Peripheral serotonin measures in prepubertal psychiatric inpatients and normal children: associations with suicidal behavior and its risk factors

Unlocking the Secrets: Exploring the Biochemical Correlates of Suicidal Thoughts and Behaviors in Adults with Autism Spectrum Conditions

Involving 1 million people a year, suicide represents one of the major topics of psychiatric research. Despite the focus in recent years on neurobiological underpinnings, understanding and predicting suicide remains a challenge. Many sociodemographical risk factors and prognostic markers have been proposed but they have poor predictive accuracy. Biomarkers can provide essential information acting as predictive indicators, providing proof of treatment response and proposing potential targets while offering more assurance than psychological measures. In this framework, the aim of this study is to open the way in this field and evaluate the correlation between blood levels of serotonin, brain derived neurotrophic factor, tryptophan and its metabolites, IL-6 and homocysteine levels and suicidality. Blood samples were taken from 24 adults with autism, their first-degree relatives, and 24 controls. Biochemical parameters were measured with enzyme-linked immunosorbent assays. Suicidality was measured through selected items of the MOODS-SR. Here we confirm the link between suicidality and autism and provide more evidence regarding the association of suicidality with increased homocysteine (0.278) and IL-6 (0.487) levels and decreased tryptophan (-0.132) and kynurenic acid (-0.253) ones. Our results suggest a possible transnosographic association between these biochemical parameters and increased suicide risk.

Baseline platelet serotonin in a multi-site treatment study of depression in veterans administration patients: Distribution and effects of demographic variables and serotonin reuptake inhibitors

BACKGROUND

The objectives of the study were: (1) to examine the overall distribution of baseline platelet serotonin (5-hydroxytryptamine, 5-HT) values in patients seeking treatment for depression and to define subgroups based on the apparent presence or absence of drug exposure; (2) to assess the bioeffect of 5-HT reuptake inhibitors (SRIs) at the platelet 5-HT transporter; and (3) to examine the relationships of demographic variables including population (ancestry), sex, age, and season of sampling to platelet 5-HT concentration.

METHODS

Platelet 5-HT levels were measured in a cross-sectional study of 1433 Veterans Administration (VA) patients participating in a pragmatic multi-site pharmacogenomic treatment study of depression. Patients were characterized medically and demographically using VA health records and self-report.

RESULTS

A clearly bimodal distribution was observed for platelet 5-HT levels with the lower mode associated with patients exposed to SRIs at baseline. Median transporter blockade bioeffects were similar across the various selective 5-HT reuptake inhibitors (SSRIs) and 5-HT/norepinephrine reuptake inhibitors (SNRIs). In a subset of patients apparently not exposed to an SRI, significant effects of population and sex were observed with group mean platelet 5-HT levels being 25 % greater (p < 0.001) in African-American (AA) individuals compared to European-Americans (EAs). The female group mean was 14 % (p < 0.001) greater than male group mean. An effect of age was observed (r = -0.11, p < 0.001) and no effect of season or month of sampling was seen.

CONCLUSIONS

Further research is warranted to understand the bases and clinical implications of the population and sex differences. The apparent similarity in bioeffect at the 5-HT transporter across SSRIs and when comparing SSRIs and SNRIs informs discussions about initiating, dose adjustment and switching of 5-HT reuptake inhibitors.

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.

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.

Suicidal thoughts and behaviors in preadolescents: Findings and replication in two population-based samples

INTRODUCTION

Given increasing concern in suicide in preadolescent children, this study aimed to characterize and identify potential indicators of risk for suicidal ideation (SI) and suicide attempts (SAs) in this population.

METHODS

Data were drawn from two population-based samples of preadolescents: the 2007 and 2010 Minnesota Student Survey and analyses were restricted to 11- and 12-year-olds. Sociodemographic characteristics, childhood maltreatment, parental relations, peer relations, and school climate were examined in relation to past-year SI and SA. To examine correlates of SI, unconfounded by risk for SA, individuals with a history of SA were excluded from SI analyses. Correlates of SA were examined among individuals with past-year SI. Logistic regression analyses were conducted with past-year SI and SA as criterion variables.

RESULTS

Results from the 2007 and 2010 data sets were highly consistent. The prevalence of past-year SI was 9.28% and 9.25% in 2007 and 2010, respectively. Of the total sample, 1.90% and 1.87% reported a past-year SA (17.00% and 16.78% of those with past-year SI). Overall, effect sizes were generally modest to medium. The strongest effects were observed for sexual and physical abuse, parental support, and perceived safety at school (ps < .001). In multivariate analyses of SI and SA, sexual and physical abuse had the largest effect sizes (ORSI  = 2.18 [95% CI = 1.90-2.51] to 2.96 [95% CI = 2.69-3.26]; ORSA  = 1.55 [95% CI = 1.29-1.86] to 2.26 [95% CI = 1.82-2.80]).

