Fronto-limbic brain structures in suicidal and non-suicidal female patients with major depressive disorder

5-HTTLPR, anxiety and gender interaction moderates right amygdala volume in healthy subjects

Genetic variants within the serotonin transporter gene (5-HTTLPR) impact the neurobiology and risk for anxiety-related behaviours. There are also gender differences in the prevalence of anxiety-related behaviours. Although numerous studies have investigated the influence of 5-HTTLPR genotype on the neural systems involved in emotional regulation, none have investigated how these effects are modulated by gender and anxiety. We investigated this issue using two complementary region of interest-based structural neuroimaging approaches (voxel-based morphometry and Freesurfer) in 138 healthy individuals categorized into 'no anxiety' and 'subclinical anxiety' groups based on the Hamilton Rating Scale for Anxiety (HAM-A). Preliminarily, using anxiety as a continuous variable, we found a significant interaction effect of genotype by gender on anxiety. Females homozygous for the Short allele showed the highest HAM-A scores and males the lowest. In addition, a three-way significant interaction among genotype, gender and anxiety category was found for the right amygdala volume. Post hoc tests revealed that homozygous females carrying the Short variant with a subclinical anxiety condition had larger volume. The reported interaction effects demonstrate that gender strongly modulates the relationship between 5-HTTLPR genotype and subclinical expression of anxiety acting on amygdala, one region of the emotional neural network specifically involved in the anxiety-like behaviours.

[Suicide in the elderly: age-related specificities?]

Suicide in the elderly raises the question of our relationship with aging and death. Suicide rate is relatively high in this group and is significantly related to depression widely under-diagnosed in the elderly. Suicidal behaviour in the elderly has clinical specificities including high intentionality and lethality, usually little personal history of suicidal behaviour and low levels of impulsivity-aggression. Suicidal vulnerability could rely on etiopathogenic mechanisms both common and different according to age; for example, a preponderance of early developmental factors and impulsivity-aggression in adolescents and young adults vs. pathological aging in older adults, but partly similar neurocognitive deficits leading individuals not to respond adequately to their environment (itself different with age). Direct comparisons between elderly and younger subjects would be required. The article concludes with a summary of the principles of recognition and management of suicide risk.

Iowa gambling task performance in currently depressed suicide attempters

Deficits in decision-making using the Iowa Gambling Task (IGT) have been found in past suicide attempters, but primarily euthymic and/or medicated patients. This study compared IGT performance among medication-free, currently depressed patients (unipolar and bipolar) with (n=26) and without (n=46) a past history of suicide attempt, and healthy volunteers (n=42). Attempter status, in a sample whose attempts were predominantly non-violent, was not associated with impaired IGT performance even when accounting for sex, mood disorder type, and comorbid Borderline Personality Disorder. A non-significant trend towards poorer performance was found in a small subgroup of past attempters who had used a violent method, consistent with prior studies. Suicide intent and ideation were unrelated to IGT scores. There were no consistent associations between IGT performance and ratings of impulsiveness (Barratt Impulsiveness Scale (BIS)), hostility (Buss-Durkee Hostility Inventory (BDHI)) or aggression (Brown-Goodwin Aggression Inventory (BGAI)). Results suggest that decision-making impairment is related to specific subtypes of suicidal behavior, but may not be universally sensitive to suicide risk in all types of attempters, especially those using non-violent means. Psychometric and conceptual issues surrounding the IGT also appear to affect its utility as a general marker of suicidal behavior risk.

Opposite effective connectivity in the posterior cingulate and medial prefrontal cortex between first-episode schizophrenic patients with suicide risk and healthy controls

Objective

The schizophrenic patients with high suicide risk are characterized by depression, better cognitive function, and prominent positive symptoms. However, the neurobiological basis of suicide attempts in schizophrenia is not clear. The suicide in schizophrenia is implicated in the defects in emotional process and decision-making, which are associated with prefrontal-cingulate circuit. In order to explore the possible neurobiological basis of suicide in schizophrenia, we investigated the correlation of prefrontal-cingulate circuit with suicide risk in schizophrenia via dynamic casual modelling.

Method

Participants were 33 first-episode schizophrenic patients comprising of a high suicide risk group (N = 14) and a low suicide risk group (N = 19). A comparison group of healthy controls (N = 15) were matched for age, gender and education. N-back tasking functional magnetic resonance imaging data was collected.

Results

Compared with healthy controls group, the two patients groups showed decreased task-related suppression during 2-back task state versus baseline state in the left posterior cingulate and medial prefrontal cortex; the hyper-connectivity from the left posterior cingulate cortex to the left medial prefrontal cortex existed in both schizophrenic patients groups, but hypo-connectivity in the opposite direction only existed in the schizophrenic patients group with high suicide risk.

Conclusions

The hyper-connectivity from the left posterior cingulate cortex to the left medial prefrontal cortex may suggest that the abnormal effective connectivity was associated with risk for schizophrenia. The hypo-connectivity in the opposite direction may represent a possible correlate of increased vulnerability to suicide attempt.

[Predicting suicide or predicting the unpredictable in an uncertain world: Reinforcement Learning Model-Based analysis]

In general, it appears that the suicidal act is highly unpredictable with the current scientific means available. In this article, the author submits the hypothesis that predicting suicide is complex because it results in predicting a choice, in itself unpredictable. The article proposes a Reinforcement learning model-based analysis. In this model, we integrate on the one hand, four ascending modulatory neurotransmitter systems (acetylcholine, noradrenalin, serotonin, and dopamine) with their regions of respective projections and afferences, and on the other hand, various observations of brain imaging identified until now in the suicidal process.

Dynamic connectivity laterality of the amygdala under negative stimulus in depression: a MEG study

Depression is a mental disorder characterized by emotional and cognitive dysfunction, which is related to the abnormal activity in brain regions involving emotion processing such as amygdala (AMYG). The laterality of AMYG during emotional information processing has always been a controversial issue in any depression study, however, the dynamic characteristic of laterality in the AMYG has been ignored. In this paper, we proposed to explore the time-varying functional coupling between the anterior cingulate cortex (ACC) and the bilateral AMYG in the time-frequency domain. As a result, an emotional facial expression paradigm was undertaken in this study. Using magnetoencephalogram (MEG) data acquired from 16 patients with major depression disorder and 16 matched healthy controls, we calculated the wavelet coherence. The research led to the conclusion that, after sad facial stimuli, the ACC-bilateral AMYG connectivity in depressive patients showed a significant decrease in the beta band during the first 100 ms. In addition, the ACC-left AMYG connectivity led to a significant increase in the gamma band around 400 ms and in beta band around 700 ms. Our work suggests a lack of sufficient inhibition of the ACC on the bilateral AMYG in the early period and the lateralized dysregulation of the ACC on the left AMYG in late period during the sad facial information processing task. We hypothesized that the clinical manifestations of depression may partly result from it.

The neuroprogressive nature of major depressive disorder: pathways to disease evolution and resistance, and therapeutic implications

In some patients with major depressive disorder (MDD), individual illness characteristics appear consistent with those of a neuroprogressive illness. Features of neuroprogression include poorer symptomatic, treatment and functional outcomes in patients with earlier disease onset and increased number and length of depressive episodes. In such patients, longer and more frequent depressive episodes appear to increase vulnerability for further episodes, precipitating an accelerating and progressive illness course leading to functional decline. Evidence from clinical, biochemical and neuroimaging studies appear to support this model and are informing novel therapeutic approaches. This paper reviews current knowledge of the neuroprogressive processes that may occur in MDD, including structural brain consequences and potential molecular mechanisms including the role of neurotransmitter systems, inflammatory, oxidative and nitrosative stress pathways, neurotrophins and regulation of neurogenesis, cortisol and the hypothalamic-pituitary-adrenal axis modulation, mitochondrial dysfunction and epigenetic and dietary influences. Evidence-based novel treatments informed by this knowledge are discussed.

