Plasma serotonin levels and suicidal behavior in adolescents

Peripheral biological correlates of suicidality in children and adolescents: A systematic review and meta-analysis

A systematic review and meta-analysis were conducted to identify peripheral biological correlates of suicidality in children and adolescents. The review was pre-registered through PROSPERO (CRD42023417128) and included four databases (PubMed, Cochrane Library, Embase, and PsycINFO). From 27,977 non-duplicated articles, 102 full-text studies were selected. Studies investigated suicide attempts (n = 52), suicidal ideation (n = 42), or individuals with suicidal ideation or attempts grouped together (n = 22). Seropositive toxoplasmosis, cortisol, neutrophil, and neutrophil to lymphocyte ratio (NLR) exhibited significant effect size after Bonferroni correction. Effect sizes for biological correlates of suicidality were pooled using Cohen's d (effect size = -0.04, 95% confidence interval [CI]: -1.36 to 1.27) and odds ratio (effect size = -0.31, 95% CI: -1.06 to 0.42). Meta-regression analysis revealed that type of suicidality, type of control, means collected, and sample size significantly impacted the pooled effect size. Analysis showed significant publication bias and heterogeneity, as well as notable moderators and potential biomarkers for future research.

Effects of physical activity in child and adolescent depression and anxiety: role of inflammatory cytokines and stress-related peptide hormones

Depression and anxiety are the most common mental illnesses affecting children and adolescents, significantly harming their well-being. Research has shown that regular physical activity can promote cognitive, emotional, fundamental movement skills, and motor coordination, as a preventative measure for depression while reducing the suicide rate. However, little is known about the potential role of physical activity in adolescent depression and anxiety. The studies reviewed in this paper suggest that exercise can be an effective adjunctive treatment to improve depressive and anxiety symptoms in adolescents, although research on its neurobiological effects remains limited.

Epidermal Wearable Biosensors for the Continuous Monitoring of Biomarkers of Chronic Disease in Interstitial Fluid

Healthcare technology has allowed individuals to monitor and track various physiological and biological parameters. With the growing trend of the use of the internet of things and big data, wearable biosensors have shown great potential in gaining access to the human body, and providing additional functionality to analyze physiological and biochemical information, which has led to a better personalized and more efficient healthcare. In this review, we summarize the biomarkers in interstitial fluid, introduce and explain the extraction methods for interstitial fluid, and discuss the application of epidermal wearable biosensors for the continuous monitoring of markers in clinical biology. In addition, the current needs, development prospects and challenges are briefly discussed.

Multiple serum biomarkers for predicting suicidal behaviours in depressive patients receiving pharmacotherapy

BACKGROUND

Predictive values of multiple serum biomarkers for suicidal behaviours (SBs) have rarely been tested. This study sought to evaluate and develop a panel of multiple serum biomarkers for predicting SBs in outpatients receiving a 12-month pharmacotherapy programme for depressive disorders.

METHODS

At baseline, 14 serum biomarkers and socio-demographic/clinical characteristics including previous suicidal attempt and present suicidal severity were evaluated in 1094 patients with depressive disorders without a bipolar diagnosis. Of these, 884 were followed for increased suicidal severity and fatal/non-fatal suicide attempt outcomes over a 12-month treatment period. Individual and combined effects of serum biomarkers on these two prospective SBs were estimated using logistic regression analysis after adjustment for relevant covariates.

RESULTS

Increased suicidal severity and fatal/non-fatal suicide attempt during the 12-month pharmacotherapy were present in 155 (17.5%) and 38 (4.3%) participants, respectively. Combined cortisol, total cholesterol, and folate serum biomarkers predicted fatal/non-fatal suicide attempt, and these with interleukin-1 beta and homocysteine additionally predicted increased suicidal severity, with clear gradients robust to adjustment (p values < 0.001).

CONCLUSIONS

Application of multiple serum biomarkers could considerably improve the predictability of SBs during the outpatient treatment of depressive disorders, potentially highlighting the need for more frequent monitoring and risk appraisal.

Could peripheral 5-HT level be used as a biomarker for depression diagnosis and treatment? A narrative minireview

The serotonin hypothesis of depression is still influential, but the relationship between peripheral 5-HT levels and depression is still unknown. This review aimed to verify whether peripheral 5-HT levels could be used as a biomarker for depression diagnosis and treatment. PubMed and EMBASE were searched using terms appropriate to the area of research. Articles from 1957 to 2022 in the following terms were identified: depression, 5-HT, serotonin and peripheral (serum, plasma, blood platelets). 33 studies were included: seven clinical trials about periphery 5-HT levels in depressive patients compared to normal subjects, 15 clinical trials about changes of peripheral 5-HT levels in patients with depression after drug treatment and 11 animal experiments about peripheral 5-HT levels in animal models of depression. Peripheral 5-HT levels presented three different outcomes before and after antidepressant treatments: increased, decreased and no significant change. In conclusion, changes in peripheral 5-HT levels did not show consistent results among these studies. Peripheral 5-HT level could not be used as a biomarker both for depression diagnosis and for antidepressant efficacy evaluation.

