Citalopram intervention for hostility: results of a randomized clinical trial

Understanding the Role of Oxidative Stress, Neuroinflammation and Abnormal Myelination in Excessive Aggression Associated with Depression: Recent Input from Mechanistic Studies

Aggression and deficient cognitive control problems are widespread in psychiatric disorders, including major depressive disorder (MDD). These abnormalities are known to contribute significantly to the accompanying functional impairment and the global burden of disease. Progress in the development of targeted treatments of excessive aggression and accompanying symptoms has been limited, and there exists a major unmet need to develop more efficacious treatments for depressed patients. Due to the complex nature and the clinical heterogeneity of MDD and the lack of precise knowledge regarding its pathophysiology, effective management is challenging. Nonetheless, the aetiology and pathophysiology of MDD has been the subject of extensive research and there is a vast body of the latest literature that points to new mechanisms for this disorder. Here, we overview the key mechanisms, which include neuroinflammation, oxidative stress, insulin receptor signalling and abnormal myelination. We discuss the hypotheses that have been proposed to unify these processes, as many of these pathways are integrated for the neurobiology of MDD. We also describe the current translational approaches in modelling depression, including the recent advances in stress models of MDD, and emerging novel therapies, including novel approaches to management of excessive aggression, such as anti-diabetic drugs, antioxidant treatment and herbal compositions.

Hostility, Anger, Psycho-emotional Factors and Cardiovascular Disease

The review presents the main aspects of the relationship between psychoemotional factors, hostility, anger and cardiovascular diseases. The first chapter describes the main historical stages in the study of this problem, starting from the Middle Ages and ending with fundamental research of the 19-20 centuries. In the second part, the authors demonstrated that hostility/anger are a risk factor for the CVD development and affect the prognosis and course of CVD (hypertension, ischemic heart disease, various cardiac arrhythmias, etc.). In the third chapter, there were studies that found that high rates of hostility/ anger reduced the effectiveness of cardiovascular therapy. In the fourth part, there are the main correlation mechanisms of negative emotions, hostility/anger and the cardiovascular system, carried out through the relationships with the activation of the hypothalamic-pituitary-adrenal, autonomic nervous system, platelet activation, with the changes in the risk factors characteristics etc. In the final chapter, the authors suggested prospects for further study of the problem, probably associated with the assessment of behavioral interventions, pharmacological or complex effects on the severity of hostility/anger to reduce CVD mortality in individuals with high rates of hostility / anger.

Prescribed aggression of fishes: Pharmaceuticals modify aggression in environmentally relevant concentrations

Traces of psychoactive substances have been found in freshwaters globally. Fish are chronically exposed to pollution at low concentrations. The changes of aggressive behaviour of chub (Squalius cephalus) were determined under the exposure to four psychoactive compounds (sertraline, citalopram, tramadol, methamphetamine) at environmentally relevant concentrations of 1 μg/L for 42 days. We tested whether (A) the behavioural effect of compounds varies within a single species; (B) there is a correlation between the individual brain concentration of the tested pollutants and fish aggression using the novel analysis of pollutants in brain; and (C) there is detectable threshold to effective pollutant concentration in brain. Behaviour and pollutant concentrations in brain were determined repeatedly (1st, 7th, 21st, 42nd and 56th days), including a two-week-long depuration period. The effect of particular compounds varied. Citalopram and methamphetamine generally increased the fish aggression, while no such effect was found after exposure to tramadol or sertraline. The longitudinal analysis showed an aggression increase after depuration, indicating the presence of withdrawal effects in methamphetamine- and tramadol-exposed fish. The analysis of pollutant concentration in brain revealed a positive linear relationship of citalopram concentration and aggression, while no such effect was detected for other compounds and/or their metabolites. Structural break analyses detected concentration thresholds of citalopram (1 and 3 ng/g) and sertraline (1000 ng/g) in brain tissue, from which a significant effect on behaviour was manifested. While the effect of sertraline was not detected using traditional approaches, there was a reduction in aggression after considering its threshold concentration in the brain. Our results suggest that pursuing the concentration threshold of psychoactive compounds can help to reduce false negative results and provide more realistic predictions on behavioural outcomes in freshwater environments, especially in the case of compounds with bioaccumulation potential such as sertraline.