Enlarged thalamic volumes and increased fractional anisotropy in the thalamic radiations in veterans with suicide behaviors

Post-mortem studies have suggested a link between the thalamus, psychiatric disorders, and suicide. We evaluated the thalamus and anterior thalamic radiations (ATR) in a group of Veterans with and without a history of suicidal behavior (SB) to determine if thalamic abnormalities were associated with an increased risk of SB. Forty Veterans with mild traumatic brain injury (TBI) and no SB (TBI-SB), 19 Veterans with mild TBI and a history of SB (TB + SB), and 15 healthy controls (HC) underwent magnetic resonance imaging scanning including a structural and diffusion tensor imaging scan. SBs were evaluated utilizing the Columbia Suicide Rating Scale and impulsivity was measured using the Barratt Impulsiveness Scale (BIS). Differences in thalamic volumes and ATR fractional anisotropy (FA) were examined between (1) TBI + SB versus HC and (2) TBI + SB versus combined HC and TBI-SB and (3) between TBI + SB and TBI-SB. Left and right thalamic volumes were significantly increased in those with TBI + SB compared to the HC, TBI-SB, and the combined group. Veterans with TBI + SB had increased FA bilaterally compared to the HC, HC and TBI-SB group, and the TBI-SB only group. Significant positive associations were found for bilateral ATR and BIS in the TBI + SB group. Our findings of thalamic enlargement and increased FA in individuals with TBI + SB suggest that this region may be a biomarker for suicide risk. Our findings are consistent with previous evidence indicating that suicide may be associated with behavioral disinhibition and frontal-thalamic-limbic dysfunction and suggest a neurobiologic mechanism that may increase vulnerability to suicide.

Prefrontal cortical thickness in depressed patients with high-risk for suicidal behavior

Major depressive disorder (MDD) is associated with an increased risk for suicide. There is considerable evidence that a predisposition to suicidal behavior may exist which is independent of the MDD itself. Recent studies suggest a familial transmission of the diathesis for suicidal behavior, reflected in the observation of suicide aggregation in families and higher rate of suicidal behavior in first-degree relatives of suicide attempters with MDD. One of these transmission factors may be neurobiological alterations. The main goal of the present study was therefore to study abnormalities in cortical thickness in the hypothesized fronto-cingulate network in depressed patients with high risk for suicide. 15 MDD patients with documented own suicidal behavior and/or with suicidal behavior in first-degree relatives (high risk group), 15 depressed patients with non-high risk for suicide and 30 matched healthy controls participated in the study. Using an automated surface based approach (FreeSurfer) structural T1-weighted volumes were analyzed for differences in cortical thickness on a node by node basis covering the entire cortex. Patients with high risk for suicide showed significantly thinner cortex in the left dorsolateral, ventrolateral prefrontal cortex and the anterior cingulate in contrast to non-high risk patients. Together with previous morphometric results of our group, this new finding provides strong evidence for structural brain alterations in depressed patients with high risk for suicide in the fronto-cingulo-striatal network, which is strongly involved in reward processing and behavioral/emotional control. This alteration may constitute the neurobiological basis for an increased predisposition to suicidal behavior.

Regional cortical thinning in patients with major depressive disorder: a surface-based morphometry study

This study uses surfaced-based morphometry to investigate cortical thinning and its functional correlates in patients with major depressive disorder (MDD). Subjects with MDD (N=36) and healthy control subjects (N=36) were enrolled in the study. Each subject received T1 structural magnetic resonance imaging (MRI), clinical evaluations, and neuropsychological examinations of executive functions with the Color Trail Test (CTT) and the Wisconsin Card Sorting Test (WCST). This study used an automated surface-based method (FreeSurfer) to measure cortical thickness and to generate the thickness maps for each subject. Statistical comparisons were performed using a general linear model. Compared with healthy controls, subjects with MDD showed the largest area of cortical thinning in the prefrontal cortex. This study also noted smaller areas of cortical thinning in the bilateral inferior parietal cortex, left middle temporal gyrus, left entorhinal cortex, left lingual cortex, and right postcentral gyrus. Regression analysis demonstrated cortical thinning in several frontoparietal regions, predicting worse executive performance measured by CTT 2, though the patterns of cortical thickness/executive performance correlation differed in healthy controls and MDD subjects. In conclusion, the results provide further evidence for the significant role of a prefrontal structural deficit and an aberrant structural/functional relationship in patients with MDD.

The temptation of suicide: striatal gray matter, discounting of delayed rewards, and suicide attempts in late-life depression

BACKGROUND

Converging evidence implicates basal ganglia alterations in impulsivity and suicidal behavior. For example, D2/D3 agonists and subthalamic nucleus stimulation in Parkinson's disease (PD) trigger impulse control disorders and possibly suicidal behavior. Furthermore, suicidal behavior has been associated with structural basal ganglia abnormalities. Finally, low-lethality, unplanned suicide attempts are associated with increased discounting of delayed rewards, a behavior dependent upon the striatum. Thus, we tested whether, in late-life depression, changes in the basal ganglia were associated with suicide attempts and with increased delay discounting.

METHOD

Fifty-two persons aged ≥ 60 years underwent extensive clinical and cognitive characterization: 33 with major depression [13 suicide attempters (SA), 20 non-suicidal depressed elderly] and 19 non-depressed controls. Participants had high-resolution T1-weighted magnetization prepared rapid acquisition gradient-echo (MPRAGE) magnetic resonance imaging (MRI) scans. Basal ganglia gray matter voxel counts were estimated using atlas-based segmentation, with a highly deformable automated algorithm. Discounting of delayed rewards was assessed using the Monetary Choice Questionnaire (MCQ) and delay aversion with the Cambridge Gamble Task (CGT).

RESULTS

SA had lower putamen but not caudate or pallidum gray matter voxel counts, compared to the control groups. This difference persisted after accounting for substance use disorders and possible brain injury from suicide attempts. SA with lower putamen gray matter voxel counts displayed higher delay discounting but not delay aversion. Secondary analyses revealed that SA had lower voxel counts in associative and ventral but not sensorimotor striatum.

CONCLUSIONS

Our findings, although limited by small sample size and the case-control design, suggest that striatal lesions could contribute to suicidal behavior by increasing impulsivity.

Structural brain abnormalities and suicidal behavior in borderline personality disorder

BACKGROUND

Structural brain abnormalities have been demonstrated in subjects with BPD in prefrontal and fronto-limbic regions involved in the regulation of emotion and impulsive behavior, executive cognitive function and episodic memory. Impairment in these cognitive functions is associated with increased vulnerability to suicidal behavior. We compared BPD suicide attempters and non-attempters, high and low lethality attempters to healthy controls to identify neural circuits associated with suicidal behavior in BPD.

METHODS

Structural MRI scans were obtained on 68 BPD subjects (16 male, 52 female), defined by IPDE and DIB/R criteria, and 52 healthy controls (HC: 28 male, 24 female). Groups were compared by diagnosis, attempt status, and attempt lethality. ROIs were defined for areas reported to have structural or metabolic abnormalities in BPD, and included: mid-inf. orbitofrontal cortex, mid-sup temporal cortex, anterior cingulate, insula, hippocampus, amygdala, fusiform, lingual and parahippocampal gyri. Data were analyzed using optimized voxel-based morphometry implemented with DARTEL in SPM5, co-varied for age and gender, corrected for cluster extent (p < .001).

