Functional MRI study of memory-related brain regions in patients with depressive disorder

Taste dysfunction as a predictor of depression in schizophrenia: A systematic review and meta-analysis

OBJECTIVE

This study aims to investigate the relationship between taste dysfunction and depression among patients with schizophrenia, to achieve early detection of depression in clinical practice.

METHODS

Following PRISMA guidance, a comprehensive literature search was conducted globally, covering papers published from 1961 to June 2023. A total of 17 manuscripts were selected through meta-analysis and sensitivity analysis after examining available materials from seven databases to determine the correlation between depression and taste dysfunction.

RESULTS

The comparison of the 17 selected manuscripts revealed that individuals with gustatory dysfunction may be more likely to experience depressive symptoms (SMD, 0.51, 95% CI, 0.08 to 0.93, p = 0.02). Depression is associated with taste dysfunction in certain aspects, as indicated by the pleasantness ratings of sucrose solutions (SMD, -0.53, 95% confidence interval [CI] -1.11 to 0.05, p = 0.08), gustatory identification ability (SMD, 0.96, 95% CI, 0.03 to 1.89, p = 0.04), and the perception threshold of sweet taste (MD, 0.80, 95% CI, 0.79 to 0.81, p < 0.00001).

CONCLUSIONS

Due to variations in the methods, designs, and selection criteria employed in the included studies, it is necessary to establish a feasible framework. Future research using detailed and targeted approaches can provide clearer and more unified conclusions on the relationship between taste dysfunction and depression. Moreover, further high-quality research is needed to obtain clearer conclusions and explore the potential of taste dysfunction as an effective tool for early screening of depression.

TRIAL REGISTRATION

This review has been registered in the PROSPERO on April 2022 with the identifier CRD42023400172.

Neural basis of memory impairments and relation to functional disability in fully or partially remitted patients with affective disorders

Bipolar disorder (BD) and major depressive disorder (MDD) are associated with cognitive and functional impairment. Cognitive impairment is often associated with dorsal prefrontal cortex (dPFC) hypo-activity, but the neuronal correlates of functional disability is largely unknown. In this study, 91 patients with affective disorders in full or partial remission (BD, n = 67; MDD, n = 24) with objectively verified cognitive impairment and substantial functional disability underwent neuropsychological assessment and functional magnetic resonance imaging (fMRI) scan during which they completed a strategic picture-encoding task. For comparison, 36 matched healthy controls underwent an identical test protocol. Patients showed encoding-related hypo-activity in the dPFC compared to controls. In patients, lower right dlPFC activity was associated with poorer overall functioning and more antipsychotic drug use. In conclusion, memory impairments were underpinned by failure to recruit the dPFC during task performance which was associated with impaired functioning in fully or partially remitted patients with affective disorders. This aberrant neurocircuitry activity has implications for the design of future pro-cognitive interventions that aim to improve not only cognition but also real-world functioning.

Memory and processing speed impairments in first-episode drug-naïve patients with major depressive disorder

BACKGROUND

Cognitive impairment, an intrinsic feature of major depressive disorder (MDD), affects daily and social functioning in depression patients. However, the cognitive impairment profile in MDD remains ambiguous because of the high heterogeneity of previous studies.

METHODS

Four cognitive domains, including memory, processing speed, executive function (EF), and attention, were assessed in 184 first-episode drug-naïve (FEDN) MDD patients and matched 71 healthy controls (HCs). The effects of demographic and depressive factors on cognitive performance were analyzed using various statistical methods, including multi-factor analysis of variance, Mann-Whitney U test, and Spearman's rank correlation. In addition, the impact of depression severity on cognitive function was further assessed using subgroup analyses and partial correlation analyses.

RESULTS

Age and education significantly impacted most cognitive performances, and depression severity appeared to influence processing speed. Moreover, cognitive scores in memory and processing speed, rather than in EF and attention, were significantly different between FEDN MDD patients and HCs after controlling for sex, age, educational attainment, household income, and body mass index.

LIMITATIONS

The number of HCs was relatively small, which may have slightly reduced the study's statistical power.

CONCLUSIONS

Age and educational attainment have confirmative confounding effects greater than those of depression in most cognitive functions. More importantly, memory and processing speed were impaired in MDD after strictly controlling for confounders. These findings provide new information for understanding the pattern of cognitive impairment and offer clues for further exploring the pathogenesis of cognitive abnormalities in MDD.

A voxel-based meta-analysis comparing medication-naive patients of major depression with treated longer-term ill cases

Structural neuroimaging studies have identified brain areas implicated in the pathogenesis of major depressive disorder (MDD). However, findings have been inconsistent, potentially due to variable illness duration and effects of antidepressant treatment. Using a meta-analytic approach, we compared gray matter (GM) volumes in patients grouped by medication status (naïve and treated) and illness duration (early course and long-term ill) to identify potential treatment and illness duration effects on brain structure. A total of 70 studies were included, including 3682 patients and 3469 controls. The pooled analysis found frontal, temporal and limbic regions with decreased GM volume in MDD patients. Additional analyses indicated that larger GM volume in the right striatum and smaller GM volume in the right precuneus are likely to be associated with drug effects, while smaller GM volume in the right temporal gyrus may correlate with longer illness duration. Similar GM decreases in bilateral medial frontal cortex between patient subgroups suggest that this alteration may persist over the course of illness and drug treatment.

Separate neural networks of implicit emotional processing between pictures and words: A coordinate-based meta-analysis of brain imaging studies

Both pictures and words are frequently employed as experimental stimuli to investigate the neurocognitive mechanisms of emotional processing. However, it remains unclear whether emotional picture processing and emotional word processing share neural underpinnings. To address this issue, we focus on neuroimaging studies examining the implicit processing of affective words and pictures, which require participants to meet cognitive task demands under the implicit influence of emotional pictorial or verbal stimuli. A coordinate-based activation likelihood estimation meta-analysis was conducted on these studies, which revealed no common activation maximum between the picture and word conditions. Specifically, implicit negative picture processing (35 experiments, 393 foci, and 932 subjects) engages the bilateral amygdala, left hippocampus, fusiform gyri, and right insula, which are mainly located in the subcortical network and visual network associated with bottom-up emotional responses. In contrast, implicit negative word processing (34 experiments, 316 foci, and 799 subjects) engages the default mode network and fronto-parietal network including the ventrolateral prefrontal cortex, dorsolateral prefrontal cortex, and dorsomedial prefrontal cortex, indicating the involvement of top-down semantic processing and emotion regulation. Our findings indicate that affective pictures (that intrinsically have an affective valence) and affective words (that inherit the affective valence from their object) modulate implicit emotional processing in different ways, and therefore recruit distinct brain systems.

