Prefrontal 5-HT2a receptor binding index, hopelessness and personality characteristics in attempted suicide

Alterations of BDNF, mGluR5, Homer1a, p11 and excitatory/inhibitory balance in corticolimbic brain regions of suicide decedents

BACKGROUND

Developing biological based approaches for preventing suicide has become a priority. In recent years, there has been a surge in studies investigating the role of the glutamatergic system in suicide, although it remains unclear.

METHODS

We evaluated changes in the gene expression of the metabotropic glutamate receptor 5 (mGluR5) and its scaffolding proteins Homer1a and p11 in the dorsolateral prefrontal cortex (DLPFC), amygdala (AMY), and hippocampus (HIP) of 28 suicide decedents (S) (with no clinical psychiatric history or treatment with anxiolytics or antidepressants) and 26 controls (C) by real-time PCR (qPCR). Indeed, we measured BDNF gene expression and VGluT1 and VGAT immunoreactivities in the HIP by qPCR and immunohistochemistry, respectively. Cases and controls matched for age (C: 48.6 ± 11.6 years; S: 46.9 ± 14.5 years) and postmortem interval (PMI; C: 20.1 ± 13h; S: 16.9 ± 5h).

RESULTS

In DLPFC, S had lower p11 gene expression levels, but no differences were found in mGluR5 or Homer1a. In the AMY and HIP, mGluR5 and Homer1a were increased, p11 and BDNF were reduced. In the HIP, there were less VGAT-ir and more VGluT1-ir.

LIMITATIONS

Future studies are necessary to evaluate protein levels, and determine the cell types and potential compensatory mechanisms in a larger sample including S diagnosed with psychiatric disorders, females and different ethnicities.

CONCLUSIONS

This study identified significant alterations in mGluR5, Homer1a, p11, BDNF and excitatory/inhibitory balance in corticolimbic brain areas of S. These results further characterize the biological basis of suicide, contributing to the identification of potential biomarkers for suicide prevention.

Temperament and adolescent suicide attempts: a case-control study with multi-ethnic Asian adolescents

BACKGROUND

Suicide is the leading cause of death for adolescents in several parts of Asia, including Singapore. This study examines the relationship between temperament and youth suicide attempts in a sample of multi-ethnic Singaporean adolescents.

METHODS

A case-control design compared 60 adolescents (Mage = 16.40, SDage = 2.00) with a recent suicide attempt (i.e., past 6 months) with 58 adolescents (Mage = 16.00, SDage = 1.68) without any history of suicide attempts. Presence of suicide attempts was established using the semi-structured interviewer-administered Columbia Suicide Severity Rating Scale. Participants also completed self-report measures on temperament traits, psychiatric diagnoses, stressful life events, and perceived parental rejection in an interview-based format.

RESULTS

Psychiatric comorbidity, recent stressful life events, perceived parental rejection, and all five "difficult temperament" traits, were significantly overrepresented among adolescent cases relative to healthy controls. Adjusted logistic regression models revealed significant associations between suicide attempt, MDD comorbidity (OR: 10.7, 95% Cl: (2.24-51.39)), "negative mood" trait (OR: 1.12-1.18, 95% Cl: (1.00-1.27)), and the interaction term of "positive mood" and "high adaptability" traits (OR: 0.943 - 0.955, 95% Cl: (0.900 - 0.986)). Specifically, "positive mood" predicted lower likelihood of a suicide attempt when "adaptability" was high (OR: 0.335 - 0.342, 95% Cl: (0.186 - 0.500)) but not low (OR: 0.968 - 0.993, 95% Cl: (0.797 - 1.31)).

CONCLUSION

Temperament screening may be important to identify adolescents at higher or lower risk of suicide at an early stage. More longitudinal and neurobiological research converging on these temperament findings will be helpful in ascertaining temperament screening as an effective suicide prevention methodology for adolescents.

Low doses of lysergic acid diethylamide (LSD) increase reward-related brain activity

Renewed interest in classic psychedelics as treatments for psychiatric disorders warrants a deeper understanding of their neural mechanisms. Single, high doses of psychedelic drugs have shown promise in treating depressive disorders, perhaps by reversing deficits in reward processing in the brain. In addition, there are anecdotal reports that repeated ingestion of low doses of LSD, or "microdosing", improve mood, cognition, and feelings of wellbeing. However, the effects of low doses of classic psychedelics on reward processing have not been studied. The current study examined the effects of two single, low doses of LSD compared to placebo on measures of reward processing. Eighteen healthy adults completed three sessions in which they received placebo (LSD-0), 13 μg LSD (LSD-13) and 26 μg LSD (LSD-26) in a within-subject, double-blind design. Neural activity was recorded while participants completed the electrophysiological monetary incentive delay task. Event-related potentials were measured during feedback processing (Reward-Positivity: RewP, Feedback-P3: FB-P3, and Late-Positive Potential: LPP). Compared to placebo, LSD-13 increased RewP and LPP amplitudes for reward (vs. neutral) feedback, and LSD-13 and LSD-26 increased FB-P3 amplitudes for positive (vs. negative) feedback. These effects were unassociated with most subjective measures of drug effects. Thus, single, low doses of LSD (vs. placebo) increased three reward-related ERP components reflecting increased hedonic (RewP), motivational (FB-P3), and affective processing of feedback (LPP). These results constitute the first evidence that low doses of LSD increase reward-related brain activity in humans. These findings may have important implications for the treatment of depressive disorders.

Psychedelic-Induced Serotonin 2A Receptor Downregulation Does Not Predict Swim Stress Coping in Mice

Serotoninergic psychedelics such as psilocybin have been reported to elicit a long-lasting reduction in depressive symptoms. Although the main target for serotoninergic psychedelics, serotonin type 2A receptor (5-HT_2A), has been established, the possible mechanism of the antidepressant action of psychedelics remains unknown. Using the mouse forced swim test model, we examined whether the administration of the synthetic serotoninergic psychedelic 2,5-dimethoxy-4-iodoamphetamine (DOI) would modulate 5-HT_2A receptor levels in the medial prefrontal cortex (mPFC) and revert stress-induced changes in behavior. Mice subjected to swim stress developed a passive stress-coping strategy when tested in the forced swim test 6 days later. This change in behavior was not associated with the hypothesized increase in 5-HT_2A receptor-dependent head twitch behaviors or consistent changes in 5-HT_2A receptor levels in the mPFC. When DOI was administered 1 day before the forced swim test, a low dose (0.2 mg/kg i.p.) unexpectedly increased immobility while a high dose (2 mg/kg i.p.) had no significant effect on immobility. Nevertheless, DOI evoked a dose-dependent decrease in 5-HT_2A levels in the mPFC of mice previously exposed to swim stress. Our findings do not support the hypothesis that the downregulation of 5-HT_2A receptors in the mPFC contributes to the antidepressant-like properties of serotoninergic psychedelics.

