Prefrontal and Anterior Cingulate Contributions to Volition in Depression

High-frequency rTMS of the left dorsolateral prefrontal cortex for post-stroke depression: A systematic review and meta-analysis

OBJECTIVE

This meta-analysis investigated the therapeutic efficacy of high-frequency repetitive transcranial magnetic stimulation (rTMS) over the left dorsolateral prefrontal cortex (DLPFC) for treatment of post-stroke depression (PSD).

METHODS

Ten articles with 266 patients in rTMS group and 258 patients in control group were included. The primary outcome was performed to examine the efficacy of rTMS for PSD. Secondary outcomes of response rates and remission rates and subgroup analyses were further explored.

RESULTS

Our meta-analysis revealed a significant pooled effect size (the standard mean difference (SMD) was -1.45 points (95% CI, -2.04 to -0.86; p < 0.00001)). The odds ratio (OR) of the response rate and remission rate were 8.41 (95% CI, 2.52-28.12, p = 0.0005) and 6.04 (95% CI, 1.5-24.39, p = 0.01). Moreover, rTMS treatment for PSD patients in subacute phase and targeting the left DLPFC at 5-cm anterior to the left motor hotspot or the midpoint of the middle frontal gyrus showed significant antidepressant effect. In addition, the Hamilton Depression Rating Scale (HAMD) was sensitive to detect depressive changes in patients.

CONCLUSIONS

Our meta-analysis elucidated that the application of high-frequency rTMS over the left DLPFC was an effective treatment alternative for PSD.

SIGNIFICANCE

Our meta-analysis may help to develop more reasonable treatment strategies in clinical practice for PSD patients.

Short-term outcomes of physical activity counseling in in-patients with Major Depressive Disorder: Results from the PACINPAT randomized controlled trial

Introduction

A physical activity counseling intervention based on a motivation-volition model was developed and delivered to in-patients with Major Depressive Disorders with the aim of increasing lifestyle physical activity. The aim of this study is to evaluate the short-term outcomes of this intervention.

Methods

A multi-center randomized controlled trial was conducted in four Swiss psychiatric clinics. Adults who were initially insufficiently physically active and were diagnosed with Major Depressive Disorder according to ICD-10 were recruited. The sample consisted of 113 participants in the intervention group (M age = 42 years, 56% women) and 107 in the control group (M age = 40 years, 49% women). Motivation and volition determinants of physical activity were assessed with questionnaires. Implicit attitudes were assessed with an Implicit Association Test. Physical activity was self-reported and measured with hip-worn accelerometers over 7 consecutive days starting on the day following the data collection.

Results

According to accelerometer measures, step count decreased on average 1,323 steps less per day (95% CI = -2,215 to -431, p < 0.01) over time in the intervention group compared to the control group. A trend was recognized indicating that moderate-to-vigorous physical activity decreased on average 8.37 min less per day (95% CI = -16.98 to 0.23, p < 0.06) over time in the intervention group compared to the control group. The initial phase of the intervention does not seem to have affected motivational and volitional determinants of and implicit attitudes toward physical activity.

Conclusion

Physical activity counseling may be considered an important factor in the transition from in-patient treatment. Methods to optimize the intervention during this period could be further explored to fulfill the potential of this opportunity.

Clinical trial registration

https://www.isrctn.com/ISRCTN10469580, identifier ISRCTN10469580.

Examination of Home Quarantine Experiences of Individuals Diagnosed With COVID-19 Living in Turkey

The primary purpose of this research is to examine the experiences of individuals diagnosed with COVID-19 regarding the quarantine process. This research was carried out in a phenomenological design, one of the qualitative research approaches. A total of 212 volunteers, 153 women (72.2%) and 59 men (27.8), took part in this research via an online questionnaire. As a data collection tool, an online questionnaire prepared by the researcher was used. The data were analyzed within the framework of content analysis. In the findings of the research, 4 themes named as being diagnosed with COVID-19, quarantine process, worst-case scenario and coping with uncertainty were got. Based on the research findings, in staying in quarantine at home, besides the physiological effects of the virus, it can be concluded that individuals are trying to struggle with the emotional burden of the situation they are in. For this reason, it is of great importance to provide mental health support to individuals who are in quarantine at home, considering the social, psychological, and economic effects of the COVID-19 pandemic.

Resting-state functional magnetic resonance imaging-based identification of altered brain the fractional amplitude of low frequency fluctuation in adolescent major depressive disorder patients undergoing electroconvulsive therapy

PURPOSE

While electroconvulsive therapy (ECT) has been repeatedly been shown to effectively and efficiently treat the major depressive disorder (MDD), the mechanistic basis for such therapeutic efficacy remains to be firmly established. As such, further research exploring the ECT-based treatment of MDD in an adolescent population is warranted.

METHODS

This study included 30 treatment-naïve first-episode MDD patients and 30 healthy control (HC) individuals (aged 12-17 years). All participants were scanned using rs-fMRI, and the 30 MDD patients were scanned again after 2 weeks of the ECT treatment period. Intrinsic local activity in each voxel was assessed based on the fractional amplitude of low frequency fluctuation (fALFF) parameter, with all fALFF analyses being completed using the REST application. Correlations between ECT-related changes in fALFF and clinical parameters were additionally examined.