Investigation of acute organophosphate poisoning in humans based on sociodemographic and role of neurotransmitters with survival study in South India

The aim of this study was to investigate the sociodemographic characteristics of patients based on the poison chosen and different types of organophosphorus compounds. The data were collected to explore the sociodemographic characteristics of organophosphate (OP)-poisoned patients based on the source, site, and route of poisoning, education level, occupational status, and the purpose of poisoning. Furthermore, we estimated the serotonin and dopamine levels in the plasma samples of patients, and survival plots were also described. During the study of OP pesticide poisoning in 116 human subjects and 5 healthy volunteers, we observed, based on the survival plot, that75.9% of the patients were discharged, and the remaining patients died (24.1% of the patients) due to respiratory failure followed by cardiac arrest. Our findings suggest that the serotonin levels significantly (p < 0.01 and p < 0.001) decreased from 12 to 36 h, whereas the dopamine levels slightly increased from 12 to 36 h in the group with OP poisoning compared to the control group. Based on these findings, this study may aid in deciphering the precise mechanism by which pesticides cause behavioural changes that influence serotonin and dopamine levels in OP-poisoned patients. The purpose of this work was to serve as a small reminder of the risk to public health associated with organophosphate pesticides.

Clinical Study of Serum Serotonin as a Screening Marker for Anxiety and Depression in Patients with Type 2 Diabetes

Over time, studies have shown the importance of determining serotonin levels to diagnose somatic and psychiatric disorders. There are theoretical premises and practical ways to achieve a subtle correlation between the existence of comorbid psychiatric disorders and somatic diseases caused by the changes observed in serotonin levels. The present study, classified as retrospective and quantitative, provides evidence for determining the serotonin levels in patients with diabetes and anxiety or depression. A total of 48 patients with diabetes type 2 were enrolled in the study. Blood glucose level, glycated haemoglobin, and serum serotonin were noted, and they completed Hamilton A and Beck Depression Inventory questionnaires. We found robust correlations between serum serotonin and blood glucose (Sig. = 0.008), serum serotonin and HbA1c (Sig. = 0.007), serum serotonin and anxiety (Sig. = 0.000), and serum serotonin and depression (Sig. = 0.000). It is also noteworthy that women recorded extreme values higher than men for glycated haemoglobin (95% confidence interval: 6.92–7.79 in women and 6.30–7.23 in men). In conclusion, using serotonin as a marker of the mentioned diseases in clinical practice is of significant utility, considering the benefits in terms of the evolution and prognosis of comorbidities in patients with type 2 diabetes and anxiety and depressive symptoms.

Peripheral and neural correlates of self-harm in children and adolescents: a scoping review

BACKGROUND

Self-harm in children and adolescents is difficult to treat. Peripheral and neural correlates of self-harm could lead to biomarkers to guide precision care. We therefore conducted a scoping review of research on peripheral and neural correlates of self-harm in this age group.

METHODS

PubMed and Embase databases were searched from January 1980-May 2020, seeking English language peer-reviewed studies about peripheral and neural correlates of self-harm, defined as completed suicide, suicide attempts, suicidal ideation, or non-suicidal self-injury (NSSI) in subjects, birth to 19 years of age. Studies were excluded if only investigating self-harm in persons with intellectual or developmental disability syndromes. A blinded multi-stage assessment process by pairs of co-authors selected final studies for review. Risk of bias estimates were done on final studies.

RESULTS

We screened 5537 unduplicated abstracts, leading to the identification of 79 eligible studies in 76 papers. Of these, 48 investigated peripheral correlates and 31 examined neural correlates. Suicidality was the focus in 2/3 of the studies, with NSSI and any type of self-harm (subjects recruited with suicidality, NSSI, or both) investigated in the remaining studies. All studies used observational designs (primarily case-control), most used convenience samples of adolescent patients which were predominately female and half of which were recruited based on a disorder. Over a quarter of the specific correlates were investigated with only one study. Inter-study agreement on findings from specific correlates with more than one study was often low. Estimates of Good for risk of bias were assigned to 37% of the studies and the majority were rated as Fair.

CONCLUSIONS

Research on peripheral and neural correlates of self-harm is not sufficiently mature to identify potential biomarkers. Conflicting findings were reported for many of the correlates studied. Methodological problems may have produced biased findings and results are mainly generalizable to patients and girls. We provide recommendations to improve future peripheral and neural correlate research in children and adolescents, ages 3-19 years, with self-harm.

