SPECT neuropsychological activation procedure with the Verbal Fluency Test in attempted suicide patients

The CC genotype in HTR2A T102C polymorphism is associated with behavioral impulsivity in alcohol-dependent patients

High levels of impulsivity can increase the vulnerability for development of alcohol dependence. Moreover, impulsivity is considered to be a predictor of poor treatment outcomes. Few studies, however, have directly examined the genetics of impulsivity in alcohol-dependent patients. We analyzed the relationships between a well-recognized genetic marker of serotonin activity and levels of impulsivity as measured by both the Barratt Impulsiveness Scale (BIS-11) and the stop-signal task among 304 alcohol-dependent patients. The stop-signal task was used as an independent, objective method of estimating the level of behavioral impulsivity, and the BIS-11 as a self-report measure of global impulsivity. Blood was collected and analyzed for the T102C (rs6313) polymorphism in the serotonin type 2A receptor gene (HTR2A). Our results indicate a significant association between high levels of behavioral impulsivity and the C/C genotype of rs6313 in alcohol-dependent patients. The CC genotype has been previously found to be associated with a reduction in 5HT2A receptors in the central nervous system. These results support the hypothesis that genetic factors are important determinants of behavioral impulsivity in alcohol-dependent patients, and that the serotonin system plays an important role in establishing its level.

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.

Decreased cerebral blood flow in the limbic and prefrontal cortex using SPECT imaging in a cohort of completed suicides

Suicide has a high comorbidity with impulsivity and depression, and finding imaging biomarkers indicative of patients at high risk for suicidal behavior is invaluable to the clinician. Using single-photon emission computed tomography (SPECT) imaging, we have previously reported regional cerebral blood flow (rCBF) decreases in the medial prefrontal cortex, ventral tegmental area and subgenual cingulate cortex (Brodmann area 25 (BA 25)), a region found to be hypoperfused with treatment-resistant depression. From 2007 to 2010, we have extended our analysis to include nine additional completed suicides. In all, 27 healthy, age- and gender-matched subjects from a previously acquired healthy brain study served as controls to our 21 completed suicides. All 21 suicides had been previously diagnosed with depression according to Diagnostic and Statistical Manual of Mental Disorder-IV criterion. Voxel-by-voxel analyses were performed using statistical parametric mapping to compare the differences in technetium-99m hexamethylpropylene amine oxime brain uptake between the groups. Factor analysis of the data identified the top 10 regions of hypoperfusion in the suicidal group, including the bilateral superior frontal lobes, the right precuneus, the rolandic operculum, postcentral gyrus, left caudate and insular cortex. We also demonstrate more focal decreases in rCBF in the subgenual cingulate cortex (BA 25) in 18 subjects, supporting our previous hypothesis that hypoperfusion of BA 25 may be a risk factor for suicide in depressed patients. This work suggests that SPECT might be useful in predicting risk for suicide completion in subjects with depression or treatment-resistant depression. Further investigation of this work is necessary to better understand the predictive value of this finding.

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.

Neuropsychologische Aspekte der Depression

Zusammenfassung. Patienten mit Depressionen klagen häufig über Symptome und Störungen nicht nur auf der emotionalen, sondern auch auf der kognitiven Ebene. In dieser Übersichtsarbeit werden schwerpunktmäßig neuropsychologische Befunde zu kognitiven Funktionen bei unipolaren Depressionen zusammengefasst. Die kognitive Theorie der Depression postulierte eine Beeinflussung kognitiver Vorgänge durch emotionale Verzerrungen, die eine wichtige Rolle bei Vulnerabilität, Entstehung, Aufrechterhaltung und Rezidiven depressiver Episoden spielen. Befunde zu dieser Interaktion von kognitiven und emotionalen Prozessen werden dargestellt, außerdem wird auf die Bedeutung dieser Aspekte für die Emotionsregulation und für die Therapie der Depression eingegangen.