RESULTS

Relative to HCs, MDD patients exhibited increased fALFF values in the right inferior frontal gyrus (ORBinf), inferior occipital gyrus (IOG), and the left middle frontal gyrus (MFG) at baseline. Following ECT, these patients exhibited significant increases in fALFF values in the right medial superior frontal gyrus (SFGmed), dorsolateral superior frontal gyrus (SFGdor), anterior cingulate, and paracingulate gyrus (ACG), median cingulate and paracingulate gyrus (DCG), and left MFG. MDD patient HAMD scores were negatively correlated with fALFF values when analyzing pre-ECT vs. post-HCT ΔHAMD and fALFF values in the right SFGmed, SFGdor, and the left MFG.

CONCLUSION

These data suggest that ECT induced altered fALFF in some regions of the brain, suggesting that these alterations may serve as a neurobiological indicator of ECT effectiveness in MDD adolescents.

COVID-19 distress and worries: The role of attitudes, social support, and positive coping during social isolation

As the COVID-19 pandemic accelerates, one public health response has been for governments to impose quarantine 'lockdowns' which require people to socially isolate. In this study, we explored the level of psychological distress that people experienced in social isolation and the factors which might ameliorate or exacerbate it. Two hundred and thirteen participants (69% female) with a mean age of 37.82 years participated in an online study. They completed a series of questions designed as part of a larger cross-national study. A positive attitude towards social isolation introduced by government as a strategy to reduce the transmission of COVID-19 was predictive of positive coping strategies, and both attitude and coping predicted reduced psychological distress. Participants' worries about contagion of COVID-19, their financial status, and the economic and political impact of the COVID-19 pandemic predicted increases in their psychological distress. Social support from family and work colleagues was not significant in reducing worries or psychological distress but it did positively predict engagement in coping. The findings and recommendations are discussed. PRACTITIONER POINTS: Fostering a positive attitude towards social isolation in clients: reduces psychological distress, fosters engagement in positive coping behaviours. Enhancing clients' level of social support received will serve to increase positive coping and indirectly reduce psychological distress during social isolation. Strategies to reduce clients' COVID-19 worries are important as worry contributes to their overall level of psychological distress.

Dynamic functional connectivity in adolescence-onset major depression: relationships with severity and symptom dimensions

BACKGROUND

The spatial functional chronnectome is an innovative mathematical model designed to capture dynamic features in the organization of brain function derived from resting-state functional magnetic resonance imaging (rs-fMRI) data. Measurements of dynamic functional connectivity (dFC) have been developed from this model to quantify the brain dynamical self-reconfigurations at different spatial and temporal scales. This study examined whether two spatiotemporal dFC quantifications were linked to late adolescence-onset major depressive disorder (AO-MDD), and scaled with depression and symptom severity measured with the Montgomery-Asberg depression rating scale (MADRS) Methods: Thirty-five AO-MDD patients (21±6y) and fifty-three age- and gender-matched healthy young participants (20±3y) underwent 3T MRI structural and rs-fMRI acquisitions. The chronnectome here comprised seven individualized functional networks portrayed along 132 temporal overlapping windows, each framing 110s of resting brain activity Results: Based on voxelwise analyses, AO-MDD patients demonstrated significantly reduced temporal variability within the bilateral prefrontal cortex in five functional networks including the limbic network, the default-mode network (DMN) and frontoparietal network (FPN). Furthermore, the limbic network appeared to be particularly involved in this sample, and was associated with MADRS scores, and its progressive dynamic inflexibility was linked to sadness. DMN and FPN dynamics scaled with negative thoughts and neurovegetative symptoms, respectively Conclusions: This triple-network imbalance could delay spatiotemporal integration, while across-subject symptom variability would be network-specific. Therefore, the present approach supports that brain network dynamics underlie patients' symptom heterogeneity in AO-MDD.

Dorsolateral and ventrolateral prefrontal cortex structural changes relative to suicidal ideation in patients with depression

The prefrontal cortex (PFC) is enormously important in suicide and major depressive disorder (MDD). However, little is known about the structural alterations in the brains of people with MDD and suicidal ideation. We examined the gray matter volume (GMV) of the PFC of individuals with MDD and suicidal ideation to determine if PFC volumetric differences contribute to suicidal ideation in patients with MDD. Thirty-five subjects with MDD and suicidal ideation, 38 subjects with MDD but without suicidal ideation, and 43 age- and gender-matched healthy control (HC) subjects underwent T1-weighted imaging. A voxel-based morphometric analysis was conducted to compare the PFC GMVs of the three groups. Further GMV reductions in the left and right dorsolateral PFC (DLPFC) and right ventrolateral PFC (VLPFC) were detected in the MDD with suicidal ideation group compared with those in the HC group and the MDD without suicidal ideation group, whereas the MDD without suicidal ideation group only exhibited significant differences in the left DLPFC relative to the HC group. Our findings demonstrated that left DLPFC reductions were associated with MDD and suicidal ideation, and diminished GMV reductions in the right DLPFC and right VLPFC were only associated with suicidal ideation. These results help us better understand the neuropathological changes in MDD with suicidal ideation.

Neuropsychological Disorders and their Nanocarriers

Neuropsychological disorders are now growing rapidly worldwide among the people of diverse backgrounds irrespective of age, gender, and geographical region. Such disorders not only disturb the normal life and functionality of an individual but also impact the social relationships of the patient and the people associated with them, and if not treated in time, it may also result in mortality in severe conditions. Various antipsychotic drugs have been developed but their use is often limited by issues related to effective drug delivery at the site of action i.e. brain, mainly because of the blood-brain barrier. To resolve these issues, researchers and scientists have been working to develop a more effective drug delivery system where drugs can cross the blood-brain barrier and reach the brain in more effective concentrations. Drugs have been modified and formulated into nano-carriers and experimental studies for efficient and targeted delivery of drugs have been conducted. This review focuses on certain common neuropsychological diseases and their nanocarriers developed for drug delivery in the brain and are discussed with a brief description of various experimental in vitro and in vivo studies. This review also focuses on the intranasal route for the delivery of antipsychotic drugs and constraints faced due to the blood-brain barrier by the drugs.

