Serotonergic function, two-mode models of self-regulation, and vulnerability to depression: what depression has in common with impulsive aggression

Mediators of aggression among young adult offspring of depressed mothers

The current article explores the connection between maternal depression and offspring aggression during the transition to adulthood, expanding the scope of prior research on this topic. Both family-level factors (including parent-child relationship quality and maternal romantic relationship quality) and youth factors (including depression history and social functioning in midadolescence) were tested as potential mediators in a longitudinal community sample of 710 youth at ages 15 and 20. The results suggest that maternal depression confers a risk for higher levels of aggressive behavior by offspring at age 20. Structural equation models suggested that the association between maternal depression and youth aggression is fully mediated by youth history of depression by midadolescence, even when accounting for the stability of aggression between ages 15 and 20. Parent-child relationship quality, youth social functioning, and maternal relationship quality were not unique mediators of this association. Limitations and implications are discussed.

Conceptual background, development, and preliminary data from the unified protocol for transdiagnostic treatment of emotional disorders

Anxiety and mood disorders are common, chronic, costly, and characterized by high comorbidity. The development of cognitive behavioral approaches to treating anxiety and mood disorders has left us with highly efficacious treatments that are increasingly widely accepted. The proliferation of treatment manuals targeting single disorders, sometimes with trivial differences among them, leaves the mental health professional with no clear way to choose one manual over another and little chance of ever becoming familiar with most of them, let alone trained to competence in their delivery. Deepening understanding of the nature of emotional disorders reveals that commonalities in etiology and latent structures among these disorders supersedes differences. Based on empirical evidence from the domains of learning, emotional development and regulation, and cognitive science, we have distilled a set of psychological procedures that comprise a unified intervention for emotional disorders. The Unified Protocol (UP) is a transdiagnostic, emotion-focused cognitive behavioral treatment, which emphasizes the adaptive, functional nature of emotions, and seeks to identify and correct maladaptive attempts to regulate emotional experiences, thereby facilitating appropriate processing and extinction of excessive emotional responding to both internal (somatic) and external cues. The treatment components of the UP are briefly outlined. Theory and rationale supporting this new approach are described along with some preliminary evidence supporting its efficacy. Implications for the treatment of emotional disorders using the UP are discussed.

Brain substrates of behavioral programs associated with self-regulation

The present paper proposes that four neuromodulator systems underpin highly generalized behavioral sets, but each targets either dorsomedial or ventrolateral cortical systems, where it produces its effects in either a proactive or reactive orientation to the environment. This way systems are discriminated that control reactive approach (dopaminergic), reactive avoidance (cholinergic), proactive behavior (noradrenergic), and withdrawal (serotonergic). This model is compared with models of temperament, affect, personality, and so-called two-system models from psychology. Although the present model converges with previous models that point to a basic scheme underlying temperamental and affective space, at the same time it suggest that specific additional discriminations are necessary to improve descriptive fit to data and solve inconsistencies and confusions. We demonstrate how proactive and reactive actions and controls can be confused, and that this has many potential implications for psychology and neurobiology. We uncover conceptual problems regarding constructs such as effortful control, positive affect, approach-avoidance, extraversion, impulsivity, impulse-control, and goal-directedness of behavior. By delineating those problems, our approach also opens up ways to tackle them.

Intervention to strengthen emotional self-regulation in children with emerging mental health problems: proximal impact on school behavior

A model for teaching children skills to strengthen emotional self-regulation is introduced, informed by the developmental concept of scaffolding. Adult modeling/instruction, role-play and in vivo coaching are tailored to children's level of understanding and skill to promote use of skills in real life contexts. Two-hundred twenty-six kindergarten-3rd grade children identified with elevated behavioral and social classroom problems from a population-based screening participated in a wait listed randomized trial of the Rochester Resilience Project derived from this model. In 14 lessons with school-based mentors, children were taught a hierarchical set of skills: monitoring of emotions; self control/ reducing escalation of emotions; and maintaining control and regaining equilibrium. Mentors provided classroom reinforcement of skill use. Multi-level modeling accounting for the nesting of children in schools and classrooms showed the following effects at post-intervention: reduced problems rated by teachers in behavior control, peer social skills, shy-withdrawn and off-task behaviors (ES 0.31-0.47). Peer social skills improved for girls but not for boys. Children receiving the intervention had a 46% mean decrease in disciplinary referrals and a 43% decrease in suspensions during the 4-month intervention period. Limitations and future directions to promote skill transfer are discussed.

Cognitive theory and therapy of anxiety and depression: convergence with neurobiological findings

In this review paper a modified cognitive neurophysiological model of Aaron T. Beck's cognitive formulation of anxiety and depression is proposed that provides an elaborated account of the cognitive and neural mediational processes of cognitive therapy (CT). Empirical evidence consistent with this model is discussed that indicates the effectiveness of cognitive therapy could be associated with reduced activation of the amygdalohippocampal subcortical regions implicated in the generation of negative emotion and increased activation of higher-order frontal regions involved in cognitive control of negative emotion. Future cognitive neuroscience research is needed on the unique brain substrates affected by CT and their role in facilitating symptom change. This future research would have important implications for improving the efficiency and efficacy of this treatment approach.