Involvement of dorsal raphe nucleus serotonergic systems in social approach-avoidance behaviour and in the response to fluoxetine treatment in peri-adolescent female BALB/c mice

Serotonergic systems are involved in the development and regulation of social behaviour, and drugs that target serotonin neurotransmission, such as selective serotonin reuptake inhibitors (SSRIs), also alter aspects of social approach-avoidance. The midbrain dorsal raphe nucleus (DR), which is a major serotonergic nucleus and main source of serotonergic innervation of the forebrain, has been proposed as an important target for SSRIs, although evidence in females is lacking. In this study, we examined the involvement of the DR serotonergic systems in social behaviour and in response to SSRI treatment, using peri-adolescent female BALB/c mice. Mice were exposed to the SSRI fluoxetine either chronically (18 mg/kg/day, in drinking water, for 12 days) or acutely (18 mg/kg, i.p.), or to vehicle control condition (0.9 % saline, i.p.), prior to being exposed to the three-chambered sociability test. Activation of serotonergic neurons across subregions of the DR were subsequently measured, using dual-label immunohistochemistry for TPH2 and c-Fos. Acute fluoxetine administration increased generalised and social avoidance, while mice exposed to chronic fluoxetine treatment showed levels of social approach behaviour that were comparable to controls. Serotonergic populations across the DR showed reduced activity following acute fluoxetine treatment. Further, activation of serotonergic neurons in the ventral DR correlated with social approach behaviour in vehicle-treated control mice. These data provide some support for the involvement of discrete populations of DR serotonergic neurons in the regulation of social approach-avoidance, although more research is needed to understand the effects and mechanisms of chronic SSRI treatment in females.

From Description to Explanation: Integrating Across Multiple Levels of Analysis to Inform Neuroscientific Accounts of Dimensional Personality Pathology

Dimensional approaches to psychiatric nosology are rapidly transforming the way researchers and clinicians conceptualize personality pathology, leading to a growing interest in describing how individuals differ from one another. Yet, in order to successfully prevent and treat personality pathology, it is also necessary to explain the sources of these individual differences. The emerging field of personality neuroscience is well-positioned to guide the transition from description to explanation within personality pathology research. However, establishing comprehensive, mechanistic accounts of personality pathology will require personality neuroscientists to move beyond atheoretical studies that link trait differences to neural correlates without considering the algorithmic processes that are carried out by those correlates. We highlight some of the dangers we see in overpopulating personality neuroscience with brain-trait associational studies and offer a series of recommendations for personality neuroscientists seeking to build explanatory theories of personality pathology.

Hostility Dimensions and Metabolic Syndrome in a Healthy, Midlife Sample

OBJECTIVE

Evidence links trait hostility with components of the metabolic syndrome (MetS), a clustering of cardiometabolic risk factors, but which hostility dimensions (e.g., expressive or cognitive hostility) relate to MetS are not well known. Further, there may be age and sex differences in the extent to which hostility dimensions relate to MetS. The present study evaluated associations between dimensions of hostility and the metabolic syndrome and its individual components as well as the moderating effects of sex and age.

METHODS

In a cross-sectional sample of 478 employed adults, a principal component analysis from common trait hostility questionnaires yielded a two-factor solution: expressive hostility (anger and aggression) and cognitive hostility (cynicism). Each of these two components of hostility was examined as predictors of each of two aggregated MetS outcomes: a dichotomous measure of MetS, based upon the NCEP-ATP III definition, and a continuous measure based upon the average of standardized scores for each component; and they were examined as predictors of individual MetS components as well.

RESULTS

Expressive hostility was associated with MetS severity (b = 0.110, p = 0.04) and waist circumference (b = 2.75, p = 0.01). Moderation analyses revealed that elevated expressive hostility was associated with elevated waist circumference in women but not men. Cognitive hostility was not related to any metabolic syndrome component or aggregated outcome, and no moderation was observed.

CONCLUSIONS

Among multiple individual components and two aggregated scores, only trait dispositions to expressed hostile affect and behavior were associated with MetS severity and waist circumference. The effects were small but statistically significant. The association between cognitive hostility and metabolic syndrome measures may not be robust in a large sample of healthy, midlife adults.