Abnormal functional connectivity of habenula in untreated patients with first-episode major depressive disorder

Major depressive disorder (MDD) is associated with abnormalities in emotional/cognitive processing and low reward sensitivity. The habenula has a pivotal role in these processes that may contribute to depression. However, there has been little research on the abnormal connectivity between the habenula and whole brain of first-onset MDD. We aimed to explore the differences of functional connectivity between patients and healthy controls using functional magnetic resonance imaging. We used seed-based resting-state fMRI to examine functional connectivity between the habenula and whole-brain in 49 first-episode depressive patients and 25 healthy controls. Compared to controls, patients with MDD demonstrated significant increases in functional connectivity between the habenula and the dorsolateral prefrontal cortex (dlPFC). Furthermore, the receiver operating characteristic (ROC) curve proved that connectivity between the habenula and dlPFC was highly predictive. Additionally, there was a positive correlation between Hamilton Rating Scale for Depression (HAMD) score and functional connectivity between the habenula and right dlPFC. We found that the aberrant functional connectivity to the habenula and dlPFC can distinguish MDD patients from the normal.

Repetitive Transcranial Magnetic Stimulation Improves Depressive Symptoms and Quality of Life of Poststroke Patients-Prospective Case Series Study

Background:

Poststroke depression (PSD) is a serious psychiatric complication often reported after a stroke. Nearly a third of stroke survivors experience depressive symptoms at some point, affecting their functional recovery and quality of life. In recent years, repetitive transcranial magnetic stimulation (rTMS) has been studied by many researchers and found to be a safe supporting tool for the treatment of PSD.

Objective:

We aim to evaluate the effects of rTMS on PSD and on the quality of life of poststroke patients.

Method:

A prospective clinical case series, performed at CRER Rehabilitation, Brazil, between June 2016 and May 2017. A nonprobabilistic sample (n = 15) was divided into 2 groups (excitatory stimulation in F3, n = 8; inhibitory stimulation in F4, n = 7) and underwent 20 sessions of rTMS. Individuals were assessed according to the 17-item Hamilton Depression Rating Scale (HAM-D17) and World Health Organization Quality of Life-Brief Version (WHOQOL-BREF) questionnaire at 3 different moments: baseline, at the end of the treatment, and in a 1-month follow-up meeting.

Results:

Both groups presented a significant change in the score of all WHOQOL-BREF domains and in HAM-D17. In the group that received inhibitory stimulation (F4), score changes were continuous and gradual, comparing the 3 moments. In the excitatory stimulated (F3) group, however, the improvement in scores was more expressive between baseline and the second moment, without significant changes in the follow-up.

Conclusions:

The findings of this clinical study suggest that rTMS can be a promising tool, capable of relieving depressive symptoms and helping in the improvement of poststroke patients’ quality of life.

Neural correlates of body comparison and weight estimation in weight-recovered anorexia nervosa: a functional magnetic resonance imaging study

Background

The neural mechanisms underlying body dissatisfaction and emotional problems evoked by social comparisons in patients with anorexia nervosa (AN) are currently unclear. Here, we elucidate patterns of brain activation among recovered patients with AN (recAN) during body comparison and weight estimation with functional magnetic resonance imaging (fMRI).

Methods

We used fMRI to examine 12 patients with recAN and 13 healthy controls while they performed body comparison and weight estimation tasks with images of underweight, healthy weight, and overweight female bodies. In the body comparison task, participants rated their anxiety levels while comparing their own body with the presented image. In the weight estimation task, participants estimated the weight of the body in the presented image. We used between-group region of interest (ROI) analyses of the blood oxygen level dependent (BOLD) signal to analyze differences in brain activation patterns between the groups. In addition, to investigate activation outside predetermined ROIs, we performed an exploratory whole-brain analysis to identify group differences.

Results

We found that, compared to healthy controls, patients with recAN exhibited significantly greater activation in the pregenual anterior cingulate cortex (pgACC) when comparing their own bodies with images of underweight female bodies. In addition, we found that, compared with healthy controls, patients with recAN exhibited significantly smaller activation in the middle temporal gyrus corresponding to the extrastriate body area (EBA) when comparing their own bodies, irrespective of weight, during self-other comparisons of body shape.

Conclusions

Our findings from a group of patients with recAN suggest that the pathology of AN may lie in an inability to regulate negative affect in response to body images via pgACC activation during body comparisons. The findings also suggest that altered body image processing in the brain persists even after recovery from AN.

Electronic supplementary material

The online version of this article (10.1186/s13030-018-0134-z) contains supplementary material, which is available to authorized users.

Understanding the pathophysiology of depression: From monoamines to the neurogenesis hypothesis model - are we there yet?

A number of factors (biogenic amine deficiency, genetic, environmental, immunologic, endocrine factors and neurogenesis) have been identified as mechanisms which provide unitary explanations for the pathophysiology of depression. Rather than a unitary construct, the combination and linkage of these factors have been implicated in the pathogenesis of depression. That is, environmental stressors and heritable genetic factors acting through immunologic and endocrine responses initiate structural and functional changes in many brain regions, resulting in dysfunctional neurogenesis and neurotransmission which then manifest as a constellation of symptoms which present as depression.

