Postmortem findings in suicide victims. Implications for in vivo imaging studies

Grey matter abnormalities in major depressive disorder patients with suicide attempts: A systematic review of age-specific differences

Background

Previous studies have reported alterations in brain structure in major depressive disorder (MDD) patients with suicide attempts. However, age-related changes in suicidal MDD patients remain unclear.

Methods

We performed a systematic review following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Embase, PubMed, and Web of Science were searched to identify relevant studies from inception to January 2023. All voxel-based and surface-based morphometry studies comparing suicidal MDD patients to MDD or healthy controls were included. Studies were then grouped by age range (old, middle-age, adolescent) and the commonalities and age-related structural brain alterations were summarized. The included studies were evaluated using the Newcastle-Ottawa Scale (NOS).

Results

A total of 17 studies met the inclusion criteria, including 3 of late-life depression (LLD) patients, 11 of middle-aged depression (MAD) patients, and 3 of adolescent depression (AOD) patients. The majority of studies had moderate to high NOS scores, indicating good quality. Patients in all three age groups exhibited extensive alterations in the lateral, medial, and orbital regions of the frontal lobes. Furthermore, suicidal MAD patients showed a specific decrease in the gray matter volume of the dorsolateral prefrontal cortex compared to suicidal LLD patients. Cortical thickness and left angular gyrus volume were decreased in suicidal MAD and suicidal LLD patients, but increased in suicidal AOD patients.

Conclusion

This systematic review summarizes structural brain changes in suicidal MDD patients at three age groups: elderly, middle-aged, and adolescent. These findings help elucidate the common circuitry of MDD related to suicide over the lifespan and highlight unique circuitry associated with different ages. These findings may help predict the risk of suicide in MDD patients at different ages.

The neuropeptide cycloprolylglycine produces antidepressant-like effect and enhances BDNF gene expression in the mice cortex

BACKGROUND

Cycloprolylglycine (CPG) is an endogenous dipeptide with a wide range of psychotropic activity and putative therapeutic potential for depression. A small but growing body of data suggests that antidepressant-like effect of CPG is associated with neuroplastic changes in the brain or 5-HT system modulation. However, the mechanisms of the dipeptide action remain elusive.

AIMS

Here, we characterize the effects of chronic CPG administration on behavior and genes expression of antidepressants sensitive catalepsy (ASC) mice strain, characterized by depressive-like behavior.

METHODS

ASC mice were injected with saline, fluoxetine (10 mg/kg/day), or CPG (1 and 2 mg/kg/day) during 2 weeks. Behavior was studied using the open field test, novel object test, elevated plus maze test, forced swim test, and tail suspension test (TST). The expressions of genes coding BDNF, CREB, 5-HT_1A and 5-HT_2A receptors, TPH2, and SERT in the brain were measured with quantitative real-time reverse transcription polymerase chain reaction (RT-PCR).

RESULTS

Chronic intraperitoneal administration of 1 and 2 mg/kg of CPG revealed the significant antidepressant-like effect by decreasing immobility time in the TST. At the same time, CPG did not negatively affect locomotor activity, cognition, or anxiety. In the real-time quantitative polymerase chain reaction (PCR) assay, chronic CPG treatment (2 mg/kg for 14 days) increased Bdnf mRNA level in the frontal cortex.

CONCLUSIONS

Our findings extend the evidence for the effectiveness of CPG to reduce depressive-like behaviors. The antidepressant-like effect of CPG is mediated, as least in part, by BDNF-dependent mechanism. The exact mechanism remains to be elucidated, and further studies are warranted.

In search of sex-related mediators of affective illness

Sex differences in the rates of affective disorders have been recognized for decades. Studies of physiologic sex-related differences in animals and humans, however, have generally yielded little in terms of explaining these differences. Furthermore, the significance of these findings is difficult to interpret given the dynamic, integrative, and highly context-dependent nature of human physiology. In this article, we provide an overview of the current literature on sex differences as they relate to mood disorders, organizing existing findings into five levels at which sex differences conceivably influence physiology relevant to affective states. These levels include the following: brain structure, network connectivity, signal transduction, transcription/translation, and epigenesis. We then evaluate the importance and limitations of this body of work, as well as offer perspectives on the future of research into sex differences. In creating this overview, we attempt to bring perspective to a body of research that is complex, poorly synthesized, and far from complete, as well as provide a theoretical framework for thinking about the role that sex differences ultimately play in affective regulation. Despite the overall gaps regarding both the underlying pathogenesis of affective illness and the role of sex-related factors in the development of affective disorders, it is evident that sex should be considered as an important contributor to alterations in neural function giving rise to susceptibility to and expression of depression.

Search for solutions, learning, simulation, and choice processes in suicidal behavior

Suicide may be viewed as an unfortunate outcome of failures in decision processes. Such failures occur when the demands of a crisis exceed a person's capacity to (i) search for options, (ii) learn and simulate possible futures, and (iii) make advantageous value‐based choices. Can individual‐level decision deficits and biases drive the progression of the suicidal crisis? Our overview of the evidence on this question is informed by clinical theory and grounded in reinforcement learning and behavioral economics. Cohort and case–control studies provide strong evidence that limited cognitive capacity and particularly impaired cognitive control are associated with suicidal behavior, imposing cognitive constraints on decision‐making. We conceptualize suicidal ideation as an element of impoverished consideration sets resulting from a search for solutions under cognitive constraints and mood‐congruent Pavlovian influences, a view supported by mostly indirect evidence. More compelling is the evidence of impaired learning in people with a history of suicidal behavior. We speculate that an inability to simulate alternative futures using one's model of the world may undermine alternative solutions in a suicidal crisis. The hypothesis supported by the strongest evidence is that the selection of suicide over alternatives is facilitated by a choice process undermined by randomness. Case–control studies using gambling tasks, armed bandits, and delay discounting support this claim. Future experimental studies will need to uncover real‐time dynamics of choice processes in suicidal people. In summary, the decision process framework sheds light on neurocognitive mechanisms that facilitate the progression of the suicidal crisis.