The associations between suicide-related behaviors, prefrontal dysfunction in emotional cognition, and personality traits in mood disorders

Suicide is a serious public health problem, and it is urgent to identify biomarkers associated with suicide to prevent it. We aimed to clarify the association across suicidal behavior, personality traits, and brain activation by emotional stimulation tasks using near-infrared spectroscopy (NIRS) in patients with mood disorders. 11 mood disorder patients with a history of suicide attempt (MDSA), 18 mood disorder patients with no history of suicide attempt (MDNSA), and 17 healthy individuals were studied. The MDSA patients showed significantly high impulsivity and hopeless compared to healthy subjects, great response to the thread word task in the orbitofrontal cortex (OFC) and dorsolateral prefrontal cortex (DLPFC) compared to MDNSA patients, and the significant correlation between the personality traits and brain activation. The MDNSA did not show the trend. The results suggest that the personality traits and the activation of OFC and DLPFC during the negative emotional cognitive stimuli is associated with suicidal behavior, indicating the findings are involved in the pathophysiology of suicidality in mood disorders.

Differences in temperament and character inventory (TCI) profile between suicidal and nonsuicidal psychiatric outpatients

The purpose of this study was to identify personality traits associated with suicide attempt in a clinical sample. Temperament and character inventory (TCI) profiles of 759 patients who met the inclusion criteria among 1000 randomly selected hospital records collected. Of these 759 patients, 103 had a history of at least 1 actual suicide attempt (suicidal group) whereas 656 had no such history (nonsuicidal group). The suicidal group showed higher scores of novelty seeking (mean ± SD: 36.1 ± 1.2 vs 33.3 ± 0.5; P = .026) and harm avoidance (57.1 ± 1.5 vs 53.0 ± 0.6; P = .01) but lower scores of self-directedness (27.5 ± 1.5 vs 34.4 ± 0.6; P < .001) than the nonsuicidal group. Higher novelty seeking (OR [95% CI]: 1.031 [1.008-1.054]; P = .007) and lower self-directedness: 0.955 [0.927-0.983]; P = .002 were also associated with suicide attempts in the analysis of 7 personality scales. These findings suggest that patients who attempt suicide differ from nonattempters in terms of personality traits, especially in novelty seeking (NS), harm avoidance (HA), and self-directedness (SD). It is noteworthy that this study contains data from actual visits to the emergency room to evaluate suicide attempts. Abbreviations: CO = cooperativeness, Ha = harm avoidance, NS = novelty seeking, PS = persistence, RD = reward dependence, SD = self-directedness, ST = self-transcendence, TCI = temperament and character inventory.

Radiotracers for the Central Serotoninergic System

This review lists the most important radiotracers described so far for imaging the central serotoninergic system. Single-photon emission computed tomography and positron emission tomography radiotracers are reviewed and critically discussed for each receptor.

Psilocybin, a Naturally Occurring Indoleamine Compound, Could Be Useful to Prevent Suicidal Behaviors

The available interventions for people who are at risk of suicide have limited efficacy. Recently, research on new mental health treatments has started to consider psychedelic compounds, particularly psilocybin, a molecule with a few thousand years of history of use in human societies. The possible effects of psilocybin on suicidal ideation and behaviors have not been specifically studied yet; however, the current knowledge on the suicidal process and the available data on es/ketamine suggest that psylocibin could be used to modulate the thoughts and behavioral patterns in individuals who are at risk of suicidal behaviors. Here, we summarize the available evidence on the possible mechanisms underlying psilocybin positive effects on suicide risk. Major pathways related to suicidal behaviors that might be modulated by psylocibin include serotonin receptors. Specifically, psylocibin directly stimulates the serotonin 2A receptor (5HT_2A), targeting the inflammatory and oxidative stress pathways and leading to a rapid increase in brain plasticity and inflammation suppression and increases in cognitive flexibility, spirituality, and empathy. We also present preliminary epidemiological data and provide a rationale for studying psilocybin in individuals with suicidal ideation or who are at risk of suicidal behaviors. This review presents a framework to understand the basis for psilocybin use in individuals who are at risk of suicidal behaviors and calls for clinical studies.

Temperament, character and decision-making characteristics of patients with major depressive disorder following a suicide attempt

BACKGROUND

Multiple psychological factors of suicidal behaviour have been identified so far; however, little is known about state-dependent alterations and the interplay of the most prominent components in a suicidal crisis. Thus, the combined effect of particular personality characteristics and decision-making performance was observed within individuals who recently attempted suicide during a major depressive episode.

METHODS

Fifty-nine medication-free major depressed patients with a recent suicide attempt (within 72 h) and forty-five healthy control individuals were enrolled in this cross-sectional study. Temperament and character factors, impulsivity and decision-making performance were assessed. Statistical analyses aimed to explore between-group differences and the most powerful contributors to suicidal behaviour during a depressive episode.

RESULTS

Decision-making and personality differences (i.e. impulsivity, harm avoidance, self-directedness, cooperativeness and transcendence) were observed between the patient and the control group. Among these variables, decision-making, harm avoidance and self-directedness were shown to have the strongest impact on a recent suicide attempt of individuals with a diagnosis of major depressive disorder according to the results of the binary logistic regression analysis. The model was significant, adequately fitted the data and correctly classified 79.8% of the cases.

CONCLUSIONS

The relevance of deficient decision-making, high harm avoidance and low self-directedness was modelled in the case of major depressed participants with a recent suicide attempt; meaning that these individuals can be described with the myopia for future consequences, a pessimistic, anxious temperament; and a character component resulting in the experience of aimlessness and helplessness. Further studies that use a within-subject design should identify and confirm additional characteristics specific to the suicidal mind.

Pancreatic β-Cell Senescence: Mechanisms and Association with Diabetes

Senescence occurs as a part of the cellular response to different stressors. With increasing age, continuous exposure to stressors leads to age-induced senescence. Pancreatic β-cell proliferation and glucose homeostasis also decrease with age, which results in a decrease in β cell mass and, eventually, the possible development of diabetes. This process is mediated through impaired cell cycle regulators, along with specific increases in cell cycle inhibitors, telomere shortening, and defective DNA repair mechanisms. Diabetes contributes to β-cell senescence through hyperglycaemia, dyslipidaemia, oxidative stress, and inflammation. β cells isolated from patients with Type 2 diabetes mellitus have been shown to have senescence markers, such as senescence-associated secretory phenotype genes and β-galactosidase. In this paper, the authors discuss the mechanisms of cellular senescence, how senescence is impacted by the diabetic microenvironment, and the possible mechanisms and factors contributing to β-cell senescence.

Hostility in medication-resistant major depression and comorbid generalized anxiety disorder is related to increased hippocampal-amygdala 5-HT2A receptor density

Major depressive disorder (MDD) and generalized anxiety disorder (GAD) are severe and difficult-to-treat psychiatric illnesses with high rates of comorbidity. Although both disorders are treated with serotonergic based psychotropic agents, little is known on the influence of the serotonergic neurotransmitter system on the occurrence of comorbid GAD when clinically depressed. To investigate this poorly understood clinical question, we examined the involvement of frontolimbic post-synaptic 5-HT_2A receptors in 20 medication-resistant depressed (MRD) patients with half of them diagnosed with comorbid GAD with ¹²³I-5-I-R91150 SPECT. To explore whether 5-HT_2A receptor-binding indices (BI) associated with comorbid GAD could be related to distinct psychopathological symptoms, all were assessed with the symptom Checklist-90-Revised (SCL-90-R). MRD patients with comorbid GAD displayed significantly higher 5-HT_2A receptor BI in the hippocampal-amygdala complex, compared to MRD patients without GAD. Correlation analyses revealed that the 5-HT_2A receptor BI in these areas were significantly related to the SCL-90-R subscale hostility (HOS), especially for those MRD patients with comorbid GAD. Comorbid MRD-GAD may be characterized with increased hippocampal-amygdala 5-HT_2A receptor BI which could represent enhanced levels in hostility in such kinds of patients. Adapted psychotherapeutic interventions may be warranted.