CONCLUSIONS

SI and SA occur at a concerning rate among preadolescent children. Screening for childhood sexual and physical abuse may be important for identifying those at risk for these clinical outcomes.

The role of the kynurenine pathway in suicidality in adolescent major depressive disorder

The neuroimmunological kynurenine pathway (KP) has been implicated in major depressive disorder (MDD) in adults and adolescents, most recently in suicidality in adults. The KP is initiated by the enzyme indoleamine 2,3-dioxygenase (IDO), which degrades tryptophan (TRP) into kynurenine (KYN) en route to neurotoxins. Here, we examined the KP in 20 suicidal depressed adolescents-composed of past attempters and those who expressed active suicidal intent-30 non-suicidal depressed youth, and 22 healthy controls (HC). Plasma levels of TRP, KYN, 3-hydroxyanthranilic acid (3-HAA), and KYN/TRP (index of IDO) were assessed. Suicidal adolescents showed decreased TRP and elevated KYN/TRP compared to both non-suicidal depressed adolescents and HC. Findings became more significantly pronounced when excluding medicated participants, wherein there was also a significant positive correlation between KYN/TRP and suicidality. Finally, although depressed adolescents with a history of suicide attempt differed from acutely suicidal adolescents with respect to disease severity, anhedonia, and suicidality, the groups did not differ in KP measures. Our findings suggest a possible specific role of the KP in suicidality in depressed adolescents, while illustrating the clinical phenomenon that depressed adolescents with a history of suicide attempt are similar to acutely suicidal youth and are at increased risk for completion of suicide.

The role of serotonin in adolescent suicide: theoretical, methodological, and clinical concerns

INTRODUCTION

Adolescent suicide is a complex phenomenon that has similarities and differences with adult suicidal behavior. Serotonergic (5-HT) dysfunction has extensively been studied in adults and has been postulated as a biological marker for suicide.

METHODS

We conducted a comprehensive review of the studies available in MEDLINE from January 1998 until January 2014 on the role of "serotonin" both in adults' and adolescents' "completed suicide", "suicide attempts", and "suicidal ideation".

RESULTS

Studies on 5-HT conducted in adults and replicated in adolescents have yielded inconsistent results. Although some genes related to the serotonergic system have been associated with an increased risk of suicide, attempts to reproduce those findings have been unsuccessful and a common genetic variant associated to suicidal behavior has yet to be identified.

DISCUSSION

Studies on the neurobiology of adolescent suicide should consider the biological specificities of this life stage and of gender differences during this period. Future research designs should also try to integrate findings in the psychological and biological domains. Prospective studies may help understand the process that leads from suicidal ideation to suicide attempts or completed suicides in this population.

Brain as an endocrine source of circulating 5-hydroxytryptamine in ontogenesis in rats

This study was aimed to test the authors' hypothesis stating that the developing brain before the closure of the blood brain barrier (BBB) operates as an endocrine organ that secretes classical neurotransmitters and neuropeptides into the general circulation. 5-Hydroxytryptamine (5-HT) was selected as a marker of brain endocrine activity though it is also secreted by peripheral organs. 5-HT was detected in blood of rats in a biologically active concentration at any studied age, from the 21st embryonic day till the 30th postnatal day. The brain was proven to be a source of circulating 5-HT before the BBB closure by showing that the 5-HT concentration in blood decreased significantly after the inhibition of 5-HT synthesis in the brain of neonates. The 5-HT concentration in blood was not diminished after the BBB closure, apparently due to compensatory increase of 5-HT secretion by peripheral sources. Thus, brain-derived 5-HT is delivered to the general circulation before the BBB closure being potentially capable of providing endocrine regulation of target organs.

Association of attention-deficit/hyperactivity disorder and celiac disease: a brief report

OBJECTIVE

A possible association of celiac disease with psychiatric and psychological disturbances such as attention-deficit/hyperactivity disorder (ADHD) has been reported repeatedly. The objective of this study was to observe whether a gluten-free diet could alleviate the behavioral symptoms in patients with celiac disease and ADHD.

METHOD

Sixty-seven subjects aged 7 to 42 years (mean = 11.4 years) with ADHD were enrolled in the study in South Tyrol, Italy, from 2004 to 2008. Hypescheme, an operational criteria checklist that incorporates DSM-IV and ICD-10 criteria, was used to assess ADHD-like symptomatology. Additionally, blood serum levels of all subjects were assessed for possible celiac disease by examining antigliadine and antiendomysium antibodies. A gluten-free diet was initiated for at least 6 months in celiac disease-positive patients with ADHD.

RESULTS

Of the 67 patients with ADHD, 10 were positive for celiac disease. After initiation of the gluten-free diet, patients or their parents reported a significant improvement in their behavior and functioning compared to the period before celiac diagnosis and treatment, which was evident in the overall mean score on the Hypescheme questionnaire (t = 4.22, P = .023).