This article is categorized under:

Economics > Individual Decision‐Making

Psychology > Emotion and Motivation

Psychology > Learning

Neuroscience > Behavior

Sex and the serotonergic underpinnings of depression and migraine

Most psychiatric disorders demonstrate sex differences in their prevalence and symptomatology, and in their response to treatment. These differences are particularly pronounced in mood disorders. Differences in sex hormone levels are among the most overt distinctions between males and females and are thus an intuitive underpinning for these clinical observations. In fact, treatment with estrogen and testosterone was shown to exert antidepressant effects, which underscores this link. Changes to monoaminergic signaling in general, and serotonergic transmission in particular, are understood as central components of depressive pathophysiology. Thus, modulation of the serotonin system may serve as a mechanism via which sex hormones exert their clinical effects in mental health disorders. Over the past 20 years, various experimental approaches have been applied to identify modes of influence of sex and sex hormones on the serotonin system. This chapter provides an overview of different molecular components of the serotonin system, followed by a review of studies performed in animals and in humans with the purpose of elucidating sex hormone effects. Particular emphasis will be placed on studies performed with positron emission tomography, a method that allows for human in vivo molecular imaging and, therefore, assessment of effects in a clinically representative context. The studies addressed in this chapter provide a wealth of information on the interaction between sex, sex hormones, and serotonin in the brain. In general, they offer evidence for the concept that the influence of sex hormones on various components of the serotonin system may serve as an underpinning for the clinical effects these hormones demonstrate.

Ventromedial prefrontal value signals and functional connectivity during decision-making in suicidal behavior and impulsivity

Suicide is linked to impaired value-based decision-making and impulsivity, but whether these risk factors share neural underpinnings is unclear. Disrupted ventromedial prefrontal cortex (vmPFC) value signals may underlie this behavioral phenotype. We investigated vmPFC value signals, vmPFC-frontoparietal connectivity, and the impact of impulsivity during decision-making in depressed individuals with and without suicidal behavior. Middle-aged and older adults (n = 116; 35 with a history of suicide attempts, 25 with ideation only, 25 depressed controls with no ideation, and 31 nonpsychiatric controls) completed a decision-making task with drifting reward probabilities during fMRI. Values of choices, estimated by a reinforcement learning model, were regressed against BOLD signal. VmPFC value activation was compared between groups. Moderating effects of impulsivity on vmPFC-frontoparietal connectivity were assessed in nonpsychiatric controls and compared among patient groups. VmPFC value responses in participants with a history of suicide attempts were reduced relative to nonpsychiatric controls (p < 0.05). In nonpsychiatric controls, vmPFC-frontoparietal connectivity was negatively moderated by impulsivity (pFWE corrected < 0.05). This effect was preserved in comparison patient groups but abolished in suicide attempters (p < 0.001). This change in neural connectivity patterns also affected behavior: people with a history of suicide attempts showed a disrupted effect of vmPFC-frontoparietal connectivity, impulsivity, and reinforcement on choice quality (p < 0.001). These effects were specific to vmPFC and not to striatum. In summary, findings from this study largely support disrupted vmPFC value signals in suicidal behavior. In addition, it uncovers an altered pattern of vmPFC-frontoparietal connectivity in impulsive people with suicidal behavior, which may underlie disrupted choice processes in a suicidal crisis.

Quantification of 5-HT1A and 5-HT2A receptor Binding in Depressed Suicide Attempters and Non-Attempters

OBJECTIVE

To determine serotonin system abnormalities related to major depression or previous suicidal behavior.

METHODS

[¹¹C]WAY100635, [¹⁸F]altanserin and positron emission tomography were used to compare 5-HT_1A and 5-HT_2A binding in MDD patients divided into eight past suicide attempters (>4yrs prior to scanning) and eight lifetime non-attempters, and both groups were compared to eight healthy volunteers.

RESULTS

The two receptor types differed in binding pattern across brain regions from each other, but there were no differences in binding between healthy volunteers and the two depressed groups or between depressed suicide attempters and non-attempters. No effects of depression severity or lifetime aggression were observed for either receptor.

CONCLUSION

Limitations of this study include small sample size and absence of high lethality suicide attempts in the depressed attempter group. No trait-like binding correlations with past suicide attempt or current depression were observed. Given the heterogeneity of nonfatal suicidal behavior, a larger sample study emphasizing higher lethality suicide attempts may find the serotonin biological phenotype seen in suicide decedents.

Behavioral empathy failures and suicidal behavior

Impaired decision-making has recently gained recognition as a component of the suicidal diathesis. Yet, although precipitants and particularly deterrents to suicidal behavior are often interpersonal, little is known about social decision-making in suicidal individuals. This study employed a novel version of the Ultimatum Game to investigate how empathy moderates responses to social conflict in 149 older adults, comprising groups of suicide attempters (n = 49), suicide ideators (n = 32), non-suicidal depressed controls (n = 33), and a non-psychiatric control group (n = 35). Participants acted as responder to a series of single-shot financial offers that varied in fairness. Some offers were paired with social context information on the proposer, designed to evoke either empathy or punishment. Offer acceptance was sensitive to Fairness and Social Context, such that participants accepted more offers in the empathy condition and fewer offers in the punishment condition. A Group * Context interaction was observed, wherein the suicide attempters adjusted their acceptance rates less in the empathy condition than the non-psychiatric controls. Thus, older adults with a history of suicide attempt were less influenced by empathy scenarios, indicating that a failure to integrate others' emotions into decisions may undermine social deterrents to suicide.

Reduced kynurenine pathway metabolism and cytokine expression in the prefrontal cortex of depressed individuals

BACKGROUND

Neuroinflammatory processes are increasingly believed to participate in the pathophysiology of a number of major psychiatric diseases, including depression. Immune activation stimulates the conversion of the amino acid tryptophan to kynurenine, leading to the formation of neuroactive metabolites, such as quinolinic acid and kynurenic acid. These compounds affect glutamatergic neurotransmission, which plays a prominent role in depressive pathology. Increased tryptophan degradation along the kynurenine pathway (KP) has been proposed to contribute to disease etiology.

METHODS

We used postmortem brain tissue from the ventrolateral prefrontal cortex (VLPFC) to assess tissue levels of tryptophan and KP metabolites, the expression of several KP enzymes and a series of cytokines as well as tissue pathology, including microglial activation. Tissue samples came from nonpsychiatric controls (n = 36) and individuals with depressive disorder not otherwise specified (DD-NOS, n = 45) who died of natural causes, homicide, accident, or suicide.