Serotonin modifies the impact of sleep disturbance on suicidality in patients with acute coronary syndrome

BACKGROUND

This study investigated the associations of sleep disturbance and serum serotonin levels with suicidal ideation, and evaluated the potential modifying effects of serotonin on these associations in patients with the acute coronary syndrome (ACS).

METHODS

In total, 969 ACS patients were recruited from a tertiary university hospital in Korea within 2 weeks of disease onset and evaluated in terms of sleep disturbance (using the Leeds Sleep Evaluation Questionnaire), serum serotonin levels, and suicidal ideation (using the "suicidal thoughts" item of the Montgomery-Åsberg Depression Rating Scale). Covariates included sociodemographics, depression, vascular risk factors, and disease severity. After 1 year, 711 patients were re-evaluated in terms of suicidal ideation. Logistic regression analysis was performed with adjustment for covariates.

RESULTS

Sleep disturbance was significantly associated with suicidal ideation at baseline and follow-up. Serum serotonin showed no such association but modified the association of sleep disturbance with suicidal ideation such that it was significant only in the lower serum serotonin group, with significant interaction terms obtained after adjustment for relevant covariates.

CONCLUSION

Evaluating sleep disturbance and serum serotonin levels could improve the accuracy of clinical predictions of suicidal ideation in the acute and chronic phases of ACS.

Suicide prevention in childhood and adolescence: a narrative review of current knowledge on risk and protective factors and effectiveness of interventions

INTRODUCTION

Suicide is a global mental health problem for people of all ages. While rates of suicide in children and adolescents are reported as lower than those in older populations worldwide, they represent the third leading cause of death in 15-19-year-olds. The rates are higher among boys than girls worldwide, though the death rates for girls exceed those for boys in Bangladesh, China, India, and Nepal. There has been a general decrease in adolescent suicide rates over recent decades. However, increases are reported in South East Asia as well as South America over the same time period.

METHODS

A narrative review method has been used to summarize current knowledge about risk and protective factors for suicide among children and adolescents and to discuss evidence-based strategy for suicide prevention in this age group.

RESULTS

Identified suicide risk and protective factors for children and adolescents largely overlap with those for adults. Nevertheless, developmental characteristics may strengthen the impact of some factors, such as decision-making style, coping strategies, family and peer relationships, and victimization. The implementation of evidence-based suicide preventive strategies is needed. Restricting access to lethal means, school-based awareness and skill training programs, and interventions delivered in clinical and community settings have been proven effective. The effectiveness of gatekeeper training and screening programs in reducing suicidal ideation and behavior is unproven but widely examined in selected settings.

DISCUSSION

Since most studies have been conducted in western countries, future research should assess the effectiveness of these promising strategies in different cultural contexts. The use of more rigorous study designs, the use of both short- and long-term follow-up evaluations, the larger inclusion of individuals belonging to vulnerable groups, the evaluation of online intervention, and the analysis of programs' cost-effectiveness are also required.

Optimizing drug selection in psychopharmacology based on 40 significant CYP2C19- and CYP2D6-biased adverse drug reactions of selective serotonin reuptake inhibitors

Background

Selective serotonin reuptake inhibitors (SSRIs) are among the most widely prescribed class of drugs in the practice of psychiatry. Cytochrome P450 (CYP) 2C19 and CYP2D6 are established as clinically relevant drug metabolizing enzymes (DMEs) that influence the pharmacokinetics of SSRIs and may either be grouped as being primarily metabolized by CYP2C19 or CYP2D6. The aim of this study is to test the hypothesis that the primary drug metabolizing pathway for SSRI antidepressants are associated with adverse drug reactions (ADRs) related to physiological modulation of organs with the highest gene tissue expression.

Methods

Post-marketing ADR cases were obtained from the United States Food and Drug Administration’s Adverse Events Reporting System from each of the four quarters for the years 2016 and 2017. Cases were grouped based on one of two primary pharmacokinetic pharmacogenomic pathway biomarkers CYP2C19 and CYP2D6. Citalopram, escitalopram, and sertraline were grouped as CYP2C19 substrates and fluvoxamine, fluoxetine, and paroxetine as CYP2D6 substrates. Logistic regression was computed for the reported SSRI ADRs associated with one of two aforementioned DMEs. All data homogenization and computations were performed in R for statistical programming.