Understanding vulnerability for depression from a cognitive neuroscience perspective: A reappraisal of attentional factors and a new conceptual framework

We propose a framework to understand increases in vulnerability for depression after recurrent episodes that links attention processes and schema activation to negative mood states, by integrating cognitive and neurobiological findings. Depression is characterized by a mood-congruent attentional bias at later stages of information processing. The basic idea of our framework is that decreased activity in prefrontal areas, mediated by the serotonin metabolism which the HPA axis controls, is associated with an impaired attenuation of subcortical regions, resulting in prolonged activation of the amygdala in response to stressors in the environment. Reduced prefrontal control in interaction with depressogenic schemas leads to impaired ability to exert attentional inhibitory control over negative elaborative processes such as rumination, leading in turn to sustained negative affect. These elaborative processes are triggered by the activation of negative schemas after confrontation with stressors. In our framework, attentional impairments are postulated as a crucial process in explaining the increasing vulnerability after depressive episodes, linking cognitive and biological vulnerability factors. We review the empirical data on the biological factors associated with the attentional impairments and detail how they are associated with rumination and mood regulation. The aim of our framework is to stimulate translational research.

The modification of attentional bias to emotional information: A review of the techniques, mechanisms, and relevance to emotional disorders

A negative bias in the deployment of attention to emotional stimuli is commonly found in both anxiety and depression. Recent work has highlighted that such biases are causally related to emotional vulnerability, suggesting that interventions that ameliorate them may be therapeutic. Here, we review the evidence that attentional bias can be modified using both pharmacological and psychological interventions. We highlight the behavioral and neuroimaging studies that suggest that these interventions impact upon attention via alteration of distinct neural mechanisms. Specifically, pharmacological interventions appear to influence the initial deployment of attention via an effect on the amygdala-based stimulus appraisal system, whereas psychological interventions influence attention at later time points and may alter activity in the lateral prefrontal cortex. Finally, we suggest a conceptual framework that embraces both pharmacological and psychological approaches and consider the possible implications of this work for future research and treatment development.

Sleep disturbance as transdiagnostic: consideration of neurobiological mechanisms

Sleep disturbance is increasingly recognized as an important, but understudied, mechanism in the complex and multi-factorial causation of the symptoms and functional disability associated with psychiatric disorders. This review proposes that it is biologically plausible for sleep disturbance to be mechanistically transdiagnostic. More specifically, we propose that sleep disturbance is aetiologically linked to various forms of psychopathology through: its reciprocal relationship with emotion regulation and its shared/interacting neurobiological substrates in (a) genetics--genes known to be important in the generation and regulation of circadian rhythms have been linked to a range of disorders and (b) dopaminergic and serotonergic function--we review evidence for the interplay between these systems and sleep/circadian biology. The clinical implications include potentially powerful and inexpensive interventions including interventions targeting light exposure, dark exposure, the regulation of social rhythms and the reduction of anxiety. We also consider the possibility of developing a 'transdiagnostic' treatment; one treatment that would reduce sleep disturbance across psychiatric disorders.

Rumination and impaired resource allocation in depression

Depression is characterized by a range of cognitive deficits that theorists posit are due to the resource capturing properties of rumination. The present study was designed to examine the relation between rumination and resource allocation in depression. Twenty-five depressed and 25 nondepressed participants completed a modified dual-task version of the recency-probes task, which assesses the controlled allocation of cognitive resources by comparing performance across low- and high-interference conditions. In low-interference conditions, participants performed either the recency-probes task or a tracking task, which required participants to track specific stimuli across trials (i.e., no dual-task interference). In the high-interference condition, participants performed both the recency-probes task and the tracking task, which required the controlled allocation of resources to resolve dual-task interference. Depressed participants performed significantly worse than did their nondepressed counterparts in only the high-interference condition; performance of the 2 groups was comparable in the low-interference conditions. Furthermore, the degree to which depressed participants were impaired in the high-interference condition was correlated .74 with rumination. These findings suggest that an association between rumination and impairments in resource allocation underlies the cognitive difficulties experienced by depressed individuals.

Mechanisms of attentional biases towards threat in anxiety disorders: An integrative review

A wealth of research demonstrates attentional biases toward threat in the anxiety disorders. Several models have been advanced to explain these biases in anxiety, yet the mechanisms comprising and mediating the biases remain unclear. In the present article, we review evidence regarding the mechanisms of attentional biases through careful examination of the components of attentional bias, the mechanisms underlying these components, and the stage of information processing during which the biases occur. Facilitated attention, difficulty in disengagement, and attentional avoidance comprise the components of attentional bias. A threat detection mechanism likely underlies facilitated attention, a process that may be neurally centered around the amygdala. Attentional control ability likely underlies difficulty in disengagement, emotion regulation goals likely underlie attentional avoidance, and both of these processes may be neurally centered around prefrontal cortex functioning. The threat detection mechanism may be a mostly automatic process, attentional avoidance may be a mostly strategic process, and difficulty in disengagement may be a mixture of automatic and strategic processing. Recommendations for future research are discussed.