Hostility predicts alcohol consumption over a 21-year follow-up in the Gazel cohort

BACKGROUND

Hostility has been found to be positively associated with alcohol intake in cross-sectional studies. Our aim was to examine prospectively the long-lasting association of hostility with alcohol consumption.

METHODS

We included 10,612 men and 3834 women from the French Gazel cohort with mean ages in 1993 of 48.6 (SD=2.9) and 45.7(SD=4.2), respectively. Hostility (i.e., total, cognitive and behavioral) was assessed in 1993 with the Buss and Durkee Hostility Inventory. Alcohol consumption was self-reported annually from 1994 to 2014. Hostility scores were introduced successively in general linear mixed models with annual alcohol consumption in drinks per week as dependent variable. Multivariable analyses were adjusted for age, occupational status, marital status, retirement status and depression score. All the analyses were stratified by sex.

RESULTS

Among men (women), 83.0% (76.2%) completed at least 75% of all annual assessment of alcohol consumption over a 21-year follow-up. In univariate analysis, alcohol consumption was associated with total and behavioral hostility in both sex (all p<0.001). In multivariable analyses, these associations remained significant with a greater size effect for behavioral hostility. Estimated means of alcohol consumptions ranged from 10.50 [95CI%: 10.01-10.92] drinks per week to 13.32 [95%CI: 12.90-13.74] in men and from 4.09 [95%CI: 3.71-4.46] to 5.78 [95%CI: 5.39-6.17] in women, for the first and last quartiles respectively (p trends<0.001 and all pairwise comparisons<0.01). Similar effects were observed among participants with at-risk alcohol consumption at baseline.

CONCLUSIONS

In both men and women, behavioral hostility predicted alcohol consumption over a 21-year follow-up. Interventions aiming at modulating behavioral hostility may help reducing its long-lasting influence on alcohol consumption.

An Exploration of the Relationships between Attitudes Towards Anger Expression and Personal Style of Anger Expression in Women in the USA and Canada

This study surveyed 228 women, ages 18-75, to assess their attitudes towards anger expression in themselves and other women. Following exposure to an anger-inducing vignette, the women were asked to complete the STAXI-2 and evaluate five possible responses based on how appropriate the response was and how likely they felt that other women would respond similarly. Correlation analyses revealed positive and negative relationships between the women's attitudes towards anger expression and their own style of anger expression, as measured by the STAXI-2. The authors discuss implications for practice and future research.

Studying the neurobiology of human social interaction: Making the case for ecological validity

With this commentary we make the case for an increased focus on the ecological validity of the measures used to assess aspects of human social functioning. Impairments in social functioning are seen in many types of psychopathology, negatively affecting the lives of psychiatric patients and those around them. Yet the neurobiology underlying abnormal social interaction remains unclear. As an example of human social neuroscience research with relevance to biological psychiatry and clinical psychopharmacology, this commentary discusses published experimental studies involving manipulation of the human brain serotonin system that included assessments of social behavior. To date, these studies have mostly been laboratory-based and included computer tasks, observations by others, or single-administration self-report measures. Most laboratory measures used so far inform about the role of serotonin in aspects of social interaction, but the relevance for real-life interaction is often unclear. Few studies have used naturalistic assessments in real life. We suggest several laboratory methods with high ecological validity as well as ecological momentary assessment, which involves intensive repeated measures in naturalistic settings. In sum, this commentary intends to stimulate experimental research on the neurobiology of human social interaction as it occurs in real life.

Stability of the DSM-5 Section III pathological personality traits and their longitudinal associations with psychosocial functioning in personality disordered individuals

This study was conducted to establish (a) the stability of the DSM-5 Section III personality disorder (PD) traits, (b) whether these traits predict future psychosocial functioning, and (c) whether changes in traits track with changes in psychosocial functioning across time. Ninety-three outpatients (61% female) diagnosed with at least 1 PD completed patient-report measures at 2 time-points (M time between assessments = 1.44 years), including the Personality Inventory for the DSM-5 and several measures of psychosocial functioning. Effect sizes of rank-order and mean-level change were calculated. In addition, Time 1 traits were used to predict functioning measures at Time 2. Finally, latent change score models were estimated for DSM-5 Section III traits and functioning measures, and correlations among latent change scores were calculated to establish the relationship between change in traits and functional outcomes. Findings demonstrated that the DSM-5 Section III traits were highly stable in terms of normative (i.e., mean-level) change and rank-order stability over the course of the study. Furthermore, traits prospectively predicted psychosocial functioning. However, at the individual level traits and functioning were not entirely static over the study, and change in individuals' functioning tracked with changes in trait levels. These findings demonstrate that the DSM-5 Section III traits are highly stable consistent with the definition of PD, prospectively predictive of psychosocial functioning, and are dynamically associated with functioning over time. This study provides important evidence in support of the DSM-5 Section III PD model.