Results

The most commonly reported ADR among the SSRIs was anxiety (n = 3,332). The top two ADRs associated with SSRIs metabolized by CYP2D6 are: nightmare (n = 983) reporting odds-ratio (OR) = 4.37 (95% confidence interval (CI) [3.67–5.20]) and panic attack (n = 1,243) OR = 2.43 (95% CI [2.11–2.79]). Contrastingly, the top two ADRs for CYP2C19 metabolized SSRIs are: electrocardiogram QT prolonged (n = 351) OR = 0.18 (95% CI [0.13–0.24]) and small for dates baby (n = 306) OR = 0.19 (95% CI [0.14–0.26]). The study tested and produced 40 statistically significant CYP2C19- and CYP2D6-biased ADRs. In overall context, the results suggest that CYPC19 SSRI substrates are associated with ADRs related to modulation of the autonomic nervous system, seizure, pain, erectile-dysfunction, and absorption. Contrastingly, CYP2D6 SSRI substrates are associated with ADRs related to nightmares, withdrawal syndrome, and de-realization of cognitive processes. The results of this study may aid as guidance to optimize drug selection in psychopharmacology.

The influence of the serotonin transporter gene 5-HTTLPR polymorphism on suicidal behaviors: a meta-analysis

Suicidal Behavior (SB) is the second leading cause of death among youths worldwide and the tenth among all age groups. Inherited genetic differences have a role in suicidality with heritability ranging from 30 to 55%. The SLC6A4 5-HTTLPR gene variant has been largely investigated for association with SB, with controversial results. In this work, we sought to determine whether the results of previous meta-analyses were confirmed or modified subsequent to the inclusion of more recent literature data. An electronic literature search was performed to identify relevant studies published until July 2018. Data were analysed through RevMan v5.3. Subgroup and sensitivity meta-analyses were performed considering different SB sub-phenotypes, ethnicity, gender and psychiatric diagnostic categories. Our literature search yielded 1186 articles; among these, we identified 45 pertinent case-control studies (15,341 subjects). No association was found between low-expressing alleles or genotypes (S + L_G alleles or S' carrier genotypes) and SB in the primary analyses. However, low-expressing alleles (S + L_G) were associated with an increased risk of Violent Suicide Attempt (OR = 1.44, C.I. 1.17-1.78, p = .0007). An effect of the same alleles on SB was found in a subpopulation of substance abusers, but this result was not confirmed after the exclusion of healthy subjects from the control group. The other sensitivity meta-analyses did not show any significant effect. Our findings contribute to clarify the conflicting previous evidence by suggesting an association between the 5-HTTLPR and Violent SB. Nonetheless, many other modulators, including environmental factors and epigenetic mechanisms may act to further increase the level of complexity.

Annual Research Review: Suicide among youth - epidemiology, (potential) etiology, and treatment

BACKGROUND

Suicide is a leading cause of death and a complex clinical outcome. Here, we summarize the current state of research pertaining to suicidal thoughts and behaviors in youth. We review their definitions/measurement and phenomenology, epidemiology, potential etiological mechanisms, and psychological treatment and prevention efforts.

RESULTS

We identify key patterns and gaps in knowledge that should guide future work. Regarding epidemiology, the prevalence of suicidal thoughts and behaviors among youth varies across countries and sociodemographic populations. Despite this, studies are rarely conducted cross-nationally and do not uniformly account for high-risk populations. Regarding etiology, the majority of risk factors have been identified within the realm of environmental and psychological factors (notably negative affect-related processes), and most frequently using self-report measures. Little research has spanned across additional units of analyses including behavior, physiology, molecules, cells, and genes. Finally, there has been growing evidence in support of select psychotherapeutic treatment and prevention strategies, and preliminary evidence for technology-based interventions.

CONCLUSIONS

There is much work to be done to better understand suicidal thoughts and behaviors among youth. We strongly encourage future research to: (1) continue improving the conceptualization and operationalization of suicidal thoughts and behaviors; (2) improve etiological understanding by focusing on individual (preferably malleable) mechanisms; (3) improve etiological understanding also by integrating findings across multiple units of analyses and developing short-term prediction models; (4) demonstrate greater developmental sensitivity overall; and (5) account for diverse high-risk populations via sampling and reporting of sample characteristics. These serve as initial steps to improve the scientific approach, knowledge base, and ultimately prevention of suicidal thoughts and behaviors among youth.

Research on potential biomarker correlates for suicidal behavior: A review

Suicide is a world health priority. Studies over the last few decades have revealed the complexity underlying the neurobiological mechanisms of suicide. Researchers have found dysregulations in the serotonergic system, the stress system, neural plasticity, lipid metabolism, and cell signaling pathways in relation to suicidal behaviors. These findings have provided more insight into the final path leading to suicide, at which medical intervention should be applied to prevent the action. However, because these molecular mechanisms have been implicated in both depression and suicide, the specificity of the mechanisms has been obscured. In this review, we summarize the main findings of studies on molecular mechanisms of suicidal behavior from the last 2 decades, with particular emphasis on the potential, independent role of each mechanism that is not contingent upon an underlying psychopathology, such as depression. The act of suicide is multifactorial; no single molecular mechanism is sufficient to fully account for the act. Knowledge of the reciprocal interactions among these molecular mechanisms and studying them in the context of brain circuitry by using neuroimaging techniques will provide a better understanding of the neurobiology of suicide.