RESULTS

We found a reduction in the enzymatic conversion of tryptophan to kynurenine, determined using the kynurenine:tryptophan ratio, and reduced messenger RNA expression of the enzymes indoleamine-2,3-dioxygenase 1 and 2 and tryptophan-2,3-dioxygenase in depressed individuals irrespective of the cause of death. These findings correlated with reductions in the expression of several cytokines, including interferon-γ and tumour necrosis factor-α. Notably, quinolinic acid levels were also lower in depressed individuals than controls.

LIMITATIONS

Information on the use of antidepressants and other psychotropic medications was insufficient for statistical comparisons.

CONCLUSION

Contrary to expectations, the present results indicate that depression, in the absence of medical illness or an overt inflammatory process, is associated with compromised, rather than increased, KP metabolism in the VLPFC.

Different stress-related gene expression in depression and suicide

OBJECTIVE

Suicide occurs in some, but not all depressed patients. So far, it remains unknown whether the studied stress-related candidate genes change in depression, suicide or both. The prefrontal cortex (PFC) is involved in, among other things, impulse control and inhibitory behavior and plays an important role in both suicide and depression.

METHODS

We have employed qPCR to study 124 anterior cingulate cortex (ACC) and dorsolateral PFC (DLPFC) brain samples, obtained from two brain banks, from: i) young depressed patients (average age 43 years) who committed suicide (MDD-S) and depressed patients who died from causes other than suicide (MDD-NS) and from ii) elderly depressed patients (average age 75 years) who did not commit suicide (DEP). Both cohorts were individually matched with non-psychiatric non-suicide control subjects. We determined the transcript levels of hypothalamic-pituitary-adrenal axis-regulating molecules (corticotropin-releasing hormone (CRH), CRH receptors, CRH binding protein, mineralocorticoid receptor/glucocorticoid receptor), transcription factors that regulate CRH expression, CRH-stimulating cytokines, chaperone proteins, retinoid signaling, brain-derived neurotrophic factor and tropomyosin-related kinase B, cytochrome proteins, nitric oxide synthase (NOS) and monoamines.

RESULTS

In the MDD-S group, expression levels of CRH and neuronal NOS-interacting DHHC domain-containing protein with dendritic mRNA (NIDD) were increased. Other changes were only present in the DEP group, i.e. decreased NIDD, and increased and 5-hydroxytryptamine receptor 1A (5-HT1A) expression levels. Changes were found to be more pronounced in the anterior cingulate cortex than in the dorsolateral PFC.

CONCLUSION

Depressed patients who committed suicide have different gene expression patterns than depressed patients who died of causes other than suicide.

Intact alternation performance in high lethality suicide attempters

Suicide attempters often perform poorly on tasks linked to ventral prefrontal cortical (VPFC) function. Object Alternation (OA) - a VPFC probe - has not been used in these studies. In this study, currently depressed medication-free past suicide attempters whose most severe attempt was of high (n=31) vs. low (n=64) lethality, 114 medication-free depressed non-attempters, and 86 non-patients completed a computerized OA task. Participants also completed comparison tasks assessing the discriminant validity of OA (Wisconsin Card Sort), its concurrent validity relative to tasks associated with past attempt status (computerized Stroop task, Buschke Selective Reminding Test), and its construct validity as a VPFC measure (Go-No Go and Iowa Gambling Task). Against expectations, high lethality suicide attempters - the majority of whom used non-violent methods in their attempts with some planning - outperformed other depressed groups on OA, with no group differences observed on Wisconsin Card Sort. Despite intact performance on OA, past attempters exhibited deficits on the Stroop and Buschke. OA performance was associated with performance on Go-No Go and Iowa Gambling, confirming that OA measures a similar construct. VPFC dysfunction may not be a characteristic of all suicide attempters, especially those who make more carefully planned, non-violent - though potentially lethal - attempts.

Neural correlates of four broad temperament dimensions: testing predictions for a novel construct of personality

Four suites of behavioral traits have been associated with four broad neural systems: the 1) dopamine and related norepinephrine system; 2) serotonin; 3) testosterone; 4) and estrogen and oxytocin system. A 56-item questionnaire, the Fisher Temperament Inventory (FTI), was developed to define four temperament dimensions associated with these behavioral traits and neural systems. The questionnaire has been used to suggest romantic partner compatibility. The dimensions were named: Curious/Energetic; Cautious/Social Norm Compliant; Analytical/Tough-minded; and Prosocial/Empathetic. For the present study, the FTI was administered to participants in two functional magnetic resonance imaging studies that elicited feelings of love and attachment, near-universal human experiences. Scores for the Curious/Energetic dimension co-varied with activation in a region of the substantia nigra, consistent with the prediction that this dimension reflects activity in the dopamine system. Scores for the Cautious/Social Norm Compliant dimension correlated with activation in the ventrolateral prefrontal cortex in regions associated with social norm compliance, a trait linked with the serotonin system. Scores on the Analytical/Tough-minded scale co-varied with activity in regions of the occipital and parietal cortices associated with visual acuity and mathematical thinking, traits linked with testosterone. Also, testosterone contributes to brain architecture in these areas. Scores on the Prosocial/Empathetic scale correlated with activity in regions of the inferior frontal gyrus, anterior insula and fusiform gyrus. These are regions associated with mirror neurons or empathy, a trait linked with the estrogen/oxytocin system, and where estrogen contributes to brain architecture. These findings, replicated across two studies, suggest that the FTI measures influences of four broad neural systems, and that these temperament dimensions and neural systems could constitute foundational mechanisms in personality structure and play a role in romantic partnerships.

Research review: the role of cytokines in depression in adolescents: a systematic review

BACKGROUND

While cytokines have been implicated in the pathophysiology of depression in adults, the potential role in younger age groups such as adolescents is less clear. This article therefore reviews the literature (a) to explore the relationship between cytokines and depression in adolescents, and (b) to examine how cytokines may be related to adolescent depression in the context of other neurobiological theories of depression.

METHOD

A systematic review of the scientific literature on the subject was conducted in February 2013, searching the Web of Knowledge, PubMed (Medline), PsycInfo and Cochrane electronic databases.

