Denosologization of biological psychiatry or the specificity of 5-HT disturbances in psychiatric disorders

Oxidative and Excitatory Neurotoxic Stresses in CRISPR/Cas9-Induced Kynurenine Aminotransferase Knockout Mice: A Novel Model for Despair-Based Depression and Post-Traumatic Stress Disorder

BACKGROUNDS

Memory and emotion are especially vulnerable to psychiatric disorders such as post-traumatic stress disorder (PTSD), which is linked to disruptions in serotonin (5-HT) metabolism. Over 90% of the 5-HT precursor tryptophan (Trp) is metabolized via the Trp-kynurenine (KYN) metabolic pathway, which generates a variety of bioactive molecules. Dysregulation of KYN metabolism, particularly low levels of kynurenic acid (KYNA), appears to be linked to neuropsychiatric disorders. The majority of KYNA is produced by the aadat (kat2) gene-encoded mitochondrial kynurenine aminotransferase (KAT) isotype 2. Little is known about the consequences of deleting the KYN enzyme gene.

METHODS

In CRISPR/Cas9-induced aadat knockout (kat2-/-) mice, we examined the effects on emotion, memory, motor function, Trp and its metabolite levels, enzyme activities in the plasma and urine of 8-week-old males compared to wild-type mice.

RESULTS

Transgenic mice showed more depressive-like behaviors in the forced swim test, but not in the tail suspension, anxiety, or memory tests. They also had fewer center field and corner entries, shorter walking distances, and fewer jumping counts in the open field test. Plasma metabolite levels are generally consistent with those of urine: antioxidant KYNs, 5-hydroxyindoleacetic acid, and indole-3-acetic acid levels were lower; enzyme activities in KATs, kynureninase, and monoamine oxidase/aldehyde dehydrogenase were lower, but kynurenine 3-monooxygenase was higher; and oxidative stress and excitotoxicity indices were higher. Transgenic mice displayed depression-like behavior in a learned helplessness model, emotional indifference, and motor deficits, coupled with a decrease in KYNA, a shift of Trp metabolism toward the KYN-3-hydroxykynurenine pathway, and a partial decrease in the gut microbial Trp-indole pathway metabolite.

CONCLUSIONS

This is the first evidence that deleting the aadat gene induces depression-like behaviors uniquely linked to experiences of despair, which appear to be associated with excitatory neurotoxic and oxidative stresses. This may lead to the development of a double-hit preclinical model in despair-based depression, a better understanding of these complex conditions, and more effective therapeutic strategies by elucidating the relationship between Trp metabolism and PTSD pathogenesis.

What kind of «thing» is mental illness? Listening to Kraepelin, Jaspers and Kronfeld

Since its beginnings psychiatry controversely debated about the appropriate concept of illness, about nosology and the diagnostic terms and procedures based upon it. This paper discusses the approaches introduced by Emil Kraepelin (1856-1926), Karl Jaspers (1883-1969) and Arthur Kronfeld (1886-1941). Whereas Kraepelin postulated the existence of «natural entities» with regard to mental illness, Jaspers acknowledged the heuristic value of the term «disease entity», but declared it a «regulative idea» in a Kantian sense, i.e. an appropriate and useful, albeit never fully achievable aim. Kronfeld, in a way situated «between» Kraepelin and Jaspers, defended the notion of disease entities. However, he spoke clearly against primarily anchoring these entities in neighbouring scientific fields like neurobiology or social sciences. Psychiatry should stay (or become) «autological», in the first place using the psychological perspective. In full respect for neighbouring approaches as scientific fields in their own right, he rejected their premature transfer to mental phenomena as «heterological», i.e. as unduly narrowing down the scope of psychiatry. These issues, up to debate 100 years ago, still are of utmost relevance for psychiatry in the 21st century, a field struggling with its rather fragile scientific identity.

Epistemological reflections on chances and borders of "biological psychiatry"

OBJECTIVES

After decades of intensive research in the field of biological psychiatry and its partly modest and non-specific results, the self-critical question arises as to whether basic predispositions in epistemology and philosophy of science prevent bigger successes.

METHODS/RESULTS

Central here are the arguments that the brain is unable to recognise itself completely and that the psychological mental level cannot be connected with the physiological neurobiological level in a causal way.

CONCLUSION

In conclusion, for biological psychiatry it might be well advised to reflect on the research, diagnostics and treatment realistically achievable according to the theoretical framework, so that the impression of valid knowledge progress, although limited, remains motivating for our younger generation.

Diagnosis as dialogue: historical and current perspectives

Ever since psychiatry emerged as a clinical discipline and field of scientific inquiry in the late 18th century, debates about diagnosis have been at its very heart. Considered by many a requirement for clinical communication as well as for systematic study, others have critiqued psychiatric diagnosis for being modeled on a medical conception of disease that is ill-suited to the specific nature of mental disorders. Based on a review of seminal positions in the conceptual history of psychiatry and an examination of their epistemological underpinnings, we propose to consider diagnosis as dialogue. Such understanding, we argue, can serve as a meta-framework that provides a conceptual and practical umbrella to encourage open-minded conversation across the diverse conceptual and experiential frameworks that are characteristic of psychiatry. In this perspective psychopathology will also reinforce the interpersonal realm as a necessary element of any clinical encounter, be it diagnostic in purpose or otherwise. Current challenges to traditional diagnostic systems like Research Domain Criteria (RDoC) and Hierarchical Taxonomy of Psychopathology (HiTOP) are discussed in light of these considerations.


Serotonergic mechanisms and suicidal behavior

Disturbances in central serotonin (5-hydroxytryptamine, 5-HT) were first described in depression. They were inferred to exist based on the finding of lowered baseline and post-probenecid concentrations of 5-HIAA in CSF. Initially, depressed patients with and without deimonstrable disturbances in central 5-H1 seemed psychopathologically indistinguishable. Interpreting the available data, at that time, we introduced in 1971 the concept of biochemical heterogeneity of depression. Some forms, we postulated, are linked to disturbances in 5-HT functions, others are not or, to a much lesser extent. Subsequently, we showed the concept of a separate «5-HT depression» to be untenable. It seems more likely now that 5-HT disturbances in depression are not linked to a particular syndromal depression type, but to particular psychopathological dimensions, i.e. heightened anxiety and disturbed aggression regulation. These dimensions might form a prominent aspect of depression or may be virtually absent. They are moreover not specific for depression, but can occur in other psychiatric disorders as well. This might explain the seemingly capricious occurrence of 5-HT disorders in depression as well as their nosological non-specificity.

Based on the dimensional 5-HT hypothesis one might expect drugs that increase 5-HT availability in the brain to be effective in the various anxiety disorders, in depressions marked by increased anxiety and disturbed aggression regulation and in personality disorders with strong aggressive tendencies.

Sérotonine et capacité à différer une conduite un modèle psychobiologique

Des troubles du fonctionnement sérotoninergique ont été impliqués dans de nombreuses pathologies ou dysrégulations du système nerveux central: trouble dépressif, trouble anxieux, schizophrénie, psychopathie, agressivité, boulimie, éthylisme, etc.