Reward Contributions to Serotonergic Functions

The brain serotonin systems participate in numerous aspects of reward processing, although it remains elusive how exactly serotonin signals regulate neural computation and reward-related behavior. The application of optogenetics and imaging techniques during the last decade has provided many insights. Here, we review recent progress on the organization and physiology of the dorsal raphe serotonin neurons and the relationships between their activity and behavioral functions in the context of reward processing. We also discuss several interesting theories on serotonin's function and how these theories may be reconciled by the possibility that serotonin, acting in synergy with coreleased glutamate, tracks and calculates the so-called beneficialness of the current state to guide an animal's behavior in dynamic environments.

Innovative Molecular Imaging for Clinical Research, Therapeutic Stratification, and Nosography in Neuroscience

Over the past few decades, several radiotracers have been developed for neuroimaging applications, especially in PET. Because of their low steric hindrance, PET radionuclides can be used to label molecules that are small enough to cross the blood brain barrier, without modifying their biological properties. As the use of 11C is limited by its short physical half-life (20 min), there has been an increasing focus on developing tracers labeled with 18F for clinical use. The first such tracers allowed cerebral blood flow and glucose metabolism to be measured, and the development of molecular imaging has since enabled to focus more closely on specific targets such as receptors, neurotransmitter transporters, and other proteins. Hence, PET and SPECT biomarkers have become indispensable for innovative clinical research. Currently, the treatment options for a number of pathologies, notably neurodegenerative diseases, remain only supportive and symptomatic. Treatments that slow down or reverse disease progression are therefore the subject of numerous studies, in which molecular imaging is proving to be a powerful tool. PET and SPECT biomarkers already make it possible to diagnose several neurological diseases in vivo and at preclinical stages, yielding topographic, and quantitative data about the target. As a result, they can be used for assessing patients' eligibility for new treatments, or for treatment follow-up. The aim of the present review was to map major innovative radiotracers used in neuroscience, and explain their contribution to clinical research. We categorized them according to their target: dopaminergic, cholinergic or serotoninergic systems, β-amyloid plaques, tau protein, neuroinflammation, glutamate or GABA receptors, or α-synuclein. Most neurological disorders, and indeed mental disorders, involve the dysfunction of one or more of these targets. Combinations of molecular imaging biomarkers can afford us a better understanding of the mechanisms underlying disease development over time, and contribute to early detection/screening, diagnosis, therapy delivery/monitoring, and treatment follow-up in both research and clinical settings.

Selective vulnerability of dorsal raphe-medial prefrontal cortex projection neurons to corticosterone-induced hypofunction

Glucocorticoid hormones and serotonin (5-HT) are strongly associated with the development and treatment of depression, respectively. Glucocorticoids regulate the function of serotonergic neurons in the dorsal raphe nucleus (DR), which are the major source of 5-HT to the forebrain. DR 5-HT neurons are electrophysiologically heterogeneous, though whether this phenotypic variation aligns with specific brain functions or neuropsychiatric disease states is largely unknown. The goal of this work was to determine if chronic exogenous glucocorticoid administration differentially affects the electrophysiological profile of DR neurons implicated in the regulation of emotion versus visual sensation by comparing properties of cells projecting to medial prefrontal cortex (mPFC) versus lateral geniculate nucleus (LGN). Following retrograde tracer injection into mPFC or LGN, male Sprague-Dawley rats received daily injections of corticosterone (CORT) for 21 days, after which whole-cell patch clamp recordings were made from retrogradely labeled DR neurons. CORT-treatment significantly increased the action potential half-width of LGN-projecting DR neurons, but did not significantly affect the firing frequency or excitatory postsynaptic currents of these cells. CORT-treatment significantly reduced the input resistance, evoked firing frequency, and spontaneous excitatory postsynaptic current frequency of mPFC-projecting DR neurons, indicating a concurrent reduction of both intrinsic excitability and excitatory drive. Our results suggest that the serotonergic regulation of cognitive and emotional networks in the mPFC may be more sensitive to the effects of glucocorticoid excess than visual sensory circuits in the LGN and that reduced 5-HT transmission in the mPFC may underlie the association between glucocorticoid excess and depression.

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.

Alterations in Gene and Protein Expression of Cannabinoid CB2 and GPR55 Receptors in the Dorsolateral Prefrontal Cortex of Suicide Victims

Recent studies point to the cannabinoid CB2 receptors (CB2r) and the non-cannabinoid receptor GPR55 as potential key targets involved in the response to stress, anxiety, and depression. Considering the close relationship between neuropsychiatric disorders and suicide, the purpose of this study was to evaluate the potential alterations of CB2r and GPR55 in suicide victims. We analyzed gene and protein expression of both receptors by real-time PCR and western blot, respectively, in the dorsolateral prefrontal cortex (DLPFC) of 18 suicide victims with no clinical psychiatric history or treatment with anxiolytics or antidepressants, and 15 corresponding controls. We used in situ proximity ligation assay to evaluate whether the receptors formed heteromeric complexes and to determine the expression level of these heteromers, also assessing the co-expression of heteromers in neurons, astroglia, or microglia cells. CB2r and GPR55 gene expressions were significantly lower (by 33 and 41%, respectively) in the DLPFC of suicide cases. CB2r protein expression was higher, as were CB2-GPR55 heteroreceptor complexes. The results also revealed the presence of CB2-GPR55 receptor heteromers in both neurons and astrocytes, whereas microglial cells showed no expression. We did not observe any significant alterations of GPR55 protein expression. Additional studies will be necessary to evaluate if these alterations are reproducible in suicide victims diagnosed with different psychiatric disorders. Taken together, the results suggest that CB2r and GPR55 may play a relevant role in the neurobiology of suicide.

The association between hope and mortality in homebound elders

OBJECTIVE

Despite high rates of mortality and depression, there is limited knowledge of how depressive symptoms, especially feeling of hopefulness, affect mortality in the homebound elderly.

METHODS

We conducted a secondary analysis of data from a community sample of 1034 adults, age 60 years and older. The Center for Epidemiologic Studies Depression Scale was used to evaluate the mood symptoms and feeling of hopefulness at baseline. The death data were collected within an 8-year follow-up period. Analysis of variance and Chi-square were used to compare the clinical conditions among the groups of individuals who feel hopeful always, sometimes, and rarely. Logistic regression was used to explore the association between the hopefulness about the future and mortality as an outcome.