Frontocingulate dysfunction in depression: toward biomarkers of treatment response

Increased rostral anterior cingulate cortex (rACC) activity has emerged as a promising predictor of treatment response in depression, but neither the reliability of this relationship nor the mechanisms supporting it have been thoroughly investigated. This review takes a three-pronged approach to these issues. First, I present a meta-analysis demonstrating that the relationship between resting rACC activity and treatment response is robust. Second, I propose that the rACC plays a key role in treatment outcome because of its 'hub' position in the default network. Specifically, I hypothesize that elevated resting rACC activity confers better treatment outcomes by fostering adaptive self-referential processing and by helping to recalibrate relationships between the default network and a 'task-positive network' that comprises dorsolateral prefrontal and dorsal cingulate regions implicated in cognitive control. Third, I support this hypothesis by reviewing neuropsychological, electrophysiological, and neuroimaging data on frontocingulate dysfunction in depression. The review ends with a discussion of the limitations of current work and future directions.

Brain functional changes (QEEG cordance) and worsening suicidal ideation and mood symptoms during antidepressant treatment

OBJECTIVE

Antidepressant medications are efficacious overall; however, some individuals experience worsening mood symptoms and increased suicidal ideation (SI) during treatment. We examined the quantitative electroencephalographic (QEEG) cordance biomarker of brain function biomarker in relation to treatment-emergent symptom worsening.

METHOD

Seventy-two major depressive disorder (MDD) subjects were treated with fluoxetine 20 mg (n = 13), venlafaxine 150 mg (n = 24), or placebo (n = 35) under double-blind conditions. Behavioral ratings determined whether each subject demonstrated worsening of depressed mood, anxiety, or SI during treatment. QEEG cordance data were analyzed to determine whether symptom worsening was associated with neurophysiological changes.

RESULTS

Antidepressant treatment-emergent SI (13.5%) was associated with a large transient decrease in midline-and-right-frontal (MRF) cordance 48 h after start of medication.

CONCLUSION

Hypothesis-generating results suggest a pattern of functional changes in midline and right frontal brain regions associated with antidepressant treatment-emergent SI in MDD.

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.

Poor performance on cognitive tasks in depression: Doing too much or not enough?

Depressed people perform poorly on cognitive tasks. It is unclear whether these deficits are due to decreased devotion of task-related resources or to increased attention to non-task-related information. In the present study, we examined the degree to which depressed and healthy adults displayed pupillary motility that varied at the frequency of presented stimuli on a cognitive task, which we interpreted as task-related processing, and at other frequencies, which we interpreted as reflecting intrinsic processing. Depressed participants made more consecutive errors than did controls. More pupillary motility at other frequencies was associated with poorer performance, whereas more pupillary motility at the frequency of presented stimuli was associated with better performance. Depressed participants had more pupillary motility at other frequencies, which partially mediated observed deficits in cognitive performance. These findings support the hypothesis that allocating cognitive resources to intrinsic processing contributes to observed cognitive deficits in depression.

Differential SPECT activation patterns associated with PASAT performance may indicate frontocerebellar functional dissociation in chronic mild traumatic brain injury

Patients with mild traumatic brain injury (TBI) often complain of cognitive fatigue during the chronic recovery phase. The Paced Auditory Serial Addition Test (PASAT) is a complex psychologic measure that may demonstrate subtle deficiencies in higher cognitive functions. The purpose of this study was to investigate the brain activation of regional cerebral blood flow (rCBF) with PASAT in patients with mild TBI to explore mechanisms for the cognitive fatigue.

METHODS

Two groups consisting of 15 patients with mild TBI and 15 healthy control subjects underwent (99m)Tc-ethylene cysteine dimer SPECT at rest and during PASAT on a separate day. Cortical rCBF was extracted using a 3-dimensional stereotactic surface projection and statistically analyzed to identify areas of activation, which were compared with PASAT performance scores.