Personality-informed interventions for healthy aging: conclusions from a National Institute on Aging work group

We describe 2 frameworks in which personality dimensions relevant to health, such as Conscientiousness, can be used to inform interventions designed to promote health aging. First, contemporary data and theory do not suggest that personality is "immutable," but instead focus on questions of who changes, in what way, why, when, and how. In fact, the notion that personality could be changed was part and parcel of many schools of psychotherapy, which suggested that long-term and meaningful change in symptoms could not be achieved without change in relevant aspects of personality. We review intervention research documenting change in personality. On the basis of an integrative view of personality as a complex system, we describe a bottom-up model of change in which interventions to change basic personality processes eventuate in changes at the trait level. A 2nd framework leverages the descriptive and predictive power of personality to tailor individual risk prediction and treatment, as well as refine public health programs, to the relevant dispositional characteristics of the target population. These methods dovetail with, and add a systematic and rigorous psychosocial dimension to, the personalized medicine and patient-centeredness movements in medicine. In addition to improving health through earlier intervention and increased fit between treatments and persons, cost-effectiveness improvements can be realized by more accurate resource allocation. Numerous examples from the personality, health, and aging literature on Conscientiousness and other traits are provided throughout, and we conclude with a series of recommendations for research in these emerging areas.

Dissociable and common effects of methylphenidate, atomoxetine and citalopram on response inhibition neural networks

Response inhibition is an executive function that allows the detection and modification of unwanted actions. Its underlying neurochemistry and neurobiology have been explored by combining classic neuropsychological paradigms, such as the go/no-go task (GNG), with targeted pharmacology and functional neuroimaging. We sought to further this literature by using single doses of methylphenidate (30 mg), atomoxetine (60 mg), citalopram (30 mg) and placebo to probe dopaminergic, noradrenergic and serotonergic aspects of response inhibition. Twenty-seven (27) healthy, right-handed males participated in a randomised, double blind, placebo-controlled, within subject, crossover fMRI study to examine stop-related BOLD activation correlates of a modified GNG task. Methylphenidate demonstrated activation versus placebo in the pregenual cingulate (dorsal anterior cingulate), right inferior frontal, left middle frontal, left angular and right superior temporal gyri and right caudate. Atomoxetine demonstrated activation versus placebo across a broad network of cortical regions. Both methylphenidate and atomoxetine, but not citalopram, activated superior temporal, right inferior frontal and left middle frontal clusters. Citalopram only activated the left inferior occipital lobe. Taking the above as functionally defined regions of interest, we examined the specificity of stop-related drug activity by comparing mean activations across the four conditions. Only methylphenidate demonstrated drug-specific effects with increased activation of the pregenual cingulate and decreased activation of the caudate. Direct comparison of methylphenidate and atomoxetine showed broad recruitment of prefrontal regions but specific effects of methylphenidate in the pregenual cingulate and caudate revealing dissociable modulations of response inhibition networks.

Possible role of more positive social behaviour in the clinical effect of antidepressant drugs

Increasing serotonin decreases quarrelsome behaviours and enhances agreeable behaviours in humans. Antidepressants, even those whose primary action is not on serotonin, seem to increase serotonin function. We suggest that antidepressants act in part by effects on social behaviour, which leads to a gradual improvement in mood. We review the evidence supporting the idea that antidepressants may be moving behaviour from quarrelsome to agreeable. The more positive social responses of interaction partners would initiate a cycle of more positive social behaviour, and this iterative process would result in a clinically significant improvement in mood.