RESULTS

In the 8-year follow-up period, frequency of feeling hopeful, but not other individual depressive symptoms, was associated with mortality rate. The mortality rate among those who always, sometimes, and rarely felt hopeful were 21.6%, 26.4%, and 35.7%, respectively (P = 0.002). Logistic regression also confirmed that individuals who rarely feel hopeful had higher odds of decease within the 8-year follow-up period than those who always felt hopeful (OR = 1.74, CI = 1.14-2.65) after adjusting for age and medical conditions.

CONCLUSIONS

Baseline hopefulness predicts mortality outcome among the homebound elderly in the community. Identifying individuals who are depressed with hopelessness in the elderly and providing early intervention may improve the mortality rate. Copyright © 2017 John Wiley & Sons, Ltd.

Neurochemical differences between target-specific populations of rat dorsal raphe projection neurons

Serotonin (5-HT)-containing neurons in the dorsal raphe (DR) nucleus project throughout the forebrain and are implicated in many physiological processes and neuropsychiatric disorders. Diversity among these neurons has been characterized in terms of their neurochemistry and anatomical organization, but a clear sense of whether these attributes align with specific brain functions or terminal fields is lacking. DR 5-HT neurons can co-express additional neuroactive substances, increasing the potential for individualized regulation of target circuits. The goal of this study was to link DR neurons to a specific functional role by characterizing cells according to both their neurotransmitter expression and efferent connectivity; specifically, cells projecting to the medial prefrontal cortex (mPFC), a region implicated in cognition, emotion, and responses to stress. Following retrograde tracer injection, brainstem sections from Sprague-Dawley rats were immunohistochemically stained for markers of serotonin, glutamate, GABA, and nitric oxide (NO). 98% of the mPFC-projecting serotonergic neurons co-expressed the marker for glutamate, while the markers for NO and GABA were observed in 60% and less than 1% of those neurons, respectively. To identify potential target-specific differences in co-transmitter expression, we also characterized DR neurons projecting to a visual sensory structure, the lateral geniculate nucleus (LGN). The proportion of serotonergic neurons co-expressing NO was greater amongst cells targeting the mPFC vs LGN (60% vs 22%). The established role of 5-HT in affective disorders and the emerging role of NO in stress signaling suggest that the impact of 5-HT/NO co-localization in DR neurons that regulate mPFC circuit function may be clinically relevant.

New Trends and Current Status of Positron-Emission Tomography and Single-Photon-Emission Computerized Tomography Radioligands for Neuronal Serotonin Receptors and Serotonin Transporter

The critical role of serotonin (5-hydroxytryptamine; 5-HT) and its receptors (5-HTRs) in the pathophysiology of diverse neuropsychiatric and neurodegenerative disorders render them attractive diagnostic and therapeutic targets for brain disorders. Therefore, the in vivo assessment of binding of 5-HT receptor ligands under a multitude of physiologic and pathologic scenarios may support more-accurate identification of disease and its progression and the patient's response to therapy as well as the screening of novel therapeutic strategies. The present Review aims to focus on the current status of radioligands used for positron-emission tomography (PET) and single-photon-emission computerized tomography (SPECT) imaging of human brain serotonin receptors. We further elaborate upon and emphasize the attributes that qualify a radioligand for theranostics on the basis of its frequency of use in clinics, its benefit to risk assessment in humans, and its continuous evolution, along with the major limitations.

Serotonin and brain function: a tale of two receptors

Previous attempts to identify a unified theory of brain serotonin function have largely failed to achieve consensus. In this present synthesis, we integrate previous perspectives with new and older data to create a novel bipartite model centred on the view that serotonin neurotransmission enhances two distinct adaptive responses to adversity, mediated in large part by its two most prevalent and researched brain receptors: the 5-HT1A and 5-HT2A receptors. We propose that passive coping (i.e. tolerating a source of stress) is mediated by postsynaptic 5-HT1AR signalling and characterised by stress moderation. Conversely, we argue that active coping (i.e. actively addressing a source of stress) is mediated by 5-HT2AR signalling and characterised by enhanced plasticity (defined as capacity for change). We propose that 5-HT1AR-mediated stress moderation may be the brain's default response to adversity but that an improved ability to change one's situation and/or relationship to it via 5-HT2AR-mediated plasticity may also be important - and increasingly so as the level of adversity reaches a critical point. We propose that the 5-HT1AR pathway is enhanced by conventional 5-HT reuptake blocking antidepressants such as the selective serotonin reuptake inhibitors (SSRIs), whereas the 5-HT2AR pathway is enhanced by 5-HT2AR-agonist psychedelics. This bipartite model purports to explain how different drugs (SSRIs and psychedelics) that modulate the serotonergic system in different ways, can achieve complementary adaptive and potentially therapeutic outcomes.

ABCA1 Polymorphism, a Genetic Risk Factor of Harm Avoidance

Abstract. Even though cholesterol homeostasis and self-harm behaviors have shown to be associated, gene polymorphisms of the cholesterol system have not been studied yet in the context of self-harm related personality traits. Here we present an association study between six ABCA1 polymorphisms and temperament scales measured by Cloninger’s Temperament and Character Inventory on 253 young adults. An association between ABCA1 rs4149264 and harm avoidance has been observed. This association remained significant after Bonferroni correction. Haplotype analysis confirmed an independent association between rs4149264 and harm avoidance. ABCA1, a cholesterol homeostasis gene, is a candidate gene for harm related personality traits.

Differential effects of cannabinoid CB1 inverse agonists and antagonists on impulsivity in male Sprague Dawley rats: identification of a possibly clinically relevant vulnerability involving the serotonin 5HT1A receptor

RATIONALE

Cannabinoid CB1 inverse agonists hold therapeutic promise as appetite suppressants but have produced suicidal behaviors among a small subpopulation in clinical trials. Anatomical and pharmacological evidence implicate the 5HT_1A serotonin receptor in suicide in humans and impulsivity in humans and animals.

OBJECTIVE

The objective of the study is to assess whether 5HT_1A blockade is necessary for CB1 ligands to produce impulsivity.

METHODS

Sprague Dawley rats were administered the CB1 inverse agonist AM 251, the CB1 antagonist AM 6527, or the peripherally restricted antagonist AM 6545, with or without pretreatment with the 5HT_1A antagonist WAY 100,635 (WAY) on the paced fixed consecutive number (FCN) task, which measures choice to terminate a chain of responses prematurely. As FCN is sensitive to changes in time perception, which have been demonstrated with CB1 blockade, a novel variable consecutive number task with discriminative stimulus (VCN-S _D ) was also performed and proposed to be less sensitive to changes in timing.

RESULTS

Pretreatment with WAY enabled mild but significant reductions in FCN accuracy for AM 251 and AM 6527. No effects were found for AM 6545. On the VCN-S _D task, substantial impairments were found for the combination of WAY and AM 251.

CONCLUSIONS

AM 251, but not the antagonists AM 6527 or AM 6545, produced impulsivity only following systemic 5HT_1A blockade. Although preliminary, the results may indicate that disrupted serotonin signaling produces a vulnerability to undesirable effects of CB1 inverse agonists, which is not evident in the general population. Furthermore, neutral CB1 antagonists do not produce this effect and therefore may have greater safety.