The underlying neurobiology of key functional domains in young people with mood and anxiety disorders: a systematic review

BACKGROUND

Mood and anxiety disorders are leading causes of disability and mortality, due largely to their onset during adolescence and young adulthood and broader impact on functioning. Key factors that are associated with disability and these disorders in young people are social and economic participation (e.g. education, employment), physical health, suicide and self-harm behaviours, and alcohol and substance use. A better understanding of the objective markers (i.e. neurobiological parameters) associated with these factors is important for the development of effective early interventions that reduce the impact of disability and illness persistence.

METHODS

We systematically reviewed the literature for neurobiological parameters (i.e. neuropsychology, neuroimaging, sleep-wake and circadian biology, neurophysiology and metabolic measures) associated with functional domains in young people (12 to 30 years) with mood and/or anxiety disorders.

RESULTS

Of the one hundred and thirty-four studies selected, 7.6 % investigated social and economic participation, 2.1 % physical health, 15.3 % suicide and self-harm behaviours, 6.9 % alcohol and substance use, whereas the majority (68.1 %) focussed on clinical syndrome.

CONCLUSIONS

Despite the predominance of studies that solely examine the clinical syndrome of young people the literature also provides evidence of distinct associations among objective measures (indexing various aspects of brain circuitry) and other functional domains. We suggest that a shift in focus towards characterising the mechanisms that underlie and/or mediate multiple functional domains will optimise personalised interventions and improve illness trajectories.

Depressed suicidal adolescent males have an altered cortisol response to a pharmacological challenge

Dysregulation of the HPA axis and the dysfunction of the central serotonin (5HT) system are the most replicated biomarkers of depression and suicidal ideation and behavior. However, few studies have examined the two systems simultaneously. In this study, cortisol response was measured in depressed adolescents, following the administration of a central serotonin receptor agonist, meta-chlorphenylpiprazine (mCPP). Adolescents with major depression (MDD; n = 44; males = 15, females = 29; mean age ± SD = 15.5 ± 1.5) were divided into two groups: non-suicidal or those who reported passive suicidal ideation (n = 21), and those who had either threatened suicide or engaged in suicidal acts (n = 23). Sequential infusions of normal saline and mCPP were administered, and serial blood samples were collected for cortisol response. A differential time by group pattern of cortisol response following mCPP was found in the entire group (F(6,242) = 2.6, p=0.018). However, this was mostly attributed to males (F(6,73) = 2.3, p = 0.043) who had threatened or engaged in suicidal acts and displayed a higher cortisol response at 10 and 25 min after the infusion of mCPP, which was not affected by the severity of depression. This differential pattern of cortisol secretion in response to a serotonergic agonist may be a biomarker for more severe forms of suicidal ideation and behavior in adolescent males.

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.

The effects of music relaxation and muscle relaxation techniques on sleep quality and emotional measures among individuals with posttraumatic stress disorder

Posttraumatic stress disorder (PTSD), an anxiety disorder with lifetime prevalence of 7.8%, is characterized by symptoms that develop following exposure to traumatic life events and that cause an immediate experience of intense fear, helplessness or horror. PTSD is marked by recurrent nightmares typified by the recall of intrusive experiences and by extended disturbance throughout sleep. Individuals with PTSD respond poorly to drug treatments for insomnia. The disadvantages of drug treatment for insomnia underline the importance of non-pharmacological alternatives. Thus, the present study had three aims: first, to compare the efficiency of two relaxation techniques (muscular relaxation and progressive music relaxation) in alleviating insomnia among individuals with PTSD using both objective and subjective measures of sleep quality; second, to examine whether these two techniques have different effects on psychological indicators of PTSD, such as depression and anxiety; and finally, to examine how initial PTSD symptom severity and baseline emotional measures are related to the efficiency of these two relaxation methods. Thirteen PTSD patients with no other major psychiatric or neurological disorders participated in the study. The study comprised one seven-day running-in, no-treatment period, followed by two seven-day experimental periods. The treatments constituted either music relaxation or muscle relaxation techniques at desired bedtime. These treatments were randomly assigned. During each of these three experimental periods, subjects' sleep was continuously monitored with a wrist actigraph (Ambulatory Monitoring, Inc.), and subjects were asked to fill out several questionnaires concerned with a wide spectrum of issues, such as sleep, depression, and anxiety. Analyses revealed a significant increase in objective and subjective sleep efficiency and a significant reduction in depression level following music relaxation. Moreover, following music relaxation, a highly significant negative correlation was found between improvement in objective sleep efficiency and reduction in depression scale. The study's findings provide evidence that music relaxation at bedtime can be used as treatment for insomnia among individuals with PTSD.