RESULTS

Eighteen studies were identified measuring both depression or depressive symptoms and cytokines or immune markers in adolescents. Adolescents with depression show age-specific characteristics of the immune and inflammatory system, specifically in NK cell activity and in pro-inflammatory cytokines (such as IL-1β and TNF-α). In addition, the role of cytokines in adolescent depression is influenced by neurodevelopment, hormonal changes, stress and trauma.

CONCLUSIONS

There may be differences in the neurobiology of adolescent major depressive disorder (MDD) compared with adult MDD. Increased understanding of the role of cytokines in adolescent MDD may lead to improved outcomes in the treatment of adolescent depression.

Body mass index and suicidal behaviors: a critical review of epidemiological evidence

INTRODUCTION

Obesity has been associated with an elevated risk of depression and other mental health symptoms. An increasing number of robust prospective studies, however, counter-intuitively and consistently suggested that body mass index (BMI) was inversely associated with the risk of completed suicide in a dose-response fashion. The current contribution appraised the epidemiological evidence and examined the nature of the purported relationship.

METHOD

We conducted a systematic review of English publications of original studies using the terms "obesity", "overweight", "body mass index", "BMI", "attempted suicide", "completed suicide", "suicide ideation", "suicidal behaviors" and "suicide". Data were extracted primarily through MEDLINE and PUBMED databases.

RESULTS

Almost all cohort studies reported an inverse relationship between BMI and the risk of completed suicide irrespective of region of origin and the gender of study participants. Overall, among men, a high BMI was associated with a low risk of attempted or completed suicide. There was a paradox among women, namely, a high BMI was associated with an elevated risk of attempted suicide but a low risk of completed suicide.

LIMITATIONS

As a narrative review, the current report was interpretive and qualitative in nature.

CONCLUSION

Consideration of observational data, methodological issues stemmed from the rarity of deaths by suicide, homogeneity of study populations, heterogeneity of suicide methods, and the corresponding neurobiological changes made interpretation difficult. Intercultural cohort observations across countries may help to weigh the contributions from biological and socio-cultural factors. The purported association not only represents a scientific challenge, it's also an opportunity potentially leading to important insights into prevention of suicide death.

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.

The serotonergic system in mood disorders and suicidal behaviour

A stress-diathesis explanatory model of suicidal behaviour has proved to be of heuristic value, and both clinical and neurobiological components can be integrated into such a model. A trait deficiency in serotonin input to the anterior cingulate and ventromedial prefrontal cortex is found in association with suicide, and more recently non-fatal suicidal behaviour, and is linked to decision-making and suicide intent by imaging and related studies in vivo. The same neural circuitry and serotonin deficiency may contribute to impulsive aggressive traits that are part of the diathesis for suicidal behaviour and are associated with early onset mood disorders and greater risk for suicidal behaviour. Other brain areas manifest deficient serotonin input, that is, a trait related to recurrent major depressive disorder and bipolar disorder. Thus the serotonin system is involved in both the diathesis for suicidal behaviour in terms of decision-making, and to a major stressor, namely episodes of major depression.

Regional brain glucose uptake distinguishes suicide attempters from non-attempters in major depression

This study compared regional cerebral metabolic rates of glucose (rCMRglu) determined by [(18)F]-fluoro-2-deoxyglucose positron emission tomography (FDG-PET) in suicide attempters and non-attempters. Medication-free patients with major depression (n = 29) had FDG-PET after single-blind administration of placebo (day 1) and fenfluramine (day 2). Suicide attempt history was obtained before scanning and at assessments over 2 subsequent years. Statistical parametric mapping evaluated associations between attempt status and rCMRglu, controlling for age. The study included 13 patients with and 16 without a history of suicide attempt within 2 years before or after scanning. After placebo, rCMRglu in attempters was lower in right dorsolateral prefrontal regions and higher in ventromedial regions than in non-attempters. After fenfluramine, relatively hypometabolic areas enlarged, and no hypermetabolic areas were detected. Distinct rCMRglu patterns may be serotonin-sensitive biomarkers of suicide risk.

The neurobiology of depression and antidepressant action

We present a comprehensive overview of the neurobiology of unipolar major depression and antidepressant drug action, integrating data from affective neuroscience, neuro- and psychopharmacology, neuroendocrinology, neuroanatomy, and molecular biology. We suggest that the problem of depression comprises three sub-problems: first episodes in people with low vulnerability ('simple' depressions), which are strongly stress-dependent; an increase in vulnerability and autonomy from stress that develops over episodes of depression (kindling); and factors that confer vulnerability to a first episode (a depressive diathesis). We describe key processes in the onset of a 'simple' depression and show that kindling and depressive diatheses reproduce many of the neurobiological features of depression. We also review the neurobiological mechanisms of antidepressant drug action, and show that resistance to antidepressant treatment is associated with genetic and other factors that are largely similar to those implicated in vulnerability to depression. We discuss the implications of these conclusions for the understanding and treatment of depression, and make some strategic recommendations for future research.

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.

Neuron density and serotonin receptor binding in prefrontal cortex in suicide

Although serotonin receptor and cytoarchitectonic alterations are reported in prefrontal cortex (PFC) in suicide and depression, no study has considered binding relative to neuron density. Therefore, we measured neuron density and serotonin transporter (SERT), 5-HT1A and 5-HT2A binding in matched suicides and controls. Suicides and normal controls (n=15 matched pairs) were psychiatrically characterized. Neuron density and binding were determined in dorsal [Brodmann area (BA) 9] and ventral (BA 47) PFC by stereology and quantitative autoradiography in near-adjacent sections. Binding index was defined as the ratio of receptor binding to neuron density. Suicides had lower neuron density in the gyrus of both areas. The binding index was lower for SERT in BA 47 but not in BA9; the 5-HT1A binding index was higher in BA 9 but not in BA 47, while the 5-HT2A binding index was not different between groups. SERT binding was lower in suicides in BA 47 but not BA 9, while 5-HT1A binding was higher in BA 9 but not BA 47. SERT binding negatively correlated with 5-HT1A binding in BA 47 in suicides. Neuron density decreased with age. The 5-HT1A binding index was higher in females than males. We found lower neuron density and lower SERT binding index in both PFC regions in suicides. More 5-HT1A binding with less SERT binding and the negative correlation in depressed suicides suggests post-synaptic receptor up-regulation, and it is independent of the difference in neuron density. Thus, abnormalities in both cortical neurons and in their serotonergic innervation are present in suicides and future studies will need to determine whether cortical changes reflect the trophic effect of altered serotonin innervation.