Effect of escitalopram on mental stress-induced myocardial ischemia: results of the REMIT trial

IMPORTANCE

Mental stress can induce myocardial ischemia and also has been implicated in triggering cardiac events. However, pharmacological interventions aimed at reducing mental stress-induced myocardial ischemia (MSIMI) have not been well studied.

OBJECTIVE

To examine the effects of 6 weeks of escitalopram treatment vs placebo on MSIMI and other psychological stress-related biophysiological and emotional parameters.

DESIGN, SETTING, AND PARTICIPANTS

The REMIT (Responses of Mental Stress Induced Myocardial Ischemia to Escitalopram Treatment) study, a randomized, double-blind, placebo-controlled trial of patients with clinically stable coronary heart disease and laboratory-diagnosed MSIMI. Enrollment occurred from July 24, 2007, through August 24, 2011, at a tertiary medical center.

INTERVENTIONS

Eligible participants were randomized 1:1 to receive escitalopram (dose began at 5 mg/d, with titration to 20 mg/d in 3 weeks) or placebo over 6 weeks.

MAIN OUTCOMES AND MEASURES

Occurrence of MSIMI, defined as development or worsening of regional wall motion abnormality; left ventricular ejection fraction reduction of 8% or more; and/or horizontal or down-sloping ST-segment depression of 1 mm or more in 2 or more leads, lasting for 3 or more consecutive beats, during 1 or more of 3 mental stressor tasks.

RESULTS

Of 127 participants randomized to receive escitalopram (n = 64) or placebo (n = 63), 112 (88.2%) completed end point assessments (n = 56 in each group). At the end of 6 weeks, more patients taking escitalopram (34.2% [95% CI, 25.4%-43.0%]) had absence of MSIMI during the 3 mental stressor tasks compared with patients taking placebo (17.5% [95% CI, 10.4%-24.5%]), based on the unadjusted multiple imputation model for intention-to-treat analysis. A significant difference favoring escitalopram was observed (odds ratio, 2.62 [95% CI, 1.06-6.44]). Rates of exercise-induced ischemia were slightly lower at 6 weeks in the escitalopram group (45.8% [95% CI, 36.6%-55.0%]) than in patients receiving placebo (52.5% [95% CI, 43.3%-61.8%]), but this difference was not statistically significant (adjusted odds ratio; 1.24 [95% CI, 0.60-2.58]; P = .56).

CONCLUSIONS AND RELEVANCE

Among patients with stable coronary heart disease and baseline MSIMI, 6 weeks of escitalopram, compared with placebo, resulted in a lower rate of MSIMI. There was no statistically significant difference in exercise-induced ischemia. Replication of these results in multicenter settings and investigations of other medications for reducing MSIMI are needed.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT00574847.

Hostile mood and social strain during daily life: a test of the transactional model

BACKGROUND

Hostility is a multidimensional construct related to cardiovascular (CV) disease risk. Daily hostile mood and social interactions may precipitate stress-related CV responses in hostile individuals.

PURPOSE

Determine whether trait cognitive hostility best predicts daily hostile mood and social interactions relative to other trait hostility factors and explore the temporal links between these daily measures.

METHODS

One hundred seventy-one participants completed assessments of four trait hostility scales. Participants completed an electronic diary across 3 days, assessing current hostile mood and social interaction quality.

RESULTS

Multiple regression analyses revealed both affective and cognitive hostility to be significant predictors of daily hostile mood, and cognitive hostility alone to predict daily social strain. Additional analyses revealed previous social strain to predict elevated subsequent hostile mood.

CONCLUSIONS

Episodes of social strain may give rise to elevated hostile mood. Trait cognitive hostility may be an important factor in predicting daily social strain.

Anger and the heart: perspectives on cardiac risk, mechanisms and interventions

In the popular imagination, anger has long been linked to cardiovascular diseases (CVD), but empirical validation from case-control and prospective studies emerged only in the 1970's. After describing the multidimensional nature of anger and its assessment (via self-report or observed in structured interviews), this paper selectively reviews evidence in (a) behavioral epidemiology, (b) stress and biological processes with implications for cardiopathogenesis, and (c) behavioral/pharmacological interventions for anger/hostility reduction. Although evidence is inconsistent, chronic feelings of anger, cynical distrust and antagonistic behavior are at least modestly associated with risk of both initiation and progression of CVD. Anger/hostility also is linked to stress exposure and reactivity, exaggerated autonomic function, reduced heart rate variability, platelet aggregation and inflammation. Clinical and pharmacologic treatment of anger/hostility has the potential to reduce anger and its health-damaging effects. Limitations, including third-variable explanations and overlap among the negative emotions, and implications for cardiology and behavioral medicine research and practice are discussed.