RESULTS

Compared to HC, BPD attempters had significantly diminished gray matter concentrations in 8 of 9 ROIs, non-attempters in 5 of 9 ROIs. Within the BPD sample, attempters had diminished gray matter in Lt. insula compared to non-attempters. High lethality attempters had significant decreases in Rt. mid-sup. temporal gyrus, Rt. mid-inf. orbitofrontal gyrus, Rt. insular cortex, Lt. fusiform gyrus, Lt. lingual gyrus and Rt. parahippocampal gyrus compared to low lethality attempters.

CONCLUSIONS

Specific structural abnormalities discriminate BPD attempters from non-attempters and high from low lethality attempters.

Meta-analysis of volumetric abnormalities in cortico-striatal-pallidal-thalamic circuits in major depressive disorder

BACKGROUND

Abnormalities in cortico-striatal-pallidal-thalamic (CSPT) circuits have been implicated in major depressive disorder (MDD). However, the robustness of these findings across studies is unclear, as is the extent to which they are influenced by demographic, clinical and pharmacological factors.

METHOD

With the aim of clarifying these questions, we conducted a meta-analysis to map the volumetric abnormalities that were most robustly identified in CSPT circuits of individuals with MDD. A systematic search identified 41 studies meeting our inclusion criteria.

RESULTS

There were significant volume reductions in prefrontal (especially orbitofrontal) and anterior cingulate cortices, and also in subcortical structures such as the caudate nucleus and putamen, with effect sizes ranging from small to moderate. The subgenual anterior cingulate and orbitofrontal cortices were significantly smaller in antidepressant-free samples compared to medicated patients. Late-life depression (LLD) tended to be associated with smaller volumes in circumscribed frontal and subcortical structures, with the most robust differences being found in thalamic volume.

CONCLUSIONS

Individuals with major depression demonstrate volumetric abnormalities of CSPT circuits. However, these observations may be restricted to certain subgroups, highlighting the clinical heterogeneity of the disorder. On the basis of this meta-analysis, CSPT abnormalities were more prominent in those with LLD whereas antidepressant use seemed to normalize certain cortical volumetric abnormalities.

Fronto-limbic volumetric changes in major depressive disorder

BACKGROUND

Fronto-limbic dysregulation in major depressive disorder (MDD) may be influenced by early life stress and antidepressant treatment. The present structural MRI study aimed to determine the relationship between amygdala, cingulate and subgenual prefrontal cortex volumes in MDD and their associations with child abuse and antidepressants.

METHODS

Right-handed subjects (21-50 years), meeting DSM-IV criteria for MDD, either with (n=19) or without (n=20) childhood sexual or physical abuse. Healthy controls (n=34) were matched for age, sex, education and smoking. 3D-MPRAGE images with a spatial resolution of 1.5 mm×1.0 mm×1.0 mm were acquired with a Siemens Sonata 1.5 T system. Volumes of subgenual prefrontal cortex, amygdala and affective, cognitive, superior and posterior divisions of cingulate cortex were analyzed using DISPLAY software using reliable volumetric protocols. Groups were compared using ANCOVA, with intracranial volume as a covariate.

RESULTS

MDD subjects had low cingulate (cognitive division) and high amygdala volumes. Low cingulate volume was related to abuse and treatment history. Amygdala volume was predicted by subgenual prefrontal and cingulate (cognitive division) volumes and the presence of paracingulate cortex.

LIMITATIONS

This study was cross sectional and the sample size was limited for subgroup and correlational analyses.

SUMMARY

Our data suggest that MDD may be associated with alterations in anterior cingulate cortex and amygdala. Morphological variation, early stress and stress-protective factors may contribute to differences in fronto-limbic structures in MDD.

Relationship between suicidality and impulsivity in bipolar I disorder: a diffusion tensor imaging study

BACKGROUND

Impulsivity is characteristic of individuals with bipolar disorder and may be a contributing factor to the high rate of suicide in patients with this disorder. Although white matter abnormalities have been implicated in the pathophysiology of bipolar disorder, their relationship to impulsivity and suicidality in this disorder has not been well-investigated.

METHODS

Diffusion tensor imaging scans were acquired in 14 bipolar disorder patients with a prior suicide attempt, 15 bipolar disorder patients with no prior suicide attempt, and 15 healthy volunteers. Bipolar disorder patients received clinical assessments including measures of impulsivity, depression, mania, and anxiety. Images were processed using the Tract-Based Spatial Statistics method in the FSL software package.

RESULTS

Bipolar disorder patients with a prior suicide attempt had lower fractional anisotropy (FA) within the left orbital frontal white matter (p < 0.05, corrected) and higher overall impulsivity compared to patients without a previous suicide attempt. Among patients with a prior suicide attempt, FA in the orbital frontal white matter region correlated inversely with motor impulsivity.

CONCLUSIONS

Abnormal orbital frontal white matter may play a role in impulsive and suicidal behavior among patients with bipolar disorder.

Magnetic resonance imaging studies in unipolar depression: systematic review and meta-regression analyses

Previous meta-analyses of structural MRI studies have shown diffuse cortical and sub-cortical abnormalities in unipolar depression. However, the presence of duplicate publications, recruitment of particular age groups and the selection of specific regions of interest means that there is uncertainty about the balance of current research. Moreover, the lack of systematic exploration of highly significant heterogeneity has prevented the generalisability of finding. A systematic review and random-effects meta-analysis was carried out to estimate effect sizes. Possible publication bias, and the impact of various study design characteristics on the magnitude of the observed effect size were systematically explored. The aim of this study was 1) to include structural MRI studies systematically comparing unipolar depression with bipolar disorder and healthy volunteers; 2) to consider all available structures of interest without specific age limits, avoiding data duplication, and 3) to explore the influence of factors contributing to the measured effect sizes systematically with meta-regression analyses. Unipolar depression was characterised by reduced brain volume in areas involved in emotional processing, including the frontal cortex, orbitofrontal cortex, cingulate cortex, hippocampus and striatum. There was also evidence of pituitary enlargement and an excess of white matter hyperintensity volume in unipolar depression. Factors which influenced the magnitude of the observed effect sizes were differences in methods, clinical variables, pharmacological interventions and sample age.

The neurodevelopmental origins of suicidal behavior

Suicide and related behaviors are complex phenomena associated with different risk factors. Although most individuals who display suicidal behavior do not have a history of early-life adversity, a significant minority does. Recent animal and human data have suggested that early-life adversity leads to epigenetic regulation of genes involved in stress-response systems. Here, we review this evidence and suggest that early-life adversity increases risk of suicide in susceptible individuals by influencing the development of stable emotional, behavioral and cognitive phenotypes that are likely to result from the epigenetic regulation of the hypothalamic-pituitary-adrenal axis and other systems involved in responses to stress.

Can depression be diagnosed by response to mother's face? A personalized attachment-based paradigm for diagnostic fMRI

Objective

Objective measurement of depression remains elusive. Depression has been associated with insecure attachment, and both have been associated with changes in brain reactivity in response to viewing standard emotional and neutral faces. In this study, we developed a method to calculate predicted scores for the Beck Depression Inventory II (BDI-II) using personalized stimuli: fMRI imaging of subjects viewing pictures of their own mothers.

Methods

28 female subjects ages 18–30 (14 healthy controls and 14 unipolar depressed diagnosed by MINI psychiatric interview) were scored on the Beck Depression Inventory II (BDI-II) and the Adult Attachment Interview (AAI) coherence of mind scale of global attachment security. Subjects viewed pictures of Mother (M), Friend (F) and Stranger (S), during functional magnetic resonance imaging (fMRI). Using a principal component regression method (PCR), a predicted Beck Depression Inventory II (BDI-II) score was obtained from activity patterns in the paracingulate gyrus (Brodmann area 32) and compared to clinical diagnosis and the measured BDI-II score. The same procedure was performed for AAI coherence of mind scores.