Brain Activation during Memory Retrieval is Associated with Depression Severity in Women

Major depressive disorder (MDD) is a debilitating disorder that interferes with daily functioning, and that occurs at higher rates in women than in men. Structural and functional alterations in hippocampus and frontal lobe have been reported in MDD, which likely contribute to the multifaceted nature of MDD. One area impacted by MDD is hippocampal-mediated memory, which can be probed using a spatial virtual Morris water task (MWT). Women (n=24) across a spectrum of depression severity underwent functional magnetic resonance imaging (fMRI) during MWT. Depression severity, assessed via Beck Depression Inventory (BDI), was examined relative to brain activation during task performance. Significant brain activation was evident in areas traditionally implicated in spatial memory processing, including right hippocampus and frontal lobe regions, for retrieval > motor contrast. When BDI was included as a regressor, significantly less functional activation was evident in left hippocampus, and other non-frontal, task relevant regions for retrieval > rest contrast. Consistent with previous studies, depression severity was associated with functional alterations observed during spatial memory performance. These findings may contribute to understanding neurobiological underpinnings of depression severity and associated memory impairments, which may have implications for treatment approaches aimed at alleviating effects of depression in women.

Exercise, brain plasticity, and depression

Depression is a common mental disorder characterized by high incidence, high disability, and high fatality, causing great burden to the society, families, and individuals. The changes in brain plasticity may be a main reason for depression. Recent studies have shown that exercise plays a positive role in depression, but systematic and comprehensive studies are lacking on brain plasticity changes in depression. To further understand the antidepressive effect of exercise and the changes in brain plasticity, we retrieved related literatures using key words "depression," "depressive disorder," "exercise," "brain plasticity," "brain structure," and "brain function" from the database of Web of Science, PubMed, EBSCO host, and CNKI, hoping to provide evidence for exercise in preventing and treating depression. Increase in exercise has been found negatively correlated with the risk of depression. Randomized controlled experiments have shown that aerobic exercise, resistance exercise, and mind-body exercise can improve depressive symptoms and levels. The intensity and long-term effect of exercise are now topical research issues. Exercise has been proven to reshape the brain structure of depression patients, activate the function of related brain areas, promote behavioral adaptation changes, and maintain the integrity of hippocampal and white matter volume, thus improving the brain neuroprocessing and delaying cognitive degradation in depression patients. Future studies are urgently needed to establish accurate exercise prescriptions for improving depressive symptoms, and studies on different depressive populations and studies using multimodal brain imaging combined with multiple analytical methods are also needed.

The Effect of Second-Generation Antidepressant Treatment on the Memory of Patients With Major Depressive Disorder: A Meta-analysis Study With Structural Equation Models

BACKGROUND

Major depressive disorder (MDD) has been linked to episodic memory deficits that may be improved after pharmacological treatment, but it is unclear whether there is a class of antidepressants that is more effective than others to ameliorate these deficits in MDD. In addition, the possible effects of clinical and sociodemographic variables on the improvement of MDD memory deficits after pharmacological treatment are currently unknown. Our aims are to study the possible neuropsychological effects of second-generation antidepressant classes on the episodic memory of MDD patients and to study the potential effects of clinical and demographic variables as moderators of the effects of antidepressants on the memory of depressed patients through a meta-analysis approach.

PROCEDURES

Nine articles were included in our study. A structural equation model meta-analysis was performed.

RESULTS

Our results suggest that selective serotonin reuptake inhibitors and serotonine-noradrenaline reuptake inhibitors would bring about a substantial improvement in the memory of depressed patients, whereas other antidepressant classes would cause rather modest effects. Our results also suggest that clinical and demographic variables play a very important role as mediators of memory improvement after MDD treatment. Thus, a relatively low level of symptom severity, a high degree of clinical improvement, a younger age, and more years of education were positively related to memory improvement after MDD treatment.

CONCLUSIONS

Although antidepressant class is an important variable linked to memory improvement in MDD, overall, the degree of memory amelioration in depression is very closely related to clinical and demographic variables of patients with depression.

Depression related cerebral pathology and its relationship with cognitive functioning: A systematic review

BACKGROUND

Depression's relationship with cerebral abnormalities and cognitive decline is temporally dynamic. Despite clear clinical utility, understanding depression's effect on cerebral structures, cognitive impairment and the interaction between these symptoms has had limited consideration.

METHODS

This review summarised studies examining a clinical depression diagnosis or validated scales measuring depressive symptoms, data concerning amyloid-beta (Aβ) levels, brain structure and function focusing on hippocampal alterations, or white matter hyperintensities (WMH), and at least one validated neuropsychological test. Online database searches of: PsycINFO, EMBASE, MEDLINE, and Scopus were conducted to identify potential articles.

RESULTS

While depression was consistently associated with cross-sectionally cognitive decline across multiple domains, the neuropathological basis of this dysfunction remained unclear. Hippocampal, frontal, and limbic dysfunction as well as cortical thinning, WMH, and Aβ burden all provide inconsistent findings, likely due to depression subtypes. The consistency of these findings additionally decreases when examining this relationship longitudinally, as these results are further confounded by pre-dementia states. The therapeutic interventions examined were more efficacious in the younger compared with the older samples, who were characterised by greater WMH and Aβ burden.

LIMITATIONS

The limited number of longitudinal and interventional studies in addition to the heterogeneity of the samples restricts their generalisability.

CONCLUSIONS

Symptomatological differences between early-onset and late-onset depression (EOD and LOD) appear crucial in understanding whether late-life depression is the primary or secondary source of cerebral pathology. Though severe cognitive impairments and clearer neuropathological underpinnings are more characteristic of LOD than EOD, the inconsistency of valid biomarkers remains problematic.

Altered hippocampal function with preserved cognitive performance in treatment-naive major depressive disorder

The hippocampus is implicated in the pathophysiology of major depressive disorder (MDD), with evidence that morphological changes occur with disease progression. It was hypothesized that treatment-naive patients with depression would show performance deficits in hippocampus-dependent memory trials, with concurrent hippocampal activation deficits on functional magnetic resonance imaging, compared with control participants. Thirteen treatment-naive patients with MDD and 13 control participants completed a hippocampus-dependent memory functional magnetic resonance imaging process-dissociation task. On behavioural measures of habit memory and guessing, there were no significant differences between groups. Functional magnetic resonance imaging analysis indicated that compared with the control group, the MDD group showed increased activation in the parahippocampal gyrus and hippocampus on habit memory and nonitem trials. These alterations in hippocampal functioning with preserved cognitive performance on a test of hippocampus-dependent memory in MDD may be indicative of a compensatory mechanism.