Abnormal Neural Basis of Emotional Conflict Control in Treatment-Resistant Depression

Emotional conflict has received increased attention as a research topic. The objective of this study is to confirm that the processing of emotional conflict is impaired in treatment-resistant depression (TRD). We compared the event-related potentials of 17 patients with TRD and 17 healthy controls during the face-word Stroop task, which is an effective way of assessing the effects of emotional conflict directly. Compared with healthy controls, the accuracy scores of the TRD patients were lower in both "congruent stimuli" and "incongruent stimuli" conditions, and their response times were longer. The TRD patients also had larger N2 amplitudes over the frontal region, regardless of stimulus condition, which might reflect that TRD patients pay more attention to emotional information. A larger P3 amplitude over the frontal region for "incongruent stimuli minus congruent stimuli" was also found among patients with TRD, which indicates interference effects in the Stroop task. The results of this study provide novel behavioral and neurophysiological evidence of anomalies in cognitive inhibition among patients with TRD using the word-face task. These findings not only improve our understanding of deficient inhibition in TRD, but also pave the way for a cognitive neuropsychiatric model of depression.

Genome-wide gene-based analysis suggests an association between Neuroligin 1 (NLGN1) and post-traumatic stress disorder

Post-traumatic stress disorder (PTSD) develops in only some people following trauma exposure, but the mechanisms differentially explaining risk versus resilience remain largely unknown. PTSD is heritable but candidate gene studies and genome-wide association studies (GWAS) have identified only a modest number of genes that reliably contribute to PTSD. New gene-based methods may help identify additional genes that increase risk for PTSD development or severity. We applied gene-based testing to GWAS data from the Grady Trauma Project (GTP), a primarily African American cohort, and identified two genes (NLGN1 and ZNRD1-AS1) that associate with PTSD after multiple test correction. Although the top SNP from NLGN1 did not replicate, we observed gene-based replication of NLGN1 with PTSD in the Drakenstein Child Health Study (DCHS) cohort from Cape Town. NLGN1 has previously been associated with autism, and it encodes neuroligin 1, a protein involved in synaptogenesis, learning, and memory. Within the GTP dataset, a single nucleotide polymorphism (SNP), rs6779753, underlying the gene-based association, associated with the intermediate phenotypes of higher startle response and greater functional magnetic resonance imaging activation of the amygdala, orbitofrontal cortex, right thalamus and right fusiform gyrus in response to fearful faces. These findings support a contribution of the NLGN1 gene pathway to the neurobiological underpinnings of PTSD.

Maternal Depression Is Related to Reduced Error-Related Brain Activity in Child and Adolescent Offspring

Chronic parental depression is associated with an increased likelihood of depression in offspring. One mechanism by which parental depression may increase risk is through physiological or cognitive tendencies in offspring. Error processing has been studied using the error-related negativity (ERN), an event-related potential that occurs around the time someone commits an error, and has previously been shown to be heritable and blunted in depressed individuals. The current study examined the ERN as a potential biomarker of risk in a sample of never-depressed children whose mothers had a history of recurrent major depressive disorder (MDD), a single episode of MDD, or no lifetime history of any mood disorder. Seventy-eight mother-child dyads participated. The average age for children was 13.13 years (SD = 2.07) and 50% were female. Diagnostic interviews and self-report questionnaires were used to assess depression in both mothers and children. A flankers task was used to elicit the ERN and the correct response negativity (CRN) in children. Children of mothers with a history of recurrent MDD exhibited a reduced difference between the ERN and CRN compared to children of mothers with no depression history, even after controlling for children's current depression symptoms. Furthermore, current maternal depression symptoms related to a smaller difference between ERN and CRN in children. This pattern of findings suggests that blunted neural activity differentiating error from correct responses may be one mechanism by which recurrent maternal depression increases risk for depression in offspring and may be useful biomarker of risk.

Brain-derived neurotrophic factor promoter methylation and cortical thickness in recurrent major depressive disorder

Recent studies have reported that methylation of the brain-derived neurotrophic factor (BDNF) gene promoter is associated with major depressive disorder (MDD). This study aimed to investigate the association between cortical thickness and methylation of BDNF promoters as well as serum BDNF levels in MDD. The participants consisted of 65 patients with recurrent MDD and 65 age- and gender-matched healthy controls. Methylation of BDNF promoters and cortical thickness were compared between the groups. The right medial orbitofrontal, right lingual, right lateral occipital, left lateral orbitofrontal, left pars triangularis, and left lingual cortices were thinner in patients with MDD than in healthy controls. Among the MDD group, right pericalcarine, right medical orbitofrontal, right rostral middle frontal, right postcentral, right inferior temporal, right cuneus, right precuneus, left frontal pole, left superior frontal, left superior temporal, left rostral middle frontal and left lingual cortices had inverse correlations with methylation of BDNF promoters. Higher levels of BDNF promoter methylation may be closely associated with the reduced cortical thickness among patients with MDD. Serum BDNF levels were significantly lower in MDD, and showed an inverse relationship with BDNF methylation only in healthy controls. Particularly the prefrontal and occipital cortices seem to indicate key regions in which BDNF methylation has a significant effect on structure.