Results

Activity patterns in BA-32 identified depressed subjects. The categorical agreement between the derived BDI-II score (using the standard clinical cut-score of 14 on the BDI-II) and depression diagnosis by MINI psychiatric interview was 89%, with sensitivity 85.7% and specificity 92.8%. Predicted and measured BDI-II scores had a correlation of 0.55. Prediction of attachment security was not statistically significant.

Conclusions

Brain activity in response to viewing one's mother may be diagnostic of depression. Functional magnetic resonance imaging using personalized paradigms has the potential to provide objective assessments, even when behavioral measures are not informative. Further, fMRI based diagnostic algorithms may enhance our understanding of the neural mechanisms of depression by identifying distinctive neural features of the illness.

Opposite effects of suicidality and lithium on gray matter volumes in bipolar depression

BACKGROUND

Mood disorders are associated with the highest increase of attempted and completed suicide. Suicidality in major depressive disorder and in schizophrenia has been associated with reduced gray matter volumes in orbitofrontal cortex. Lithium reduces the suicide risk of patients with bipolar disorder (BD) to the same levels of the general population, and can increase GM volumes. We studied the effect of a positive history of attempted suicide and ongoing lithium treatment on regional GM volumes of patients affected by bipolar depression.

METHODS

With a correlational design, we studied 57 currently depressed inpatients with bipolar disorder: 19 with and 38 without a positive history of suicide attempts, 39 unmedicated and 18 with ongoing lithium treatment. Total and regional gray matter volumes were assessed using voxel-based morphometry.

RESULTS

Total GM volume is inversely correlated with depression severity. A positive history of suicide attempts was associated with higher stress in early life. Suicide attempters showed reduced GM volumes in several brain areas including dorsolateral prefrontal cortex, orbitofrontal cortex, anterior cingulate, superior temporal cortex, parieto-occipital cortex, and basal ganglia. Long term lithium treatment was associated with increased GM volumes in the same areas where suicide was associated with decreased GM.

CONCLUSIONS

Reduced GM volumes in critical cortical areas of suicidal patients could be a biological correlate of an impaired ability to associate choices and outcomes and to plan goal-directed behaviors based on a lifetime historical perspective, which, coupled with mood-congruent depressive cognitive distortions, could lead to more hopelessness and suicide. Lithium could exert its specific therapeutic effect on suicide by acting in the same areas.

Neuroimaging correlates of traumatic brain injury and suicidal behavior

INTRODUCTION

There is an urgent need to define the neurobiological and cognitive underpinnings of suicidal ideation and behavior in veterans with traumatic brain injury (TBI). Separate studies implicate frontal white matter systems in the pathophysiology of TBI, suicidality, and impulsivity. We examined the relationship between the integrity of major frontal white matter (WM) systems on measures of impulsivity and suicidality in veterans with TBI.

METHODS

Fifteen male veterans with TBI and 17 matched healthy controls (HC) received clinical ratings, measures of impulsivity and MRI scans on a 3T magnet. Diffusion tensor imaging (DTI) data for the genu and cingulum were analyzed using Freesurfer and FSL. Correlations were performed for fractional anisotropy (FA) (DTI) values and measures of suicidality and impulsivity for veterans with TBI.

RESULTS

Significantly decreased in FA values in the left cingulum (P = 0.02), and left (P = 0.02) and total genu (P = 0.01) were observed in the TBI group relative to controls. Measures of impulsivity were significantly greater for the TBI group and total and right cingulum FA positively correlated with current suicidal ideation and measures of impulsivity (P <0.03).

CONCLUSION

These data demonstrate a significant reduction in FA in frontal WM tracts in veterans with mild TBI that was associated with both impulsivity and suicidality. These findings may reflect a neurobiological vulnerability to suicidal risk related to white matter microstructure.

Common structural correlates of trait impulsiveness and perceptual reasoning in adolescence

BACKGROUND

Trait impulsiveness is a potential factor that predicts both substance use and certain psychiatric disorders. This study investigates whether there are common structural cerebral correlates of trait impulsiveness and cognitive functioning in a large sample of healthy adolescents from the IMAGEN project.

METHODS

Clusters of gray matter (GM) volume associated with trait impulsiveness, Cloningers' revised temperament, and character inventory impulsiveness (TCI-R-I) were identified in a whole brain analysis using optimized voxel-based morphometry in 115 healthy 14-year-olds. The clusters were tested for correlations with performance on the nonverbal tests (Block Design, BD; Matrix Reasoning, MT) of the Wechsler Scale of Intelligence for Children IV reflecting perceptual reasoning.

RESULTS

Cloningers' impulsiveness (TCI-R-I) score was significantly inversely associated with GM volume in left orbitofrontal cortex (OFC). Frontal clusters found were positively correlated with performance in perceptual reasoning tasks (Bonferroni corrected). No significant correlations between TCI-R-I and perceptual reasoning were observed.

CONCLUSIONS

The neural correlate of trait impulsiveness in the OFC matches an area where brain function has previously been related to inhibitory control. Additionally, orbitofrontal GM volume was associated with scores for perceptual reasoning. The data show for the first time structural correlates of both cognitive functioning and impulsiveness in healthy adolescent subjects.

The effects of antidepressants on human brain as detected by imaging studies. Focus on major depression

Recent brain imaging studies have shed light on understanding the pathogenesis of mood disorders. Evidence of structural, chemical, and functional brain changes, particularly in prefrontal cortex, cingulate, and amygdala, has been revealed in major depressive disorder (MDD). Furthermore, imaging techniques have been applied to monitor the effects of antidepressants (ADs) both in the brains of healthy volunteers and MDD patients. Although with some discrepancies due to the differences in study designs and patient samples, imaging findings have shown that ADs, particularly those having effects on the serotonergic system, modulate the volumes, functions and biochemistry of brain structures, i.e. dorsolateral prefrontal cortex, anterior cingulate and amygdala, which have been demonstrated abnormal in MDD by earlier imaging studies. This paper reviews imaging studies conducted in MDD patients and healthy controls treated with different ADs.

Biomarkers for major depression and its delineation from neurodegenerative disorders

Major depressive disorders (MDD) are among the most debilitating diseases worldwide and occur with a high prevalence in elderly individuals. Neurodegenerative diseases (in particular Alzheimer's disease, AD) do also show a strong age-dependent increase in incidence and prevalence among the elderly population. A high number of geriatric patients with MDD show cognitive deficits and a very high proportion of AD patients present co-morbid MDD, which poses difficult diagnostic and prognostic questions. Especially in prodromal and in very early stages of AD, it is almost impossible to differentiate between pure MDD and MDD with underlying AD. Here, we give a comprehensive review of the literature on the current state of candidate biomarkers for MDD ("positive MDD markers") and briefly refer to established and validated diagnostic AD biomarkers in order to rule out underlying AD pathophysiology in elderly MDD subjects with cognitive impairments ("negative MDD biomarkers"). In summary, to date there is no evidence for positive diagnostic MDD biomarkers and the only way to delineate MDD from AD is to use "negative MDD" biomarkers. Because of this highly unsatisfactory current state of MDD biomarker research, we propose a research strategy targeting to detect and validate positive MDD biomarkers, which is based on a complex (genetic, molecular and neurophysiological) biological model that incorporates current state of the art knowledge on the pathobiology of MDD. This model delineates common pathways and the intersection between AD and MDD. Applying these concepts to MDD gives hope that positive MDD biomarkers can be successfully identified in the near future.