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.

Social emotion recognition, social functioning, and attempted suicide in late-life depression

OBJECTIVES

: Lack of feeling connected and poor social problem solving have been described in suicide attempters. However, cognitive substrates of this apparent social impairment in suicide attempters remain unknown. One possible deficit, the inability to recognize others' complex emotional states has been observed not only in disorders characterized by prominent social deficits (autism-spectrum disorders and frontotemporal dementia) but also in depression and normal aging. This study assessed the relationship between social emotion recognition, problem solving, social functioning, and attempted suicide in late-life depression.

DESIGN, PARTICIPANTS, MEASUREMENTS

: There were 90 participants: 24 older depressed suicide attempters, 38 nonsuicidal depressed elders, and 28 comparison subjects with no psychiatric history. We compared performance on the Reading the Mind in the Eyes test and measures of social networks, social support, social problem solving, and chronic interpersonal difficulties in these three groups.

RESULTS

: Suicide attempters committed significantly more errors in social emotion recognition and showed poorer global cognitive performance than elders with no psychiatric history. Attempters had restricted social networks: they were less likely to talk to their children, had fewer close friends, and did not engage in volunteer activities, compared to nonsuicidal depressed elders and those with no psychiatric history. They also reported a pattern of struggle against others and hostility in relationships, felt a lack of social support, perceived social problems as impossible to resolve, and displayed a careless/impulsive approach to problems.

CONCLUSIONS

: Suicide attempts in depressed elders were associated with poor social problem solving, constricted social networks, and disruptive interpersonal relationships. Impaired social emotion recognition in the suicide attempter group was related.

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.

Suicide in older adults

This article makes the case that late-life suicide is a cause for great concern that warrants ongoing attention from researchers, health care providers, policy makers, and society at large. It reviews the evidence for factors that place older adults at risk for suicide, or protect them from it. The authors introduce the notion that suicide preventive interventions target individuals or groups at different levels of risk at different points on the developmental trajectory toward death by suicide, offering examples and recommending their strategic, combined application to create an effective, community-level response to the mounting problem of suicide in older adults.

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.

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.

Gender, personality, and serotonin-2A receptor binding in healthy subjects

The vulnerability to mood disorders, impulsive-aggression, eating disorders, and suicidal behavior varies greatly with gender, and may reflect gender differences in central serotonergic function. We investigated the relationships of gender, mood, impulsivity, aggression and temperament to 5HT(2A) receptor binding in 21 healthy subjects using [18F]altanserin and PET neuroimaging. Binding potentials in pre-defined regions-of-interest (ROI) were calculated using the Logan graphical method, corrected for partial volume effects, and compared by gender with age co-varied. SPM analysis was used for voxel level comparisons. Altanserin binding (BP(P)) was greater in male than female subjects in the following nine ROIs: hippocampus (HIP) and Lt. HIP, lateral orbital frontal cortex (LOF) and Lt. LOF, left medial frontal cortex (Lt. MFC), left medial temporal cortex (Lt. MTC), left occipital cortex (Lt. OCC), thalamus (THL) and Lt. THL. Differences in Lt. HIP and Lt. MTL remained significant after Bonferroni correction. Gender differences were noted in the co-variation of psychological traits with BP(P) values in specific ROIs. Among males alone, aggression was negatively correlated with BP(P) values in Lt. LOF and Lt. MFC, and Suspiciousness positively correlated in LOF, Lt. LOF and Lt. MFC. Among female subjects alone, Negativism was positively correlated with BP(P) values in HIP, and Verbal Hostility in Lt. HIP. Altanserin binding in Lt. MTC was positively correlated with Persistence, with no significant gender effect. Gender differences in 5HT(2A) receptor function in specific ROIs may mediate expression of psychological characteristics such as aggression, suspiciousness and negativism. Future studies of 5HT(2A) receptor function and its relationship to behavior should control for gender.

The evolution of violence in men: the function of central cholesterol and serotonin

Numerous studies point to central serotonin as an important modulator of maladaptive behaviors. In men, for instance, low concentrations of this neurotransmitter are related to hostile aggression. A key player in serotonin metabolism seems to be central cholesterol. It plays a fundamental role in maintaining the soundness of neuron membranes, especially in the exocytosis transport of serotonin vesicles into the synaptic cleft. In this review, we attempt an evolutionary approach to the neurobiological basis of human male violence. Hominid evolution was shaped by periods of starvation but also by energy demands of an increasingly complex brain. A lack of food resources reduces uptake of glucose and results in a decreased energy-supply for autonomous brain cholesterol synthesis. Consequently, concentrations of neuromembrane cholesterol decrease, which lead to a failure of the presynaptic re-uptake mechanism of serotonin and ultimately to low central serotonin. We propose that starvation might have affected the larger male brains earlier than those of females. Furthermore, this neurophysiological process diminished the threshold for hostile aggression, which in effect represented a prerequisite for being a successful hunter or scavenger. In a Darwinian sense, the odds to acquire reliable energetic resources made those males to attractive spouses in terms of paternal care and mate support. To underpin these mechanisms, a hypothetical four-stage model of synaptic membrane destabilization effected by a prolonged shortage of high-energy, cholesterol-containing food is illustrated.

Diffusion tensor imaging study of white matter fiber tracts in pediatric bipolar disorder and attention-deficit/hyperactivity disorder

BACKGROUND

To investigate microstructure of white matter fiber tracts in pediatric bipolar disorder (PBD) and attention-deficit/hyperactivity disorder (ADHD).

METHODS

A diffusion tensor imaging (DTI) study was conducted at 3 Tesla on age- and IQ-matched children and adolescents with PBD (n = 13), ADHD (n = 13), and healthy control subjects (HC) (n = 15). Three DTI parameters, fractional anisotropy (FA), apparent diffusion coefficient (ADC), and regional fiber coherence index (r-FCI), were examined in eight fiber tracts: anterior corona radiata (ACR), anterior limb of the internal capsule (ALIC), superior region of the internal capsule (SRI), posterior limb of the internal capsule (PLIC), superior longitudinal fasciculus (SLF), inferior longitudinal fasciculus (ILF), cingulum (CG), and splenium (SP).