Blood Levels of Serotonin Are Differentially Affected by Romantic Love in Men and Women

People who are in love think about their beloved the whole day, which is supposed to be associated with serotonin. The research questions were how peripheral serotonin levels differ between individuals that are in love compared to individuals that are not in love, and how these levels are associated with obsessive thinking about the beloved. Because gender differences exist in romantic love and in the serotonergic system, gender differences were tested. Twenty participants who were in love (10 men) and 20 who were not in love (10 men) completed several questionnaires, and plasma and serum serotonin levels were assessed. The men who were in love had lower serotonin levels than the men who were not in love, while women showed the opposite pattern. The participants that were in love reported obsessive thinking about their beloved for 65% of their waking hours. In women, obsessive thinking about the beloved was associated with an increased serotonin level in serum. The serotonergic system seems to play a role in romantic love, but the effects appear opposite for men and women.

The Measurement of Platelet-Poor Plasma Serotonin: A Systematic Review of Prior Reports and Recommendations for Improved Analysis

BACKGROUND

Recent reports of new and important roles for serotonin (5-hydroxytryptamine, 5-HT) in the periphery have substantially increased interest in measuring peripheral serotonin. Nearly all circulating serotonin is found within platelets and this pool has been assessed by measuring serotonin in whole blood or in platelet-rich plasma. Measurement of the much smaller but potentially critically important pool of human free plasma serotonin in platelet-poor plasma (PPP) has proven much more difficult, with a wide range of reference values reported.

CONTENT

To characterize the available data we carried out a systematic literature search of previous reports of PPP serotonin and attempted to determine the best estimate of true PPP serotonin concentration in humans. A total of 101 published reports that included PPP serotonin values in healthy controls were found and included in the summary statistical analyses. The distribution of PPP serotonin values demonstrated high skewness (+1.98), and the reported values ranged from 0.6 to 179 nmol/L, with a mean of 31.6 nmol/L, an SD of 38.9 nmol/L, and a median of 14.8 nmol/L.

SUMMARY

Reported concentrations for human PPP or free plasma serotonin were highly discrepant, with most reports giving erroneously high values that should be disregarded. Inherent difficulties in selectively measuring the extremely low concentrations of serotonin present in PPP and in preparing PPP without contamination from platelet-derived serotonin contributed to the problem, as did the failure of researchers to compare their results with those from prior studies. There is a clear and pressing need for reference materials for the measurement of plasma (PPP) serotonin.

Altered affinity of the platelet vesicular monoamine transporter 2 to dihydrotetrabenazine in children with major depression

Platelet vesicular monoamine transporter (VMAT2) binding characteristics were assessed, using high affinity dihydrotetrabenazine ([(3)H]TBZOH) binding, in 14 children with major depression (MDD) and 16 matched controls. All participants underwent a thorough diagnostic evaluation and the levels of depression and anxiety were measured. K (d) values were significantly lower in children with MDD versus controls (2.93 ± 0.84 vs. 3.63 ± 0.56 nM, respectively, t = 2.4, df = 18.4, p = 0.025). B (max) values did not differ significantly. This preliminary finding indicates a possible structural change in platelet VMAT2 in children with MDD.

Association of polymorphisms of the serotonergic pathways with clinical traits of impulsive-aggression and suicidality in adolescents: a multi-center study

OBJECTIVES

Suicidal behaviour runs in families. This study evaluated association between common polymorphisms in the serotonergic and adrenergic candidate genes (HTR2A, 5HTTLPR, and MAOA) and suicidality, psychopathology and aggression in adolescents.

METHODS

Four groups of adolescents were included: Suicidal (N=35) and non-suicidal (N=30) psychiatric inpatients, suicide attempters admitted to three psychiatric emergency rooms (N=51) and a community-based control group (N=95). All were genotyped and underwent psychological assessment for relevant endophenotypes and plasma serotonin content (p5HT) was measured.

RESULTS

Homozygosity for the T allele of the HTR2A 102T/C polymorphism was associated with lower impulsivity (P=0.03) and aggression (P=0.01) compared to TC carriers. Low activity MAOA genotypes were associated with suicidality (P=0.04). No association was found between p5HT level and the examined polymorphisms.