The suicidal mind and brain: a review of neuropsychological and neuroimaging studies

OBJECTIVES. We aimed at reviewing studies exploring dysfunctional cognitive processes, and their neuroanatomical basis, in suicidal behaviour, and to develop a neurocognitive working model. Methods. A literature search was conducted. RESULTS. Several limitations were found. The main reported neuropsychological findings are a higher attention to specific negative emotional stimuli, impaired decision-making, lower problem-solving abilities, reduced verbal fluency, and possible reduced non-specific attention and reversal learning in suicide attempters. Neuroimaging studies mainly showed the involvement of ventrolateral orbital, dorsomedial and dorsolateral prefrontal cortices, the anterior cingulate gyrus, and, to a lesser extent, the amygdala. In addition, alterations in white matter connections are suggested. CONCLUSIONS. These studies support the concept of alterations in suicidal behaviour distinct from those of comorbid disorders. We propose that a series of neurocognitive dysfunctions, some with trait-like characteristics, may facilitate the development of a suicidal crisis during stressful circumstances: (1) an altered modulation of value attribution, (2) an inadequate regulation of emotional and cognitive responses, and (3) a facilitation of acts in an emotional context. This preliminary model may represent a framework for the design of future studies on the pathophysiology, prediction and prevention of these complex human behaviours.

Cortical thickness correlates with impulsiveness in healthy adults

BACKGROUND

Impulsiveness is a central domain of human personality and of relevance for the development of substance use and certain psychiatric disorders. This study investigates whether there are overlapping as well as distinct structural cerebral correlates of attentional, motor and nonplanning impulsiveness in healthy adults.

METHODS

High-resolution magnetic resonance scans were acquired in 32 healthy adults to model the gray-white and gray-cerebrospinal fluid borders for each individual cortex and to compute the distance of these surfaces as a measure of cortical thickness (CT). Associations between CT and the dimensions of impulsiveness (Barratt-Impulsiveness-Scale 11, BIS) were identified in entire cortex analyses.

RESULTS

We observed a significant negative correlation between left middle frontal gyrus (MFG) CT and the attention BIS score (FDR p<.05), motor, nonplanning and total BIS score (each p<0.001 uncorrected). In addition, CT of the orbitofrontal (OFC) and superior frontal gyrus (SFG) were inversely correlated (p<0.001 uncorrected) with BIS total and motor score. Among other negative associations only one positive correlation (right inferior temporal with nonplanning score, p<0.001 uncorrected) was found.

CONCLUSIONS

The MFG is crucial for top-down control, executive and attentional processes. The MFG together with the OFC and SFG appears to be part of brain structures, which have previously been shown to mediate behavioral inhibition, well-planned action and attention, which are core facets of impulsiveness as measured with the Barratt-Impulsiveness-Scale.

Differential effects of executive functioning on suicide attempts

Suicide is common among individuals with psychiatric illness; executive functioning may be associated with suicide risk. The authors examined demographic, clinical, and executive-functioning variables in suicide ideators and suicide attempters, hypothesizing that attempters would demonstrate poorer executive-functioning skills. Seventy-seven participants with psychiatric illness completed a neuropsychological battery while hospitalized or residing in crisis-houses after expressing suicidal ideation (N=40) or making a suicide attempt (N=37). Logistic regression predicted suicide Ideator versus suicide Attempter status; suicide Attempters exhibited poorer inhibition but better problem-solving ability than suicide Ideators. Suicide attempt risk may be associated with better problem-solving skills, but worse inhibitory control.

Structural and functional neuroimaging studies of the suicidal brain

Suicidality is a major challenge for today's health care. Evidence suggests that there are differences in cognitive functioning of suicidal patients but the knowledge about the underlying neurobiology is limited. Brain imaging offers the advantage of a non-invasive in vivo direct estimation of detailed brain structure, regional brain functioning and estimation of molecular processes in the brain. We have reviewed the literature on neuroimaging studies of the suicidal brain. This article contains studies on structural imaging such as Computed Tomography (CT) and Magnetic Resonance Imaging (MRI) and functional imaging, consisting of Positron Emission Tomography (PET), Single Photon Emission Tomography (SPECT) and functional MRI (fMRI). We classified the results of the different imaging modalities in structural and functional imaging. Within our research, we found no significant differences in the suicidal brain demonstrated by Computed Tomography. Magnetic Resonance Imaging studies in subjects with a history of suicide attempt on the other hand deliver differing results, mostly pointing at a higher prevalence of white (especially deep white matter and periventricular) and grey matter hyperintensities in the frontal, temporal and/or parietal lobe and decreased volumes in the frontal and temporal lobe. There seems to be a trend towards findings of reduced grey matter volume in the frontal lobe. Overall, there is no consensus of opinion on structural imaging of the suicidal brain. Research on functional imaging is further divided into studies in resting state, studies in activation conditions and studies on brain neurotransmitters, transporters and receptors. A common finding in functional neuroimaging in resting conditions is a decreased perfusion in the prefrontal cortex of suicidal patients. During cognitive activation, perfusion deficits in the prefrontal cortex have been observed. After fenfluramine challenge, the prefrontal cortex metabolism seems to be inversely correlated to the lethality of previous suicide attempt. The few studies that examined the serotonin transporter in suicide found no significant differences in binding potential. In suicide attempters there seems to be a negative correlation between impulsivity and SERT binding. Our group found a reduced 5-HT(2A) binding in the frontal cortex in patients with a recent suicide attempt. The binding index was significantly lower in the deliberate self injury patients compared to the deliberate self poisoning patients. The few authors that examined DAT binding in suicide found no significant DAT differences between patients and controls. However they demonstrated significant negative correlations between DAT binding potential and mental energy among suicide attempters, but not in healthy control subjects. We did not find studies measuring the binding potential of the noradrenalin or gamma amino butyric acid transporter or receptor in suicidal subjects. Several reports have suggested abnormalities of GABA neurotransmission in depression. During our literature search, we have focused on neuroimaging studies in suicidal populations, but in the absence of evidence in the literature on this group or when further collateral evidence is appropriate, this overview expands to results in impulsive aggressive or in depressed subjects.

Impairment in risk-sensitive decision-making in older suicide attempters with depression

Suicidal behavior is a potentially lethal complication of late-life depression. In younger adults, suicide has been linked to abnormal decision-making ability. Given that there are substantial age-related decreases in decision-making ability, and that older adults experience environmental stressors that require effective decision-making, we reasoned that impaired decision-making may be particularly relevant to suicidal behavior in the elderly. We thus compared performance on a probabilistic decision-making task that does not involve working memory ("Cambridge Gamble Task") in four groups of older adults: (1) individuals with major depression and a history of suicide attempt (n = 25), (2) individuals with major depression with active suicidal ideation but no suicide attempt (n = 13), (3) individuals with major depression without suicidality (n = 35), and (4) nondepressed control subjects (n = 22). There was a significant effect of group on quality of decision-making, whereby the suicide attempters exhibited poorer ability to choose the likely outcome, compared with the nonsuicidal depressed and nondepressed comparison subjects. There were no group differences in betting behavior. The suicide attempters differed in several aspects of social problem-solving on a self-report scale. Quality of decision-making was negatively correlated with the score on the impulsive/careless problem-solving subscale. These data suggest that older suicide attempters have a deficit in risk-sensitive decision-making, extending observations in younger adults. More specifically, older suicide attempters seem to neglect outcome probability and make poor choices. These impairments may precipitate and perpetuate suicidal crisis in depressed elders. Identification of decision-making impairment in suicidal elders may help with designing effective interventions.