RESULTS

Image analysis demonstrated a difference in the pattern of activation between patients with mild TBI and healthy control subjects. Healthy control subjects activated the superior temporal cortex (Brodmann area [BA] 22) bilaterally, the precentral gyrus (BA 9) on the left, and the precentral gyrus (BA 6) and cerebellum bilaterally. Patients with mild TBI demonstrated a larger area of supratentorial activation (BAs 9, 10, 13, and 46) but a smaller area of activation in the cerebellum, indicating frontocerebellar dissociation.

CONCLUSION

Patients with mild TBI and cognitive fatigue demonstrated a different pattern of activation during PASAT. Frontocerebellar dissociation may explain cognitive impairment and cognitive fatigue in the chronic recovery phase of mild traumatic brain injury.

Candidate endophenotypes for genetic studies of suicidal behavior

Twin, adoption, and family studies have established the heritability of suicide attempts and suicide. Identifying specific suicide diathesis-related genes has proven more difficult. As with psychiatric disorders in general, methodological difficulties include complexity of the phenotype for suicidal behavior and distinguishing suicide diathesis-related genes from genes associated with mood disorders and other suicide-associated psychiatric illness. Adopting an endophenotype approach involving identification of genes associated with heritable intermediate phenotypes, including biological and/or behavioral markers more proximal to genes, is an approach being used for other psychiatric disorders. Therefore, a workshop convened by the American Foundation for Suicide Prevention, the Department of Psychiatry at Columbia University, and the National Institute of Mental Health sought to identify potential target endophenotypes for genetic studies of suicidal behavior. The most promising endophenotypes were trait aggression/impulsivity, early-onset major depression, neurocognitive function, and cortisol social stress response. Other candidate endophenotypes requiring further investigation include serotonergic neurotransmission, second messenger systems, and borderline personality disorder traits.

An fMRI study of prefrontal brain activation during multiple tasks in patients with major depressive disorder

OBJECTIVE

Previous research has provided conflicting information regarding the pattern of brain activation associated with cognitive performance in depressed people. We aimed to assess brain activation related to cognitive performance during planning and working memory tasks.

METHOD

fMRI scans were conducted using a modified Tower of London task and a 2-back task in 13 patients with major depressive disorder and a matched control group.

RESULTS

Task performance was impaired in the depressed group on the Tower of London task but there were no differences between the groups in task performance on the n-back task. The patient group showed widespread increased brain activation in both tasks. There was considerable overlap in increased activation between the two tasks, especially in right prefrontal cortical regions.

CONCLUSIONS

Patients with depression exhibit increased brain activation, especially in right prefrontal regions, across several types of cognitive task activity. Patients with depression may recruit greater brain regions to achieve similar or even poorer task performance than control subjects.

Response conflict and frontocingulate dysfunction in unmedicated participants with major depression

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

Functional imaging studies of cognition using 99mTc-HMPAO SPECT: empirical validation using the n-back working memory paradigm

Purpose

Functional activation protocols are widely applied for the study of brain-cognition relations. Only few take advantage of the intrinsic characteristics of SPECT, particularly those allowing cognitive assessment outside of the camera, in settings close to the standard clinical or laboratory ones. The purpose of the study was to assess the feasibility of a split-dose activation protocol with ^99mTc-HMPAO using low irradiation dose.

Materials and methods

A two-scans protocol was applied to 12 healthy young volunteers using 270 MBq of ^99mTc-HMPAO per scan, with each image associated to a particular experimental condition of the verbal n-back working memory task (0-back, 2-back). Subtraction method was used to identify regional brain activity related to the task.

Results

Voxel-wise statistical analysis showed left lateralized activity associated with the 2-back task, compared to the 0-back task. Activated regions, mainly prefrontal and parietal, were similar to those observed in previous fMRI and ¹⁵O-PET studies.

Conclusion

The results support the use of ^99mTc-HMPAO SPECT for the investigation of brain-cognition relations and demonstrate the feasibility of optimal quality images despite low radiopharmaceutical doses. The findings also acknowledge the use of HMPAO as a radioligand to capture neuro-energetic modulations linked to cognitive activity. They encourage extending the application of the described activation protocol to clinical populations.