Neuronal underpinnings of cognitive impairment and - improvement in mood disorders

Neuropsychiatric illnesses including mood disorders are accompanied by cognitive impairment, which impairs work capacity and quality of life. However, there is a lack of treatment options that would lead to solid and lasting improvement of cognition. This is partially due to the absence of valid and reliable neurocircuitry-based biomarkers for pro-cognitive effects. This systematic review therefore examined the most consistent neural underpinnings of cognitive impairment and cognitive improvement in unipolar and bipolar disorders. We identified 100 studies of the neuronal underpinnings of working memory and executive skills, learning and memory, attention, and implicit learning and 9 studies of the neuronal basis for cognitive improvements. Impairments across several cognitive domains were consistently accompanied by abnormal activity in dorsal prefrontal (PFC) cognitive control regions-with the direction of this activity depending on patients' performance levels-and failure to suppress default mode network (DMN) activity. Candidate cognition treatments seemed to enhance task-related dorsal PFC and temporo-parietal activity when performance increases were observed, and to reduce their activity when performance levels were unchanged. These treatments also attenuated DMN hyper-activity. In contrast, nonspecific cognitive improvement following symptom reduction was typically accompanied by decreased limbic reactivity and reversal of pre-treatment fronto-parietal hyper-activity. Together, the findings highlight some common neural correlates of cognitive impairments and cognitive improvements. Based on this evidence, studies are warranted to examine the reliability and predictive validity of target engagement in the identified neurocircuitries as a biomarker model of pro-cognitive effects.

Decreased Response to Positive Facial Affect in a Depressed Cohort in the Dorsal Striatum During a Working Memory Task-A Preliminary fMRI Study

People with depression have shown alterations in processing emotional information and working memory functionality. There is some evidence that emotional content may interact with working memory update processes, however neurological correlates are current unknown. In this preliminary study we utilized a novel version of the emotional variant of the n-back working memory task in fMRI. We examined BOLD response of 14 healthy controls and 13 depressed participants in response to happy, sad, and neutral displays of facial affect. No accuracy or reaction time differences were found between the two groups. The depressed group showed significantly decreased BOLD response to happy faces compared to the control group areas of the dorsal striatum and anterior cingulate. Significant, moderate, positive associations were found between right caudate activation with anxiety score and anterior cingulate activation with depression score in those with depression. Our novel task was able to elicit group level differences in emotional processing during working memory update. These results suggest those with depression fail to differentiate between positive emotional stimuli and stimuli with no emotional content.

Disentangling the Neural Basis of Cognitive Behavioral Therapy in Psychiatric Disorders: A Focus on Depression

Background: Major depressive disorder (MDD) stands among the most frequent psychiatric disorders. Cognitive behavioral therapy (CBT) has been shown to be effective for treating depression, yet its neural mechanisms of action are not well elucidated. The objective of this work is to assess the available neuroimaging studies exploring CBT’s effects in adult patients with MDD. Methods: Computerized databases were consulted till April 2018 and a research was conducted according to PRISMA guidelines in order to identify original research articles published at any time in English and French languages on this topic. Results: Seventeen studies were identified. Only one study was randomized comparing CBT to pharmacological interventions, and none included an effective control. Following CBT, changes occurred in cerebral areas that are part of the fronto-limbic system, namely the cingulate cortex, prefrontal cortex and amygdala-hippocampal complex. However, the pattern of activation and connectivity in these areas varied across the studies. Conclusion: A considerable heterogeneity exists with regard to study design, adapted CBT type and intensity, and employed neuroimaging paradigms, all of which may partly explain the difference in studies’ outcomes. The lack of randomization and effective controls in most of them makes it difficult to draw formal conclusion whether the observed effects are CBT mediated or due to spontaneous recovery. Despite the observed inconsistencies and dearth of data, CBT appears to exert its anti-depressant effects mainly by modulating the function of affective and cognitive networks devoted to emotions generation and control, respectively. This concept remains to be validated in large scale randomized controlled trials.

Effects of antidepressant therapy on neural components of verbal working memory in depression

Impairments in verbal working memory are evident in major depression. Verbal working memory is comprised of the components of encoding, maintenance and retrieval. Whether the neural impairments are expressed in specific components, and how pharmacological therapy could modify the neural correlates are not well understood. We investigated the neural correlates of verbal working memory components in depression using the Sternberg task in a longitudinal magnetic resonance imaging study. Serial scans were acquired in 23 patients (mean age 39.8 years) during an acute depressive episode and following 12 weeks of pharmacological therapy with duloxetine and in 22 matched healthy controls (mean age 39.1 years) at the same time points. A significant group by time interaction was evident during the long maintenance phase, extending from the left middle frontal to the middle temporal and caudate regions, in which there was reduced activation in healthy participants at the follow -up scan but there were no changes in patients. Persistent neural engagement during the maintenance phase following treatment was revealed in major depression. The findings emphasize that impairments in verbal working memory may be initiated in the maintenance phase in major depression in order to sustain performance. Further research with larger sample size and using randomized, placebo-controlled double-blind studies are required to confirm our results.

Elevated triglyceride levels are associated with cognitive impairments among patients with major depressive disorder

BACKGROUND

Cognitive deficits have been identified as one of core clinical symptoms of major depressive disorder (MDD). Accumulating evidence indicated that triglycerides (TG) might be associated with MDD and cognitive decline.

OBJECTIVE

This study examined whether patients with MDD had poorer cognitive functions than healthy controls, and further investigate whether TG levels were involved in MDD, and its cognitive impairments in a Han Chinese population.

METHOD

115 patients with MDD and 119 healthy controls were enrolled. Cognitive functions were assessed by the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS), and serum TG levels were examined using enzymatic colorimetry.

RESULTS

TG levels were higher in patients with MDD than healthy controls after controlling for the variables. Cognitive test scores were lower in patients with MDD than healthy controls except for visuospatial/constructional index after controlling for the variables. TG levels were negatively correlated with visuospatial/constructional score, delayed memory score and RBANS total score of MDD. Further multivariate regression analysis showed that TG levels were negatively associated with visuospatial/constructional score, attention score, delayed memory score and RBANS total score of MDD.

CONCLUSIONS

Our findings supported that serum TG levels might be involved in MDD, and play an important role in cognitive impairments of MDD, especially in delayed memory. Moreover, patients with MDD experienced greater cognitive impairments than healthy controls except for visuospatial/constructional index.

Effects of erythropoietin on memory-relevant neurocircuitry activity and recall in mood disorders

OBJECTIVE

Erythropoietin (EPO) improves verbal memory and reverses subfield hippocampal volume loss across depression and bipolar disorder (BD). This study aimed to investigate with functional magnetic resonance imaging (fMRI) whether these effects were accompanied by functional changes in memory-relevant neuro-circuits in this cohort.