CONCLUSIONS

Celiac disease is markedly overrepresented among patients presenting with ADHD. A gluten-free diet significantly improved ADHD symptoms in patients with celiac disease in this study. The results further suggest that celiac disease should be included in the ADHD symptom checklist.

Suicidal thoughts are associated with platelet counts in adolescent inpatients

OBJECTIVE

Platelets (PLT), which serve as the primary hemostatic indicator, can be used as a peripheral model for studying monoamine turnover in the brain. Therefore, they are attractive targets as circulatory biomarkers for the detection of psychiatric disorders. However, PLT counts have not been utilized as a peripheral biomarker of psychopathology.

METHODS

This study was a retrospective analysis of PLT counts upon admission of 108drug-naïve adolescents hospitalized in an inpatient psychiatric department. PLT counts of patients with suicidal ideation (SI) were compared with those of nonsuicidal in patients (NSI) and those of 77 healthy adolescents, serving as a control group. The patients' disorders were diagnosed and classified by one of four American Psychiatric Association, Diagnostic and Statistical Manual of Mental Disorders, 4th ed. (DSM IV) diagnoses, that is, unipolar depression, bipolar depression, schizophrenia, and a pooled group of conduct and borderline personality disorders.

RESULTS

Significantly higher PLT counts were observed in SI patients, as compared with NSI patients (300,200±53.3/mL vs. 253,900±53.2/mL, respectively; p=0.0001). A significant difference in PLT counts in SI patients, relative to the control group, was also noted (300,200±53.3/mL vs. 254,000±52/mL, respectively; p=<10(-26)). Finally, a significant difference in PLT counts was observed between conduct/borderline personality disorders patient with and without suicidal ideation (292,000±55/mL vs. 246,000±64/mL, respectively; p=0.001).

CONCLUSIONS

PLT counts are higher in suicidal hospitalized adolescents than in nonsuicidal inpatients, as well as than in controls.

Examining autism spectrum disorders by biomarkers: example from the oxytocin and serotonin systems

OBJECTIVE

Autism spectrum disorder (ASD) is a heritable but highly heterogeneous neuropsychiatric syndrome, which poses challenges for research relying solely on behavioral symptoms or diagnosis. Examining biomarkers may give us ways to identify individuals who demonstrate specific developmental trajectories and etiological factors related to ASD. Plasma oxytocin (OT) and whole-blood serotonin (5-HT) levels are consistently altered in some individuals with ASD. Reciprocal relationships have been described between brain oxytocin and serotonin systems during development. We therefore investigated the relationship between these peripheral biomarkers as well as their relationships with age.

METHOD

In our first study, we analyzed correlations between these two biomarkers in 31 children and adolescents who were diagnosed with autism and were not on medications. In our second study, we explored whether whole-blood 5-HT levels are altered in mice lacking the oxytocin receptor gene Oxtr.

RESULTS

In humans, OT and 5-HT were negatively correlated with each other (p < .05) and this relationship was most prominent in children less than 11 years old. Paralleling human findings, mice lacking Oxtr showed increased whole-blood 5-HT levels (p = .05), with this effect driven exclusively by mice less than 4 months old (p < .01).

CONCLUSIONS

Identifying relationships between identified ASD biomarkers may be a useful approach to connect otherwise disparate findings that span multiple systems in this heterogeneous disorder. Using neurochemical biomarkers to perform parallel studies in animal and human populations within a developmental context is a plausible approach to probe the root causes of ASD and to identify potential interventions.

Plasma kynurenine levels are elevated in suicide attempters with major depressive disorder

BACKGROUND

Inflammation has been linked to depression and suicide risk. One inflammatory process that has been minimally investigated in this regard is cytokine-stimulated production of kynurenine (KYN) from tryptophan (TRP). Recent data suggest that KYN increases in cerebrospinal fluid (CSF) are associated with depressive symptoms secondary to immune activation. KYN may alter dopaminergic and glutamatergic tone, thereby contributing to increased arousal, agitation and impulsivity - important risk factors in suicide. We hypothesized that patients with major depressive disorder (MDD) and a history of suicide attempt would have higher levels of KYN than depressed nonattempters, who in turn would have higher levels than healthy volunteers.

METHODS

Plasma KYN, TRP, and neopterin were assayed by high performance liquid chromatography in three groups: healthy volunteers (n=31) and patients with MDD with (n=14) and without (n=16) history of suicide attempt. Analysis of variance tested for group differences in KYN levels.

RESULTS

KYN levels differed across groups (F=4.03, df=(2,58), and p=0.023): a priori planned contrasts showed that KYN was higher in the MDD suicide attempter subgroup compared with MDD non-attempters (t=2.105, df=58, and p=0.040), who did not differ from healthy volunteers (t=0.418, df=58, and p=0.677). In post hoc testing, KYN but not TRP was associated with attempt status, and only suicide attempters exhibited a positive correlation of the cytokine activation marker neopterin with the KYN:TRP ratio, suggesting that KYN production may be influenced by inflammatory processes among suicide attempters.