RESULTS

Significantly lower FA was observed in ACR in both PBD and ADHD relative to HC. In addition, FA and r-FCI values were significantly lower in ADHD relative to PBD and HC in both the ALIC and the SRI. Further, ADC was significantly greater in ADHD relative to both the PBD and HC in ACR, ALIC, PLIC, SRI, CG, ILF, and SLF.

CONCLUSIONS

Decreased FA in ACR implies an impaired fiber density or reduced myelination in both PBD and ADHD in this prefrontal tract. These abnormalities, together with the reduced fiber coherence, extended to corticobulbar tracts in ADHD. Increased ADC across multiple white matter tracts in ADHD indicates extensive cellular abnormalities with less diffusion restriction in ADHD relative to PBD.

Inferior frontal white matter volume and suicidality in schizophrenia

The neurobiology of suicidality in schizophrenia is largely unknown. We therefore assessed gray and white matter volumes associated with past suicidality and current self-aggression in schizophrenia. Fifty-five outpatients with schizophrenia (n=55) and healthy controls (n=55), matched for age, gender and handedness, were recruited. Ten patients had a life-time history of one or more suicide attempts. Current self-aggression was assessed using the Modified Overt Aggression Scale. High resolution structural magnetic resonance images were analyzed by voxel-based morphometry. We found significantly larger inferior frontal white matter volumes bilaterally in patients with a previous suicide attempt as compared with those patients without a history of suicidality. No other significant white or gray matter volume differences were observed. White matter volume in these regions did not differ between healthy controls and those patients without a previous suicide attempt. Furthermore, among patients, the level of current self-aggression showed a significant positive correlation with white matter volume in the same regions. Inferior frontal white matter alterations in fronto-temporo-limbic circuits may be associated with suicidality and self-aggression in schizophrenia.

Elevated 5-HT 2A receptors in postmortem prefrontal cortex in major depression is associated with reduced activity of protein kinase A

Previous human postmortem brain tissue research has implicated abnormalities of 5-HT receptor availability in depression and suicide. Although altered abundance of 5-HT 1A, 5-HT 2A, and 5-HT 2C receptors (5-HT(1A), 5-HT(2A), and 5-HT(2C)) has been reported, the causes remain obscure. This study evaluated the availability of these three receptor subtypes in postmortem brain tissue specimens from persons with a history of major depression (MDD) and normal controls and tested the relationships to protein kinases A and C (PKA, PKC). Samples were obtained from postmortem brain tissue (Brodmann area 10) from 20 persons with a history of MDD and 20 matched controls as determined by a retrospective diagnostic evaluation obtained from family members. Levels of 5-HT(1A), 5-HT(2A), and 5-HT(2C) receptor were quantitated via Western blot analyses. Basal and stimulated PKA and PKC activity were also determined. The depressed samples showed significantly increased 5-HT(2A) receptor abundance relative to controls, but no differences in 5-HT(1A) or 5-HT(2C) receptors. Basal and cyclic AMP-stimulated PKA activity was also reduced in the depressed sample; PKC activity was not different between groups. 5-HT(2A) receptor availability was significantly inversely correlated with PKC activity in controls, but with PKA activity in the depressed sample. Increased 5-HT(2A) receptor abundance and decreased PKA activity in the depressed sample are consistent with prior reports. The correlation of 5-HT(2A) receptor levels with PKA activity in the depressed group suggests that abnormalities of 5-HT(2A) receptor abundance may depend on receptor uncoupling and heterologous regulation by PKA.

Increased serotonin 2C receptor mRNA editing: a possible risk factor for suicide

Suicide is a major public health problem with approximately 1 million victims each year worldwide. Up to 90% of adults who commit suicide have at least one psychiatric diagnosis such as major depression, bipolar disorder (BPD), schizophrenia (SZ), substance abuse or dependence. A question that has remained unanswered is whether the biological substrates of suicide are distinct from those of the psychiatric disorders in which it occurs. The serotonin 2C receptor (5-HT 2C R) has been implicated in depression and suicide. We, therefore, compared the frequencies of its mRNA editing variants in postmortem prefrontal cortical specimens from subjects who committed suicide or who died from other causes. All suicides occurred in the context of either SZ or BPD. The non-suicide cases included subjects with either SZ or BPD as well as subjects with no psychiatric diagnosis. We identified 5-HT 2CR mRNA editing variations that were associated with suicide but not with the comorbid psychiatric diagnoses, and were not influenced by demographic characteristics (age and sex) and alcohol or drug use. These variations consisted of a significant increase in the pool of mRNA variants (ACD and ABCD) that encode one of the most prevalent and highly edited isoforms of 5-HT 2C R, that is, VSV (Val156-Ser158-Val160). Because the VSV isoform of 5-HT 2C R exhibits low functional activity, an increase in its expression frequency may significantly influence the serotonergic regulation of the brain. Thus, at least in patients with SZ or BPD, overexpression of the VSV isoform in the prefrontal cortex may represent an additional risk factor for suicidal behavior.

Frontolimbic serotonin 2A receptor binding in healthy subjects is associated with personality risk factors for affective disorder

BACKGROUND

Serotonergic dysfunction has been associated with affective disorders. High trait neuroticism, as measured on personality inventories, is a risk factor for major depression. In this study we investigated whether neuroticism is associated with serotonin 2A receptor binding in brain regions of relevance for affective disorders.

METHODS

Eighty-three healthy volunteers completed the standardized personality questionnaire NEO-PI-R (Revised NEO Personality Inventory) and underwent [(18)F]altanserin positron emission tomography imaging for assessment of serotonin 2A receptor binding. The correlation between the neuroticism score and frontolimbic serotonin 2A receptor binding was evaluated by multiple linear regression analysis with adjustment for age and gender.

RESULTS

Neuroticism correlated positively with frontolimbic serotonin 2A receptor binding [r(79) = .24, p = .028]. Post hoc analysis of the contributions from the six constituent traits of neuroticism showed that the correlation was primarily driven by two of them: vulnerability and anxiety. Indeed, vulnerability, defined as a person's difficulties in coping with stress, displayed the strongest positive correlation, which remained significant after correction for multiple comparisons (r = .35, p = .009).