Citalopram improves metabolic risk factors among high hostile adults: results of a placebo-controlled intervention

Hostility is associated with a number of metabolic risk factors for cardiovascular disease, including waist-hip ratio, glucose, and triglycerides. Along with hostility, many of these measures have also been shown to be associated with reduced central serotonergic function. We have previously reported that a citalopram intervention was successful in reducing hostility by self-report assessment (Kamarck et al., 2009). Here we examine the effects of this serotonergic intervention on metabolic risk factors in the same sample. 159 healthy adults with elevated hostility scores were randomized to citalopram or placebo for a 2-month period. Citalopram favorably changed metabolic risk factors, including waist circumference (p=.003), glucose (p=.02), HDL cholesterol (p=.04), triglycerides (p=.03), insulin sensitivity (p=.045) and diastolic blood pressure by automated assessment (p=.0021). All of these metabolic changes were significantly mediated by treatment-related changes in body mass index (in most cases, p<.01). In addition, the changes in blood glucose were significantly mediated by treatment-related changes in hostility (p<.05). Mechanisms accounting for these associations remain to be explored.

Serotonergic contribution to boys' behavioral regulation

Objectives

Animal and human adult studies reveal a contribution of serotonin to behavior regulation. Whether these findings apply to children is unclear. The present study investigated serotonergic functioning in boys with a history of behavior regulation difficulties through a double-blind, acute tryptophan supplementation procedure.

Method

Participants were 23 boys (age 10 years) with a history of elevated physical aggression, recruited from a community sample. Eleven were given a chocolate milkshake supplemented with 500mg tryptophan, and 12 received a chocolate milkshake without tryptophan. Boys engaged in a competitive reaction time game against a fictitious opponent, which assessed response to provocation, impulsivity, perspective taking, and sharing. Impulsivity was further assessed through a Go/No-Go paradigm. A computerized emotion recognition task and a staged instrumental help incident were also administered.

Results

Boys, regardless of group, responded similarly to high provocation by the fictitious opponent. However, boys in the tryptophan group adjusted their level of responding optimally as a function of the level of provocation, whereas boys in the control group significantly decreased their level of responding towards the end of the competition. Boys in the tryptophan group tended to show greater perspective taking, tended to better distinguish facial expressions of fear and happiness, and tended to provide greater instrumental help to the experimenter.

Conclusions

The present study provides initial evidence for the feasibility of acute tryptophan supplementation in children and some effect of tryptophan supplementation on children's behaviors. Further studies are warranted to explore the potential impact of increased serotonergic functioning on boys' dominant and affiliative behaviors.

Neuropsychiatry of aggression

Aggression is a serious medical problem that can place both the patient and the health care provider at risk. Aggression can result from medical, neurologic, and/or psychiatric disorders. A comprehensive patient evaluation is needed. Treatment options include pharmacotherapy as well as nonpharmacologic interventions, both of which need to be individualized to the patient.

Inflammation, sanitation, and consternation: loss of contact with coevolved, tolerogenic microorganisms and the pathophysiology and treatment of major depression

CONTEXT

Inflammation is increasingly recognized as contributing to the pathogenesis of major depressive disorder (MDD), even in individuals who are otherwise medically healthy. Most studies in search of sources for this increased inflammation have focused on factors such as psychosocial stress and obesity that are known to activate inflammatory processes and increase the risk for depression. However, MDD may be so prevalent in the modern world not just because proinflammatory factors are widespread, but also because we have lost contact with previously available sources of anti-inflammatory, immunoregulatory signaling.

OBJECTIVE

To examine evidence that disruptions in coevolved relationships with a variety of tolerogenic microorganisms that were previously ubiquitous in soil, food, and the gut, but that are largely missing from industrialized societies, may contribute to increasing rates of MDD in the modern world.