Le rôle de cette amine dans l’inhibition de la survenue de certains comportements est décrit depuis longtemps. Chez l’animal, ce rôle semble organiser la capacité à différer une conduite et/ou à tolérer sans réponse comportementale une situation de contrainte. Chez l’homme, la sérotonine semble réguler une capacité à contrôler les réponses impulsives dans le cadre des troubles très différents tels que passage à l’acte suicidaire, conduite boulimique, compulsions itératives, conduite éthylique, etc. Les inhibiteurs du recaptage de la sérotonine semblent améliorer l’existence de ces troubles de façon transnosologique.

Nous faisons l’hypothèse que certains diagnostics pourraient être la conséquence d’un fonctionnement «limite» sur le plan biologique facilitant le passage à l’acte et des troubles de personnalité. Aucune des deux dimensions ne serait en soi pathologique. Le manque d’adaptabilité de certains fonctionnements mentaux (caractère, personnalité) ajoutée à un fonctionnement biologique «limite” (difficulté à différer sa réponse) seraient par leur coexistence responsables de la décompensation qui aboutit à ce qu’on appelle un diagnostic.

Platelet serotonin-binding and dexamethasone suppression test in melancholia and dysthymia

Platelet serotonin-binding (Bmax), using tritiated-seroionin as the ligand, was determined in 75 patients suffering from major depression with melancholia and in 26 patients diagnosed from dysthymic disorder. Twenty-five normal subjects were used as a control group. The melancholic group had significantly lower Bmaxvalues (mean: 6.7 ± 6.1 pmol/108platelets) than either dysthymic (9.3 ± 3.9 pmol/108platelets) or control (9.2 ± 4.8 pmol/108platelets) groups, while there were no significant differences between the two latter groups. There was also a significant difference on postdexamethasone Cortisol between melancholic (6.3 ± 7.1μg/dL) and dysthymic (1.4 ± 1.4μg/dL) groups, with a higher rate of nonsuppressors in melancholic groups. Although both tests were abnormal in the melancholic group, no relationship was found between platelet serotonin-binding and the dexaniethasone suppression test.

Loss of automatic processes and blunted-affect in depression: a P3 study

The P3 components (P3a and P3b) of the event-related potentials have been analysed in sixteen in-patients with a major depressive episode (DSM III-R) according to their subtype - anxious-agitated and impulsiveversusretarded and blunted-affect - assuming that these two opposite dimensions of the depressive mood would rely on different physiopathological mechanisms. The P3a component, which indexes automatic cognitive processes, was dramatically decreased in the retarded and blunted-affect group. This suggests that this special type of cognitive dysfunction in depression is rather related to negative symptoms than to depression itself.

Endogenous evoked potentials assessment in depression: a review

Over the past 15 years, researchers have shown an increasing interest in using event-related potentials (ERPs) to study depression. These studies generally fall into four classes: 1), ERPs as a means of detecting depression; 2), ERPs as a tool for distinguishing subtypes of depression; 3), ERPs as a measure of pharmacological effectiveness; 4), ERPs as indicators of defective cognitive operations in depressed subjects. Results from these heterogeneous approaches are often inconsistent and disappointing. Although some ERP components often show increased latencies and diminished amplitudes, these changes seem to reflect principally a variety of non-specific disorders affecting a wide range of cognitive functions rather than a precise and consistent deficit of a particular function. These disappointing results seem to be attributable to methodological problems (heterogeneous patient populations, disproportionate use of the odd-ball paradigm), and do not necessarily call into question the value of studying the ERPs. Furthermore, recent advances in ERP methodology have opened up new perspectives for ERP use in psychopathology.

Biological correlates of personality: considerations on the possible usefulness of central nervous system peripheral markers

Although a great deal of biological research has been carried out on several psychiatric disorders, it is disappointing to see how little progress has been made in the field of the biology of personality. The authors underline the methodological problems that arise in the investigation of biological substrates of human personality and review both currently available and putative peripheral markers of the central nervous system that might be used in further human studies.

The impulsivity rating scale (IRS): preliminary results

Until now, the instruments for the clinical evaluation of impulsivity have relied essentially on either personality inventories or to a lesser extent on specific questionnaires. Therefore this paper presents the preliminary results of a new rating scale: the Impulsivity Rating Scale (IRS). This is a 7-item hetero-evaluation of impulsivity based on the behaviour of the patient in usual life situations. The administration of the scale is easy and short: 15 minutes. The IRS was tested in five different population samples: 31 impulsive inpatients, 36 adults with major depressive episode, 15 healthy control subjects, 56 smokers before and after one week of tobacco withdrawal, and 47 adolescent depressed inpatients before and four weeks after antidepressant treatment. The results show good construct validity, good concurrent validity, good inter-rater reliability and sensitivity to change. A threshold of 8 for the total score (range 0 to 21) gives good specificity and sensitivity. The principal component analysis shows the existence of a main factor composed of all items, with lower correlation for two items which may belong to a second factor needing further investigations.

Serotonin-related, anxiety/aggression-driven, stressor-precipitated depression. A psycho-biological hypothesis

The concept of a 5-HT related, anxiety and/or aggression-driven, stressor-precipitated depression is formulated and discussed. It comprises the following elements. The 5-HT ergic disturbances found in some depressed individuals - and of them particularly lowered CSF 5-HIAA - are linked to the anxiety- and the aggression-components of the depressive sydrome. In this type of depression - called 5-HT related depression - dysregulation of anxiety and/or aggression are primordial and mood lowering is a derivative phenomenon. In other words this is a group of anxiety/aggression-driven depressions. The 5-HT ergic impairment in certain types of depression is a trait-phenomenon, ie, persists during remission. This disturbance makes the individual susceptable for perturbation of anxiety- and aggression-regulation. Anxiety and (overt or suppressed) anger, are core constituents of the stress-syndrome. Thus, the 5-HT ergic disturbance will induce a heightened sensitivity for stressful events, ie, the latter will induce more readily than normal, stress phenomena , among which anxiety and anger. The latter psychological features induce lowering of mood and thus “drive” the patient into a fullblown depression. Furthermore it is predicted that anxiolytics and serenics (ie, anti-aggressive drugs) that act via normalisation of 5-HT ergic circuits, will exert a antidepressant effect in 5-HT related depression, in addition to their therapeutic actions in anxiety disorders and states of increased aggressiveness, respectively. The exact nature of the 5-HT ergic impairment in 5-HT related depression has yet to be elucidated.

Attempting to disentangle the relationship between impulsivity and longitudinal self-harm: Epidemiological analysis of UK household survey data

BACKGROUND

Impulsivity may be an important risk factor in terms of future self-harm. However, the extent of this, whether it may relate to self-harm that is new in onset and/or repetition of self-harm, and the detail of any interaction with mood instability (MI) and childhood sexual abuse (CSA) requires detailed examination.

AIMS

We used the 2000 Adult Psychiatry Morbidity Survey and an 18-month follow-up data to test hypotheses relating to the role of impulsivity, CSA and MI in the inception and persistence of self-harm.