METHOD

Eighty-four patients with treatment-resistant unipolar depression who were moderately depressed or BD in remission were randomized to eight weekly EPO (40 000 IU) or saline infusions in a double-blind, parallel-group design. Participants underwent whole-brain fMRI at 3T, mood ratings, and blood tests at baseline and week 14. During fMRI, participants performed a picture encoding task followed by postscan recall.

RESULTS

Sixty-two patients had complete data (EPO: N = 32, saline: N = 30). EPO improved picture recall and increased encoding-related activity in dorsolateral prefrontal cortex (dlPFC) and temporo-parietal regions, but not in hippocampus. Recall correlated with activity in the identified dlPFC and temporo-parietal regions at baseline, and change in recall correlated with activity change in these regions from baseline to follow-up across the entire cohort. The effects of EPO were not correlated with change in mood, red blood cells, blood pressure, or medication.

CONCLUSION

The findings highlight enhanced encoding-related dlPFC and temporo-parietal activity as key neuronal underpinnings of EPO-associated memory improvement.

Altered hippocampal function in major depression despite intact structure and resting perfusion

BACKGROUND

Hippocampal volume reductions in major depression have been frequently reported. However, evidence for functional abnormalities in the same region in depression has been less clear. We investigated hippocampal function in depression using functional magnetic resonance imaging (fMRI) and neuropsychological tasks tapping spatial memory function, with complementing measures of hippocampal volume and resting blood flow to aid interpretation.

METHOD

A total of 20 patients with major depressive disorder (MDD) and a matched group of 20 healthy individuals participated. Participants underwent multimodal magnetic resonance imaging (MRI): fMRI during a spatial memory task, and structural MRI and resting blood flow measurements of the hippocampal region using arterial spin labelling. An offline battery of neuropsychological tests, including several measures of spatial memory, was also completed.

RESULTS

The fMRI analysis showed significant group differences in bilateral anterior regions of the hippocampus. While control participants showed task-dependent differences in blood oxygen level-dependent (BOLD) signal, depressed patients did not. No group differences were detected with regard to hippocampal volume or resting blood flow. Patients showed reduced performance in several offline neuropsychological measures. All group differences were independent of differences in hippocampal volume and hippocampal blood flow.

CONCLUSIONS

Functional abnormalities of the hippocampus can be observed in patients with MDD even when the volume and resting perfusion in the same region appear normal. This suggests that changes in hippocampal function can be observed independently of structural abnormalities of the hippocampus in depression.

Decreased Fronto-Limbic Activation and Disrupted Semantic-Cued List Learning in Major Depressive Disorder

OBJECTIVES

Individuals with major depressive disorder (MDD) demonstrate poorer learning and memory skills relative to never-depressed comparisons (NDC). Previous studies report decreased volume and disrupted function of frontal lobes and hippocampi in MDD during memory challenge. However, it has been difficult to dissociate contributions of short-term memory and executive functioning to memory difficulties from those that might be attributable to long-term memory deficits.

METHODS

Adult males (MDD, n=19; NDC, n=22) and females (MDD, n=23; NDC, n=19) performed the Semantic List Learning Task (SLLT) during functional magnetic resonance imaging. The SLLT Encoding condition consists of 15 lists, each containing 14 words. After each list, a Distractor condition occurs, followed by cued Silent Rehearsal instructions. Post-scan recall and recognition were collected. Groups were compared using block (Encoding-Silent Rehearsal) and event-related (Words Recalled) models.

RESULTS

MDD displayed lower recall relative to NDC. NDC displayed greater activation in several temporal, frontal, and parietal regions, for both Encoding-Silent Rehearsal and the Words Recalled analyses. Groups also differed in activation patterns in regions of the Papez circuit in planned analyses. The majority of activation differences were not related to performance, presence of medications, presence of comorbid anxiety disorder, or decreased gray matter volume in MDD.

CONCLUSIONS

Adults with MDD exhibit memory difficulties during a task designed to reduce the contribution of individual variability from short-term memory and executive functioning processes, parallel with decreased activation in memory and executive functioning circuits. Ecologically valid long-term memory tasks are imperative for uncovering neural correlates of memory performance deficits in adults with MDD.

The papez circuit in first-episode, treatment-naive adults with major depressive disorder: combined atlas-based tract-specific quantification analysis and voxel-based analysis

Previous findings suggest that the Papez Circuit may have a role in major depressive disorders. We used atlas-based tract-specific quantification analysis and voxel-based analysis to examine the integrity of white matter tracts involved in mood regulation (including tracts in the Papez Circuit). Diffusion tensor imaging acquired from 35 first-episode, treatment-naive adults with major depressive disorders and 34 healthy adult controls were compared. Our statistical approach compared structural integrity of 11 major white matter tracts between the major depressive disorder and adult controls, as well as illness duration influence in patients. Fractional anisotropy was decreased in the hippocampal cingulum and in the anterior thalamic radiation according to both analytical approaches, all of which were important tracts included in the Papez Circuit. Our results support the role of the Papez Circuit in major depressive disorders with the minimal probability of false positive due to similar findings in both analyses that have complementary advantages. Dysfunction of the Papez Circuit may be a potential marker for studying the pathogenesis of major depressive disorders.

Neural effects of cognitive-behavioural therapy on dysfunctional attitudes in depression

BACKGROUND

Dysfunctional attitudes are a feature of depression that has been correlated with receptor binding abnormalities in limbic and cortical regions. We sought to investigate the functional neuroanatomy of dysfunctional attitudes in major depressive disorder (MDD) and the effects of treatment with cognitive-behavioural therapy (CBT).

METHOD

Participants were 16 patients with unipolar depression in an acute depressive episode (mean age 40.0 years) and 16 matched healthy controls (mean age 39.9 years). Patients were medication free and received a course of treatment with CBT. All participants underwent functional magnetic resonance imaging (fMRI) scans at baseline and at week 16, prior to the initiation of therapy and following the course of CBT for patients. During each fMRI scan, participants indicated their attributions to statements from a modified Dysfunctional Attitudes Scale (mDAS-48).

RESULTS

MDD patients in an acute depressive episode endorsed a greater number of extreme responses to DAS statements, which normalized following CBT treatment. Extreme attributions were associated with greater activation in the left hippocampal region, inferior parietal lobe and precuneus in MDD patients as compared with healthy controls as a main effect of group. An interaction effect was found in the left parahippocampal region, which showed less attenuation in MDD patients at the follow-up scan relative to healthy controls.