Pronounced prefronto-temporal cortical thinning in schizophrenia: Neuroanatomical correlate of suicidal behavior?

Schizophrenia is characterized by increased mortality for which suicidality is the decisive factor. An analysis of cortical thickness and folding to further elucidate neuroanatomical correlates of suicidality in schizophrenia has not yet been performed. We searched for relevant brain regions with such differences between patients with suicide-attempts, patients without any suicidal thoughts and healthy controls. 37 schizophrenia patients (14 suicide-attempters and 23 non-suicidal) and 50 age- and gender-matched healthy controls were included. Suicidality was documented through clinical interview and chart review. All participants underwent T1-weighted MRI scans. Whole brain node-by-node cortical thickness and folding were estimated (FreeSurfer Software) and compared. Additionally a three group comparison for prefrontal regions-of-interest was performed in SPSS using a multifactorial GLM. Compared with the healthy controls patients showed a typical pattern of cortical thinning in prefronto-temporal regions and altered cortical folding in the right medial temporal cortex. Patients with suicidal behavior compared with non-suicidal patients demonstrated pronounced (p<0.05) cortical thinning in the right DLPFC and the superior temporal cortex. Comparing cortical thickness in suicidal patients with non-suicidal patients significant (p<0.05) cortical thinning was additionally found in the right superior and middle temporal, temporopolar and insular cortex. Our findings extend the evidence for neuroanatomical underpinnings of suicidal behaviour in schizophrenia. We identified cortical thinning in a network strongly involved in regulation of impulsivity, emotions and planning of behaviour in suicide attempters, which might lead to neuronal dysregulation in this network and consequently to a higher risk of suicidal behavior.

Personality differences in early versus late suicide attempters

BACKGROUND

Suicidality is an individual behaviour caused by a complex framework of internal and external factors. The predictive values of personality traits for a suicide attempt have been demonstrated, especially in conjunction with Cloninger's TCI and impulsivity. Two issues remain unsolved, namely whether these traits alter over time after a suicide attempt, and how they may be influenced by depressive symptoms.

METHODS

We studied two patient cohorts: one sample of 81 patients after a suicide attempt no longer than 3 months previously (SA early) and another sample of 32 patients whose attempt had taken place more than 6 months previously (SA late). We carried out structured interviews with these subjects addressing diagnosis (MINI), suicidality (Scale for suicide ideation), depression (HAMD-17), temperament and character inventory (TCI), and impulsivity (BIS-10). Data analysis was done using SPSS 16.0.

RESULTS

Our two groups did not differ significantly in sociodemographics or suicidality. However, patients in the SA early group were significantly more depressed (p < 0.001), and scored lower in reward dependence (p < 0.001) and persistence (p = 0.005) but higher in harm avoidance (p < 0.001); they did not differ significantly in impulsivity (p < 0.01). Reward dependence, persistence, and harm avoidance remained significantly different between the two groups after controlling for depressive symptoms.

CONCLUSIONS

Our findings suggest that some personality traits vary after a suicide attempt. Further investigations are necessary to verify our results, ideally in longitudinal studies with larger, carefully-described cohorts. It would be also clinically important to investigate the influence of therapeutic strategies on the variability of personality traits and their impact on suicidal behavior.

Processing of decision-making and social threat in patients with history of suicidal attempt: A neuroimaging replication study

Suicidal vulnerability has been related to impaired value-based decision-making and increased sensitivity to social threat, mediated by the prefrontal cortex. Using functional magnetic resonance imaging, we aimed at replicating these previous findings by measuring brain activation during the Iowa Gambling Task and an emotional faces viewing task. Participants comprised 15 euthymic suicide attempters (history of depression and suicidal behavior) who were compared with 23 euthymic patient controls (history of depression without suicidal history) and 35 healthy controls. The following five model-based regions of interest were investigated: the orbitofrontal cortex (OFC), ventrolateral prefrontal cortex (VLPFC), anterior cingulate cortex (ACC), medial (MPFC) and dorsal prefrontal cortex (DPFC). Suicide attempters relative to patient controls showed (1) increased response to angry vs. neutral faces in the left OFC and the VLPFC, as previously reported; (2) increased response to wins vs. losses in the right OFC, DPFC and ACC; (3) decreased response to risky vs. safe choices in the left DPFC; and (4) decreased response to sad vs. neutral faces in the right ACC. This study links impaired valuation processing (here for signals of social threat, sadness and reward) to prefrontal cortex dysfunction in suicide attempters. These long-term deficits may underlie the impaired decision-making and social difficulties found in suicide attempters.

Temperament and character personality profile and affective temperaments in self-poisoning nonlethal suicide attempters

Involvement of personality traits in susceptibility to suicidal behaviour has attracted considerable research interest over the past decades. This study was motivated by reports that emotionality may play a potentially confounding role in the association between the personality profile and suicidal behaviour. We assessed the association between personality traits, as measured using the Temperament and Character Inventory (TCI), and suicidal behaviour, while controlling for the effects of Affective Temperaments, measured using the Temperament Evaluation of the Memphis, Pisa, Paris and San Diego auto-questionnaire (TEMPS-A) in a sample of 140 consecutive self-poisoning nonlethal suicide (SNS) attempters admitted to the Emergency Toxicology Clinic, comparing them with a sample of 140 age and sex matched healthy controls. After controlling for Affective Temperaments, the temperament dimension of Novelty Seeking (NS) and the character dimensions of Self-directedness and Self-transcendence remained significantly associated with SNS attempts. NS, in particular, was most consistently and uniquely associated with suicidal behaviour. The present study conveys the difficulty in disentangling the personality profile of SNS attempters from their emotionality. We conclude that the risk associated with certain personality traits is often entirely mediated by Affective Temperaments and few dimensions independently contribute to the risk of self-poisoning nonlethal suicidal behaviour.

Relationship of temperament and character in remitted depressed patients with suicidal ideation and suicide attempts--results from the CRESCEND study

The aim of this study was to evaluate the Temperament and Character Inventory (TCI) scores of a sample of Korean patients with remitted depression who had attempted suicide and reported suicidal ideation and to compare their scores with those of remitted depressed patients without suicidal ideation. Adult depression patients who had completed 12 weeks of follow-up (N = 138) were divided into three groups: patients with a history of suicide attempts (N = 23); patients with current suicidal ideation (N = 59); and patients without current suicidal ideation (N = 56). After controlling for covariates, no significant differences were found among the three groups on any measure of temperament or character except self-directedness and self-transcendence. The self-transcendence scores of the lifetime suicide-attempt group were significantly higher compared with those of the suicidal-ideation group; post hoc analysis revealed that self-directedness was significantly lower in the suicide-attempt group compared with the non-suicidal group. The results from the present study suggest that remitted depression patients with a history of suicide attempts do not differ from non-attempters in temperament, but do differ in certain character traits.

