscopy in depressed patients. Twenty patients diagnosed as having major depressive disorder according to DSM-IV and 18 healthy volunteer subjects were included in the study. Twelve of patients had their first episode and were drug-naïve. Other depressed patients were drug-free for at least 4 weeks. The severity of depression was assessed by HAM-D and Clinical Global Impression Scale-Severity (CGI-S). Single voxel, 8 cm(3), 1H MR spectra of left medial frontal cortex was acquired both before and following antidepressant treatment. The concentrations and ratios of N-acetyl aspartate (NAA), Creatine+Phosphocreatine (Cr+PCr) and Choline (Cho) were measured. Pretreatment NAA/Cr values of patients were lower than those of healthy controls, but this difference did not reach to statistically significant levels (t=1.83, df=36, p=0.07). However, antidepressant treatment had significant effect on NAA/Cr ratios (groupxtreatment interaction: F=9.93 df=1,36, p=0.03). After the treatment, NAA/Cr values of patients increased significantly compared to pretreatment values (t=3.32, df=19, p=0.004). No significant difference was observed between the post-treatment NAA/Cr values of patients and those of controls (t=1.64, df=36, p=0.19). Correlation analysis detected negative correlation between pretreatment CGI-S scores and NAA/Cr ratios (r=-0.51, p=0.02). This preliminary result suggests that there might be a possible defect in the neuronal integrity in the left medial frontal cortex (mainly left anterior cingulate cortex) of depressed patients. Antidepressant treatment with its neurotrophic effects might play a positive role in restoring the neuronal integrity. Further studies are needed to support these initial findings.

The use of single photon emission computed tomography in depressive disorders

Single photon emission computed tomography (SPECT) and positron emission tomography (PET) have advanced our understanding of the biological underpinnings of depression. There is, however, considerable variability in the literature. Depression is a complex disorder with marked heterogeneity in diagnosis and treatment. There is also evidence of heterogeneity in pathophysiology. In addition, the literature is marked by inconsistencies in the use of imaging techniques and data-analytical procedures. In this review we have attempted to focus on the SPECT studies that have used more refined methodologies and more homogenous clinical sub-groups of patients. We have focused on the main diagnostic sub-types of depression and on specific issues such as treatment response, correlates of neuroimaging abnormalities in depression, and so-called 'emotional circuitry' - the connectivity of regions implicated in depression. The future of molecular imaging in depression will be determined by the pace of the development of useful ligands and the exciting opportunities emerging in the field of imaging genomics. Future studies must attend to several key confounds including clinical heterogeneity, medication and the problems surrounding recruitment of drug-naive patients. It remains the case that longitudinal studies are the design of choice if questions relating to state and trait are to be addressed. Molecular imaging will be used increasingly to quantify neuroreceptor and transporter binding, and the activity of neurtransmitters, allowing the neurochemistry of this complex condition to be explored.