CONCLUSIONS

Attenuation of activity in the parahippocampal region may be indicative of an improvement in dysfunctional thinking following CBT treatment in depression, while persistent engagement of regions involved in attentional processing and memory retrieval with extreme attributions reflects a trait feature of depression.

DISC1 gene and affective psychopathology: a combined structural and functional MRI study

The gene Disrupted-In-Schizophrenia-1 (DISC1) has been indicated as a determinant of psychopathology, including affective disorders, and shown to influence prefrontal cortex (PFC) and hippocampus functioning, regions of major interest for affective disorders. We aimed to investigate whether DISC1 differentially modulates brain function during executive and memory processing, and morphology in regions relevant for depression and anxiety disorders (affective disorders). 128 participants, with (n = 103) and without (controls; n = 25) affective disorders underwent genotyping for Ser704Cys (with Cys-allele considered as risk-allele) and structural and functional (f) Magnetic Resonance Imaging (MRI) during visuospatial planning and emotional episodic memory tasks. For both voxel-based morphometry and fMRI analyses, we investigated the effect of genotype in controls and explored genotypeXdiagnosis interactions. Results are reported at p < 0.05 FWE small volume corrected. In controls, Cys-carriers showed smaller bilateral (para)hippocampal volumes compared with Ser-homozygotes, and lower activation in the anterior cingulate cortex (ACC) and dorsolateral PFC during visuospatial planning. In anxiety patients, Cys-carriers showed larger (para)hippocampal volumes and more ACC activation during visuospatial planning. In depressive patients, no effect of genotype was observed and overall, no effect of genotype on episodic memory processing was detected. We demonstrated that Ser704Cys-genotype influences (para)hippocampal structure and functioning the dorsal PFC during executive planning, most prominently in unaffected controls. Results suggest that presence of psychopathology moderates Ser704Cys effects.

A meta-analysis of changes in brain activity in clinical depression

Insights into neurobiological mechanisms of depression are increasingly being sought via brain imaging studies. Our aim was to quantitatively summarize overlap and divergence in regions of altered brain activation associated with depression under emotionally valenced compared to cognitively demanding task conditions, and with reference to intrinsic functional connectivity. We hypothesized differences reflective of task demands. A co-ordinate-based meta-analysis technique, activation likelihood estimation, was used to analyze relevant imaging literature. These studies compared brain activity in depressed adults relative to healthy controls during three conditions: (i) emotionally valenced (cognitively easy) tasks (n = 29); (ii) cognitively demanding tasks (n = 15); and (iii) resting conditions (n = 21). The meta-analyses identified five, eight, and seven significant clusters of altered brain activity under emotion, cognition, and resting conditions, respectively, in depressed individuals compared to healthy controls. Regions of overlap and divergence between pairs of the three separate meta-analyses were quantified. There were no significant regions of overlap between emotion and cognition meta-analyses, but several divergent clusters were found. Cognitively demanding conditions were associated with greater activation of right medial frontal and insula regions while bilateral amygdala was more significantly altered during emotion (cognitively undemanding) conditions; consistent with task demands. Overlap was present in left amygdala and right subcallosal cingulate between emotion and resting meta-analyses, with no significant divergence. Our meta-analyses highlight alteration of common brain regions, during cognitively undemanding emotional tasks and resting conditions but divergence of regions between emotional and cognitively demanding tasks. Regions altered reflect current biological and system-level models of depression and highlight the relationship with task condition and difficulty.

Increased neural activity during overt and continuous semantic verbal fluency in major depression: mainly a failure to deactivate

Major depression is associated with impairments in semantic verbal fluency (VF). However, the neural correlates underlying dysfunctional cognitive processing in depressed subjects during the production of semantic category members still remain unclear. In the current study, an overt and continuous semantic VF paradigm was used to examine these mechanisms in a representative sample of 33 patients diagnosed with a current episode of unipolar depression and 33 statistically matched healthy controls. Subjects articulated words in response to semantic category cues while brain activity was measured with functional magnetic resonance imaging (fMRI). Compared to controls, patients showed poorer task performance. On the neural level, a group by condition interaction analysis, corrected for task performance, revealed a reduced task-related deactivation in patients in the right parahippocampal gyrus, the right fusiform gyrus, and the right supplementary motor area. An additional and an increased task-related activation in patients were observed in the right precentral gyrus and the left cerebellum, respectively. These results indicate that a failure to suppress potentially interfering activity from inferior temporal regions involved in default-mode network functions and visual imagery, accompanied by an enhanced recruitment of areas implicated in speech initiation and higher-order language processes, may underlie dysfunctional cognitive processing during semantic VF in depression. The finding that patients with depression demonstrated both decreased performance and aberrant brain activation during the current semantic VF task demonstrates that this paradigm is a sensitive tool for assessing brain dysfunctions in clinical populations.

Neurophysiological correlates of autobiographical memory deficits in currently and formerly depressed subjects

BACKGROUND

Individuals with major depressive disorder (MDD) tested in either the depressed (dMDD) or remitted phase (rMDD) recall fewer specific and more categorical autobiographical memories (AMs) compared to healthy controls (HCs). The current study aimed to replicate findings of AM overgenerality in dMDD or rMDD, and to elucidate differences in neurophysiological correlates of AM recall between these MDD samples and HCs.

METHOD

Unmedicated participants who met criteria for the dMDD, rMDD or HC groups (n = 16/group) underwent functional magnetic resonance imaging (fMRI) while recalling AMs in response to emotionally valenced cue words. Control tasks involved generating examples from an assigned semantic category and counting the number of risers in a letter string.

RESULTS

The results showed fewer specific and more categorical AMs in both MDD samples versus HCs; dMDDs and rMDDs performed similarly on these measures. The neuroimaging results showed differences between groups in the dorsomedial prefrontal cortex (DMPFC), lateral orbitofrontal cortex (OFC), anterior insula, inferior temporal gyrus and parahippocampus/hippocampus during specific AM recall versus example generation. During specific AM recall cued by positively valenced words, group differences were evident in the DMPFC, middle temporal gyrus, parahippocampus/hippocampus and occipital gyrus, whereas differences during specific AM recall cued by negatively valenced words were evident in the DMPFC, superior temporal gyrus and hippocampus.

CONCLUSIONS

AM deficits exist in rMDDs, suggesting that these impairments constitute trait-like abnormalities in MDD. We also found distinct patterns of hemodynamic activity for each group as they recalled specific AMs, raising the possibility that each group used a partly unique strategy for self-referential focus during successful retrieval of specific memories.

Structural and functional imaging of the hippocampus in young people at familial risk of depression

BACKGROUND

Major depression is associated with abnormalities in the function and structure of the hippocampus. However, it is unclear whether these abnormalities might also be present in people 'at risk' of illness.