DATA SOURCES

Relevant studies were identified using PubMed and Ovid MEDLINE.

STUDY SELECTION

Included were laboratory animal and human studies relevant to immune functioning, the hygiene hypothesis, and major depressive disorder identified via PubMed and Ovid MEDLINE searches.

DATA EXTRACTION

Studies were reviewed by all authors, and data considered to be potentially relevant to the contribution of hygiene-related immune variables to major depressive disorder were extracted.

DATA SYNTHESIS

Significant data suggest that a variety of microorganisms (frequently referred to as the "old friends") were tasked by coevolutionary processes with training the human immune system to tolerate a wide array of non-threatening but potentially proinflammatory stimuli. Lacking such immune training, vulnerable individuals in the modern world are at significantly increased risk of mounting inappropriate inflammatory attacks on harmless environmental antigens (leading to asthma), benign food contents and commensals in the gut (leading to inflammatory bowel disease), or self-antigens (leading to any of a host of autoimmune diseases). Loss of exposure to the old friends may promote MDD by increasing background levels of depressogenic cytokines and may predispose vulnerable individuals in industrialized societies to mount inappropriately aggressive inflammatory responses to psychosocial stressors, again leading to increased rates of depression.

CONCLUSION

Measured exposure to the old friends or their antigens may offer promise for the prevention and treatment of MDD in modern industrialized societies.

Effect of fluoxetine on blood concentrations of serotonin, cortisol and dehydroepiandrosterone in canine aggression

Canine aggression directed towards people is the most frequent reason for referral to behaviour practices. The serotonergic system and the hypothalamic-pituitary-adrenal (HPA) axis are believed to play an important role in controlling aggression. The selective serotonin reuptake inhibitor fluoxetine is the most commonly used drug in canine aggression. The aim of the present study was to assess the effect of a 30-day-long fluoxetine treatment on the peripheral serotonergic system and the HPA axis in canine aggression. To this end, the concentrations of serum serotonin (5-HT) and plasma cortisol and dehydroepiandrosterone (DHEA) were analysed in a group of aggressive (n = 22) and nonaggressive dogs (n = 9) during pre- (day 0) and posttreatment (day 30) conditions. Treatment caused a significant decrease in 5-HT concentrations (46% in the aggressive group and 32% in the control group). There was a trend towards a rise of DHEA/cortisol ratio values after treatment both in the aggressive and the control group. The determination of blood 5-HT and the DHEA/cortisol ratio could have important clinical applications in the future for deciding which animals might benefit from a given treatment as well as for monitoring the response. Further large-scale studies with this aim should be carried out to obtain sound conclusions.

Hostility now, depression later? Longitudinal associations among emotional risk factors for coronary artery disease

BACKGROUND/PURPOSE

Given that emotional risk factors for coronary artery disease (CAD) tend to cluster within individuals, surprisingly little is known about how these negative emotions might influence one another over time. We examined the longitudinal associations among measures of depressive symptoms and hostility/anger in a cohort of 296 healthy, older adults.

METHODS

Participants completed the Beck Depression Inventory-II (BDI-II), Cook-Medley Hostility (Ho) scale, and Anger-In and Anger-Out subscales of the State-Trait Anger Expression Inventory at baseline and 6-year follow-up. We conducted a series of path analyses to evaluate the directionality of the depression-hostility/anger relationship.

RESULTS

Baseline Ho scale was a predictor of 6-year increases in BDI-II (beta = 0.15, p = 0.004), Anger-In (beta = 0.14, p = 0.002), and Anger-Out (beta = 0.11, p = 0.01). In contrast, baseline BDI-II, Anger-In, and Anger-Out did not predict change in any of the emotional variables. Additional path analytic models revealed that the pattern of relationships was not altered after controlling for demographic, biomedical, and behavioral covariates; anxiety symptoms; social support; and subjective sleep quality.

CONCLUSIONS

The present results suggest that the cognitive aspects of hostility/anger may precede and independently predict future increases in depressive symptoms but not vice versa. Our findings lead us to speculate that (a) hostility may exert part of its cardiotoxic influence by acting to precipitate and/or maintain symptoms of depression and that (b) the potency of depression interventions designed to improve cardiovascular outcomes might be enhanced by incorporating treatments addressing hostility.