Frontal and limbic activation during inhibitory control predicts treatment response in major depressive disorder

BACKGROUND

Inhibitory control or regulatory difficulties have been explored in major depressive disorder (MDD) but typically in the context of affectively salient information. Inhibitory control is addressed specifically by using a task devoid of affectively-laden stimuli, to disentangle the effects of altered affect and altered inhibitory processes in MDD.

METHODS

Twenty MDD and 22 control volunteer participants matched by age and gender completed a contextual inhibitory control task, the Parametric Go/No-go (PGNG) task during functional magnetic resonance imaging. The PGNG includes three levels of difficulty, a typical continuous performance task and two progressively more difficult versions including Go/No-go hit and rejection trials. After this test, 15 of 20 MDD patients completed a full 10-week treatment with s-citalopram.

RESULTS

There was a significant interaction among response time (control subjects better), hits (control subjects better), and rejections (patients better). The MDD participants had greater activation compared with the control group in frontal and anterior temporal areas during correct rejections (inhibition). Activation during successful inhibitory events in bilateral inferior frontal and left amygdala, insula, and nucleus accumbens and during unsuccessful inhibition (commission errors) in rostral anterior cingulate predicted post-treatment improvement in depression symptoms.

CONCLUSIONS

The imaging findings suggest that in MDD subjects, greater neural activation in frontal, limbic, and temporal regions during correct rejection of lures is necessary to achieve behavioral performance equivalent to control subjects. Greater activation in similar regions was further predictive of better treatment response in MDD.

[Executive functions in patients with depression. The role of prefrontal activation]

Depression is a multifarious disease, having an impact on most aspects of everyday life. Cognitive deficits cause considerable impairments and restraints in performance and have become one of the major clinical and research foci in recent years. According to previous work, deficits in executive functioning seem to be particularly prominent. At present only a few functional neuroimaging studies investigated the neurofunctional correlates aimed at these deficits by using specific activation tasks. These findings are somewhat controversial, revealing prefrontal hypo- as well as hyperactivation as a substrate of executive performance. This paper reviews current functional neuroimaging findings within a framework of depression as a dysfunction in limbic-cortical circuits. As a conclusion, the concept of "simple" hypofrontality does not offer a satisfactory explanation. Rather, a more dynamic model will be necessary in order to achieve a more realistic concept of executive deficits in depression.

Increased left prefrontal activation in patients with unipolar depression: an event-related, parametric, performance-controlled fMRI study

BACKGROUND

Executive deficits associated with frontal lobe dysfunction are prominent in depression. We applied a newly developed WM task to investigate the neural correlates of executive processes with functional magnetic resonance imaging (fMRI) at comparable performance levels analyzing correct trials only.

METHODS

We studied 12 partially remitted, medicated inpatients meeting DSM-IV criteria for major depressive disorder and 17 healthy controls. We used a parametric version of a delayed match-to-sample WM task requiring manipulation of verbal material during a delay period in an event-related fMRI design.

RESULTS

Depressed patients were generally slower and load-dependently less accurate than healthy controls. Patients showed significantly more activation of left dorsolateral prefrontal cortex with highest cognitive load. Additionally, they showed higher activation in ventromedial prefrontal cortex during the control condition.

LIMITATIONS

The fact that patients were taking different antidepressant drugs could limit the explanatory power of the present results.

CONCLUSIONS

Increased lateral prefrontal activation despite comparably successful performance - when only correct trials were analyzed - in patients with depression can be interpreted as evidence for compensatory recruitment of prefrontal cortical resources.