CONCLUSION

These preliminary results suggest that KYN and related molecular pathways may be implicated in the pathophysiology of suicidal behavior.

Platelet monoamine oxidase activity in children with attention-deficit/hyperactivity disorder

Attention-deficit/hyperactivity disorder (ADHD) is a highly heritable developmental disorder characterized by symptoms of impulsivity, hyperactivity and/or inattention, and associated with structural and biochemical abnormalities in cortical and limbic structures innervated by dopamine, noradrenalin and serotonin. The enzyme monoamine oxidase, type B (MAO-B), is expressed in platelets, and metabolizes endogenous amines. Its activity has been proposed to represent a peripheral marker of various traits and forms of psychopathology. This study evaluated platelet MAO activity with a spectrofluorimetric method in 72 boys and 12 girls with predominantly hyperactive, predominantly inattentive, and combined subtype of ADHD (DSM-IV criteria), and in 64 control children. The results showed significantly lower platelet MAO activity in children with hyperactive, inattentive, and combined subtype of ADHD than in control children. There was no significant association between platelet MAO activity and gender or age. The limitation of the study was in the small sample of girls with ADHD (N=12), and in the determination of only one peripheral marker. In line with hypotheses of lower platelet MAO activity in different types of psychopathology, children with different subtypes of ADHD had significantly lower platelet MAO-B activity than control children.

A preliminary study of cytokines in suicidal and nonsuicidal adolescents with major depression

BACKGROUND

Increased systemic cytokine levels, modulators of the immune system, have been repeatedly documented in adult and adolescent major depressive disorder (MDD). This preliminary study extends this work to test the role of cytokines in suicidal symptomatology in adolescent MDD. Hypotheses were that acutely suicidal depressed adolescents would have: (1) increased plasma levels of interferon-gamma (IFN-gamma), tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6), and IL-1beta, and (2) a proinflammatory/antiinflammatory cytokine imbalance (indexed by plasma IFN-gamma/IL-4), compared to nonsuicidal depressed adolescents and healthy controls.

METHODS

Twelve suicidal adolescents with MDD (7 females [58%]; 5 medication-free/naïve), 18 nonsuicidal adolescents with MDD (12 females [67%]; 8 medication-free/naïve), and 15 controls (8 females [53%]) were enrolled. MDD had to be of at least 6 weeks duration, with a minimum severity score of 40 on the Children's Depression Rating Scale-Revised. Plasma cytokines were examined using enzyme-linked immunosorbent assays. Nonparametric tests were used to compare subject groups.

RESULTS

Unexpectedly, suicidal adolescents with MDD had significantly decreased plasma TNF-alpha concentrations compared to nonsuicidal adolescents with MDD (1.33 +/- 2.95 pg/mL versus 30.9 +/- 110.9 pg/mL; p = 0.03). IFN-gamma was increased in both suicidal and nonsuicidal adolescents with MDD compared to controls (2.14 +/- 6.22 and 4.20 +/- 14.48 versus 0.37 +/- 0.64; p < 0.02, p = 0.005). Findings remained evident when controlled for age and gender.

CONCLUSIONS

Our preliminary findings suggest that immune system dysregulation may be associated with suicidal symptomatology in adolescent MDD. These findings should be replicated in larger samples with medication-free adolescents.

Completed suicide in childhood

Suicide in children and young adolescents up to 14 years of age has increased in many countries, warranting research and clinical awareness. International reported suicide rates per 100,000 in this young population vary between 3.1 and 0 (mean rate worldwide, approximately 0.6/100.000; male-female ratio, 2:1). Suicide occurs only in vulnerable children; this vulnerability begins with parental mood disorder and impulsive aggression, and family history of suicide. Childhood affective and disruptive disorders and abuse are the most often reported psychiatric risk factors. Suicide becomes increasingly common after puberty, most probably because of pubertal onset of depression and substance abuse, which substantially aggravate suicide risk. Biologic findings are scarce; however, serotonergic dysfunction is assumed. The most common precipitants are school and family problems and may include actual/anticipated transitions in these environments. Suicides in children and young adolescents up to 14 years of age often follow a brief period of stress. Cognitive immaturity/misjudgment, age-related impulsivity, and availability of suicide methods play an important role. Psychologic autopsy studies that focus on suicides in this age group are needed.

A preliminary investigation of ADHD symptoms in persons with celiac disease

OBJECTIVE

Several studies report a possible association of celiac disease (CD) with psychiatric and psychological disturbances, such as ADHD.