Neurobiological risk factors for suicide: insights from brain imaging

CONTEXT

This article reviews neuroimaging studies on neural circuitry associated with suicide-related thoughts and behaviors to identify areas of convergence in findings. Gaps in the literature for which additional research is needed are identified.

EVIDENCE ACQUISITION

A PubMed search was conducted and articles published before March 2014 were reviewed that compared individuals who made suicide attempts to those with similar diagnoses who had not made attempts or to healthy comparison subjects. Articles on adults with suicidal ideation and adolescents who had made attempts, or with suicidal ideation, were also included. Reviewed imaging modalities included structural magnetic resonance imaging, diffusion tensor imaging, single photon emission computed tomography, positron emission tomography, and functional magnetic resonance imaging.

EVIDENCE SYNTHESIS

Although many studies include small samples, and subject characteristics and imaging methods vary across studies, there were convergent findings involving the structure and function of frontal neural systems and the serotonergic system.

CONCLUSIONS

These initial neuroimaging studies of suicide behavior have provided promising results. Future neuroimaging efforts could be strengthened by more strategic use of common data elements and a focus on suicide risk trajectories. At-risk subgroups defined by biopsychosocial risk factors and multidimensional assessment of suicidal thoughts and behaviors may provide a clearer picture of the neural circuitry associated with risk status-both current and lifetime. Also needed are studies investigating neural changes associated with interventions that are effective in risk reduction.

Temperament, hopelessness, and attempted suicide: direct and indirect effects

This study evaluated whether hopelessness mediated the relations between temperament and recent suicide attempter status in a psychiatric sample. Negative temperament and positive temperament (particularly the positive emotionality subscale) uniquely predicted levels of hopelessness. Although these temperament constructs also demonstrated significant indirect effects on recent suicide attempter status, the effects were partially (for the broad temperament scales) or fully (for the positive emotionality subscale) mediated by the levels of hopelessness. These findings indicate that a tendency to experience excessive negative emotions as well as a paucity of positive emotions may lead individuals to experience hopelessness. Although temperament may also indirectly influence suicide attempter status, hopelessness mediates these relations.

Suicide attempts in women with eating disorders

We evaluated whether the prevalence of lifetime suicide attempts/completions was higher in women with a lifetime history of an eating disorder than in women with no eating disorder and assessed whether eating disorder features, comorbid psychopathology, and personality characteristics were associated with suicide attempts in women with anorexia nervosa, restricting subtype (ANR), anorexia nervosa, binge-purge subtype (ANBP), lifetime history of both anorexia nervosa and bulimia nervosa (ANBN), bulimia nervosa (BN), binge eating disorder (BED), and purging disorder (PD). Participants were part of the Swedish Twin study of Adults: Genes and Environment (N = 13,035) cohort. Lifetime suicide attempts were identified using diagnoses from the Swedish National Patient and Cause of Death Registers. General linear models were applied to evaluate whether eating disorder category (ANR, ANBP, ANBN, BN, BED, PD, or no eating disorder [no ED]) was associated with suicide attempts and to identify factors associated with suicide attempts. Relative to women with no ED, lifetime suicide attempts were significantly more common in women with all types of eating disorder. None of the eating disorder features or personality variables was significantly associated with suicide attempts. In the ANBP and ANBN groups, the prevalence of comorbid psychiatric conditions was higher in individuals with than without a lifetime suicide attempt. The odds of suicide were highest in presentations that included purging behavior (ANBN, ANBN, BN, and PD), but were elevated in all eating disorders. To improve outcomes and decrease mortality, it is critical to be vigilant for suicide and identify indices for those who are at greatest risk.

The role of temperament and character in the outcome of depressive mood in eating disorders

OBJECTIVES

The aims were to see which temperament and character dimensions were associated with depression, mainly with its outcome at two-year follow up in eating disorders (EDs).

METHODS

Participants (N=151) were 44 Anorexia nervosa (AN), 55 Bulimia nervosa (BN) and 52 Eating disorders not otherwise specified (EDNOS) patients. The Beck Depression Inventory (BDI), State and Trait Anxiety Inventory (STAI), Rosenberg Self Esteem Questionnaire (RSE), Eating Disorder Inventory (EDI-2) and Temperament and Character Inventory (TCI) were administered.

RESULTS

Depression at the beginning (t0) was severe in 22% of the cases. Harm Avoidance and Novelty Seeking had an effect on depressed mood at t0, mediated by Ineffectiveness. Responsibility (SD1) was associated with scores on the BDI at two-year follow up (β=-0.37, 95% CI -2.6, -0.6, p<0.01).

CONCLUSION

The evaluation of personality dimension in EDs has therapeutic and prognostic implications: To enhance self-efficacy and self-directness is crucial for good clinical outcome.

Personality traits associated with suicidal behaviors in patients with depression: the CRESCEND study

The aim of the current study was to identify personality traits associated with suicidal behavior in patients with depression. Of the 1183 patients screened for an observational cohort study of depression, 334 (28.2%) who completed the Temperament and Character Inventory (TCI) were included in these analyses. To minimize the effect of current mood state, the TCI was performed 12 weeks after initiation of treatment, and we adjusted for the severity of depression. Of the 344 participants, 59 had a lifetime history of at least one suicide attempt, 37 had a lifetime history of multiple suicide attempts, and 5 attempted suicide during the 12-week study period. At baseline, patients with a lifetime history of at least one suicide attempt, a lifetime history of multiple suicide attempts, and a suicide attempt during the study period expressed more serious current suicidal ideation than did those without such a history, despite the absence of differences among the groups in the severity of depressive and anxiety symptoms. Of the seven personality scales of the TCI, lower scores on the self-directedness scale of the character dimension were associated with a history of at least one suicide attempt (OR [95% CI], 0.91 [0.87-0.96]; p<0.001), a history of multiple suicide attempts (0.91 [0.86-0.97]; p=0.003), and suicide attempts during study period (0.80 [0.69-0.94]; p=0.006). These findings suggest that depressed patients with a history of suicidal behavior differ from non-attempters with regard to personality traits, especially the character dimension of self-directedness. It is noteworthy that this result emerged after controlling for the effect of current mood state.

Effects of serotonin-2A receptor binding and gender on personality traits and suicidal behavior in borderline personality disorder

Impulsivity and aggressiveness are personality traits associated with a vulnerability to suicidal behavior. Behavioral expression of these traits differs by gender and has been related to central serotonergic function. We assessed the relationships between serotonin-2A receptor function, gender, and personality traits in borderline personality disorder (BPD), a disorder characterized by impulsive-aggression and recurrent suicidal behavior. Participants, who included 33 BPD patients and 27 healthy controls (HC), were assessed for Axis I and II disorders with the Structured Clinical Interview for DSM-IV and the International Personality Disorders Examination, and with the Diagnostic Interview for Borderline Patients-Revised for BPD. Depressed mood, impulsivity, aggression, and temperament were assessed with standardized measures. Positron emission tomography with [(18)F]altanserin as ligand and arterial blood sampling was used to determine the binding potentials (BPND) of serotonin-2A receptors in 11 regions of interest. Data were analyzed using Logan graphical analysis, controlling for age and non-specific binding. Among BPD subjects, aggression, Cluster B co-morbidity, antisocial PD, and childhood abuse were each related to altanserin binding. BPND values predicted impulsivity and aggression in BPD females (but not BPD males), and in HC males (but not HC females.) Altanserin binding was greater in BPD females than males in every contrast, but it did not discriminate suicide attempters from non-attempters. Region-specific differences in serotonin-2A receptor binding related to diagnosis and gender predicted clinical expression of aggression and impulsivity. Vulnerability to suicidal behavior in BPD may be related to serotonin-2A binding through expression of personality risk factors.