Resting state networks in major depressive disorder

Resting state functional magnetic resonance imaging (fMRI) examines the spontaneous low frequency neural activity of the brain to reveal networks of correlated neural activity. A number of different methodologies, each with its own advantages and disadvantages, have been used to examine networks of neural activity that may be related to clinical presentation. Major depressive disorder (MDD) research has largely focused on the default mode network (DMN), which is most active at rest and may relate to negative rumination. However, other networks can be discerned in the resting state such as salience and affective and cognitive control networks, all of which may be relevant to MDD psychopathology. This article reviews the rapidly increasing literature on resting state networks. A number of state- and trait-dependent abnormalities have been reported in MDD in a wide variety of regions including the cerebellum, lingual gyrus, anterior cingulate cortex (ACC), middle frontal gyrus (MFG), dorsolateral prefrontal cortex (dlPFC), amygdala and insula. Current and chronic medication is often a potential confound. Few trials have examined the immediate or delayed effects of antidepressants on resting state networks. This article presents a novel approach to the analysis of drug effects, the identification of signatures of efficacy, and thus for drug development.

The vascular depression hypothesis: mechanisms linking vascular disease with depression

The 'Vascular Depression' hypothesis posits that cerebrovascular disease may predispose, precipitate or perpetuate some geriatric depressive syndromes. This hypothesis stimulated much research that has improved our understanding of the complex relationships between late-life depression (LLD), vascular risk factors, and cognition. Succinctly, there are well-established relationships between LLD, vascular risk factors and cerebral hyperintensities, the radiological hallmark of vascular depression. Cognitive dysfunction is common in LLD, particularly executive dysfunction, a finding predictive of poor antidepressant response. Over time, progression of hyperintensities and cognitive deficits predicts a poor course of depression and may reflect underlying worsening of vascular disease. This work laid the foundation for examining the mechanisms by which vascular disease influences brain circuits and influences the development and course of depression. We review data testing the vascular depression hypothesis with a focus on identifying potential underlying vascular mechanisms. We propose a disconnection hypothesis, wherein focal vascular damage and white matter lesion location is a crucial factor, influencing neural connectivity that contributes to clinical symptomatology. We also propose inflammatory and hypoperfusion hypotheses, concepts that link underlying vascular processes with adverse effects on brain function that influence the development of depression. Testing such hypotheses will not only inform the relationship between vascular disease and depression, but also provide guidance on the potential repurposing of pharmacological agents that may improve LLD outcomes.

Modulation of attention network activation under antidepressant agents in healthy subjects

While antidepressants are supposed to exert similar effects on mood and drive via various mechanisms of action, diverging effects are observed regarding side-effects and accordingly on neural correlates of motivation, emotion, reward and salient stimuli processing as a function of the drugs impact on neurotransmission. In the context of erotic stimulation, a unidirectional modulation of attentional functioning despite opposite effects on sexual arousal has been suggested for the selective serotonin reuptake-inhibitor (SSRI) paroxetine and the selective dopamine and noradrenaline reuptake-inhibitor (SDNRI) bupropion. To further elucidate the effects of antidepressant-related alterations of neural attention networks, we investigated 18 healthy males under subchronic administration (7 d) of paroxetine (20 mg), bupropion (150 mg) and placebo within a randomized placebo-controlled cross-over double-blind functional magnetic resonance imaging (fMRI) design during an established preceding attention task. Neuropsychological effects beyond the fMRI-paradigm were assessed by measuring alertness and divided attention. Comparing preceding attention periods of salient vs. neutral pictures, we revealed congruent effects of both drugs vs. placebo within the anterior midcingulate cortex, dorsolateral prefrontal cortex, anterior prefrontal cortex, superior temporal gyrus, anterior insula and the thalamus. Relatively decreased activation in this network was paralleled by slower reaction times in the divided attention task in both verum conditions compared to placebo. Our results suggest similar effects of antidepressant treatments on behavioural and neural attentional functioning by diverging neurochemical pathways. Concurrent alterations of brain regions within a fronto-parietal and cingulo-opercular attention network for top-down control could point to basic neural mechanisms of antidepressant action irrespective of receptor profiles.

Alterations in regional homogeneity of spontaneous brain activity in late-life subthreshold depression

The early detection of major depression in elderly individuals who are at risk of developing the disease is of prime importance when it comes to the prevention of geriatric depression. We used resting-state functional magnetic resonance imaging (fMRI) to examine changes in regional homogeneity (ReHo) of spontaneous activity in late-life subthreshold depression (StD), and we evaluated the sensitivity/specificity performance of these changes. Nineteen elderly individuals with StD and 18 elderly controls underwent a resting-state fMRI scan. The ReHo approach was employed to examine whether StD was related to alterations in resting-state neural activity, in the form of abnormal regional synchronization. Receiver operating characteristic curve analysis and the Fisher stepwise discriminant analysis were used to evaluate the sensitivity/specificity characteristics of the ReHo index in discriminating between the StD subjects and normal controls. The results demonstrated that, compared to controls, StD subjects display lower ReHo in the right orbitofrontal cortex (OFC), left dorsolateral prefrontal cortex (DLPFC), left postcentral gyrus (PCG), and left middle frontal and inferior temporal gyri, as well as higher ReHo in the bilateral insula and right DLPFC. The left PCG and the right DLPFC, OFC, and posterior insula, together reported a predictive accuracy of 91.9%. These results suggest that the regional activity coherence was changed in the resting brain of StD subjects, and that these alterations may serve as potential markers for the early detection of StD in late-life depression.