METHODS

We assessed associations of impulsivity with (1) suicidal self-harm (SSH) and (2) non-SSH (NSSH) at baseline and follow-up, controlling for confounders including MI. Finally, we tested whether impulsivity mediated the relationship between CSA and self-harm.

RESULTS

A total of 8,580 respondents were assessed at baseline and 2,406 at follow-up as planned. Impulsivity significantly predicted emergence of new NSSH at 18-month follow-up even after adjustment for MI and other confounders. Impulsivity did not significantly predict repetition of NSSH, or repetition or new inception of SSH, even before inclusion of MI in the model. However, the absolute numbers involved were small. Cross-sectionally, impulsivity was a stronger mediator of the link between CSA and SSH (13.1%) than that between CSA and NSSH (4.8%).

CONCLUSION

Impulsivity may increase the risk of future development of NSSH independently of MI, which is clinically important for risk assessment. The involvement of impulsivity in the repetition of self-harm generally appears less certain. However, impulsivity may have a role in SSH in the context of previous CSA.

Breaking Away: The Role of Homeostatic Drive in Perpetuating Depression

We propose that the complexity of regulatory interactions modulating brain neurochemistry and behavior is such that multiple stable responses may be supported, and that some of these alternate regulatory programs may play a role in perpetuating persistent psychological dysfunction. To explore this, we constructed a model network representing major neurotransmission and behavioral mechanisms reported in literature as discrete logic circuits. Connectivity and information flow through this biobehavioral circuitry supported two distinct and stable regulatory programs. One such program perpetuated a depressive state with a characteristic neurochemical signature including low serotonin. Further analysis suggested that small irregularities in glutamate levels may render this pathology more directly accessible. Computer simulations mimicking selective serotonin reuptake inhibitor (SSRI) therapy in the presence of everyday stressors predicted recidivism rates similar to those reported clinically and highlighted the potentially significant benefit of concurrent behavioral stress management therapy.

Increasing Resilience to Traumatic Stress: Understanding the Protective Role of Well-Being

The brain maintains homeostasis in part through a network of feedback and feed-forward mechanisms, where neurochemicals and immune markers act as mediators. Using a previously constructed model of biobehavioral feedback, we found that in addition to healthy equilibrium another stable regulatory program supported chronic depression and anxiety. Exploring mechanisms that might underlie the contributions of subjective well-being to improved therapeutic outcomes in depression, we iteratively screened 288 candidate feedback patterns linking well-being to molecular signaling networks for those that maintained the original homeostatic regimes. Simulating stressful trigger events on each candidate network while maintaining high levels of subjective well-being isolated a specific feedback network where well-being was promoted by dopamine and acetylcholine, and itself promoted norepinephrine while inhibiting cortisol expression. This biobehavioral feedback mechanism was especially effective in reproducing well-being's clinically documented ability to promote resilience and protect against onset of depression and anxiety.

Child sexual abuse and the development of psychiatric disorders: a neurobiological trajectory of pathogenesis

Child sexual abuse (CSA) is an important public health problem with long-standing neurobiological, developmental, and psychiatric abnormalities. The present review analyzes the long-term effects of CSA from a developmental, psychiatric morbidity, neurochemical and neurobiological perspective and then tries to posit a developmental neurobiological trajectory from CSA to the genesis of psychopathology in later life. The role of various neurotransmitters such as serotonin and dopamine affected by CSA are discussed. Serotonin abnormalities have been reported in various studies among participants exposed to CSA. Structures such as the prefrontal cortex, superior temporal gyrus, corpus callosum, parietal lobes, hippocampus, and cerebellum all demonstrate volumetric and structural changes in response to the trauma of CSA. Neurocognitive studies demonstrate memory and spatial awareness as well as decrements in general cognitive performance and memory when compared to normal individuals. The hypothalamic-pituitary-adrenal axis has also been implicated in CSA, and there is an alteration in corticotropin-releasing hormone response due to the continuous cumulative trauma of CSA. This paper also reviews a section on the role of genetic and epigenetic factors in the development of psychiatric disorders as a result of exposure to episodes of CSA where studies have demonstrated changes in DNA methylation in response to CSA. This review tries to hypothesize a developmental trajectory framework which is individual for every case where exposure to CSA may lead to psychopathology and psychiatric morbidity later in life. Rapid and emerging fields such as developmental traumatology in relation to CSA are also discussed.

[Schizophrenia: pars pro toto for psychiatry? : A historical essay on the status of schizophrenia in psychiatric discourse]

In the history of psychiatry, "schizophrenia" has often been portrayed as the discipline's pars pro toto, which prototypically represents mental illness as such and which draws together the fundamental questions concerning psychiatric epistemology and practice. Taking a conceptual history approach, this essay examines how "schizophrenia" is represented in psychiatric discourse and what aspects of its representation account for the pars pro toto status. Three such aspects are identified: a pragmatic, an existential and a justificatory aspect. Following up these aspects in present day psychiatric discourse, it is concluded that "schizophrenia" is losing its special status as the representations of psychiatry and of mental illness have changed and become more diverse. Tentative conclusions regarding current debates about the abolition of "schizophrenia" are drawn.

The Kraepelinian tradition

Emil Kraepelin (1856-1926) was an influential figure in the history of psychiatry as a clinical science. This paper, after briefly presenting his biography, discusses the conceptual foundations of his concept of mental illness and follows this line of thought through to late 20th-century “Neo-Kraepelinianism,” including recent criticism, particularly of the nosological dichotomy of endogenous psychoses. Throughout his professional life, Kraepelin put emphasis on establishing psychiatry as a clinical science with a strong empirical background. He preferred pragmatic attitudes and arguments, thus underestimating the philosophical presuppositions of his work. As for nosology, his central hypothesis is the existence and scientific accessibility of “natural disease entities” (“natürliche Krankheitseinheiten”) in psychiatry. Notwithstanding contemporary criticism that he commented upon, this concept stayed at the very center of Kraepelin's thinking, and therefore profoundly shaped his clinical nosology.

[Computer-assisted treatment pathway for schizophrenia. Development and initial experiences]

Standardization in psychiatry is a developmental process which, following on from psychopathology and nosology is now increasingly affecting the field of treatment. The development of guidelines for the treatment of psychiatric diseases has now become well accepted, although the impact on routine practice is still limited. Treatment pathways bring recommendations from guidelines into a clear and practice-oriented algorithm. The prerequisite for this is the inclusion of all aspects and elements of the treatment as well as all professions involved in the treatment and a valid electronic data processing foundation. Such an approach is presented here with the example of the development and implementation of a clinical pathway for inpatients with schizophrenia. Initial results revealed that patients who received multi-professional treatment within such a clinical pathway, improved better than patients of the control group, as measured by CGI, PANSS and PSP. This shows that introduction of a clinical pathway leads to an improvement of treatment quality. Standardization of psychiatric treatment processes could be highly relevant in respect to the new remuneration system for psychiatry in Germany.