CONCLUSIONS

In healthy subjects the personality dimension neuroticism and particularly its constituent trait, vulnerability, are positively associated with frontolimbic serotonin 2A binding. Our findings point to a neurobiological link between personality risk factors for affective disorder and the serotonergic transmitter system and identify the serotonin 2A receptor as a biomarker for vulnerability to affective disorder.

Elevated cytokine expression in the orbitofrontal cortex of victims of suicide

OBJECTIVE

Based on the reported association between cytokines with depression and suicide, and evidence of increased markers of inflammation in the brain of suicide victims, the present study examined the expression of cytokines in the orbitofrontal cortex of suicide victims.

METHOD

In a postmortem sample obtained from the Brodman area 11 of suicides (n = 34) and controls (n = 17), real-time RT-PCR was used to compare the expression of mRNA species for tumor necrosis factor-alpha (TNF-alpha), interleukin (IL)-1 beta, 4, 5, 6, and 13.

RESULTS

Increased expression of IL-4 was found in women suicide victims and IL-13 in men suicide victims. Elevated but not significant cytokine expression was also observed for TNF-alpha in women suicide victims.

CONCLUSION

To our knowledge, these results provide the first evidence of the presence of mRNA transcripts of type 2 T-helper cytokines in the human orbitofrontal cortex and their increased expression in the brain of suicides.

5HT2A receptor binding is increased in borderline personality disorder

BACKGROUND

Postmortem studies in suicide victims demonstrate an increase in the number of post-synaptic 5-HT(2A) receptor binding sites in ventral lateral and orbital frontal cortex. Diminished metabolic responses to serotonergic activation are noted in these areas in impulsive subjects with borderline personality disorder (BPD), a group at high risk for suicidal behaviors. We examined 5HT(2A) receptor binding potential (BP) in impulsive subjects with BPD, with positron emission tomography neuroimaging with [(18)F] altanserin.

METHODS

Fourteen female subjects with BPD were assessed for Axis I comorbidity, depressed mood, impulsivity, aggression, suicidality, childhood abuse, and compared with 11 healthy female control subjects. The 5HT(2A) receptor binding was evaluated in prefrontal cortex, anterior cingulate, hippocampus, temporal lobe, occipital cortex, and thalamus. Data were analyzed with Logan graphical analysis and a four-compartment (4C) model.

RESULTS

Hippocampal 5HT(2A) receptor binding was significantly increased in BPD subjects compared with control subjects in both Logan and 4C analyses, covarying for age. Hippocampal BP values were related to comorbid major depressive episode, with highest values found in non-depressed BPD subjects and lowest in healthy control subjects. The BP values were not related to depressed mood, impulsivity, aggression, suicidality, or childhood abuse.

CONCLUSIONS

5HT(2A) receptor binding is increased in the hippocampus of BPD subjects independent of depressed mood, impulsivity, aggression, suicidality, or childhood abuse. Dysregulation of serotonergic function in hippocampus might contribute to affective and behavioral symptoms in BPD.

Molecular genetic findings in suicidal behavior: what is beyond the serotonergic system?

Various studies provide consistent evidence for a genetic component in suicidal behavior. First molecular genetic studies concentrated on genes of the serotonergic system based on the biochemical evidence that serotonergic neurotransmission is implicated in this behavior. Furthermore, genes of the dopaminergic and noradrenergic neurotransmitter systems have also been the subjects of investigations in this context. Some epidemical and clinical studies showed that low serum cholesterol levels are associated with suicidal behavior and genes involved in these pathways have been investigated. Microarray experiments provide the possibility of genome-wide gene expression analysis and help to investigate associated molecular mechanisms. The aim of this article is to review molecular genetic studies in suicidal behavior and to emphasize findings on new genes.

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.

Brain SPECT imaging and whole-body biodistribution with [123I]ADAM — a serotonin transporter radiotracer in healthy human subjects

INTRODUCTION

[(123)I]-2-((2-((dimethylamino)methyl)phenyl)thio)-5-iodophenylamine ([(123)I]ADAM), a novel radiotracer, has promising application in the imaging of the serotonin transporter (SERT) in the human brain. In this study, the optimal scanning time for acquiring brain single photon emission computed tomography (SPECT) images was determined by performing dynamic SPECT studies at intervals from 0 to 6 h postinjection of [(123)I]ADAM. Additionally, radiation-absorbed doses were determined for three healthy human subjects using attenuation-corrected images.

METHODS

Twelve subjects were randomized into one of three study groups as follows: whole-body distribution imaging (n=3), dynamic SPECT imaging (n=3) and brain SPECT imaging (n=6). The radiation-absorbed dose was calculated using MIRDOSE 3.0 software with attenuation-corrected data. The specific binding (SB) ratio of the brain stem was measured from dynamic SPECT images to determine the optimal scanning time.

RESULTS

Dynamic SPECT images showed that the SB of the brain stem gradually increased to a maximum 4 h postinjection. Single photon emission computed tomography images at 4 h postinjection showed a high uptake of the radiotracer (SB) in the hypothalamus (1.40+/-0.12), brain stem (1.44+/-0.16), pons (1.13+/-0.14) and medial temporal lobe (0.59+/-0.10). The mean adult male value of effective dose was 3.37 x 10(-2) mSv/MBq with a 4.8-h urine-voiding interval. Initial high uptake in SERT-rich sites was demonstrated in the lung and brain. A prominent washout of the radiotracer from the lung further increased brain radioactivity that reached a peak value of 5.03% of injected dose 40 min postinjection.

CONCLUSIONS

[(123)I]ADAM is a promising radiotracer for SPECT imaging of SERT in humans with acceptable dosimetry and high uptake in SERT-rich regions. Brain SPECT images taken within 4 h following injection show optimal levels of radiotracer uptake in known SERT sites. However, dynamic changes in lung SERT distribution must be carefully evaluated.