Prefrontal hyperactivation during working memory task in untreated individuals with major depressive disorder

The prefrontal cortex, a part of the limbic-thalamic-cortical network, participates in regulation of mood, cognition and behavior and has been implicated in the pathophysiology of major depressive disorder (MDD). Many neuropsychological studies demonstrate impairment of working memory in patients with MDD. However, there are few functional neuroimaging studies of MDD patients during working memory processing, and most of the available ones included medicated patients or patients with both MDD and bipolar disorder. We used functional magnetic resonance imaging (fMRI) to measure prefrontal cortex function during working memory processing in untreated depressed patients with MDD. Fifteen untreated individuals with Diagnostic and Statistical Manual of Mental Disorders-Fourth Edition recurrent MDD (mean age+/-s.d.=34.3+/-11.5 years) and 15 healthy comparison subjects (37.7+/-12.1 years) matched for age, sex and race were studied using a GE/Elscint 2T MR system. An echo-planar MRI sequence was used to acquire 24 axial slices. The n-back task (0-back, 1-back and 2-back) was used to elicit frontal cortex activation. Data were analyzed with a multiple regression analysis using the FSL-FEAT software. MDD patients showed significantly greater left dorsolateral cortex activation during the n-back task compared to the healthy controls (P<0.01), although task performance was similar in the two groups. Furthermore, the patients showed significant anterior cingulate cortex activation during the task, but the comparison subjects did not (P<0.01). This study provides in vivo imaging evidence of abnormal frontolimbic circuit function during working memory processing in individuals with MDD.

Regional brain serotonin and dopamine transporter binding capacity in suicide attempters relate to impulsiveness and mental energy

To study different aspects of regional pre-synaptic brain (123)I-beta-CIT uptake on serotonin and dopamine re-uptake sites in drug-free suicide attempters in comparison with age- and sex matched control subjects, single photon emission computed tomography (SPECT) measurements were analysed for regional serotonin re-uptake (5HTT) and dopamine re-uptake (DAT) capacity (binding potential, BP()) after i.v. (123)I-beta-CIT administration. All suicide attempters were examined concerning seriousness of the attempt, and DSM-IV diagnosis. Both suicide attempters and control subjects were tested for psychotropic drugs, and completed the Marke-Nyman Temperament (MNT) test, including solidity (level of impulsiveness/initiative) and validity (level of mental energy). We found no significant difference between suicide attempters and control subjects concerning the regional levels of 5HTT BP() or DAT BP(). However, in suicide attempters, but not controls, we found significant regional correlations between MNT variables and SPECT results. We interpret the discrepant findings in suicide attempters and control subjects to be due to a disability of the suicide attempters to regulate their serotonin and dopamine levels, e.g. in response to external stress.

The neuropsychological correlates of borderline personality disorder and suicidal behaviour

OBJECTIVE

In subjects with borderline personality disorder (BPD), compared with subjects who attempted suicide, to review neuropsychological (NP) function that may predispose to suicidal behaviour along a continuum of high and low lethality.

METHOD

We undertook electronic searches of MEDLINE, PsycINFO, EMBASE, Biosos Reviews, and Cinhal. The searches were restricted to English-language publications from 1985 onward. The search terms borderline personality disorder, suicide, suicide attempt, self-harm behaviour, neuropsychological, executive function (EF), neurocognitive, and neuropsychological function produced 29 neuropsychology studies involving BPD and 7 neuropsychology studies of suicide attempters, regardless of psychiatric diagnosis.

RESULTS

Of the BPD studies, 83% found NP impairment in one or more cognitive domains, irrespective of depression, involving specific or generalized deficits linked to the dorsolateral prefrontal and orbitofrontal regions. The functions most frequently reported (in 71% to 86% of BPD studies) are response-inhibitory processes affecting executive function performance that requires speeded attention and visuomotor skills. Decision making and visual memory impairment are also most frequently affected; 60% to 67% of BPD studies report attentional impairment, verbal memory impairment, and visuospatial organizational impairment. Least affected processes in BPD appear to involve spatial working memory, planning, and possibly, IQ. The similarities in NP deficits found in BPD and suicide-attempt studies involve decision making and Trails performances. BPD studies, however, reflect more frequent impairment on the Stroop Test and Wisconsin Card Sort Test performance than the suicide-attempt studies, whereas verbal fluency appears to be more frequently impaired in those attempting suicide.