Dorsal prefrontal cortical serotonin 2A receptor binding indices are differentially related to individual scores on harm avoidance

Although the serotonergic system has been implicated in healthy as well as in pathological emotional states, knowledge about its involvement in personality is limited. Earlier research on this topic suggests that post-synaptic 5-HT2A receptors could be involved in particular in frontal cortical areas. In drug-naïve healthy individuals, we examined the relationship between these 5-HT2A receptors and the temperament dimension harm avoidance (HA) using 123I-5-I-R91150 single photon emission computed tomography (SPECT). HA is a personality feature closely related to stress, anxiety and depression proneness, and it is thought to be mediated by the serotonergic system. We focused on the prefrontal cortices as these regions are frequently implicated in cognitive processes related to a variety of affective disorders. We found a positive relationship between dorsal prefrontal cortical (DPFC) 5-HT2A receptor binding indices (BI) and individual HA scores. Further, our results suggest that those individuals with a tendency to worry or to ruminate are particularly prone to display significantly higher 5-HT2A receptor BI in the left DPFC. Although we only examined psychologically healthy individuals, this relationship suggests a possible vulnerability for affective disorders.

Do headache and abdominal pain in childhood predict suicides and severe suicide attempts? Finnish nationwide 1981 birth cohort study

This study investigated associations between pain symptoms in mid-childhood and severe suicidality in adolescence and early adulthood. Severe suicidality was defined as completed suicide or suicidal attempt requiring hospital admission. In a nationwide prospective population-based study (n = 6,017), parents and children were asked about the child's headache and abdominal pain at age eight. The outcome was register-based data on suicide or suicidal attempt requiring hospital treatment by age 24. Family composition, parental educational level, and the child's psychiatric symptoms reported by the child, parents and teacher at baseline were included as covariates in statistical analyses. Boys' abdominal pain reported by the parents was associated with later severe suicidality after adjusting for family composition, parental educational level, and childhood psychiatric symptoms at baseline. In addition, the association between boys' own report of headache and later severe suicidality reached borderline significance in unadjusted analysis. Girls' pain symptoms did not predict later severe suicidality.

Differential improvement in depressive symptoms for tDCS alone and combined with pharmacotherapy: an exploratory analysis from the Sertraline vs. Electrical Current Therapy for Treating Depression Clinical Study

Transcranial direct current stimulation (tDCS) is a promising therapy for major depression treatment, although little is known of its effects in ameliorating distinct symptoms of depression. Thus, it is important, not only to increase knowledge of its antidepressant mechanisms, but also to guide its potential use in clinical practice. Using data from a recent factorial, double-blinded, placebo-controlled trial applying tDCS-alone and combined with sertraline to treat 120 depressed outpatients over 6 wk (Brunoni et al., 2013), we investigated the pattern of improvement in symptoms of depression from the Montgomery-Asberg depression scale (MADRS). First, we performed one multivariate analysis of variance with the score improvement of the 10 MADRS items as dependent variables. Significant (p < 0.05) results were further explored with follow-up analyses of variance. TDCS (alone and combined with sertraline) improved concentration difficulties and pessimistic and suicidal thoughts. The combined treatment also improved apparent and reported sadness, lassitude and inability to feel. Indeed, tDCS/sertraline significantly ameliorated all but the 'vegetative' depression symptoms (inner tension, sleep and appetite items). We further discuss whether bifrontal tDCS over the dorsolateral prefrontal cortex could be associated with improvement in cognitive (concentration) and affective (pessimistic/suicidal thoughts) processing, while the combined treatment might have a more widespread antidepressant effect by simultaneously acting on different depression pathways. We also identified patterns of antidepressant improvement for tDCS that might aid in tailoring specific interventions for different subtypes of depressed patients, e.g. particularly those with suicidal ideation.

Biological basis of suicide and suicidal behavior

OBJECTIVE

Suicide is a major public health concern as each year 30000 people die by suicide in the USA alone. In the teenage population, it is the second leading cause of death. There have been extensive studies of psychosocial factors associated with suicide and suicidal behavior. However, very little is known about the neurobiology of suicide. Recent research has provided some understanding of the neurobiology of suicide, which is the topic of this review.

METHODS

Neurobiology of suicide has been studied using peripheral tissues such as platelets, lymphocytes, and cerebrospinal fluid obtained from suicidal patients or from the postmortem brains of suicide victims.

RESULTS

These studies have provided encouraging information with regard to the neurobiology of suicide. They show an abnormality of the serotonergic mechanism, such as increased serotonin receptor subtypes and decreased serotonin metabolites (e.g. 5-hydroxyindoleacetic acid). These studies also suggest abnormalities of receptor-linked signaling mechanisms such as phosphoinositide and adenylyl cyclase. Other biological systems that appear to be dysregulated in suicide involve the hypothalamic-pituitary-adrenal axis, and neurotrophins and neurotrophin receptors. More recently, several studies have also indicated abnormalities of neuroimmune functions in suicide.

CONCLUSIONS

Some encouraging information emerged from the present review, primarily related to some of the neurobiological mechanisms mentioned above. It is hoped that neurobiological studies may eventually result in the identification of appropriate biomarkers for suicidal behavior as well as appropriate therapeutic targets for its treatment.

5-HT2A receptors in the feline brain: 123I-5-I-R91150 kinetics and the influence of ketamine measured with micro-SPECT

Subanesthetic doses of ketamine can be used as a rapid-acting antidepressant in patients with treatment-resistant depression. Therefore, the brain kinetics of (123)I-5-I-R91150 (4-amino-N-[1-[3-(4-fluorophenyl)propyl]-4-methylpiperidin-4-yl]-5-iodo-2-methoxybenzamide) and the influence of ketamine on the postsynaptic serotonin-2A receptor (5-hydroxytryptamine-2A, or 5-HT2A) status were investigated in cats using micro-SPECT.

METHODS

This study was conducted on 6 cats using the radioligand (123)I-5-I-R91150, a 5-HT2A receptor antagonist, as the imaging probe. Anesthesia was induced and maintained with a continuous-rate infusion of propofol (8.4 ± 1.2 mg kg(-1) followed by 0.22 mg kg(-1) min(-1)) 75 min after tracer administration, and acquisition of the first image began 15 min after induction of anesthesia. After this first acquisition, propofol (0.22 mg kg(-1) min(-1)) was combined with ketamine (5 mg kg(-1) followed by 0.023 mg kg(-1) min(-1)), and the second acquisition began 15 min later. Semiquantification, with the cerebellum as a reference region, was performed to calculate the 5-HT2A receptor binding indices (parameter for available receptor density) in the frontal and temporal cortices. The binding indices were analyzed with Wilcoxon signed ranks statistics.