Major depressive disorder is associated with broad impairments on neuropsychological measures of executive function: a meta-analysis and review

Cognitive impairments are now widely acknowledged as an important aspect of major depressive disorder (MDD), and it has been proposed that executive function (EF) may be particularly impaired in patients with MDD. However, the existence and nature of EF impairments associated with depression remain strongly debated. Although many studies have found significant deficits associated with MDD on neuropsychological measures of EF, others have not, potentially due to low statistical power, task impurity, and diverse patient samples, and there have been no recent, comprehensive, meta-analyses investigating EF in patients with MDD. The current meta-analysis uses random-effects models to synthesize 113 previous research studies that compared participants with MDD to healthy control participants on at least one neuropsychological measure of EF. Results of the meta-analysis demonstrate that MDD is reliably associated with impaired performance on neuropsychological measures of EF, with effect sizes ranging from 0.32 to 0.97. Although patients with MDD also have slower processing speed, motor slowing alone cannot account for these results. In addition, some evidence suggests that deficits on neuropsychological measures of EF are greater in patients with more severe current depression symptoms, and those taking psychotropic medications, whereas evidence for effects of age was weaker. The results are consistent with the theory that MDD is associated with broad impairment in multiple aspects of EF. Implications for treatment of MDD and theories of EF are discussed. Future research is needed to establish the specificity and causal link between MDD and EF impairments.

Altered error-related brain activity in youth with major depression

Depression is associated with impairments in cognitive control including action monitoring processes, which involve the detection and processing of erroneous responses in order to adjust behavior. Although numerous studies have reported altered error-related brain activity in depressed adults, relatively little is known about age-related changes in error-related brain activity in depressed youth. This study focuses on the error-related negativity (ERN), a negative deflection in the event-related potential (ERP) that is maximal approximately 50ms following errors. High-density ERPs were examined following responses on a flanker task in 24 youth diagnosed with MDD and 14 low-risk healthy controls (HC). Results indicate that compared to HC, MDD youth had significantly smaller ERN amplitudes and did not exhibit the normative increases in ERN amplitudes as a function of age. Also, ERN amplitudes were similar in depressed youth with and without comorbid anxiety. These results suggest that depressed youth exhibit different age-related changes in brain activity associated with action monitoring processes. Findings are discussed in terms of existing work on the neural correlates of action monitoring and depression and the need for longitudinal research studies investigating the development of neural systems underlying action monitoring in youth diagnosed with and at risk for depression.

Hyperintensities on T2-weighted images in the basal ganglia of patients with major depression: cerebral perfusion and clinical implications

White matter hyperintensities on T2-weighted images (WMH T2-WI) are prevalent in depressed, particularly elderly, patients. In an earlier study we used structural magnetic resonance imaging (MRI) to study 37 depressed and 27 healthy control subjects to show that prevalence of WMH T2-WI is higher in depressed patients and that severity of depression and cognitive impairment is associated with presence of WMH T2-WI in basal ganglia. The occurrence of WMH T2-WI in depression may also be associated with cerebrovascular deficiency, although this association has not been adequately studied. We therefore performed single photon emission computed tomography (SPECT) with Technetium-99m hexamethylpropyleneamineoxime (Tc-99m HMPAO) as tracer in this same sample to seek an association between presence/location of WMH T2-WI and cerebral perfusion deficits. In addition, we examined the relationship between presence/location of WMH T2-WI and treatment response. We found that severely depressed, cognitively compromised patients with WMH T2-WI in the basal ganglia display more profuse cerebral perfusion deficits than less depressed patients with WMH T2-WI in other regions or with no WMH T2-WI but are not less responsive to antidepressant treatment. WMH T2-WI in depression are associated with cerebral perfusion deficits, although not necessarily located in the same regions as the MRI findings. Clinical symptoms are largely reversible even in depressed patients with WMH T2-WI in basal ganglia.

Joining the dots: neurobiological links in a functional analysis of depression

Depression is one of the major contributors to the Total Disease Burden and afflicts about one-sixth of Western populations. One of the most effective treatments for depression focuses upon analysis of causal chains in overt behaviour, but does not include brain-related phenomena as steps along these causal pathways. Recent research findings regarding the neurobiological concomitants of depressive behaviour suggest a sequence of structural and functional alterations to the brain which may also produce a beneficial outcome for the depressed individual--that of adaptive withdrawal from uncontrollable aversive stressors. Linking these brain-based explanations to models of observable contingencies for depressive behaviour can provide a comprehensive explanation of how depressive behaviour occurs and why it persists in many patients.

Anterior cingulate pyramidal neurons display altered dendritic branching in depressed suicides

BACKGROUND

It is hypothesized that mood disorders are accompanied by altered wiring and plasticity in key limbic brain regions such as the anterior cingulate cortex (ACC). To test this hypothesis at the cellular level, we analyzed basilar dendritic arborizations extended by layer VI pyramidal neurons in silver-impregnated postmortem ACC samples from well-characterized depressed suicide subjects (n=12) and matched sudden-death controls (n=7).

METHODS

One cm(3) tissue blocks were stained using a Golgi preparation, cut on a microtome, and mounted on slides. Basilar dendritic arbors from 195 neurons were reconstructed, and the number, length, and diameter of branches were determined at each branch order. The size and number of spines borne by these branches were also assessed.

RESULTS

Third-order branches were significantly reduced in number (24% fewer; p=0.00262) in depressed suicides compared to controls. The size and average length of these branches, as well as their number of spines/length were unaltered. On average, for each pyramidal neuron analyzed in depressed subjects, the fewer third-order branches resulted in a significant reduction in branch length (28% shorter; p=0.00976) at this branch order.