CONCLUSIONS

Our findings are in line with the associations described in adult suicidal population. Further studies are needed to evaluate the gene ? environmental interactions in larger samples in an attempt to clarify the possible role of genetic factors in pediatric suicidal and impulsive-aggressive behaviour.

Is impulsivity a link between childhood abuse and suicide?

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

Relationship between whole blood serotonin and repetitive behaviors in autism

This study was conducted to examine the relationship between whole blood serotonin level and behavioral symptoms in 78 subjects with autism. No significant associations were found between serotonin level and the primary behavioral outcome measures. However, a significant inverse relationship between serotonin level and self-injury was demonstrated.

Increased plasma serotonin in complex regional pain syndrome type 1

BACKGROUND

In patients with complex regional pain syndrome type 1 (CRPS1), some improvement can be achieved by the administration of ketanserin, a 5-HT(2A) receptor antagonist. We measured plasma levels of serotonin (5-HT) during CRPS1 and correlated these levels with disease characteristics.

METHODS

Plasma 5-HT was measured in 35 patients who had CRPS1 for 3 yr and compared with 35 age-matched healthy controls.

RESULTS

The plasma 5-HT levels were 411 +/- 263 nmol/L and 29 +/- 18 nmol/L, respectively (P < 0.001). No correlations with disease characteristics were observed.

CONCLUSIONS

The markedly elevated levels of plasma 5-HT in CRPS1 patients suggest a role for 5-HT during the course of this disease. However, because of the lack of correlations with distinct disease characteristics, 5-HT is probably one of a number of mediators in CRPS1.

Interaction of child and family psychopathology leading to suicidal behavior

According to the Centers for Disease Control and Prevention, suicide is the third leading cause of death in adolescence in the United States. Nonfatal forms of suicidal behavior are the most common reasons for the psychiatric hospitalization of adolescents in many countries. The risk for suicide attempt among offspring of suicide completers is multifactorial, challenging experts to develop a strategy that includes assessment and management that consider these factors. Although treatment of depression is necessary, antisuicide treatment strategies that solely target depression may not be sufficient to reduce suicidal risk. Other factors, such as impulsive aggression and parental history of sexual abuse, also contribute to suicidal risk.

Abnormal neurotransmitter release underlying behavioral and cognitive disorders: toward concepts of dynamic and function-specific dysregulation

Abnormalities in the regulation of neurotransmitter release and/or abnormal levels of extracellular neurotransmitter concentrations have remained core components of hypotheses on the neuronal foundations of behavioral and cognitive disorders and the symptoms of neuropsychiatric and neurodegenerative disorders. Furthermore, therapeutic drugs for the treatment of these disorders have been developed and categorized largely on the basis of their effects on neurotransmitter release and resulting receptor stimulation. This perspective stresses the theoretical and practical implications of hypotheses that address the dynamic nature of neurotransmitter dysregulation, including the multiple feedback mechanisms regulating synaptic processes, phasic and tonic components of neurotransmission, compartmentalized release, differentiation between dysregulation of basal vs activated release, and abnormal release from neuronal systems recruited by behavioral and cognitive activity. Several examples illustrate that the nature of the neurotransmitter dysregulation in animal models, including the direction of drug effects on neurotransmitter release, depends fundamentally on the state of activity of the neurotransmitter system of interest and on the behavioral and cognitive functions recruiting these systems. Evidence from evolving techniques for the measurement of neurotransmitter release at high spatial and temporal resolution is likely to advance hypotheses describing the pivotal role of neurotransmitter dysfunction in the development of essential symptoms of major neuropsychiatric disorders, and also to refine neuropharmacological mechanisms to serve as targets for new treatment approaches. The significance and usefulness of hypotheses concerning the abnormal regulation of the release of extracellular concentrations of primary messengers depend on the effective integration of emerging concepts describing the dynamic, compartmentalized, and activity-dependent characteristics of dysregulated neurotransmitter systems.

Deliberate self-harm in adolescents

PURPOSE OF REVIEW

To review literature on young people who deliberately harmed themselves that was published between March 2005 and December 2006 in English language journals.

RECENT FINDINGS

Recent follow-up studies have confirmed that deliberate self-harm at a young age is an important indication of mental health problems in later life, including a strongly increased risk of subsequent suicidal behavior. Main recent research includes study of risk factors and predictors of deliberate self-harm, and continuing study of the effects of pharmacological treatment, in particular selective serotonin reuptake inhibitors, in children and adolescents.