METHOD

The authors assess 132 participants from 3 to 57 years of age (M = 19.3 years) affected by CD for the possibility of an associated ADHD-like symptomatology, using the Conner Scale Hypescheme, a behavioral scale similar to the Conners Rating Scales, before their gluten-free diet was started and 6 months later.

RESULTS

The overall score improves significantly as well as most of the ADHD-like symptomatology specific features (Bonferroni-corrected, paired-sample t tests).

CONCLUSION

The data indicate that ADHD-like symptomatology is markedly overrepresented among untreated CD patients and that a gluten-free diet may improve symptoms significantly within a short period of time. The results of this study also suggest that CD should be included in the list of diseases associated with ADHD-like symptomatology.

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.

Peripheral serotonergic markers in acutely suicidal patients. 1. Comparison of serotonergic platelet measures between suicidal individuals, nonsuicidal patients with major depression and healthy subjects

BACKGROUND

A robust association between "suicidality" and deficits of the serotoninergic neurotransmission has been claimed in the past. However, many studies having investigated the relationship between suicidality and peripheral indicators of serotoninergic neurotransmission suffer from considering only one or a very small number of potentially useful serotoninergic parameters, whereas a synoptic multidimensional approach appears to be more appropriate. Furthermore, the psychiatric context within which suicidal behaviour occurs should be considered when interpreting biochemical findings of patients with suicidal ideation and suicide attempts.

METHODS

In the present study 5 peripheral serotonergic markers, (platelet 5HT concentration, 5HT uptake activity, 5HT(2A) receptor binding characteristics, MAO-B activity and tryptophan concentration in plasma) were assessed simultaneously. Of the 60 acutely suicidal inpatients (ICD-10: F43.xx, n = 52; F31/32/33, n = 8), 45 were suicide attempters. Data of 28 nonsuicidal patients with major depression (F31, n = 4; F32, n = 14; F33, n = 10) and 123 healthy volunteers represented the control groups.

RESULTS

Mean platelet 5HT concentration was significantly lower in suicidal inpatients when compared to nonsuicidal depressed patients, but did not differ from the figure in healthy subjects. Nonsuicidal depressed patients showed significantly higher mean platelet-5HT concentration than healthy controls. Mean V(max) of 5HT uptake in washed platelets, but not in platelet-rich plasma, was significantly higher in suicidal patients than in healthy controls, not, however, when compared to nonsuicidal depressed patients. Mean K(D) for the platelet 5HT(2A) receptor and MAO-B activity were significantly lower in suicidal patients as compared to nonsuicidal depressed patients and healthy controls. The observed differences in peripheral serotonergic markers between groups are partially due to a significant gender effect. A lower MAO-B activity was observed only in suicidal females, while the higher V(max) of 5HT uptake in washed platelets of suicidal patients was due to suicidal males.

CONCLUSIONS

In view of conflicting observations made by other authors and the present findings on suicidal patients with adjustment disorder it remains doubtful whether and if so to which extent platelet studies can provide valid information on serotonergic mechanisms related to suicidal behaviour.

Suicidal Behaviors and Alcohol Use Among Adolescents: A Developmental Psychopathology Perspective

A developmental psychopathology conceptual model was provided to represent the major categories of risk and protective factors, including alcohol use and binge drinking, that predict suicidal behaviors that range from suicidal thoughts to completed suicides. The conceptual model emphasized the importance of identifying age-specific sets of risk and protective factors to facilitate the development of effective interventions. As an empirical illustration, a multivariate mediation path model was specified and evaluated with a sample of teens. Findings indicated that several distal variables (e.g., difficult temperament, coping motives for drinking, lower family support, higher percentage of friends using alcohol) significantly predicted mediators (e.g., depression, stressful events, binge drinking) that, in turn, predicted suicidal behaviors. Binge drinking significantly predicted suicide attempts over and above the influence of depression and stressful events.

[Reduced serotonin levels in platelet-free plasma of adolescents with externalizing behaviour problems]

OBJECTIVES

A serotonergic dysfunction, in particular a reduced serotonergic neurotransmission in the frontal cortex and limbic brain regions, has been discussed in connection with the aetiology of aggressive and impulsive behaviour. Assessment of the activity in the central serotonergic system in children and adolescents is limited due to its technical complexity and ethical restrictions. Therefore, peripheral serotonergic parameters have been used as a model to obtain deeper insight into central serotonergic functions. The aim of this investigation is to examine the significance of plasma serotonin measurement with regard to behavioural problems in adolescents at risk for psychopathology.

METHODS

Within the framework of a prospective longitudinal study of children at risk, serotonin levels in platelet-free blood plasma were measured in a group of n = 10 adolescents aged 15 years with persistent externalizing behaviour (T-score > or = 60 on the "Externalizing Problems" scale of the CBCL) and in a control group of n = 20 mentally undisturbed adolescents. Groups were matched according to age and gender. Externalizing behaviour was assessed by means of a parent questionnaire, the Achenbach Child Behavior Checklist (CBCL).