CONCLUSIONS

Impaired EF and disinhibitory processes, as indicated by verbal fluency, Trails, and Stroop performance, primarily associated with dorsolateral prefrontal cortical regions may represent a dominant executive pathway to suicide attempt. A primary motivational inhibitory pathway involving conflictual, affective, and reflexive decision-making processes associated with orbitofrontal brain regions, in combination with significant cognitive rigidity, may influence the repetitive expression of self-harm or low-lethality suicidal behaviour. The hypothesis of a specific trait-like cognitive vulnerability for suicidal behaviour involving dysregulatory, disinhibiting pathways awaits confirmation.

Correlatos anatômico-funcionais das emoções mapeados com técnicas de neuroimagem funcional

Nos dias de hoje, o uso de técnicas de neuroimagem funcional permite investigações detalhadas dos circuitos cerebrais engajados durante o desempenho de paradigmas de estimulação que envolvem diferentes aspectos do processamento emocional em seres humanos saudáveis. Este artigo discute os princípios básicos dos métodos mais comumente usados em estudos de neuroimagem funcional das emoções, faz uma revisão seletiva de achados recentes obtidos nestes estudos, fornece exemplos de novos paradigmas usados atualmente neste tipo de investigação, e descreve modelos neuroanatômicos recentes para o processamento emocional formulados a partir dos achados da literatura contemporânea de neuroimagem. Por fim, enfatizamos o potencial das técnicas de neuroimagem funcional para ampliar o conhecimento a respeito da ação modulatória dos medicamentos usados para tratar condições mentais que alteram processos emocionais específicos, tais como a depressão e os transtornos de ansiedade.

Hypofrontality and microvascular dysregulation in remitted late-onset depression assessed by functional near-infrared spectroscopy

Accumulated evidence suggests the involvement of vascular factors in late-onset depression. Late-onset depression has characteristics of poor outcome, cognitive decline, and high prevalence rather than early-onset depression. The aim of the present study was to determine whether or not the functional hypofrontality--that is, hypoperfusion and hypometabolism in the frontal lobes-seen in late-onset depression is a trait-dependent abnormality of microvascular regulation. This study was conducted on 10 patients with remitted late-onset major depressive disorder (MDD) and 10 healthy volunteers matched for vascular factors and subcortical, or white matter, hyperintensities (WMH). Using near-infrared spectroscopy combined with magnetic resonance imaging, we investigated the microvascular reactivity in the prefrontal cortex during a cognitive task and during carbon dioxide (CO(2)) inhalation. Activation of the prefrontal cortex during the cognitive task was significantly less in patients as compared with controls, although task performance was not significantly different between the two groups. In the patients, a tendency of negative correlation between the reduced prefrontal activation during a cognitive task and the severity of hyperintensity in periventricular region was observed. Vasomotor reactivity to CO(2) inhalation was significantly lower in the patients than in the controls. Although there was no significant association between the activation during the cognitive and that during the CO(2) inhalation task, the present results suggest that prefrontal microvascular dysregulation as shown by NIRS is involved in the pathophysiological basis of functional hypofrontality in late-onset depression. This finding will provide a new framework for the development of diagnostic methods, treatments, and preventive strategies against late-onset depression.

Stability of cerebral blood flow measures using a split-dose technique with 99mTc-exametazime SPECT

AIM

To determine whether there is stability of cerebral blood flow (CBF) measures using single photon emission computed tomography (SPECT) imaging in healthy controls in a test-retest split-dose paradigm. Such a paradigm is frequently used in the clinical and research setting to assess various brain states.

METHODS

Five healthy volunteers underwent two brain SPECT scans after the administration of low and high doses of (99m)Tc-exametazime. The first SPECT scan was acquired approximately 30 min after the intravenous injection of approximately 259 MBq of (99m)Tc-exametazime. The second SPECT scan was acquired approximately 30 min after the intravenous injection of 925 MBq of (99m)Tc-exametazime. Both scans were acquired over approximately 30-45 min and the images were reconstructed using filtered backprojection, a low-pass filter and Chang's first-order attenuation correction. Values were obtained for regions of interest (ROIs) in major brain structures and normalized to whole brain activity. Counts on the second SPECT scan were also decay corrected for activity from the first scan.