[Is delusion a reasonable scientific term? Reflections on psychopathology in the psychiatry of the twenty-first century]

Delusion is a central but difficult and controversial term in psychiatry. Similar to the term schizophrenia at the nosological level, the basic questions in the specialty are linked in the debate on delusion at the clinical psychopathological level, beginning with epistemological and methodological aspects up to concrete embodiment of the physician-patient relationship. The text of this article reflects this development from the nineteenth century up to the present day and makes reference to the lively discussion on the future directions of psychiatric research triggered by the research domain criteria (RDoC). Under certain prerequisites, including in particular an extensive understanding of psychopathology, delusion is considered to be a reasonable scientific term, also in the future.

Heart rate variability as a transdiagnostic biomarker of psychopathology

The Research Domain Criteria (RDoC), developed by the National Institute of Mental Health as a neuroscience-informed alternative to traditional psychiatric nosology, is an explicitly dimensional system in which classification of psychopathology is derived inductively (i.e., from basic science), across multiple levels of analysis (e.g., genetic, neural, psychophysiological, and behavioral). Although RDoC is often presented as paradigmatically revolutionary, a review of the history of psychophysiology suggests that roots of RDoC thinking extend at least as far back as the mid-20th Century. In this paper, we briefly and selectively review the historical emergence of neurobiologically-informed dimensional trait models of psychopathology, and we summarize our thinking regarding high frequency heart rate variability (HF-HRV) as a transdiagnostic biomarker of self-regulation and cognitive control. When functional interactions between HF-HRV and systems of behavioral approach and avoidance are considered, diverse patterns of behavioral maladjustment can be subsumed into a single model. This model accommodates the general bifactor structure of psychopathology, and suggests that HF-HRV can be viewed as an autonomic, transdiagnostic biomarker of mental illness.

[A new classification for better care. The promises of the translational psychiatric neuroscience]

This article explores the way neuroscientists call for the "deconstruction" of the classifications of mental disorders as we know them, in order to provide solutions to the slowdown of therapeutical innovation in psychiatry. It is based on the case study of the Research Domain Criteria (RDoC) project of the US National Institute of Mental Health (NIMH). My purpose is to show that neuroscience interested in mental disorders offers narratives of innovation, transformation, and desirable futures that are at the heart of the ambitious current research projects and influence them. I approach the versions of the futures proposed by the promoters of translational psychiatric neuroscience in terms of productivity at the scientific, epistemological and socio-political levels.

Depression and impulsivity as pathways to violence: implications for antiaggressive treatment

BACKGROUND

Difficulties with affect regulation and impulse control have a strong influence on violence. The objective of this study was to determine whether baseline depression and impulsivity predict aggression and whether they predict differential response to antiaggressive treatment. This is important, as we lack knowledge as to the selection of antipsychotics for the treatment of aggression.

METHODS

Physically aggressive inpatients with schizophrenia who received an evaluation of depression and impulsivity at baseline were randomly assigned in a double-blind, parallel group, 12-week trial to clozapine, olanzapine, or haloperidol. Trait impulsivity was measured by the Barratt Impulsiveness Scale; depression by the Positive and Negative Syndrome Scale Depression factor. The number and severity of aggressive events, as measured by the Modified Overt Aggression Scale (MOAS), were the outcome measures.

RESULTS

Baseline depression and impulsivity predicted higher levels of aggression, as measured by the MOAS total score, over the 12-week treatment period across all 3 medication groups. In addition, there was a strong interaction effect between baseline depression/impulsivity and medication grouping in predicting MOAS score. In particular, when higher depression and impulsivity were present at baseline, patients on haloperidol presented with more aggression than patients on the other 3 medications.

CONCLUSIONS

Depression and impulsivity are important predictors of aggression and of differential response to antiaggressive treatment. This is most likely due to the medications' dissimilar neurotransmitter profiles. By identifying patients who will respond better to a given medication, we will be able to develop individualized strategies for the treatment of violent behavior.

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.

The failure of the antidepressant drug discovery process is systemic

Current antidepressants are crude compared with the ideal and patents on most have expired. There are therefore strong clinical and commercial pressures for new drugs to replace them. The prospects for this are, however, now markedly reduced as several major pharmaceutical companies have abandoned work in this area whilst many others have sharply decreased their research investment. These changes and the lack of progress over such a long period are indicative of a catastrophic systems failure which, it is argued, has been caused in large part by a logical flaw at the animal modelling stage. This tautology has served to lock the current antidepressant drug discovery process into an iterative loop capable only of producing further variations of that which has gone before. Drugs produced by this approach have proved to be only poorly effective in the context of the clinically depressed population as a whole. Hence, the inevitable failure of the current antidepressant drug discovery process has left little behind that can be salvaged. Therefore, it is suggested that this be urgently reformulated on more rational grounds using more appropriate species in new animal models based upon a thorough understanding of the behavioural expressions of depression in the clinic.

[Syndromal versus nosological diagnosis]

Against the background of the current preparation of ICD-11 and DSM-5, there is a discussion whether syndromal approaches should replace the traditional nosological diagnosis in psychiatry. From a historical point of view the syndromal approach results from a reaction to the nosological model of Emil Kraepelin. Later the syndromal diagnostic approach became more important because it enabled a quantitative-dimensional assessment and analysis of psychopathological data using modern statistical procedures. However, attempts to ascribe the traditional nosological categories to psychopathological syndromes using multivariate statistical methods have failed. The syndromal approach allows a differentiated recording of the cross-sectional symptomatology; however, a plurality of different syndromes might be registered without considering meaningful principles of classification and longitudinal aspects. The syndromal approach should be complemented by a nosological classification based mainly on the psychopathological course due to the absence of consistent neurobiological findings.

Interventions for preventing relapse and recurrence of a depressive disorder in children and adolescents

BACKGROUND

Depressive disorders often begin during childhood or adolescence. There is a growing body of evidence supporting effective treatments during the acute phase of a depressive disorder. However, little is known about treatments for preventing relapse or recurrence of depression once an individual has achieved remission or recovery from their symptoms.

OBJECTIVES

To determine the efficacy of early interventions, including psychological and pharmacological interventions, to prevent relapse or recurrence of depressive disorders in children and adolescents.

SEARCH METHODS

We searched the Cochrane Depression, Anxiety and Neurosis Review Group's Specialised Register (CCDANCTR) (to 1 June 2011). The CCDANCTR contains reports of relevant randomised controlled trials from The Cochrane Library (all years), EMBASE (1974 to date), MEDLINE (1950 to date) and PsycINFO (1967 to date). In addition we handsearched the references of all included studies and review articles.

SELECTION CRITERIA

Randomised controlled trials using a psychological or pharmacological intervention, with the aim of preventing relapse or recurrence from an episode of major depressive disorder (MDD) or dysthymic disorder (DD) in children and adolescents were included. Participants were required to have been diagnosed with MDD or DD according to DSM or ICD criteria, using a standardised and validated assessment tool.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed all trials for inclusion in the review, extracted trial and outcome data, and assessed trial quality. Results for dichotomous outcomes are expressed as odds ratio and continuous measures as mean difference or standardised mean difference. We combined results using random-effects meta-analyses, with 95% confidence intervals. We contacted lead authors of included trials and requested additional data where possible.