RESULTS

Significantly lower levels of plasma serotonin were found in adolescents with persistent behaviour problems than in the control group. Significant negative correlations between serotonin levels and the CBCL scales "Aggressive Behavior" and "Externalizing Problems" were obtained for the total sample.

CONCLUSIONS

Earlier findings that described a serotonergic deficit as a key mechanism in the manifestation of aggressive and antisocial behaviour are confirmed for adolescents at risk taken from a community sample.

Regulation of sexual behaviour in male macaques by sex steroid modulation of the serotonergic system

The view that androgen action is the primary impetus underlying male-typical behaviour has been irrevocably altered by the profound perturbations in social and sexual behaviour observed in recent models of oestrogen insufficiency in male mice. Evidence is also accumulating for an involvement of oestrogens in the modulation of neural systems that are thought to play important roles in male reproductive functioning. Specifically, the serotonergic system is implicated in diverse autonomic functions, most or all of which are sensitive to oestradiol as well. Although their interaction domains have yet to be examined in male primates, roles have been established for both oestrogen and serotonin in the regulation of male sexual behaviour. We used a blinded, sham-treated and self-controlled, randomized, multitreatment cross-over design to test the hypothesis that male sexual behaviour is regulated by oestrogen modulation of the serotonergic system in intact male Japanese macaques. Regression analysis revealed that oestradiol and whole blood tryptophan, but not testosterone or 5alpha-dihydrotestosterone, had additive, independent effects on male potentia over a range of hormone concentrations, whereas androgens were confirmed to be the primary determinants of sexual motivation. We suggest that modulation of the serotonergic system by 'female hormones' may be fundamental to the regulation of male mating success in higher primates. This might also explain, at least in part, why significant correlations between steroid hormones and male copulatory behaviour have traditionally proven so elusive in this order, thereby warranting a re-evaluation of the current notion that male sexual behaviour has been emancipated from activational hormonal control in higher primates.

Gluten-free diet may alleviate depressive and behavioural symptoms in adolescents with coeliac disease: a prospective follow-up case-series study

BACKGROUND

Coeliac disease in adolescents has been associated with an increased prevalence of depressive and disruptive behavioural disorders, particularly in the phase before diet treatment. We studied the possible effects of a gluten-free diet on psychiatric symptoms, on hormonal status (prolactin, thyroidal function) and on large neutral amino acid serum concentrations in adolescents with coeliac disease commencing a gluten-free diet.

METHODS

Nine adolescents with celiac disease, aged 12 to 16 years, were assessed using the semi-structured K-SADS-Present and Lifetime Diagnostic interview and several symptom scales. Seven of them were followed at 1 to 2, 3, and 6 months on a gluten-free diet.

RESULTS

Adolescent coeliac disease patients with depression had significantly lower pre-diet tryptophan/ competing amino-acid (CAA) ratios and free tryptophan concentrations, and significantly higher biopsy morning prolactin levels compared to those without depression. A significant decrease in psychiatric symptoms was found at 3 months on a gluten-free diet compared to patients' baseline condition, coinciding with significantly decreased coeliac disease activity and prolactin levels and with a significant increase in serum concentrations of CAAs.

CONCLUSION

Although our results of the amino acid analysis and prolactin levels in adolescents are only preliminary, they give support to previous findings on patients with coeliac disease, suggesting that serotonergic dysfunction due to impaired availability of tryptophan may play a role in vulnerability to depressive and behavioural disorders also among adolescents with untreated coeliac disease.

Sex hormones and biogenic amine turnover of sex offenders in relation to their temperament and character dimensions

Relationships between Cloninger's temperament and character dimensions and plasma sex hormone levels and biogenic amine turnover were studied in male prison inmates convicted of rape (n=61) or child molestation (n=24) and normal male controls (n=25). The participants completed the Temperament and Character Inventory (TCI), which includes the temperament dimensions Novelty Seeking, Harm Avoidance, Reward Dependence and Persistence as well as the character dimensions Self-Directedness, Cooperativeness and Self-Transcendence. Plasma levels of testosterone, dihydrotestosterone, sex hormone binding globulin, luteinizing hormone (LH) and follicle-stimulating hormone were estimated in plasma samples and 5-hydroxyindoleacetic acid (5-HIAA), homovanillic acid (HVA), and 3-methoxy-4-hydroxyphenylglycol (MHPG) in urine samples. Both sex offender groups had higher Novelty, Seeking and lower Reward Dependence, Self-Directedness and Cooperativeness scores compared with the controls. Plasma levels of testosterone and dihydrotestosterone were significantly higher in rapists than in controls. Novelty Seeking scores were positively correlated with LH levels in rapists, and with testosterone levels in child molesters. Harm Avoidance scores were negatively correlated with 5-HIAA levels in rapists and with HVA levels in child molesters. In rapists, the calculated free androgen index showed a negative correlation with 5-HIAA. For the sex offender sample as a whole, the subgroup with high testosterone levels had higher Harm Avoidance scores, the subgroup with low HVA levels had lower Cooperativeness scores, and the subgroups with high 5HIAA or MHPG levels had lower Persistence scores. The results indicate that Novelty Seeking behavior in the group of rapists is associated with a hyperactive hypothalamic-pituitary-gonadal axis. In addition, low serotonin turnover and low dopamine turnover seem to be associated with a passive-avoidant behavioral style in rapists and child molesters, respectively.