Left or right temporal lesion might induce aggression or escape during awake surgery, respectively: role of the amygdala

OBJECTIVE

Some patients with temporal lobe brain tumours show aggressive or escape behaviour during awake surgery. As the amygdala plays a critical role in coping with stress, we evaluated whether the left or right amygdala was involved in aggressive or escape behaviour in six patients undergoing awake surgery for temporal lobe brain tumours.

METHODS

Brain tumours were located in the left temporal lobe in cases 1-3 and in the right temporal lobe in cases 4-6. In cases 1, 2, 4 and 5, the tumours invaded the amygdala.

RESULTS

In case 1, the patient showed aggressive behaviour before partial removal of the left amygdala during awake surgery; just after partial removal of left amygdala, the patient was calm and cooperative. In case 2, the patient showed aggressive behaviour when the tumour near the left amygdala was removed. In case 3, the patient showed aggressive behaviour when awakening during awake surgery. In case 4, the patient showed escape behaviour when removal of the tumour near the right amygdala was initiated. In cases 5 and 6, patients showed escape behaviour upon awakening and upon initiation of tumour removal from the temporal lobe.

CONCLUSION

In conclusion, these results suggest that left or right temporal lesions might induce aggressive or escape behaviour during awake surgery, respectively, and that the amygdala on the respective side may play a role in these behaviours.

The neuroscience of suicidal behaviors: what can we expect from endophenotype strategies?

Vulnerability to suicidal behavior (SB) is likely mediated by an underlying genetic predisposition interacting with environmental and probable epigenetic factors throughout the lifespan to modify the function of neuronal circuits, thus rendering an individual more likely to engage in a suicidal act. Improving our understanding of the neuroscience underlying SBs, both attempts and completions, at all developmental stages is crucial for more effective preventive treatments and for better identification of vulnerable individuals. Recent studies have characterized SB using an endophenotype strategy, which aims to identify quantitative measures that reflect genetically influenced stable changes in brain function. In addition to aiding in the functional characterization of susceptibility genes, endophenotypic research strategies may have a wider impact in determining vulnerability to SB, as well as the translation of human findings to animal models, and vice versa. Endophenotypes associated with vulnerability to SB include impulsive/aggressive personality traits and disadvantageous decision making. Deficits in realistic risk evaluation represent key processes in vulnerability to SB. Serotonin dysfunction, indicated by neuroendocrine responses and neuroimaging, is also strongly implicated as a potential endophenotype and is linked with impulsive aggression and disadvantageous decision making. Specific endophenotypes may represent heritable markers for the identification of vulnerable patients and may be relevant targets for successful suicide prevention and treatments.

Brain anatomy of major depression II. Focus on amygdala

Here, we briefly summarize the most consistent structural magnetic resonance imaging (MRI) studies on amygdala in major depression and debate the effects of clinical variables on amygdalar morphology.

The hippocampus in major depression: evidence for the convergence of the bench and bedside in psychiatric research?

Major depressive disorder (MDD) has until recently been conceptualized as an episodic disorder associated with 'chemical imbalances' but no permanent brain changes. Evidence has emerged in the past decade that MDD is associated with small hippocampal volumes. This paper reviews the clinical and biological correlates of small hippocampal volumes based on literature searches of PubMed and EMBASE and discusses the ways in which these data force a re-conceptualization of MDD. Preclinical data describe the molecular and cellular effects of chronic stress and antidepressant treatment on the hippocampus, providing plausible mechanisms through which MDD might be associated with small hippocampal volumes. Small hippocampal volumes are associated with poor clinical outcome and may be a mechanism through which MDD appears to be a risk factor for Alzheimer's disease. The pathways through which stress may be linked to MDD, the emergence of chronicity or treatment resistance in MDD and the association between MDD and memory problems may be at least partially understood by dissecting the association with depression and changes in the hippocampus. MDD must be re-conceived as a complex illness, associated with persistent morphological brain changes that are detectable before illness onset and which may be modified by clinical and treatment variables.

The prefrontal-limbic network in depression: Modulation by hypothalamus, basal ganglia and midbrain

The anterior cingulate cortex, amygdala and hippocampus form part of an interconnected prefrontal neocortical and limbic archicortical network that is dysregulated in major depressive disorders (MDD). Modulation of this prefrontal-limbic network (PLN) is principally through the hypothalamus, basal ganglia and midbrain. Here the likely mechanisms by which these modulations are affected are described and the implications of their failure for depression associated with suicidal diathesis, late-life and psychoses discussed.

Suicidal attempts and increased right amygdala volume in schizophrenia

Suicide is a major cause of death in schizophrenia. Neurobiological studies suggest that suicidality is associated with abnormal brain structure and connectivity in fronto-temporo-limbic regions. However, it is still unclear whether suicidality in schizophrenia is related to volumetric abnormalities in subcortical structures that play a key role in emotion regulation, aggression and impulse control. Therefore, we aimed to examine whether the volume of selected subcortical regions is associated with previous suicidal attempts and self-aggression in schizophrenia. For this cross-sectional study, we recruited 50 outpatients with schizophrenia and 50 healthy controls (HC) matched for age and gender. Fourteen patients had a history of one or more suicide attempts. Different forms of aggression were assessed using the Modified Overt Aggression Scale. All participants underwent structural MR imaging at 3 Tesla. Physical volumetric measures were calculated for the lateral ventricles, thalamus, hippocampus, amygdala, caudate, putamen, pallidum and accumbens using an automatic segmentation method on T1-weighted high-resolution (voxel size 1×1×1mm(3)) images. Multivariate and follow-up univariate ANOVAs revealed a selective increase in volume in the right amygdala of patients with a history of suicidality compared both to patients without such a history and HC. Moreover, in the entire patient group increased right amygdala volume was related to increased self-aggression. Our findings suggest that right amygdala hypertrophy may be a risk factor for suicide attempts in patients with schizophrenia and this could be relevant for suicide prevention.

Differential effects of executive functioning on suicide attempts

Suicide is common among individuals with psychiatric illness; executive functioning may be associated with suicide risk. The authors examined demographic, clinical, and executive-functioning variables in suicide ideators and suicide attempters, hypothesizing that attempters would demonstrate poorer executive-functioning skills. Seventy-seven participants with psychiatric illness completed a neuropsychological battery while hospitalized or residing in crisis-houses after expressing suicidal ideation (N=40) or making a suicide attempt (N=37). Logistic regression predicted suicide Ideator versus suicide Attempter status; suicide Attempters exhibited poorer inhibition but better problem-solving ability than suicide Ideators. Suicide attempt risk may be associated with better problem-solving skills, but worse inhibitory control.

Obesity, smoking, and frontal brain dysfunction

Obesity, smoking, and conduct problems have all been associated with decrements in brain function. However, their additive and interactive effects have rarely been examined. To address the deficiency, we studied P300a and P300b electroencephalographic potentials in 218 women grouped by the presence versus absence of: (1) a BMI > or = 30 kg/m(2); (2) recent smoking; and (3) > or = 2 childhood conduct problems. Analyses revealed smaller P300a and P300b amplitudes over the posterior scalp among recent smokers versus nonsmokers. No corresponding group differences were found in P300 latencies or frontal scalp amplitudes. The most interesting analysis result was an interaction between conduct problems and obesity limited to the frontally generated P300a component: its latency was significantly greater in women with both attributes than in those with either or neither attribute. An exploratory ANOVA, substituting the genotype of a GABRA2 SNP for conduct problems, also demonstrated an interaction with obesity affecting P300a latency. It is hypothesized that conduct problems, and a conduct-problem-associated GABRA2 genotype, decrease the age-of-onset and/or increase the lifetime duration of obesity. As a result, they may potentiate the adverse effects of obesity on frontal white matter and thereby increase P300a latency. Smoking may affect brain function by a different mechanism to reduce posterior scalp P300a and P300b amplitudes while preserving frontal scalp P300a latency and amplitude.