Executive functioning in depressed patients with suicidal ideation

OBJECTIVE

Suicidal thinking has been associated with cognitive rigidity, however, not all depressed patients contemplate suicide. Therefore, we hypothesized that compared with depressed subjects without suicidal ideation, depressed individuals with suicidal ideation would display poorer performance on measures of executive functioning that involve mental flexibility.

METHOD

In-patients with a current major depressive episode who had no current suicidal ideation (n=28) were compared with those who had current suicidal ideation (n=5) on measures of executive functioning and two neurocognitive tests that predominantly assess non-frontal regions.

RESULTS

Compared with non-suicidal depressed patients, depressed suicidal patients performed significantly worse on several measures of executive functioning after controlling for age, IQ, severity of depression and prior suicide attempts. The two groups performed similarly on tests that predominantly assess non-frontal regions.

CONCLUSION

Depressed individuals contemplating suicide have cognitive rigidity, which does not appear to be a global brain dysfunction. Suicidal mental states may result from dysfunctional executive decision-making that is associated with the frontal lobe.

Autoradiographic distribution of serotonin transporters and receptor subtypes in human brain

Several neurochemical in vitro and in vivo imaging studies have been aimed at characterizing the localization of serotonin receptors and transporters in the human brain. In this study, a detailed comparison of the distribution of a number of 5-HT receptor subtypes and the 5-HT transporter was carried out in vitro using human postmortem brain tissue. Anatomically adjacent whole hemisphere sections were incubated with specific radioligands for the 5-HT(1A), 5-HT(1B), 5-HT(2A), 5-HT(4) receptors and the 5-HT transporter. The autoradiograms revealed different laminar and regional distribution patterns in the isocortex, where 5-HT(1A) and 5-HT(4) receptor binding showed highest densities in superficial layers and 5-HT(2A) receptor binding was most abundant in middle layers. In cortical regions, 5-HT transporters were concentrated to several limbic lobe structures (posterior uncus, entorhinal, cingulate, insular and temporal polar regions). 5-HT(1A) receptor densities were also high in limbic cortical regions (hippocampus, posterior entorhinal cortex, and subcallosal area) compared to the isocortex. Subregionally different distribution patterns were observed in the basal ganglia with a trend toward higher levels in ventral striatal (5-HT(1B) receptors) and pallidal (5-HT transporters and 5-HT(1B) receptors) regions. The localization in regions belonging to limbic cortico-striato-pallido-thalamic circuits is in line with the documented role of 5-HT in modulation of mood and emotion, and the suggested involvement of this system in pathophysiology of various psychiatric disorders. The qualitative and quantitative information reported in this study might provide important complements to in vivo neuroimaging studies of the 5-HT system.

Postmortem serotonin (5-HT) concentrations in the cerebrospinal fluid of medicolegal cases

In a medicolegal study the postmortem serotonin (5-HT) cerebrospinal fluid (CSF) concentrations were determined in routine autopsies using a high performance liquid chromatographic procedure with electrochemical detection. There was no correlation between 5-HT concentrations and age, sex or blood alcohol concentration using a postmortem delay < or = 3 days. In suicides the suboccipital CSF concentrations were significantly decreased compared to the levels measured in the control group (8.55+/-5.99 ng/ml versus 20.15+/-13.56 ng/ml). Additionally, a decrease of 5-HT was found in the suboccipital CSF of opiate fatalities (15.56+/-13.52 ng/ml). The results support the hypothesis that decreased 5-HT concentrations in the CSF are characteristic in suicides. However, due to a rather broad overlapping of values between suicides and controls the results failed to define a possible cut-off level in the 5-HT CSF concentration to distinguish between a suicidal and a non-suicidal incident.

Altered 5-HT(2A) receptor binding after recovery from bulimia-type anorexia nervosa: relationships to harm avoidance and drive for thinness

Several lines of evidence suggest that a disturbance of serotonin neuronal pathways may contribute to the pathogenesis of anorexia nervosa (AN) and bulimia nervosa (BN). This study applied positron emission tomography (PET) to investigate the brain serotonin 2A (5-HT(2A)) receptor, which could contribute to disturbances of appetite and behavior in AN and BN. To avoid the confounding effects of malnutrition, we studied 10 women recovered from bulimia-type AN (REC AN-BN, > 1 year normal weight, regular menstrual cycles, no binging, or purging) compared with 16 healthy control women (CW) using PET imaging and a specific 5-HT(2A) receptor antagonist, [18F]altanserin. REC AN-BN women had significantly reduced [18F]altanserin binding potential relative to CW in the left subgenual cingulate, the left parietal cortex, and the right occipital cortex. [18F]altanserin binding potential was positively related to harm avoidance and negatively related to novelty seeking in cingulate and temporal regions only in REC AN-BN subjects. In addition, REC AN-BN had negative relationships between [18F]altanserin binding potential and drive for thinness in several cortical regions. In conclusion, this study extends research suggesting that altered 5-HT neuronal system activity persists after recovery from bulimia-type AN, particularly in subgenual cingulate regions. Altered 5-HT neurotransmission after recovery also supports the possibility that this may be a trait-related disturbance that contributes to the pathophysiology of eating disorders. It is possible that subgenual cingulate findings are not specific for AN-BN, but may be related to the high incidence of lifetime major depressive disorder diagnosis in these subjects.

Brain serotonin 1A receptor binding in bulimia nervosa

BACKGROUND

Selective serotonin reuptake inhibitors (SSRIs) are the first choice for the pharmacologic treatment of bulimia nervosa, but there are no published data on the putative altered serotonin (5-HT) receptor characteristics in patients with bulimia. Experimental studies suggest that the therapeutic antidepressant effect of SSRIs is mediated via 5-HT(1A) receptors. The aim of this study was to measure brain 5-HT(1A) receptor binding among nonmedicated patients with bulimia nervosa.

METHODS

Positron emission tomography (PET) with a selective 5-HT(1A) ligand, [11C]WAY-100635, was performed on eight unmedicated patients with bulimia and 10 healthy comparison subjects.

RESULTS

The binding potential values were greater in patients than in control subjects in all brain regions studied. The most robust differences were observed in the angular gyrus, the medial prefrontal cortex, and the posterior cingulate cortex.

CONCLUSIONS

These results suggest that brain 5-HT(1A) receptor binding is increased in several cortical areas in patients with bulimia nervosa during their state of impulsive binge eating.