SUMMARY

Recent findings regarding risk factors of adolescent deliberate self-harm confirm the importance of depressive disorders, deficient problem solving, exposure to suicidal behavior and familial characteristics. More biological studies of young people are required to provide evidence regarding neurobiological correlates of risk factors of suicidality in young people. The association between the use of antidepressants in depressed children and adolescents and the emergence of suicidal behavior continues to be a matter of debate due to the conflicting evidence from ecological or observational studies and meta-analyses. Although psychotherapeutic approaches have been examined less extensively, the results regarding cognitive behavior therapy in depressed and suicidal young people are clearly positive. Measures to prevent suicidal behavior in young people require further research.

Preventing suicide in adolescents with alcohol use disorders

Adolescent suicide is an escalating crisis that needs to be addressed by clinicians and researchers. Alcohol use has consistently been implicated in adolescent suicide and it is generally assumed that alcohol use leads to an increased risk in suicidality, suicide attempts and completed suicides. It can lead to adolescent suicidality through alcohol myopia, disinhibition, and impaired judgment. Multiple genetically related intermediate phenotypes might contribute to the risk of alcohol misuse and suicidal behavior in adolescents. Genetic variations that enhance the risk for mood and anxiety symptoms or susceptibility to stress might increase risk through different mechanisms. Comorbid disorders such as depression are frequently exhibited in adolescents who misuse alcohol, therefore any adolescent who appears to be at risk for alcoholism or depression should always be screened for all other psychiatric disorders and for suicidality; some signs suicidal adolescents may exhibit include withdrawal, personality change, and a loss of interest in pleasurable activities. While assessment is important, prevention is crucial in any attempt to decrease the incidence of adolescent suicide. The US Center for Disease Control and Prevention (CDC) has established a set of seven guidelines that can be implemented from kindergarten through high school in order to establish alcohol prevention efforts in schools. Through beginning prevention efforts at a young age, it is hopeful that both alcohol misuse and adolescent suicide can be reduced.

Plasma serotonin levels in young violent offenders: Aggressive responding and personality correlates

70 young male violent offenders and 30 normal controls in Hunan, China were interviewed and assessed by the Minnesota Multiphasic Personality Inventory (MMPI), Point Subtraction Aggression Paradigm (PSAP) and plasma serotonin (5-HT) level. Compared to the normal controls, the violent offenders had significantly higher plasma 5-HT levels; higher scores on the MMPI subscale Pd (P < 0.01), Pa (P < 0.05); and higher PSAP-B responding and lower PSAP-C responding (P < 0.05). There was a positive correlation between the MMPI Pd score and the PSAP B response, but no significant correlation was found between Pd score and plasma 5-HT level, or between PSAP B response and plasma 5-HT level. Our data suggest that the young violent offenders are more aggressive than the normal control. But this study did not demonstrate that the plasma 5-HT level had a correlation with the PSAP aggressive response. The relationship between the aggressiveness and impulsivity in the violent behavior needs further study.

Neuropharmacological modulation of cognition

PURPOSE OF REVIEW

Problems relating to impulsivity, attention, and working memory occur in many neuropsychiatric disorders and represent important targets for pharmacological intervention. The purpose of this article is to review recent neuropharmacological manipulation studies in humans relating to these domains.

RECENT FINDINGS

Serotonin manipulations in healthy volunteers did not affect response inhibition, a cognitive function implicated in impulsive symptoms of attention deficit hyperactivity disorder, trichotillomania, and substance abuse. Serotonin manipulations did affect performance on cognitive tests involving emotionally salient rewards and feedback, suggesting involvement of this neurochemical in affective aspects of impulsivity. Attentional deficits in attention deficit hyperactivity disorder and visuospatial neglect were ameliorated by noradrenergic drugs. Noradrenergic beta-blockade suppressed the encoding of emotionally arousing unpleasant stimuli and reduced amygdala activation in healthy volunteers, with potential implications for posttraumatic stress disorder. Dopaminergic manipulations affected aspects of working memory in healthy volunteers and in patients with Parkinson's disease, with evidence for bidirectional effects depending on baseline performance.

SUMMARY

Recent findings raise exciting prospects for modulating impulsivity, attention, and working memory in a variety of neuropsychiatric disorders. Future studies should use computerized cognitive assessment, measures of functional genetic polymorphisms, and neuroimaging techniques, in order to further elucidate the neurochemical substrates of cognition and optimize treatment approaches.

Neurobiology of depression in children and adolescents

This article reviews classical and updated studies of the neurobiology of depressive disorders in children and adolescents. Most studies of childhood and adolescent depression and suicide have followed up the observations and methods used in studies in adults. These studies include neuroendocrine studies, which particularly look at the hypothalamic-pituitary-adrenal axis, the serotonergic system, peripheral blood and cerebrospinal fluid biologic markers, genetics, gene-environment interactions and sleep studies, and neuroimaging and postmortem studies, although in these areas the number of studies is limited.