METHOD

We studied 62 young people (mean age 18.8 years) at familial risk of depression (FH+) but who had never been depressed themselves. Participants underwent magnetic resonance imaging to assess hippocampal structure and neural responses to a task designed to activate hippocampal memory networks. Magnetic resonance spectroscopy was used to measure levels of a combination of glutamine and glutamate (Glx) in the right hippocampus. A total of 59 matched controls with no history of mood disorder in a first-degree relative underwent the same investigations.

RESULTS

Hippocampal volume did not differ between FH+ participants and controls; however, relative to controls, during the memory task, FH+ participants showed increased activation in brain regions encompassing the insular cortices, putamen and pallidum as well as the dorsal anterior cingulate cortex (ACC). FH+ participants also had increased hippocampal levels of Glx.

CONCLUSIONS

Euthymic individuals with a parental history of depression demonstrate increased activation of hippocampal-related neural networks during a memory task, particularly in brain regions involved in processing the salience of stimuli. Changes in the activity of the ACC replicate previous findings in FH+ participants using different psychological tasks; this suggests that task-related abnormalities in the ACC may be a marker of vulnerability to depression. Increased levels of Glx in the hippocampus might also represent a risk biomarker but follow-up studies will be required to test these various possibilities.

Altered neural function during episodic memory encoding and retrieval in major depression

Memory impairments are common in major depression. Neural processing during non-emotional episodic memory in depressed patients has only sparsely been investigated, since the majority of studies have focused on emotional stimuli. The aim of this study was to explore neural correlates of episodic memory in depressive patients and to assess brain regions related to subsequent memory performance. Forty-six participants (23 depressed patients) performed a non-emotional episodic memory encoding and retrieval task while brain activation was measured with functional magnetic resonance imaging. Patients with depression showed decreased activation in the right prefrontal cortex and right cingulate cortex during memory encoding, but increased activation in the right inferior frontal gyrus (IFG) during recognition memory. While a strong association between hippocampal and parahippocampal activation during memory encoding with subsequent memory performance became evident in healthy controls, this relationship was absent in patients with depression. Taken together, these findings demonstrate that memory related brain regions are affected in their appropriate functioning during memory encoding in depressed patients. Therefore, patients with depression may rely to a greater degree on other brain regions such as the IFG during episodic memory retrieval.

A genome-wide supported variant in CACNA1C influences hippocampal activation during episodic memory encoding and retrieval

The alpha 1C subunit of the L-type voltage-gated calcium channel (CACNA1C) gene is one of the best replicated susceptibility loci for bipolar disorder, schizophrenia and major depression. It is involved in learning, memory and brain plasticity. Genetic studies using functional magnetic resonance imaging (fMRI) reported evidence of association with the CACNA1C single nucleotide polymorphism rs1006737 with functional correlates of episodic memory encoding and retrieval, especially activations in the hippocampus. These results, however, are inconsistent with regard to the magnitude and directionality of effect. In the present study, brain activation was measured with fMRI during an episodic memory encoding and retrieval task using neutral faces in two independent samples of 94 and 111 healthy subjects, respectively. Within whole brain analyses, a main effect of genotype emerged mainly in the right hippocampus during encoding as well as retrieval within the first sample: Carriers of the minor allele (A) exhibited lower activations compared to G/G allele carriers. This effect could be replicated within the second sample, however, only for the retrieval condition. The results strengthen findings that rs1006737 is associated with neural systems related to memory processes in hippocampal regions which are detectable in healthy subjects.

Identifying major depressive disorder using Hurst exponent of resting-state brain networks

Resting-state functional magnetic resonance imaging (fMRI) studies of major depressive disorder (MDD) have revealed abnormalities of functional connectivity within or among the resting-state networks. They provide valuable insight into the pathological mechanisms of depression. However, few reports were involved in the "long-term memory" of fMRI signals. This study was to investigate the "long-term memory" of resting-state networks by calculating their Hurst exponents for identifying depressed patients from healthy controls. Resting-state networks were extracted from fMRI data of 20 MDD and 20 matched healthy control subjects. The Hurst exponent of each network was estimated by Range Scale analysis for further discriminant analysis. 95% of depressed patients and 85% of healthy controls were correctly classified by Support Vector Machine with an accuracy of 90%. The right fronto-parietal and default mode network constructed a deficit network (lower memory and more irregularity in MDD), while the left fronto-parietal, ventromedial prefrontal and salience network belonged to an excess network (longer memory in MDD), suggesting these dysfunctional networks may be related to a portion of the complex of emotional and cognitive disturbances. The abnormal "long-term memory" of resting-state networks associated with depression may provide a new possibility towards the exploration of the pathophysiological mechanisms of MDD.

Spatiotemporal analysis of relative convergence of EEGs reveals differences between brain dynamics of depressive women and men

A new nonlinear technique for analysis of brain dynamics called spatiotemporal analysis of relative convergence (STARC) of electroencephalograms (EEGs) is introduced, based on the relative convergence of EEGs of different loci. This technique shows how many times EEGs of each loci pair converge together, which in turn is used as an indicator to determine the different neuronal regions involved in performing the same task. A higher STARC value indicates that more regions are recruited to perform the same task. The STARC methodology was used to reveal sex difference pathophysiology and brain dynamics, using EEG data from 11 male and 11 female adults with major depressive disorder (MDD). The results show significant differences in relative convergences of EEGs of intraleft temporal and frontoleft temporal lobes at δ band, between male and female patients.

[Dysthymia in the Clinical Context]

Dysthymia is defined as a chronic mood disorder that persists for at least two years in adults, and one year in adolescents and children. According to DSM IV-TR, Dysthymia is classified into two subtypes: early-onset, when it begins before 21 years-old, and late onset Dysthymia, when it starts after this age. Before age 21, symptoms of conduct disorder, attention deficit disorder and hyperactivity with a few vegetative symptoms are usually present. It is important to distinguish it from other types of depression, as earlier as possible. This would allow providing these patients with the appropriate treatment to attenuate the impact of symptoms, such as poor awareness of self-mood, negative thinking, low self-esteem, and low energy for social and family activities, which progressively deteriorate their life quality. The etiology of Dysthymia is complex and multifactorial, given the various biological, psychological and social factors involved. Several hypotheses attempt to explain the etiology of Dysthymia, highlighting the genetic hypothesis, which also includes environmental factors, and an aminergic hypothesis suggesting a deficiency in serotonin, norepinephrine and dopamine in the central nervous system. From our point of view, dysthymia cannot be conceived as a simple mild depressive disorder. It is a distinct entity, characterized by a chronic depressive disorder which could persist throughout life, with important repercussions on the life quality of both patients and families.