Suicidal brains: a review of functional and structural brain studies in association with suicidal behaviour

Evidence of an association between a vulnerability to suicidal behaviour and neurobiological abnormalities is accumulating. Post-mortem studies have demonstrated structural and biochemical changes in the brains of suicide victims. More recently, imaging techniques have become available to study changes in the brain in vivo. This systematic review of comparative imaging studies of suicidal brains shows that changes in the structure and functions of the brain in association with suicidal behaviour are mainly found in the orbitofrontal and dorsolateral parts of the prefrontal cortex. Correlational studies suggest that these changes relate to neuropsychological disturbances in decision-making, problem solving and fluency, respectively. As a consequence, the findings from these studies suggest that suicidal behaviour is associated with (1) a particular sensitivity to social disapproval (2) choosing options with high immediate reward and (3) a reduced ability to generate positive future events. Further study is needed to elaborate these findings and to investigate to what extent changes in the structure and function of suicidal brains are amenable to psychological and/or biological interventions.

Cortical and subcortical abnormalities in late-onset depression with history of suicide attempts investigated with MRI and voxel-based morphometry

Late-onset major depression is thought to have a biological (vascular) basis, which could be a result of brain structure change. Vascular lesions can affect both the gray matter (GM) and white matter (WM), while most previous studies addressed WM abnormality. This study explored the disease- and symptom (history of suicide attempt) -related GM morphometry in elderly male patients with late-onset depression. A total of 70 patients with depression admitted to our geriatric psychiatric ward were investigated, and 26 age-matched males were recruited as controls. We used T1-weighted magnetic resonance imaging (MRI) to obtain cerebral structural information and adopted voxel-based morphometry (VBM) to investigate brain volume change related to disease (depression vs control) and symptom (depression with history of suicide attempt vs depression without history of suicide attempt). Late-onset depression was associated with smaller volumes in several regions of GM (insula and the posterior cingulate region) and WM (subcallosal cingulate cortex, floor of lateral ventricles, parahippocampal region, insula, and the cerebellum). Compared with nonsuicidal counterpart, suicidal depression was associated with decreased GM and WM volume in the frontal, parietal, and temporal regions, and the insula, lentiform nucleus, midbrain, and the cerebellum. Marked regional volume reduction was noticed at dorsal medial prefrontal cortex. Our results demonstrate that the development of suicidal behaviors in major depression is related to widespread but discrete volume reduction in several cortical and subcortical structures, fitting with the hypothesis that decreased cerebral volume in certain regions renders biological susceptibility to attempt suicide during depressive states.

Size of basal ganglia in suicide attempters, and its association with temperament and serotonin transporter density

Magnetic resonance imaging was used to compare subcortical volumes of seven suicide attempters with those of six healthy controls. Suicide attempters had 10% smaller right caudate nucleus and 19% bilaterally smaller globus pallidus. In suicide attempters, volumes of the globus pallidus correlated negatively with previously reported measures of solidity (non-impulsive temperament) and serotonin transporter binding potential.

Suicidality and brain volumes in pediatric epilepsy

This study examined the relationship between suicidal ideation and frontotemporal volumes, particularly orbital frontal gyrus volume, in 51 subjects with epilepsy with a mean age of 9.8 (2.1) years. Structured psychiatric interviews of the children and parents provided information on suicidal behavior and DSM-IV diagnoses. Tissue of 1.5-T MRI scans was segmented, and total brain, frontal lobe, frontal parcellations, and temporal lobe volumes were computed. The 11 subjects with epilepsy with suicidal ideation had significantly smaller right orbital frontal gyrus white matter volumes and larger left temporal lobe gray matter volumes than the 40 children without suicidal thoughts. Given the role of the orbital frontal gyrus in both emotional regulation and epilepsy, these findings highlight the biological underpinnings of suicidal ideation in pediatric epilepsy.

Reward/Punishment reversal learning in older suicide attempters

OBJECTIVE

Suicide rates are high in old age, and the contribution of cognitive risk factors remains poorly understood. Suicide may be viewed as an outcome of an altered decision process. The authors hypothesized that impairment in reward/punishment-based learning, a component of affective decision making, is associated with attempted suicide in late-life depression. They expected that suicide attempters would discount past reward/punishment history, focusing excessively on the most recent rewards and punishments. The authors further hypothesized that this impairment could be dissociated from executive abilities, such as forward planning.

METHOD

The authors assessed reward/punishment-based learning using the probabilistic reversal learning task in 65 individuals age 60 and older: suicide attempters, suicide ideators, nonsuicidal depressed elderly, and nondepressed comparison subjects. The authors used a reinforcement learning computational model to decompose reward/punishment processing over time. The Stockings of Cambridge test served as a control measure of executive function.

RESULTS

Suicide attempters but not suicide ideators showed impaired probabilistic reversal learning compared to both nonsuicidal depressed elderly and nondepressed comparison subjects, after controlling for effects of education, global cognitive function, and substance use. Model-based analyses revealed that suicide attempters discounted previous history to a higher degree relative to comparison subjects, basing their choice largely on reward/punishment received on the last trial. Groups did not differ in their performance on the Stockings of Cambridge test.

CONCLUSIONS

Older suicide attempters display impaired reward/punishment-based learning. The authors propose a hypothesis that older suicide attempters make overly present-focused decisions, ignoring past experiences. Modification of this "myopia for the past" may have therapeutic potential.

Genes, suicide and decisions

OBJECTIVE

A better understanding of the pathophysiology of suicidal behaviour (SB) may enable the discovery of more specific treatments and a better identification of vulnerable patients. The vulnerability to SB appears to be underlied by genetic factors coding for traits rendering the individual less able to cope with stressing situations, and more likely to be engaged in a suicidal process.

METHOD

During the recent years, neuroscientific studies begun to identify potential endophenotypes.

RESULTS

We have shown that disadvantageous decision making (DM) was involved in the vulnerability to SB. DM impairment appears to be independent of comorbid psychiatric disorders, associated with emotional dysregulation (i.e. affective lability trait and skin conductance responses), and modulated by serotonergic genotypes associated with SB. In recent fMRI studies, the region that is likely involved in DM, is overactivited in response to angry faces, suggesting a higher sensitivity to specific negative social stimuli. Deficit in risk evaluation and excessive response to specific emotional stimuli may represent key processes in the vulnerability to SB.

CONCLUSIONS

These potential endophenotypes may represent future relevant markers of vulnerability for the identification of vulnerable patients, and relevant targets for the development of new treatments.

Effect of tryptophan hydroxylase-2 gene variants on amygdalar and hippocampal volumes

Tryptophan hydroxylase (TPH) is the rate-limiting enzyme in the synthesis of serotonin (5-HT). Genetic variations in human TPH2, a newly identified isoform of TPH, have been shown to impact on enzymatic activity of TPH and to be associated with emotion-related personality traits and mood/anxiety disorders. Identification of an intermediate phenotype that bridges the relationship between genes and behavior may be of great importance in the further clarification of how hTPH2 contributes to emotional regulation. Previous studies have shown that a polymorphism in the upstream regulatory region of hTPH2 (SNP G-703T, rs4570625) correlates functional MRI response of the amygdala. In this study, we examined the effect of this genotype on amygdalar and hippocampal volumes in 208 mentally healthy individuals. To measure volumes of amygdala and hippocampus, gray matter regions of interest were outlined manually on three-dimensional MRI data obtained using a 1.5-T scanner. Additionally, personality traits were evaluated using the Temperament and Character Inventory (TCI). Those subjects with T allele carriers were associated with significantly smaller volumes in bilateral amygdala and hippocampus and higher reward dependence than those with G allele homozygotes. These results suggest that amygdalar and hippocampal volumes assessed using MRI may be a useful intermediate phenotype that will uncover the biological pathway linking 5-HT synthesis and emotional behaviors and affective disorders.