RESULTS

The addition of ketamine to the propofol continuous-rate infusion resulted in decreased binding indices in the right frontal cortex (1.25 ± 0.22 vs. 1.45 ± 0.16; P = 0.028), left frontal cortex (1.34 ± 0.15 vs. 1.49 ± 0.10; P = 0.028), right temporal cortex (1.30 ± 0.17 vs. 1.45 ± 0.09; P = 0.046), and left temporal cortex (1.41 ± 0.20 vs. 1.52 ± 0.20; P = 0.046).

CONCLUSION

This study showed that cats can be used as an animal model for studying alterations of the 5-HT2A receptor status with (123)I-5-I-R91150 micro-SPECT. Furthermore, an interaction between ketamine and the 5-HT2A receptors resulting in decreased binding of (123)I-5-I-R91150 in the frontal and temporal cortices was demonstrated. Whether the decreased radioligand binding resulted from a direct competition between ketamine and (123)I-5-I-R91150 or from a decreased affinity of the 5-HT2A receptor caused by ketamine remains to be elucidated.

Placebo and the new physiology of the doctor-patient relationship

Modern medicine has progressed in parallel with the advancement of biochemistry, anatomy, and physiology. By using the tools of modern medicine, the physician today can treat and prevent a number of diseases through pharmacology, genetics, and physical interventions. Besides this materia medica, the patient's mind, cognitions, and emotions play a central part as well in any therapeutic outcome, as investigated by disciplines such as psychoneuroendocrinoimmunology. This review describes recent findings that give scientific evidence to the old tenet that patients must be both cured and cared for. In fact, we are today in a good position to investigate complex psychological factors, like placebo effects and the doctor-patient relationship, by using a physiological and neuroscientific approach. These intricate psychological factors can be approached through biochemistry, anatomy, and physiology, thus eliminating the old dichotomy between biology and psychology. This is both a biomedical and a philosophical enterprise that is changing the way we approach and interpret medicine and human biology. In the first case, curing the disease only is not sufficient, and care of the patient is of tantamount importance. In the second case, the philosophical debate about the mind-body interaction can find some important answers in the study of placebo effects. Therefore, maybe paradoxically, the placebo effect and the doctor-patient relationship can be approached by using the same biochemical, cellular and physiological tools of the materia medica, which represents an epochal transition from general concepts such as suggestibility and power of mind to a true physiology of the doctor-patient interaction.

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.

Temperament personality profiles in suicidal behaviour: an investigation of associated demographic, clinical and genetic factors

BACKGROUND

Personality traits have been suggested as possible risk factors for suicidal behaviours. Cloninger's model of personality (TCI), given its neurobiological background, might provide an ideal tool for the identification of dimensions associated with suicide attempt.

METHODS

A number of 1333 suicide attempters and 589 non-suicide attempters suffering from different DSM-IV Axis I disorders were assessed using either the temperament and character inventory (TCI) or the tridimensional personality questionnaire (TPQ), as well as other self-report questionnaires evaluating dimensions associated with suicidal behaviour, such as impulsivity and anger traits. The severity of suicide attempts and the methods used were also assessed. Subjects were genotyped for polymorphisms within the key genes involved in monoaminergic pathways and the HPA axis.

RESULTS

Compared with non-suicide attempters, suicide attempters scored higher for harm avoidance (HA) and novelty seeking (NS), and lower for self-directedness (SD). The difference was independent of Axis I disorders. Higher HA and NS scores were associated with a greater severity of suicidal behaviour. A multivariate model showed that HA was the single temperamental dimension independently related to suicide attempt history, beside impulsivity and anger-related traits. The genetic factors investigated did not play a significant role in modulating these temperamental dimensions.

LIMITATIONS

The TCI was available for only half of the sample.

CONCLUSIONS

Early detection of subjects displaying high HA and low SD, associated with high impulsivity and poor anger control, may help to prevent suicidal behaviours. Physicians should therefore be aware of these risk factors so that they can offer the best primary care intervention.

Temperament, character and serotonin activity in the human brain: a positron emission tomography study based on a general population cohort

BACKGROUND

The psychobiological model of personality by Cloninger and colleagues originally hypothesized that interindividual variability in the temperament dimension 'harm avoidance' (HA) is explained by differences in the activity of the brain serotonin system. We assessed brain serotonin transporter (5-HTT) density in vivo with positron emission tomography (PET) in healthy individuals with high or low HA scores using an 'oversampling' study design. Method Subjects consistently in either upper or lower quartiles for the HA trait were selected from a population-based cohort in Finland (n = 2075) with pre-existing Temperament and Character Inventory (TCI) scores. A total of 22 subjects free of psychiatric and somatic disorders were included in the matched high- and low-HA groups. The main outcome measure was regional 5-HTT binding potential (BPND) in high- and low-HA groups estimated with PET and [11C]N,N-dimethyl-2-(2-amino-4-methylphenylthio)benzylamine ([11C]MADAM). In secondary analyses, 5-HTT BPND was correlated with other TCI dimensions.

RESULTS

5-HTT BPND did not differ between high- and low-HA groups in the midbrain or any other brain region. This result remained the same even after adjusting for other relevant TCI dimensions. Higher 5-HTT BPND in the raphe nucleus predicted higher scores in 'self-directedness'.

CONCLUSIONS

This study does not support an association between the temperament dimension HA and serotonin transporter density in healthy subjects. However, we found a link between high serotonin transporter density and high 'self-directedness' (ability to adapt and control one's behaviour to fit situations in accord with chosen goals and values). We suggest that biological factors are more important in explaining variability in character than previously thought.

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.

Heart rate variability in patients with fully remitted major depressive disorder

OBJECTIVE

Cardiac autonomic dysregulation has been reported in major depressive disorder (MDD), but scarce studies investigated that in fully remitted MDD.

METHODS

To examine cardiac autonomic function in remitted MDD, 470 unmedicated individuals with a diagnosis of MDD earlier in life and 462 healthy volunteers, aged 18-65 years, were recruited for a case-control analysis. Cardiac autonomic function was evaluated by measuring heart rate variability (HRV) parameters. Frequency-domain indices of HRV were obtained. The obtained results were evaluated in association with personality traits assessed by the Tridimensional Personality Questionnaire.

RESULTS

In patients with remitted MDD, no differences in RR intervals and all frequency-domain indices of HRV could be detected as compared with controls. Stratified analyses by the presence of a history of suicide ideation (the SI+ vs. the SI-subgroup) revealed decreased cardiac vagal control in the SI+ subgroup. The correlation analysis revealed an inverse relation between HRV levels and the harm avoidance score (which has been suggested to be associated with serotonergic activity), mainly attributable to the robust association in the SI+ subgroup.

CONCLUSION

Our study shows that cardiac autonomic dysregulation is not shown in remitted MDD patients as a whole but is limited to the subgroup of remitted MDD patients with a history of suicidal ideation. In view of the higher risk for cardiac complications in these vulnerable individuals, one might consider the treatment to restore their autonomic function.

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.