Altered brain function underlying verbal memory encoding and retrieval in psychotic major depression

Psychotic major depression (PMD) is associated with deficits in verbal memory as well as other cognitive impairments. This study investigated brain function in individuals with PMD during a verbal declarative memory task. Participants included 16 subjects with PMD, 15 subjects with non-psychotic major depression (NPMD) and 16 healthy controls (HC). Functional magnetic resonance imaging (fMRI) data were acquired while subjects performed verbal memory encoding and retrieval tasks. During the explicit encoding task, subjects semantically categorized words as either "man-made" or "not man-made." For the retrieval task, subjects identified whether words had been presented during the encoding task. Functional MRI data were processed using SPM5 and a group by condition ANOVA. Clusters of activation showing either a significant main effect of group or an interaction of group by condition were further examined using t-tests to identify group differences. During the encoding task, the PMD group showed lower hippocampus, insula, and prefrontal activation compared to HC. During the retrieval task, the PMD group showed lower recognition accuracy and higher prefrontal and parietal cortex activation compared to both HC and NPMD groups. Verbal retrieval deficits in PMD may be associated with deficient hippocampus function during encoding. Increased brain activation during retrieval may reflect an attempt to compensate for encoding deficits.

Increased anterior cingulate cortex and hippocampus activation in Complex PTSD during encoding of negative words

Post-traumatic stress disorder (PTSD) is associated with impaired memory performance coupled with functional changes in brain areas involved in declarative memory and emotion regulation. It is not yet clear how symptom severity and comorbidity affect neurocognitive functioning in PTSD. We performed a functional magnetic resonance imaging (fMRI) study with an emotional declarative memory task in 28 Complex PTSD patients with comorbid depressive and personality disorders, and 21 healthy non-trauma-exposed controls. In Complex PTSD patients--compared to controls--encoding of later remembered negative words vs baseline was associated with increased blood oxygenation level dependent (BOLD) response in the left ventral anterior cingulate cortex (ACC) and dorsal ACC extending to the dorsomedial prefrontal cortex (dmPFC) together with a trend for increased left hippocampus activation. Patients tended to commit more False Alarms to negative words compared to controls, which was associated with enhanced left ventrolateral prefrontal and orbitofrontal cortex (vlPFC/OFC) responses. Severity of child abuse was positively correlated with left ventral ACC activity and severity of depression with (para) hippocampal and ventral ACC activity. Presented results demonstrate functional abnormalities in Complex PTSD in the frontolimbic brain circuit also implicated in fear conditioning models, but generally in the opposite direction, which may be explained by severity of the trauma and severity of comorbid depression in Complex PTSD.

Fractality analysis of frontal brain in major depressive disorder

EEGs of the frontal brain of patients diagnosed with major depressive disorder (MDD) have been investigated in recent years using linear methods but not based on nonlinear methods. This paper presents an investigation of the frontal brain of MDD patients using the wavelet-chaos methodology and Katz's and Higuchi's fractal dimensions (KFD and HFD) as measures of nonlinearity and complexity. EEGs of the frontal brain of healthy adults and MDD patients are decomposed into 5 EEG sub-bands employing a wavelet filter bank, and the FDs of the band-limited as well as those of their 5 sub-bands are computed. Then, using the ANOVA statistical test, HFDs and KFDs of the left and right frontal lobes in EEG full-band and sub-bands of MDD and healthy groups are compared in order to discover the FDs showing the most meaningful differences between the two groups. Finally, the discovered FDs are used as input to a classifier, enhanced probabilistic neural network (EPNN), to discriminate the MDD from healthy EEGs. The results of HFD show higher complexity of left, right and overall frontal lobes of the brain of MDD compared with non-MDD in beta and gamma sub-bands. Moreover, it is observed that HFD of the beta band is more discriminative than HFD of the gamma band for discriminating MDD and non-MDD participants, while the KFD did not show any meaningful difference. A high accuracy of 91.3% is achieved for classification of MDD and non-MDD EEGs based on HFDs of left, right, and overall frontal brain beta sub-band. The findings of this research, however, should be considered tentative because of limited data available to the authors.

MicroRNA expression is down-regulated and reorganized in prefrontal cortex of depressed suicide subjects

Background

Recent studies suggest that alterations in expression of genes, including those which regulate neural and structural plasticity, may be crucial in the pathogenesis of depression. MicroRNAs (miRNAs) are newly discovered regulators of gene expression that have recently been implicated in a variety of human diseases, including neuropsychiatric diseases.

Methodology/Principal Findings

The present study was undertaken to examine whether the miRNA network is altered in the brain of depressed suicide subjects. Expression of miRNAs was measured in prefrontal cortex (Brodmann Area 9) of antidepressant-free depressed suicide (n = 18) and well-matched non-psychiatric control subjects (n = 17) using multiplex RT-PCR plates. We found that overall miRNA expression was significantly and globally down-regulated in prefrontal cortex of depressed suicide subjects. Using individual tests of statistical significance, 21 miRNAs were significantly decreased at p = 0.05 or better. Many of the down-regulated miRNAs were encoded at nearby chromosomal loci, shared motifs within the 5′-seeds, and shared putative mRNA targets, several of which have been implicated in depression. In addition, a set of 29 miRNAs, whose expression was not pairwise correlated in the normal controls, showed a high degree of co-regulation across individuals in the depressed suicide group.

Conclusions/Significance

The findings show widespread changes in miRNA expression that are likely to participate in pathogenesis of major depression and/or suicide. Further studies are needed to identify whether the miRNA changes lead to altered expression of prefrontal cortex mRNAs, either directly (by acting as miRNA targets) or indirectly (e.g., by affecting transcription factors).

Frontal white matter integrity is related to psychomotor retardation in major depression

Altered frontal white matter integrity has been reported in major depression. Still, the behavioral correlates of these alterations are not established. In healthy subjects, motor activity correlated with white matter integrity in the motor system. To explore the relation of white matter integrity and motor activity in major depressive disorder, we investigated 21 medicated patients with major depressive disorder and 21 matched controls using diffusion tensor imaging and wrist actigraphy at the same day. Patients had lower activity levels (AL) compared with controls. Fractional anisotropy (FA) differed between groups in frontal white matter regions and the posterior cingulum. AL was linearly associated with white matter integrity in two clusters within the motor system. Controls had an exclusive positive association of FA and AL in white matter underneath the right dorsal premotor cortex. Only patients had a positive association within the posterior cingulum. Furthermore, patients had negative associations of FA and AL underneath the left primary motor cortex and within the left parahippocampal gyrus white matter. These differences in the associations between structure and behavior may contribute to well-known impaired motor planning or gait disturbances in major depressive disorder. Therefore, signs of psychomotor slowing in major depressive disorder may be linked to changes of the white matter integrity of the motor system.