CONCLUSIONS

These results provide the first evidence of altered cortical dendritic branching in mood disorders. Given that proximal dendritic branches grow during perinatal development, and that they are generally less plastic at maturity than distal segments, we speculate that these differences in dendritic branching may reflect a biological predisposition to depression and suicide.

Uncertainty during anticipation modulates neural responses to aversion in human insula and amygdala

Uncertainty about potential negative future outcomes can cause stress and is a central feature of anxiety disorders. The stress and anxiety associated with uncertain situations may lead individuals to overestimate the frequency with which uncertain cues are followed by negative outcomes, an example of covariation bias. Using functional magnetic resonance imaging, we found that uncertainty-related expectations modulated neural responses to aversion. Insula and amygdala responses to aversive pictures were larger after an uncertain cue (that preceded aversive or neutral pictures) than a certain cue (that always preceded aversive pictures). Anticipatory anterior cingulate cortex (ACC) activity elicited by the cues was inversely associated with the insula and amygdala responses to aversive pictures following the cues. Nearly 75% of subjects overestimated the frequency of aversive pictures following uncertain cues, and ACC and insula activity predicted this uncertainty-related covariation bias. Findings provide the first evidence of the brain mechanisms of covariation bias and highlight the temporal dynamics of ACC, insula, and amygdala recruitment for processing aversion in the context of uncertainty.

Common effects of lithium and valproate on mitochondrial functions: protection against methamphetamine-induced mitochondrial damage

Accumulating evidence suggests that mitochondrial dysfunction plays a critical role in the progression of a variety of neurodegenerative and psychiatric disorders. Thus, enhancing mitochondrial function could potentially help ameliorate the impairments of neural plasticity and cellular resilience associated with a variety of neuropsychiatric disorders. A series of studies was undertaken to investigate the effects of mood stabilizers on mitochondrial function, and against mitochondrially mediated neurotoxicity. We found that long-term treatment with lithium and valproate (VPA) enhanced cell respiration rate. Furthermore, chronic treatment with lithium or VPA enhanced mitochondrial function as determined by mitochondrial membrane potential, and mitochondrial oxidation in SH-SY5Y cells. In-vivo studies showed that long-term treatment with lithium or VPA protected against methamphetamine (Meth)-induced toxicity at the mitochondrial level. Furthermore, these agents prevented the Meth-induced reduction of mitochondrial cytochrome c, the mitochondrial anti-apoptotic Bcl-2/Bax ratio, and mitochondrial cytochrome oxidase (COX) activity. Oligoarray analysis demonstrated that the gene expression of several proteins related to the apoptotic pathway and mitochondrial functions were altered by Meth, and these changes were attenuated by treatment with lithium or VPA. One of the genes, Bcl-2, is a common target for lithium and VPA. Knock-down of Bcl-2 with specific Bcl-2 siRNA reduced the lithium- and VPA-induced increases in mitochondrial oxidation. These findings illustrate that lithium and VPA enhance mitochondrial function and protect against mitochondrially mediated toxicity. These agents may have potential clinical utility in the treatment of other diseases associated with impaired mitochondrial function, such as neurodegenerative diseases and schizophrenia.

Anticipatory activation in the amygdala and anterior cingulate in generalized anxiety disorder and prediction of treatment response

OBJECTIVE

The anticipation of adverse outcomes, or worry, is a cardinal symptom of generalized anxiety disorder. Prior work with healthy subjects has shown that anticipating aversive events recruits a network of brain regions, including the amygdala and anterior cingulate cortex. This study tested whether patients with generalized anxiety disorder have alterations in anticipatory amygdala function and whether anticipatory activity in the anterior cingulate cortex predicts treatment response.

METHOD

Functional magnetic resonance imaging (fMRI) was employed with 14 generalized anxiety disorder patients and 12 healthy comparison subjects matched for age, sex, and education. The event-related fMRI paradigm was composed of one warning cue that preceded aversive pictures and a second cue that preceded neutral pictures. Following the fMRI session, patients received 8 weeks of treatment with extended-release venlafaxine.

RESULTS

Patients with generalized anxiety disorder showed greater anticipatory activity than healthy comparison subjects in the bilateral dorsal amygdala preceding both aversive and neutral pictures. Building on prior reports of pretreatment anterior cingulate cortex activity predicting treatment response, anticipatory activity in that area was associated with clinical outcome 8 weeks later following treatment with venlafaxine. Higher levels of pretreatment anterior cingulate cortex activity in anticipation of both aversive and neutral pictures were associated with greater reductions in anxiety and worry symptoms.

CONCLUSIONS

These findings of heightened and indiscriminate amygdala responses to anticipatory signals in generalized anxiety disorder and of anterior cingulate cortex associations with treatment response provide neurobiological support for the role of anticipatory processes in the pathophysiology of generalized anxiety disorder.