Decreased activation of lateral orbitofrontal cortex during risky choices under uncertainty is associated with disadvantageous decision-making and suicidal behavior

Decision-making impairment has been linked to orbitofrontal cortex lesions and to different disorders including substance abuse, aggression and suicidal behavior. Understanding the neurocognitive mechanisms of these impairments could facilitate the development of effective treatments. In the current study, we aimed to explore the neural and cognitive basis of poor decision-making ability associated with the vulnerability to suicidal behavior, a public health issue in most western countries. Twenty-five not currently depressed male patients, 13 of whom had a history of suicidal acts (suicide attempters) and 12 of whom had none (affective controls), performed an adapted version of the Iowa Gambling Task during functional Magnetic Resonance Imaging. Task-related functional Regions-of-Interest were independently defined in 15 male healthy controls performing the same task (Lawrence et al., 2009). In comparison to affective controls, suicide attempters showed 1) poorer performance on the gambling task 2) decreased activation during risky relative to safe choices in left lateral orbitofrontal and occipital cortices 3) no difference for the contrast between wins and losses. Altered processing of risk under conditions of uncertainty, associated with left lateral orbitofrontal cortex dysfunction, could explain the decision-making deficits observed in suicide attempters. These impaired cognitive and neural processes may represent future predictive markers and therapeutic targets in a field where identification of those at risk is poor and specific treatments are lacking. These results also add to our growing understanding of the role of the orbitofrontal cortex in decision-making and psychopathology.

Is impulsivity a link between childhood abuse and suicide?

Childhood abuse and neglect are known to affect psychological states through behavioral, emotional, and cognitive pathways. They increase the risk of having psychiatric diseases in adulthood and have been considered risk factors for suicidal behavior in all diagnostic categories. Early, prolonged, and severe trauma is also known to increase impulsivity, diminishing the capacity of the brain to inhibit negative actions and to control and modulate emotions. Many neurobiological studies hold that childhood maltreatment may lead to a persistent failure of the inhibitory processes ruled mainly by the frontal cortex over a fear-motivated hyperresponsive limbic system. Multiple neurotransmitters and hormones are involved in the stress response, but, to our knowledge, the two major biological consequences of the chronic exposure to trauma are the hypofunction of the serotonergic system and changes in the hypothalamic-pituitary-adrenal axis function. Some of these findings overlap with the neurobiological features of impulsivity and of suicidal behavior. Impulsivity has also been said to be both a consequence of trauma and a risk factor for the development of a pathological response to trauma. Thus, we suggest that impulsivity could be one of the links between childhood trauma and suicidal behavior. Prevention of childhood abuse could significantly reduce suicidal behavior in adolescents and adults, in part, through a decrease in the frequency of impulsive behaviors in the future.

Brain volume abnormalities in major depressive disorder: a meta-analysis of magnetic resonance imaging studies

OBJECTIVE

So far, there have been no attempts to integrate the growing number of all brain volumetric magnetic resonance imaging studies in depression. In this comprehensive meta-analysis the magnitude and extent of brain volume differences between 2,418 patients with major depressive disorder and 1,974 healthy individuals from 64 studies was determined.

METHODS

A systematic research was conducted for volumetric magnetic resonance imaging studies of patients with major depressive disorder in relation to healthy control subjects. Studies had to report sufficient data for computation of effect sizes. For each study, the Cohen's d was calculated. All analyses were performed using the random effects model. Additionally, meta-regression analyses were done to explore the effects of potential sources of heterogeneity.

RESULTS

Patients showed large volume reductions in frontal regions, especially in the anterior cingulate and orbitofrontal cortex with smaller reductions in the prefrontal cortex. The hippocampus, the putamen and caudate nucleus showed moderate volume reductions.

CONCLUSIONS

This is the first comprehensive meta-analysis in major depressive disorder demonstrating structural brain abnormalities, particularly in those brain areas that are involved in emotion processing and stress-regulation.

Anterior genu corpus callosum and impulsivity in suicidal patients with bipolar disorder

Suicidality is a life-threatening symptom in patients with bipolar disorder (BD). Impulsivity and mood instability are associated with suicidality in mood disorders. Evidence suggests that gray and white matter abnormalities are linked with impulsivity in mood disorders, but little is known about the association between corpus callosum (CC) and impulsivity in BD. We examined the relationship between CC areas, impulsivity and suicidality in BD patients. We studied 10 female BD patients with a history of suicide attempt (mean+/-SD age 36.2+/-10.1 years), 10 female BD patients without suicide attempt history (44.2+/-12.5 years) and 27 female healthy subjects (36.9+/-13.8 years). Impulsivity was evaluated by the Barratt Impulsivity Scale (BIS). We traced MR images to measure the areas of the CC genu, anterior body, posterior body, isthmus and splenium. The genu was divided into anterior, middle and posterior regions. The suicidal and non-suicidal BD patients had significantly higher BIS total, attention and non-planning scores than the healthy subjects (ps<0.01), and the suicidal BD patients had significantly higher BIS motor scores than the non-suicidal BD and healthy subjects (ps<0.01). There were no significant differences among the three groups on any regional CC areas, although the suicidal BD patients had the smallest areas. The suicidal BD patients showed a significant inverse correlation between anterior genu area and the BIS total (r=-0.75, p=0.04), motor (r=-0.79, p=0.02) and non-planning scores (r=-0.79, p=0.02). These correlations were not found in the non-suicidal BD patients or healthy subjects. The results suggest that the anterior medial frontal region may be involved in the pathophysiology of impulsive and suicidal behaviors in BD.

Characterization of QKI gene expression, genetics, and epigenetics in suicide victims with major depressive disorder

BACKGROUND

A number of studies have suggested deficits in myelination and glial gene expression in different psychiatric disorders. We examined the brain expression and genetic/epigenetic regulation of QKI, an oligodendrocyte-specific RNA binding protein important for cell development and myelination.

METHODS

The microarray-based expression of QKI was evaluated in cortical and subcortical brain regions from suicide victims with a diagnosis of major depression (n = 16) and control subjects (n = 13). These findings were also assessed with a real-time (quantitative polymerase chain reaction [qPCR]) approach, with QKI protein levels evaluated through immunoblotting. Identification of a QKI promoter sequence was then used to examine genetic and epigenetic variation at the QKI locus.

RESULTS

The messenger RNA (mRNA) levels of multiple transcripts of QKI were evaluated on Affymetrix microarrays, revealing significant reductions in 11 cortical regions and the hippocampus and amygdala of suicide victims compared with control subjects. Microarray findings were confirmed by qPCR, and reduced expression of QKI protein was identified in orbitofrontal cortex. Analysis of promoter variation and methylation state in a subset of individuals did not identify differences at the genetic or epigenetic level between depressed suicide victims and control subjects.

CONCLUSIONS

The observation of consistent reductions in multiple isoforms of QKI mRNA in depressed suicide victims supports the growing body of evidence for a role of myelination-related deficits in the etiology of psychiatric disorders. A specific role of QKI in this process is implied by its reduced expression and known interactions with genes involved in oligodendrocyte determination; however, QKI gene variation responsible for these changes remains to be identified.