MAIN RESULTS

Nine trials with 882 participants were included in the review. In five trials the outcome assessors were blind to the participants' intervention condition and in the remainder of trials it was unclear. In the majority of trials, participants were either not blind to their intervention condition, or it was unclear whether they were or not. Allocation concealment was also unclear in the majority of trials. Although all trials treated participants in an outpatient setting, the designs implemented in trials was diverse, which limits the generalisability of the results. Three trials indicated participants treated with antidepressant medication had lower relapse-recurrence rates (40.9%) compared to those treated with placebo (66.6%) during a relapse prevention phase (odds ratio (OR) 0.34; 95% confidence interval (CI) 0.18 to 0.64, P = 0.02). One trial that compared a combination of psychological therapy and medication to medication alone favoured a combination approach over medication alone, however this result did not reach statistical significance (OR 0.26; 95% CI 0.06 to 1.15). The majority of trials that involved antidepressant medication reported adverse events including suicide-related behaviours. However, there were not enough data to show which treatment approach results in the most favourable adverse event profile.

AUTHORS' CONCLUSIONS

Currently, there is little evidence to conclude which type of treatment approach is most effective in preventing relapse or recurrence of depressive episodes in children and adolescents. Limited trials found that antidepressant medication reduces the chance of relapse-recurrence in the future, however, there is considerable diversity in the design of trials, making it difficult to compare outcomes across studies. Some of the research involving psychological therapies is encouraging, however at present more trials with larger sample sizes need to be conducted in order to explore this treatment approach further.

Newer generation antidepressants for depressive disorders in children and adolescents

BACKGROUND

Depressive disorders are common in young people and are associated with significant negative impacts. Newer generation antidepressants, particularly selective serotonin reuptake inhibitors (SSRIs), are often used, however evidence of their effectiveness in children and adolescents is not clear. Furthermore, there have been warnings against their use in this population due to concerns about increased risk of suicidal ideation and behaviour.

OBJECTIVES

To determine the efficacy and adverse outcomes, including definitive suicidal behaviour and suicidal ideation, of newer generation antidepressants compared with placebo in the treatment of depressive disorders in children and adolescents.

SEARCH METHODS

For this update of the review, we searched the Cochrane Depression, Anxiety and Neurosis Review Group's Specialised Register (CCDANCTR) to October 2011. The CCDANCTR includes relevant randomised controlled trials from the following bibliographic databases: CENTRAL (the Cochrane Central Register of Controlled Trials) (all years), EMBASE (1974 -), MEDLINE (1950 -) and PsycINFO (1967 -). We searched clinical trial registries and pharmaceutical company websites. We checked reference lists of included trials and other reviews, and sent letters to key researchers and the pharmaceutical companies of included trials from January to August 2011.

SELECTION CRITERIA

Published and unpublished randomised controlled trials (RCTs), cross-over trials and cluster trials comparing a newer generation antidepressant with a placebo in children and adolescents aged 6 to 18 years old and diagnosed with a depressive disorder were eligible for inclusion. In this update, we amended the selection criteria to include newer generation antidepressants rather than SSRIs only.

DATA COLLECTION AND ANALYSIS

Two or three review authors selected the trials, assessed their quality, and extracted trial and outcome data. We used a random-effects meta-analysis. We used risk ratio (RR) to summarise dichotomous outcomes and mean difference (MD) to summarise continuous measures.

MAIN RESULTS

Nineteen trials of a range of newer antidepressants compared with placebo, containing 3335 participants, were included. The trials excluded young people at high risk of suicide and many co-morbid conditions and the participants are likely to be less unwell than those seen in clinical practice. We judged none of these trials to be at low risk of bias, with limited information about many aspects of risk of bias, high drop out rates and issues regarding measurement instruments and the clinical usefulness of outcomes, which were often variously defined across trials. Overall, there was evidence that those treated with an antidepressant had lower depression severity scores and higher rates of response/remission than those on placebo. However, the size of these effects was small with a reduction in depression symptoms of 3.51 on a scale from 17 to 113 (14 trials; N = 2490; MD -3.51; 95% confidence interval (CI) -4.55 to -2.47). Remission rates increased from 380 per 1000 to 448 per 1000 for those treated with an antidepressant. There was evidence of an increased risk (58%) of suicide-related outcome for those on antidepressants compared with a placebo (17 trials; N = 3229; RR 1.58; 95% CI 1.02 to 2.45). This equates to an increased risk in a group with a median baseline risk from 25 in 1000 to 40 in 1000. Where rates of adverse events were reported, this was higher for those prescribed an antidepressant. There was no evidence that the magnitude of intervention effects (compared with placebo) were modified by individual drug class.

AUTHORS' CONCLUSIONS

Caution is required in interpreting the results given the methodological limitations of the included trials in terms of internal and external validity. Further, the size and clinical meaningfulness of statistically significant results are uncertain. However, given the risks of untreated depression in terms of completed suicide and impacts on functioning, if a decision to use medication is agreed, then fluoxetine might be the medication of first choice given guideline recommendations. Clinicians need to keep in mind that there is evidence of an increased risk of suicide-related outcomes in those treated with antidepressant medications.

The genetic blueprint of major depressive disorder: contributions of imaging genetics studies

OBJECTIVES

To review neuroimaging intermediate phenotypes of MDD and their relation to genetic risk variants.

METHODS

A systematic literature search of peer-reviewed English language articels using PubMed ( www.pubmed.org ) was performed.

RESULTS

Comprehensive evidence on the influence of serotonergic genes (SLC6A4, HTR1A, MAOA, TPH2) and BDNF on the following neural intermediate phenotypes is displayed: amygdala reactivity, coupling of amygdala-anterior cingulate cortex (ACC) activity, ACC volume, hippocampal volume and serotonin receptor 1A (5-HT1A) binding potential (BP).

CONCLUSIONS

Intermediate phenotypes may bridge the gap between genotype and phenotype by reducing the impreciseness of psychiatric phenotypes and yield more insights into the underlying biology.

The hypothalamic-pituitary-adrenal axis and serotonin abnormalities: a selective overview for the implications of suicide prevention

Suicidal behavior and mood disorders are one of the world's largest public health problems. The biological vulnerability for these problems includes genetic factors involved in the regulation of the serotonergic system and stress system. The hypothalamic-pituitary-adrenal (HPA) axis is a neuroendocrine system that regulates the body's response to stress and has complex interactions with brain serotonergic, noradrenergic and dopaminergic systems. Corticotropin-releasing hormone and vasopressin act synergistically to stimulate the secretion of ACTH that stimulates the biosynthesis of corticosteroids such as cortisol from cholesterol. Cortisol is a major stress hormone and has effects on many tissues, including on mineralocorticoid receptors and glucocorticoid receptors in the brain. Glucocorticoids produce behavioral changes, and one important target of glucocorticoids is the hypothalamus, which is a major controlling center of the HPA axis. Stress plays a major role in the various pathophysiological processes associated with mood disorders and suicidal behavior. Serotonergic dysfunction is a well-established substrate for mood disorders and suicidal behavior. Corticosteroids may play an important role in the relationship between stress, mood changes and perhaps suicidal behavior by interacting with 5-HT1A receptors. Abnormalities in the HPA axis in response to increased levels of stress are found to be associated with a dysregulation in the serotonergic system, both in subjects with mood disorders and those who engage in suicidal behavior. HPA over-activity may be a good predictor of mood disorders and perhaps suicidal behavior via abnormalities in the serotonergic system.