Response conflict and frontocingulate dysfunction in unmedicated participants with major depression

Individuals with major depressive disorder (MDD) often exhibit impaired executive function, particularly in experimental tasks that involve response conflict and require adaptive behavioral adjustments. Prior research suggests that these deficits might be due to dysfunction within frontocingulate pathways implicated in response conflict monitoring and the recruitment of cognitive control. However, the temporal unfolding of conflict monitoring impairments in MDD remains poorly understood. To address this issue, we recorded 128-channel event-related potentials while 20 unmedicated participants with MDD and 20 demographically matched, healthy controls performed a Stroop task. Compared to healthy controls, MDD subjects showed larger Stroop interference effects and reduced N2 and N450 amplitudes. Source localization analyses at the time of maximal N450 activity revealed that MDD subjects had significantly reduced dorsal anterior cingulate cortex (dACC; Brodmann area 24/32) and left dorsolateral prefrontal cortex (Brodmann area 10/46) activation to incongruent relative to congruent trials. Consistent with the heterogeneous nature of depression, follow-up analyses revealed that depressed participants with the lowest level of conflict-related dACC activation 620 ms post-stimulus were characterized by the largest Stroop interference effects (relatively increased slowing and reduced accuracy for incongruent trials). Conversely, MDD participants with relatively stronger dACC recruitment did not differ from controls in terms of interference effects. These findings suggest that for some, but not all individuals, MDD is associated with impaired performance in trials involving competition among different response options, and reduced recruitment of frontocingulate pathways implicated in conflict monitoring and cognitive control.

Imbalance between left and right dorsolateral prefrontal cortex in major depression is linked to negative emotional judgment: an fMRI study in severe major depressive disorder

BACKGROUND

Although recent neuroimaging and therapeutic transcranial magnetic cortex stimulation (TMS) studies suggest imbalance between left and right dorsolateral prefrontal cortex (DLPFC) in major depressive disorder (MDD) the fundamental neuropsychological characterization of left DLPFC hypoactivity and right DLPFC hyperactivity in MDD remains poorly understood.

METHODS

We used event-related functional magnetic resonance imaging (fMRI) to investigate neural activity in left and right DLPFC related to unattended (unexpected) and attended (expected) judgment of emotions. Participating in the study were 20 medication-free patients with MDD and 30 healthy subjects.

RESULTS

The MDD patients showed hypoactivity in the left DLPFC during both unattended and attended emotional judgment and hyperactivity in the right DLPFC during attended emotional judgment. In contrast to healthy subjects, left DLPFC activity during emotional judgment was not parametrically modulated by negative emotional valence and was inversely modulated by positive emotional valence in MDD patients. Hyperactivity in the right DLPFC correlated with depression severity.

CONCLUSIONS

Results demonstrate that left DLPFC hypoactivity is associated with negative emotional judgment rather than with emotional perception or attention while right DLPFC hyperactivity is linked to attentional modulation. Left-right DLPFC imbalance is characterized in neuropsychological regard, which bridges the gap from resting metabolism and therapeutic repetitive transcranial magnetic stimulation effects to functional neuroanatomy of altered emotional-cognitive interaction in MDD.

Studies of caloric vestibular stimulation: implications for the cognitive neurosciences, the clinical neurosciences and neurophilosophy

OBJECTIVE

Caloric vestibular stimulation (CVS) has traditionally been used as a tool for neurological diagnosis. More recently, however, it has been applied to a range of phenomena within the cognitive neurosciences. Here, we provide an overview of such studies and review our work using CVS to investigate the neural mechanisms of a visual phenomenon - binocular rivalry. We outline the interhemispheric switch model of rivalry supported by this work and its extension to a metarivalry model of interocular-grouping phenomena. In addition, studies showing a slow rate of binocular rivalry in bipolar disorder are discussed, and the relationship between this finding and the interhemispheric switch model is described. We also review the effects of CVS in various clinical contexts, explain how the technique is performed and discuss methodological issues in its application.

METHODS

A review of CVS and related literature was conducted.

RESULTS

Despite CVS being employed with surprising effect in a wide variety of cognitive and clinical contexts, it has been a largely underutilized brain stimulation method for both exploratory and therapeutic purposes. This is particularly so given that it is well tolerated, safe, inexpensive and easy to administer.

CONCLUSION

CVS can be used to investigate various cognitive phenomena including perceptual rivalry, attention and mood, as well as somatosensory representation, belief, hemispheric laterality and pain. The technique can also be used to investigate clinical conditions related to these phenomena and may indeed have therapeutic utility, especially with respect to postlesional disorders, mania, depression and chronic pain states. Furthermore, we propose that based on existing reports of the phenomenological effects of CVS and the brain regions it is known to activate, the technique could be used to investigate and potentially treat a range of other clinical disorders. Finally, the effects of CVS (and its potential effects) on several phenomena of interest to philosophy suggest that it is also likely to become a useful tool in experimental neurophilosophy.

The cognitive, emotional, and social sequelae of stroke: psychological and ethical concerns in post-stroke adaptation

In the clinical domain, ethical analyses involve examination of complex individual responses, psychological processes, and social context. Psychological aspects of stroke adaptation include the risk for depression and anxiety, changes in identity and personality processes, and potential for social isolation. Depression and anxiety are heterogeneous constructs and can affect individuals' emotional functioning and cognitive abilities. Executive function, self-agency, and volition may be affected. Alterations in identity and personality may also result from the interaction of fluctuating emotional, cognitive, and physical abilities as well as from changes in social context and family dynamics. Social isolation, or lack of access to social contact or resources, can be a consequence of difficulties in cognitive and emotional function that influence interpersonal relationships, changes in social roles, communication difficulties, and challenges in transportation and employment. Social stigma and marginalization also contribute to isolation. The authors describe these psychological phenomena in the context of brain damage and recovery and raise ethical concerns including impact on decision-making capacity, pre- and postinjury selves and interests, and the social milieu in which strokes are experienced.