Mental Disorders in Adolescents With Celiac Disease

A high prevalence of depressive symptoms, hypothetically related to serotonergic dysfunction, has been reported among adults with celiac disease. The authors used semistructured psychiatric interviews and symptom measurement scales to study mental disorders in 29 adolescents with celiac disease and 29 matched comparison subjects. Relative to the comparison subjects, the celiac disease patients had significantly higher lifetime prevalences of major depressive disorder (31% versus 7%) and disruptive behavior disorders (28% versus 3%). In most cases these disorders preceded the diagnosis of celiac disease and its treatment with a gluten-free diet. The prevalence of current mental disorders was similar in both groups. Celiac disease in adolescents is associated with an increased prevalence of depressive and disruptive behavioral disorders, particularly in the phase before diet treatment.

Platelet serotonin content correlates inversely with life history of aggression in personality-disordered subjects

The objective of this study was to test the hypothesis that platelet serotonin (5-hydroxytryptamine, 5-HT) content is correlated with measures of aggression in healthy human subjects. Platelet 5-HT content (ng/mg protein) was measured in personality-disordered (PD) and normal control (NC) subjects. Aggression was assessed with the Life History of Aggression (LHA), the Buss-Durkee Hostility Inventory (BDHI), and the Motor Aggression and Research Criteria for Intermittent Explosive Disorder (IED-IR); impulsivity was assessed with the Eysenck Personality Questionnaire II (EPQII) and the Barratt Impulsiveness Scale (BIS-11). LHA Aggression, but not impulsivity, scores showed significant inverse correlations with platelet 5-HT content in all subjects or in PD subjects alone. The findings in PD subjects remained significant after co-varying for race. PD subjects with IED-IR had lower platelet 5-HT content compared with PD subjects who did not have IED-IR, although this finding only approached significance after controlling for race. This study demonstrates an association between reduced platelet 5-HT content and aggression in PD subjects. Similar to other studies of platelet 5-HT markers, these data suggest that platelet 5-HT content may also reflect central 5-HT alterations and may be used as a biological marker in appropriate patient samples.

Total plasma l-tryptophan, free l-tryptophan and competing amino acid levels in a homicidal male adolescent with conduct disorder

OBJECTIVE

Several studies have shown abnormal findings in human serotonin metabolism, such as increased total plasma l-tryptophan and free l-tryptophan levels among habitually violent antisocial offenders. It is not clear if these increased l-tryptophan levels are associated with adult antisocial personality disorder (ASP) or history of substance abuse, or if these levels are already present in adolescent subjects with conduct disorder (CD).

METHOD

Total plasma and free l-tryptophan and competing amino acids (CAAs) were measured in a 15-year-old adolescent offender, who was convicted for two homicides, and in 10 healthy male controls of similar age and body mass index (BMI).

RESULTS

In the juvenile offender, plasma total l-tryptophan/CAA was 84% and free l-tryptophan/CAA 143% higher than average mean among controls.

CONCLUSION

From this very aggressive boy with CD, findings of free l- and total l-tryptophan/CAA values were similar to those of habitually violent adult ASP offenders. As severe CDs in adolescence tend to develop into adults with ASP, increased l-tryptophan/CAA and free l-tryptophan/CAA values may serve as early indicators for the development of habitually violent adult offenders.

Serum tryptophan ratio and suicidal behavior in adolescents: a prospective study

A lower ratio of tryptophan to other amino acids in serum (tryptophan ratio), established as an index of serotonin precursor available to the brain, has been shown to be associated with increased suicidal behavior in cross-sectional studies. The purpose of this study was to conduct the first prospective examination of the utility of the tryptophan ratio along with clinical variables in predicting suicidal behavior in high-risk and reference adolescents. Adolescents with alcohol use disorders (AUDs) and prior suicidal attempts (n=20), adolescents with AUDs without suicide attempts (n=20), and community controls with neither of these characteristics (n=20) were matched on demographic variables. These groups were not significantly different on the tryptophan ratio at baseline. Of 56 subjects who completed follow-up assessments, six had suicidal behavior in the follow-up period. The tryptophan ratio, along with demographic and clinical variables, was examined using Cox regression with a backward stepwise variable elimination procedure. In the final model, the tryptophan ratio and major depressive disorder both significantly contributed to the prediction of suicidal behavior. This finding suggests that the tryptophan ratio may improve the identification of adolescents at high risk for suicidal behavior.