Measuring serotonin synthesis: from conventional methods to PET tracers and their (pre)clinical implications

The serotonergic system of the brain is complex, with an extensive innervation pattern covering all brain regions and endowed with at least 15 different receptors (each with their particular distribution patterns), specific reuptake mechanisms and synthetic processes. Many aspects of the functioning of the serotonergic system are still unclear, partially because of the difficulty of measuring physiological processes in the living brain. In this review we give an overview of the conventional methods of measuring serotonin synthesis and methods using positron emission tomography (PET) tracers, more specifically with respect to serotonergic function in affective disorders. Conventional methods are invasive and do not directly measure synthesis rates. Although they may give insight into turnover rates, a more direct measurement may be preferred. PET is a noninvasive technique which can trace metabolic processes, like serotonin synthesis. Tracers developed for this purpose are α-[¹¹C]methyltryptophan ([¹¹C]AMT) and 5-hydroxy-L-[β-¹¹C]tryptophan ([¹¹C]5-HTP). Both tracers have advantages and disadvantages. [¹¹C]AMT can enter the kynurenine pathway under inflammatory conditions (and thus provide a false signal), but this tracer has been used in many studies leading to novel insights regarding antidepressant action. [¹¹C]5-HTP is difficult to produce, but trapping of this compound may better represent serotonin synthesis. AMT and 5-HTP kinetics are differently affected by tryptophan depletion and changes of mood. This may indicate that both tracers are associated with different enzymatic processes. In conclusion, PET with radiolabelled substrates for the serotonergic pathway is the only direct way to detect changes of serotonin synthesis in the living brain.

Craving's place in addiction theory: contributions of the major models

We examine in this paper the unfolding of craving concepts within 18 models that span roughly 60 years (1948-2009). The amassed evidence suggests that craving is an indispensable construct, useful as a research area because it has continued to destabilize patients seeking treatment for substances. The models fall into four categories: the conditioning-based models, the cognitive models, the psychobiological models, and the motivation models. In the conditioning models, craving is assumed to be an automatic, unconscious reaction to a stimulus. In the cognitive models, craving arises from the operation of information processing systems. In the psychobiological models, craving can be explained at least in part by biological factors with an emphasis on motivational components. Finally, in the motivation models, craving is viewed as a component of a larger decision-making framework. It is well accepted that no single model explains craving completely, suggesting that a solid understanding of the phenomenon will only occur with consideration from multiple angles. A reformulated definition of craving is proposed.

Prediction of suicidality and violence in hospitalized adolescents: comparisons by sex

OBJECTIVE

To examine psychological correlates of suicidality and violent behaviour in hospitalized adolescents and the extent to which these associations may be affected by their sex.

METHOD

A sample of 487 psychiatric inpatients (207 male, 280 female), aged 12 to 19 years, completed a battery of psychometrically sound self-report measures of psychological functioning, substance abuse, suicidality, and violent behaviour. We conducted multiple regression analyses to determine the joint and independent predictors of suicide risk and violence risk. In subsequent analyses, we examined these associations separately by sex.

RESULTS

Multiple regression analysis revealed that 9 variables (sex, age, hopelessness, self-esteem, depression, impulsivity, alcohol abuse, drug abuse, and violence risk) jointly predicted suicide risk and that an analogous model predicted violence risk. However, we found several differences with respect to which variables made significant independent contributions to these 2 predictive models. Female sex, low self-esteem, depression, drug abuse, and violence risk made independent contributions to suicide risk. Male sex, younger age, hopelessness, impulsivity, drug abuse, and suicide risk made independent contributions to violence risk. We observed a few additional differences when we considered male and female subjects separately.

CONCLUSIONS

We found overlapping but distinctive patterns of prediction for suicide risk and violence risk, as well as some differences between male and female subjects. These results may reflect distinct psychological and behavioural pathways for suicidality and violence in adolescent psychiatric patients and differing risk factors for each sex. Such differences have potential implications for prevention and treatment programs.

Serotonergic vulnerability and depression: assumptions, experimental evidence and implications

In recent years, the term serotonergic vulnerability (SV) has been used in scientific literature, but so far it has not been explicitly defined. This review article attempts to elucidate the SV concept. SV can be defined as increased sensitivity to natural or experimental alterations of the serotonergic (5-HTergic) system. Several factors that may disrupt the 5-HTergic system and hence contribute to SV are discussed, including genetic factors, female gender, personality characteristics, several types of stress and drug use. It is explained that SV can be demonstrated by means of manipulations of the 5-HTergic system, such as 5-HT challenges or acute tryptophan depletion (ATD). Results of 5-HT challenge studies and ATD studies are discussed in terms of their implications for the concept of SV. A model is proposed in which a combination of various factors that may compromise 5-HT functioning in one person can result in depression or other 5-HT-related pathology. By manipulating 5-HT levels, in particular with ATD, vulnerable subjects may be identified before pathology initiates, providing the opportunity to take preventive action. Although it is not likely that this model applies to all cases of depression, or is able to identify all vulnerable subjects, the strength of the model is that it may enable identification of vulnerable subjects before the 5-HT related pathology occurs.

Alterations in reward-related decision making in boys with recent and future depression

BACKGROUND

Altered reward processing is postulated to be a feature of depression. Reward processing may be valuable to understanding early-onset depressive disorders, which tend to be chronic and recurrent.

METHODS

Reward-related decision making was examined within a longitudinal study of 221 11-year-old boys, 25 of whom had a depressive disorder at age 10 or 11. Participants completed a behavioral decision-making task involving varying probability and magnitude of obtaining reward.

RESULTS

Under conditions involving a high probability of winning, boys with depression failed to distinguish between options involving small or large possible reward. Boys with anxiety or externalizing disorders at age 10 or 11 did not differ from others in their reward-related decisions. Low frequency of choosing the high-probability, large reward option at age 11 predicted depressive disorders, anxiety disorders, and depressive symptoms 1 year later. Furthermore, reward-related decisions predicted later depressive or anxiety disorders even when adjusting for the continuity of such disorders and the presence of concurrent externalizing disorders.

CONCLUSIONS

Findings are consistent with affective neuroscience models of altered reward processing and diminished positive affect in depression. This study represents a step toward elucidating the motivational and emotional aspects of early-onset depression.