Autobiographical memory in depression: an fMRI study

Depression is associated with three distinct alterations in memory functioning: mood-congruent recall, over-generality, and intrusive memories. These concern the autobiographical memory system, yet no previous studies have examined the neural correlates of autobiographical memory function in depression. In the present study we used functional magnetic resonance imaging (fMRI) to assess depressed and control participants during an autobiographical memory task. In their first visit to the laboratory, participants wrote a narrative account of a distressing event. Participants were scanned during the second visit while they viewed old items from their narrative and new words or phrases in a recognition memory task. Activity common to both groups during the successful identification of personal emotional memories was observed in regions previously associated with autobiographical memory retrieval. Reduced activity in the depressed group was observed in three regions of the prefrontal cortex associated with cognitive, emotional, and memory inhibition. These results are consistent with a failure by depressed individuals to inhibit task-irrelevant information during an autobiographical memory task.

Voxelwise meta-analysis of gray matter reduction in major depressive disorder

BACKGROUND

Voxel-based morphometry (VBM) has been widely used in studies of major depressive disorder (MDD) and has provided cumulative evidence of gray matter abnormalities in patients relative to controls. Thus we performed a meta-analysis to integrate the reported studies to determine the consistent gray matter alterations in MDD.

METHODS

A systematic search was conducted to identify VBM studies which contrasted MDD patients against a comparison group. The coordinates of gray matter change across studies were meta-analyzed using the activation likelihood estimation (ALE) method hybridized with the rank-based Genome Scan Meta-Analysis (GSMA) to quantitatively estimate regional gray matter reductions in MDD.

RESULTS

A total of 20 VBM studies comparing 543 major depressive patients with 750 healthy control subjects were included. Consistent gray matter reductions in all MDD patients relative to healthy controls were identified in the bilateral anterior cingulate cortex (ACC), right middle and inferior frontal gyrus, right hippocampus and left thalamus.

CONCLUSIONS

Meta-analysis of all primary VBM studies indicates that significant gray matter reductions in MDD are localized in a distributed neural network which includes frontal, limbic and thalamic regions. Future studies will benefit from the use of a longitudinal approach to examine anatomical and functional abnormalities within this network and their relationship to clinical profile, particularly in first-episode and drug-naive MDD patients.

Abnormal hippocampal activation in patients with extensive history of major depression: an fMRI study

BACKGROUND

Impairment of recollection memory is consistently reported in patients with major depressive disorder (MDD) and may reflect underlying functional hippocampal changes, particularly in those with extensive histories of illness. We hypothesized that relative to controls, patients with a protracted course of illness would show diminished hippocampal activation on functional magnetic resonance imaging (fMRI) during a recollection memory task.

METHODS

Patients who experienced 3 or more previously treated depressive episodes were compared with age- and sex-matched controls. We acquired fMRI data while participants performed a recollection memory process dissociation task.

RESULTS

Using bilateral regions of interest (ROIs) prescribed for the right and left hippocampal/parahippocampal complex, we observed increased activation of the right hippocampal and left parahippocampal gyrus in controls compared with patients with MDD during recollection memory trials. Within-group comparisons revealed heightened engagement of the hippocampal head (R/L) for controls during recollection trials, and greater activation of the hippocampal body/tail (R/L) during the learn-list encoding period in both the MDD and control groups. Recollection memory performance was significantly correlated with changes in blood oxygen level-dependent signal during recollection trials in the ROIs of the right hippocampus and right hippocampal head.

LIMITATIONS

This study was limited by the inclusion of patients taking antidepressant medication, raising the possibility that the reported findings were treatment effects.

CONCLUSION

The findings of decreased recruitment of the right hippocampal and left parahippocampalgyrus in patients with MDD suggest that these regions may be sensitive to the impact of disease burden and repeated episodes of MDD. This attenuated activation may represent stable changes in hippocampal function that occur over the course of illness in patients with MDD. The findings from within-group comparisons show that the group differences in the activation of the right hippocampal head were driven by greater engagement of this region among controls during recollection memory performance. These results also associate recollection performance impairments in patients with MDD with diminished hippocampal engagement.

How much are clinical fMRI reports influenced by standard postprocessing methods? An investigation of normalization and region of interest effects in the medial temporal lobe

Recent evidence has indicated that standard postprocessing methods such as template-based region of interest (ROI) definition and normalization of individual brains to a standard template may influence final outcome of functional magnetic resonance imaging investigations. Here, we provide the first comprehensive investigation into whether ROI definition and normalization may also change the clinical interpretation of patient data. A series of medial temporal lobe epilepsy patients were investigated with a clinical memory paradigm and individually delineated as well as template-based ROIs. Different metrics for activation quantification were applied. Results show that the application of template-based ROIs can significantly change the clinical interpretation of individual patient data. This relates to sensitivity for brain activation and hemispheric dominance. We conclude that individual ROIs should be defined on nontransformed functional data and that use of more than one metric for activation quantification is beneficial.

Brain imaging correlates of cognitive impairment in depression

This review briefly summarises recent research on the neural basis of cognition in depression. Two broad areas are covered: emotional and non-emotional processing. We consider how research findings support models of depression based on disrupted cortico-limbic circuitry, and how modern connectivity analysis techniques can be used to test such models explicitly. Finally we discuss clinical implications of cognitive imaging in depression, and specifically the possible role for these techniques in diagnosis and treatment planning.

Neural correlates of memory in depression measured by brain perfusion SPECT at rest

AIM

Brain metabolism activated studies have indicated associations between memory and the anterior cingulate cortex and hippocampus in patients with depression. The aim of the present study was therefore to investigate memory function, measured as performance on the Wechsler Memory Scale-Revised (WMS-R), and its relationship to brain perfusion using single-photon emission computed tomography (SPECT) at rest in patients with depression.

METHODS

The Hamilton Rating Scale for Depression (HAMD) and WMS-R were measured for 17 patients with depression by an independent clinical evaluation team. Voxel-based correlation analyses were performed with statistical parametric mapping at an extent threshold of 200 voxels. Associations were controlled for state and trait factors.

RESULTS

WMS-R measurements of verbal, visual, and general memory were inversely correlated with brain perfusion in the right anterior cingulate cortex, left premotor cortices, and both regions, respectively. The HAMD directly correlated with brain perfusion in the right anterior cingulate cortex.

CONCLUSION

Brain perfusion SPECT measurements of the anterior cingulate cortex at rest were associated with the severity of depression and immediate memory scores measured with the WMS-R.