RESULTS

The results demonstrated a strong correlation between the low-dose and high-dose scans for all regions (r = 0.86, P<0.0001). Symmetries were preserved with a strong correlation between low-dose and high-dose scans (r = 0.70, P<0.0001). Finally, most regions demonstrated less than a 5% difference between the low-dose and high-dose scans.

CONCLUSIONS

The results of this study demonstrate that the split-dose technique can be employed for clinical and research applications to measure CBF in different brain states using two SPECT scans on the same day.

Executive and prefrontal dysfunction in unipolar depression: a review of neuropsychological and imaging evidence

This paper reviews recent empirical findings related to prefrontal and executive function in unipolar depression. While a number of reviews have dealt with either the neuropsychological literature or findings from imaging studies, the present review addresses both, as well as findings from studies that have combined brain-imaging techniques with neuropsychological measures. This combined approach is of great interest as the performance of a structured task may act to load the areas of interest and reduce variance, thus making the imaging evidence more valuable; while the use of imaging provides a check that the neuropsychological tasks are indeed engaging the structures whose performance they are intended to assess. Prominent models of the neurobiology of depression implicate involvement of the anterior cingulate cortex (ACC) and the dorsolateral prefrontal cortex (DLPFC). The evidence from combined imaging and neuropsychological studies supports the involvement of the ACC, but is less clear in the case of the DLPFC. However, the limited number of such studies conducted to date means that conclusions must be tentative and further studies employing this combined approach may be of great value.

Unit for suicide research, University of Gent, Belgium

The Unit for Suicide Research was founded in 1996 with the aims of integrating and stimulating the study of suicidal behaviour, increasing the visibility of the research work, and providing evidence-based information to health policy-makers, the general public and the media. I am Director of the Unit, working alongside Professor Kurt Audenaert, Dr Katrien Bernagie, and psychologists Gwendolyn Portzky (Research Coordinator), Stephanie De Munck, Els Reyserhove and Hannelore Vromman. In this report I will summarise recent and current activities, which are carried out according to three lines of research: the study of the epidemiology of suicidal behaviour; the study of (the association between) biological and psychological characteristics of suicidal behaviour; and the development and evaluation of prevention strategies. Research is carried out in collaboration with other departments of the University of Gent (e.g. the Departments of Nuclear Medicine, Sociology, Radiopharmacy and Veterinary Medicine) and with a large number of other European research centres. The collaboration with Professor Hawton at the Oxford Centre for Suicide Research has been particularly important (Hawton & Van Heeringen, 2000).

The neurobiology of suicide and suicidality

OBJECTIVE

To investigate the current state of knowledge regarding the neurobiology of suicide and suicidality.

METHOD

The literature on the neurobiology of suicidality and suicide was reviewed.

RESULTS

There is clear evidence that the activity of 3 neurobiological systems has a role in the pathophysiology of suicidal behaviour. This includes hyperactivity of the hypothalamo-pituitary-adrenal axis, dysfunction of the serotonergic (5-HTergic) system, and excessive activity of the noradrenergic system. While the first and the last system appear to be involved in the response to stressful events, dysfunction of the serotonergic system is thought to be trait-dependent and associated with disturbances in the regulation of anxiety, impulsivity, and aggression. It can be hypothesized that neurobiological dysfunctions mediate the occurrence of suicidal behaviour through the disturbed modulation of basic neuropsychological functions.

CONCLUSION

Increasing insight into the neurobiological basis of suicidal behaviour suggests that serotonin (5-HT) agonists have an important role in the treatment and prevention of suicidal behaviour. Studies of the efficacy of such drugs have, however, been disappointing. Because suicidal behaviour continues to be a major public health problem, further study is clearly needed, including research on the effect of combined pharmacologic and psychotherapeutic approaches.