Sex differences in the effect of acute tryptophan depletion on declarative episodic memory: a pooled analysis of nine studies

Acute tryptophan depletion (ATD) studies have shown that serotonin plays a role in learning and memory processes. In this study, we performed a pooled analysis of nine ATD studies in order to examine the nature of the memory-impairing effects of ATD and mediating factors, such as gender, age and vulnerability for disease in which disturbed serotonin was hypothesized to play a role. All studies that were used in this pooled analysis assessed declarative episodic memory using a verbal learning task paradigm. Immediate recall, delayed recall, and delayed recognition scores were examined. A total of 211 participants were included in the analysis. The analysis revealed that ATD impaired not only delayed recall, but also immediate recall. The ATD-induced impairments were larger in females than in males. Furthermore, ATD did not interact with any other serotonergic vulnerability and age. This suggests that the only factor that actually has the properties of a serotonergic vulnerability factor for declarative memory performance is female gender. The findings provide further support for a critical role of serotonin in declarative episodic memory.

Neurosteroids, neuroactive steroids, and symptoms of affective disorders

Neurosteroids (NS) are steroids synthesized by the brain. Neuroactive steroids (NAS) refers to steroids that, independent of their origin, are capable of modifying neural activities. NAS bind and modulate different types of membrane receptors. The gamma amino butyric acid (GABA) and sigma receptor complexes have been the most extensively studied. Oxidized ring A reduced pregnanes, tetrahydroprogesterone (THP), and tetrahydrodeoxycorticosterone (THDOC) bind to the progesterone intracellular receptor (PR), and in this way can also regulate gene expression. Animal experimentation showed that salient symptoms of depression, viz., anxiety, sleep disturbances, and memory and sexual dysfunctions, are modulated by NAS. In turn, psychotropic drugs modulate NS and NAS levels. NS levels as well as NAS plasma concentrations change in patients with depression syndromes, the levels return to normal baseline with recovery, but normalization is not necessary for successful therapy. Results from current studies on the evolution of nervous systems, including evolutionary developmental biology as well as anatomical and physiological findings, almost preclude a categorical classification of the psychiatric ailments the human brain succumbs to. The persistence in maintaining such essentialist classifications may help to explain why up to now the search for biological markers in psychiatry has been an unrewarding effort. It is proposed that it would be more fruitful to focus on relationships between NAS and symptoms of psychiatric disorders, rather than with typologically defined disorders.

Plasma serotonin levels and suicidal behavior in adolescents

To evaluate the relationship between plasma serotonin (p5-HT) levels and psychometric measures in suicidal adolescents vs. controls, 211 adolescents from three sites in Israel were divided into four groups: suicidal psychiatric inpatients (n=35); non-suicidal psychiatric inpatients (n=30); adolescents referred to the emergency room (ER) due to a suicide attempt (n=51); and a community-based control group from 4 high schools in the same catchment areas (n=95). All were interviewed and assessed for violence, aggression, depression, impulsivity, anger, anxiety, and p5-HT. p5-HT levels were significantly lower in the control group compared to all other groups. A significant negative correlation was found between p5-HT level and suicidal behavior severity among the suicidal inpatients. p5-HT did not discriminate between the psychiatric diagnostic categories and was significantly lower in ER violent compared to non-violent subjects. Gender, depression, and anger were associated with suicidal behavior in all four groups. Beck Depression Inventory (BDI) scores together with p5-HT levels discriminated between healthy controls and other groups. p5-HT level in combination with some of the psychometric scales may serve as a safe and inexpensive peripheral marker of psychopathology, and may help to differentiate between sub-populations of suicidal adolescents. The biological mechanism behind the serotonin dysregulation in suicidal adolescents requires further investigation.

Can stress cause depression?

The central issue raised in this paper is: can stress cause depression? Phrased more precisely: can stress cause brain disturbances thought to underlie (certain forms of) depression or particular components of the depressive syndrome. Focussing on 5-HT and the stress hormones, this question was answered in the affirmative, based on the following two considerations: (1) changes in the 5-HT and stress hormone systems produced by sustained stress, mimic to a substantial extent the disturbances in these systems that may be observed in depression; (2) substantial evidence indicates that the 5-HT and stress hormone disturbances in depression are of pathophysiological significance and not merely a consequence of the depressed state or a product of stress generated by the depressed state. Furthermore, the question was raised whether a depression type could be identified particularly stress-inducible. This question, too, was answered in the affirmative. The depression type in question was named anxiety/aggression-driven depression and characterized on three levels: psychopathologically, biologically and psychologically. Preferential treatment of this depression type was discussed. In studying stress-inducible depression biological depression research should shift focus from depression per se to the neurobiological sequelae of stress. Treatment of stress-inducible depressions and particularly its prevention should be geared towards reduction of stress and stress sensitiveness, utilising both biological and psychological means.

Impulsivity in the prediction of suicidal behavior in adolescent populations

Impulsivity has been identified as a key factor in risk of suicidal behavior in adolescent and adult patients. However, a lack of consensus about the definition of impulsivity has led to difficulty in its measurement. Impulsivity self-report scales exhibit low intercorrelations, are subject to response bias, and incorporate multiple subfactors. Performance tests may be less sensitive to response biases, as well as be more precise measures of dimensions of impulsivity, but each test alone does not provide a comprehensive measure of the trait. Assessing impulsivity in child and adolescent groups presents additional methodological problems, such as an overlap between limited impulse control due to developmental factors and psychopathology. A multiple measures approach to assessing impulsivity is suggested.

Are there common mechanisms in sensation seeking and reality distortion in schizophrenia? A study using memory event-related potentials

A growing literature suggests that the characteristics of sensation seeking and reality distortion expressed in schizophrenia share several mechanisms. In a previous study, the comparison of patients with high vs. low reality distortion using event-related potentials (ERPs) recorded in a recognition memory task for unfamiliar faces identified neural and cognitive anomalies specifically related to the expression of these symptoms. As a follow-up, this study investigated the ERP correlates of sensation seeking in schizophrenia using the same recognition memory protocol. ERPs have been recorded in controls (N=21) and schizophrenia patients separated into high (HSS; N=13) and low (LSS; N=17) scorers according to Zuckerman's Sensation Seeking Scale. The results show a reduced P2a that was found unrelated to reality distortion in the previous study of reality distortion. It identifies interference inhibition impairment as being specifically related to sensation seeking. On the other hand, HSS scorers display enhanced fronto-central and normal P600 effects also found in high reality distortion patients. These results indicate inappropriate context processing and mnemonic binding common to sensation seeking and reality distortion. LSS scorers also display a reduced temporal N300 similar to that found in low reality distortion patients. This anomaly could reflect the lower reactivity to emotionally significant stimuli that underlies anhedonia symptoms. Finally, the N400 effect and a late frontal effect are found in both HSS and LSS. Since they were unrelated to reality distortion, these indices have been related to basic aspects of schizophrenia, e.g., deficient knowledge integration, or other mechanisms, e.g. anxiety or impulsivity. In summary, the present study examines the strategy of investigating variables, such as temperamental characteristics, in addition to symptoms, to show how discrete impairments may contribute to the expression of the illness.