Thrombozytäre Serotoninkonzentration bei depressiven Kindern und Jugendlichen

Zusammenfassung: Fragestellung: In dieser Studie wurde der Frage nachgegangen, inwieweit ein Zusammenhang zwischen thrombozytärem Serotoningehalt und depressivem bzw. suizidalem Verhalten bei Kindern und Jugendlichen besteht. Methodik: Innerhalb von 16 Monaten wurde bei allen stationär aufgenommenen Patienten im Alter von 4 bis 19 Jahren (n = 145) das thrombozytäre Serotonin mittels Fluoreszenzspektroskopie bestimmt. Zeitnah wurde bei einem Teil der Patienten der Schweregrad der depressiven Symptome durch das DIKJ erhoben. Die verschiedenen Diagnosegruppen wurden anhand der Kriterien der ICD-10 gebildet. Ergebnisse: Mit zunehmendem Alter zeigte sich ein Abfall des Serotiningehaltes im Thrombozyten. Die männlichen Patienten wiesen höhere Serotoninwerte im Vergleich zu den weiblichen auf, wobei die Mädchen allerdings höhere Depressivitätsscores im DIKJ zeigten. Es bestand eine negative Korrelation zwischen dem thrombozytären Serotonin und dem im DIKJ gemessenen Depressivitätsgrad über alle Diagnosegruppen. Unabhängig von der klinischen Diagnose ergaben sich signifikant niedrigere Serotoninkonzentrationen bei den Kindern und Jugendlichen, die unmittelbar vor der stationären Aufnahme einen Suizidversuch unternommen hatten. Auch bei der Gruppe der depressiven Störungen kristallisierte sich eine Untergruppe mit signifikant niedrigerem Serotoningehalt heraus, die kurz zuvor einen Suizidversuch verübt hatten. Schlussfolgerungen: Die vorliegenden Untersuchungen stützen die Auffassung, dass Depressivität in der Kindheit und Jugend mit einem Mangel an Serotonin im Thrombozyten bzw. analog zum Thrombozytenmodell in zentralen Strukturen verbunden ist und ein relatives Defizit an Serotonin ein Suizidalitätsmarker sein könnte.

Practice parameter for the assessment and treatment of children and adolescents with suicidal behavior. American Academy of Child and Adolescent Psychiatry

These guidelines review what is known about the epidemiology, causes, management, and prevention of suicide and attempted suicide in young people. Detailed guidelines are provided concerning the assessment and emergency management of the children and adolescents who present with suicidal behavior. The guidelines also present suggestions on how the clinician may interface with the community. Crisis hotlines, method restriction, educational programs, and screening/ case-finding suicide prevention strategies are examined, and the clinician is advised on media counseling. Intervention in the community after a suicide, minimization of suicide contagion or imitation, and the training of primary care physicians and other gatekeepers to recognize and refer the potentially suicidal child and adolescent are discussed.

Diagnosis of childhood and adolescent suicidal behavior: unmet needs for suicide prevention

This article highlights strategies for diagnosing risk for childhood and adolescent suicidal behavior. Empirical studies identifying risk factors for childhood and adolescent suicidal behavior guided recommendations for suicide risk assessment. Diagnostic assessment involves identification of multiple factors including demographic characteristics, suicidal behavior, psychopathology, interpersonal problems, family discord, family psychopathology, accessibility of lethal suicide methods, exposure to suicide, and protective factors. Interview methods and self-report questionnaires are reliable and valid in identifying suicidal risk but are limited by low base rates of suicide. Identification of risk factors as foci for intervention is important for suicide prevention.

The current status of the platelet 5-HT(2A) receptor in depression

The author reviews the current status of the platelet serotonin (5-HT)(2A) receptor in depression. Considered are studies of receptor binding, and 5-HT-induced platelet activation and aggregation. 5-HT(2A) receptor density tends to increase in depression, although this more clearly relates to suicidality than depression per se. Indeed, data are consistent with the hypothesis that increased density of platelet 5-HT(2A) receptors may be a marker for increased risk of suicide. 5-HT-induced calcium mobilization is enhanced in unipolar depression; however, unlike in bipolar depression, baseline calcium levels are not. Despite inconsistencies, 5-HT-induced aggregation appears inhibited in depression. This may manifest as a relative inhibition, i.e. no change in aggregation response despite a higher density of 5-HT(2A) receptors. The inhibited aggregation response is state dependent, and acute phase proteins or components of the stress response may be factors. It is unclear if differences between depressed and normal subjects in disposition of 5-HT(2A) receptors are generally indicative of traits or states. Nonetheless, there is little evidence that the degree of departure from normal density or activity of platelet of 5-HT(2A) receptors reflects severity of depression.