Future antidepressants: what is in the pipeline and what is missing?

Monoamine reuptake inhibitors still reign in the treatment of major depression, but possibly not for long. While medicinal chemists have been able to reduce the side effects of these drugs, their delayed onset of action and considerable non-response rate remain problematic. Of late, serious questions have been raised regarding the efficacy of monoamine reuptake inhibitors. The present review presents an inventory of what is (and until recently was) in the antidepressant pipeline of pharmaceutical companies. Novel antidepressant compounds can be categorised into four groups depending on their target(s): (i) monoamine receptors; (ii) non-monoamine receptors; (iii) neuropeptide receptors; and (iv) hormone receptors. Other possible targets include components of post-receptor intracellular processes and elements of the immune system; to date, however, compounds specifically aimed at these targets have not been the subject of clinical trials. Development of several compounds targeted at monoamine receptors has recently been discontinued. At least five neurokinin-1 (NK(1)) receptor antagonists were until recently in phase II of clinical testing. However, the apparent interest in the NK(1) receptor should not be interpreted as representing a departure from the monoamine hypothesis since neurokinins also modulate monoaminergic systems. In the authors' view, development of future antidepressants will continue to rely on the serendipity-based monoamine hypothesis. However, an alternative approach, based on the hypothesis that chronic stress precipitates depressive symptoms, might be more productive. Unfortunately, clinical results using drugs targeted at components of the HPA axis have not been very encouraging to date. In the short run, the authors believe that augmentation strategies offer the best hope for improving the efficacy of antidepressant treatment. Several approaches to improve the efficacy of SSRIs are conceivable, such as concurrent blockade of monoamine autoreceptors and the addition of antipsychotics, neuromodulators or hormones (HPA axis and gender related). In the long-term, however, construction of a scientifically verified conceptual framework will be needed before more effective antidepressants can be developed. It can be argued that it is not depression itself that should be treated, but rather that its duration should be reduced by pharmacological means. Animal models that take this concept into consideration and identify mechanisms for acceleration of recovery from the effects of stress need to be developed.

Can stress cause depression?

The central issue raised in this paper is: can stress cause depression? Phrased more precisely: can stress cause brain disturbances thought to underlie (certain forms of) depression or particular components of the depressive syndrome. Focussing on 5-hydroxytryptamine (5-HT) and the stress hormones, this question was answered in the affirmative, based on the following two considerations: changes in the 5-HT and stress hormone systems produced by sustained stress mimic to a substantial extent the disturbances in these systems that may be observed in depression. Substantial evidence indicates that the 5-HT and stress hormone disturbances in depression are of pathophysiological significance and not merely a consequence of the depressed state or a product of stress generated by the depressed state. Furthermore, the question was raised whether a depression type could be identified particularly stress-inducible. This question, too, was answered in the affirmative. The depression type in question was named anxiety/aggression-driven depression and characterized on three levels: psychopathologically, biologically and psychologically. Preferential treatment of this depression type was discussed. In studying stress-inducible depression, biological depression research should shift focus from depression per se to the neurobiological sequelae of stress. Treatment of stress-inducible depressions and particularly its prevention should be geared towards reduction of stress and stress sensitiveness, utilising both biological and psychological means.

Unipolar late-onset depression: A comprehensive review

Background

The older population increases all over the world and so also does the number of older psychiatric patients, which manifest certain specific and unique characteristics. The aim of this article is to provide a comprehensive review of the international literature on unipolar depression with onset at old age.

Methods

The authors reviewed several pages and books relevent to the subject but did not search the entire literature because of it's overwhelming size. They chose to review those considered most significant.

Results

The prevalence of major depression is estimated to be 2% in the general population over 65 years of age. The clinical picture of geriatric depression differs in many aspects from depression in younger patients. It is not yet clear whether it also varies across cultures and different socio-economic backgrounds. Biological data suggest that it is associated with an increased severity of subcortical vascular disease and greater impairment of cognitive performance. Many authors consider the existence of a somatic disorder to be related to the presence of depression in late life, even constituting a negative prognostic factor for the outcome of depression. Most studies support the opinion that geriatric depression carries a poorer prognosis than depression in younger patients. The therapeutic intervention includes pharmacotherapy, mainly with antidepressants, which is of established value and psychotherapy which is not equally validated.

Conclusion

A significant number of questions regarding the assessment and treatment of geriatric depression remain unanswered, empirical data are limited, and further research is necessary.

Comparison of the suicidal behavior of adolescent inpatients with borderline personality disorder and major depression

The objective of the study was to examine the hypothesis that some forms of suicidal behavior among adolescents are related to helplessness and depression, whereas others are related to anger and impulsivity. Sixty-five adolescents were studied. Thirty-three had borderline personality disorder (BPD), of whom 17 had made a recent suicide attempt. Thirty-two had major depressive disorder (MDD), of whom 16 had made a recent suicide attempt. Assessments were made with the Child Suicide Potential Scale, the Beck Depression Inventory, the Beck Hopelessness Scale, the Multidimensional Anger Inventory, the Overt Aggression Scale, the Impulsiveness-Control Scale, and the Suicide Intent Scale. Adolescents with BPD had more anger, aggression, and impulsiveness than those with MDD, but similar levels of depression and hopelessness. Suicidal versus nonsuicidal adolescents were more depressed, hopeless, and aggressive, but not more angry or impulsive. There were no significant differences in impulsiveness for the MDD suicidal group versus the MDD nonsuicidal group, but the suicidal BPD adolescents were significantly more impulsive than the nonsuicidal BPD adolescents. In the subjects with BPD, impulsiveness and aggression correlated significantly and positively with suicidal behavior. In the subjects with MDD, no such correlations were seen. In both diagnostic groups, depression and hopelessness correlated positively and significantly with suicidal behavior. Anger did not correlate with suicidal behavior in either of the groups. The suicidal subjects with MDD had significantly higher suicidal intent scores than the suicidal adolescents with BPD. We conclude that the nature of suicidal behavior in adolescents with BPD differs from that seen in MDD with respect to the role of anger and aggression.

Tryptophan as a link between psychopathology and somatic states

OBJECTIVE

Several somatic illnesses are associated with psychiatric comorbidity. Evidence is provided that availability of the essential amino acid tryptophan, which is the precursor of serotonin, may cause this phenomenon.

METHODS

We performed a database search to find relevant articles published between 1966 and 2002. For our search strategy, we combined several diseases from the categories hormonal, gastrointestinal, and inflammatory with the search terms "tryptophan" and "serotonin."

RESULTS

The catabolism of tryptophan is stimulated under the influence of stress, hormones and inflammation by the induction of the enzymes tryptophan pyrrolase (in the liver) and IDO (ubiquitous). Because of the reduction in blood levels of tryptophan under these circumstances the formation of cerebral serotonin is decreased.

CONCLUSIONS

It is argued that the coupling of peripheral tryptophan levels and cerebral serotonin levels has physiological significance. The clinical implications and therapeutic consequences of changes in tryptophan and consequently serotonin metabolism are discussed.