Description and validation of a dynamical systems model of presynaptic serotonin function: genetic variation, brain activation and impulsivity

Despite more than a decade of empirical work on the role of genetic polymorphisms in the serotonin system on behavior, the details across levels of analysis are not well understood. We describe a mathematical model of the genetic control of presynaptic serotonergic function that is based on control theory, implemented using systems of differential equations, and focused on better characterizing pathways from genes to behavior. We present the results of model validation tests that include the comparison of simulation outcomes with empirical data on genetic effects on brain response to affective stimuli and on impulsivity. Patterns of simulated neural firing were consistent with recent findings of additive effects of serotonin transporter and tryptophan hydroxylase-2 polymorphisms on brain activation. In addition, simulated levels of cerebral spinal fluid 5-hydroxyindoleacetic acid (CSF 5-HIAA) were negatively correlated with Barratt Impulsiveness Scale (Version 11) Total scores in college students (r = -.22, p = .002, N = 187), which is consistent with the well-established negative correlation between CSF 5-HIAA and impulsivity. The results of the validation tests suggest that the model captures important aspects of the genetic control of presynaptic serotonergic function and behavior via brain activation. The proposed model can be: (1) extended to include other system components, neurotransmitter systems, behaviors and environmental influences; (2) used to generate testable hypotheses.

Emotion-related self-regulation and its relation to children's maladjustment

The development of children's emotion-related self-regulation appears to be related to, and likely involved in, many aspects of children's development. In this review, the distinction between effortful self-regulatory processes and those that are somewhat less voluntary is discussed, and literature on the former capacities is reviewed. Emotion-related self-regulation develops rapidly in the early years of life and improves more slowly into adulthood. Individual differences in children's self-regulation are fairly stable after the first year or two of life. Such individual differences are inversely related to at least some types of externalizing problems. Findings for internalizing problems are less consistent and robust, although emotion-related self-regulation appears to be inversely related to internalizing problems after the early years. Self-regulatory capacities have been related to both genetic and environmental factors and their interaction. Some interventions designed to foster self-regulation and, hence, reduce maladjustment, have proved to be at least partially effective.

Emotion-related self-regulation and its relation to children's maladjustment

The development of children's emotion-related self-regulation appears to be related to, and likely involved in, many aspects of children's development. In this review, the distinction between effortful self-regulatory processes and those that are somewhat less voluntary is discussed, and literature on the former capacities is reviewed. Emotion-related self-regulation develops rapidly in the early years of life and improves more slowly into adulthood. Individual differences in children's self-regulation are fairly stable after the first year or two of life. Such individual differences are inversely related to at least some types of externalizing problems. Findings for internalizing problems are less consistent and robust, although emotion-related self-regulation appears to be inversely related to internalizing problems after the early years. Self-regulatory capacities have been related to both genetic and environmental factors and their interaction. Some interventions designed to foster self-regulation and, hence, reduce maladjustment, have proved to be at least partially effective.

Inducible gene manipulations in serotonergic neurons

An impairment of the serotonergic (5-HT) system has been implicated in the etiology of many neuropsychiatric disorders. Despite the considerable genetic evidence, the exact molecular and pathophysiological mechanisms underlying this dysfunction remain largely unknown. To address the lack of instruments for the molecular dissection of gene function in serotonergic neurons we have developed a new mouse transgenic tool that allows inducible Cre-mediated recombination of genes selectively in 5-HT neurons of all raphe nuclei. In this transgenic mouse line, the tamoxifen-inducible CreERT2 recombinase is expressed under the regulatory control of the mouse tryptophan hydroxylase 2 (Tph2) gene locus (177 kb). Tamoxifen treatment efficiently induced recombination selectively in serotonergic neurons with minimal background activity in vehicle-treated mice. These genetic manipulations can be initiated at any desired time during embryonic development, neonatal stage or adulthood. To illustrate the versatility of this new tool, we show that Brainbow-1.0L(TPH2-CreERT2) mice display highly efficient recombination in serotonergic neurons with individual 5-HT neurons labeling with multiple distinct fluorescent colors. This labeling is well suited for visualization and tracing of serotonergic neurons and their network architecture. Finally, the applicability of TPH2-CreERT2 for loxP-flanked candidate gene manipulation is evidenced by our successful knockout induction of the ubiquitously expressed glucocorticoid-receptor exclusively in 5-HT neurons of adult mice. The TPH2-CreERT2 line will allow detailed analysis of gene function in both developing and adult serotonergic neurons.

Dynamics of affective experience and behavior in depressed adolescents

BACKGROUND

Depression is often characterized as a disorder of affect regulation. However, research focused on delineating the key dimensions of affective experience (other than valence) that are abnormal in depressive disorder has been scarce, especially in child and adolescent samples. As definitions of affect regulation center around processes involved in initiating, maintaining, and modulating the occurrence, intensity, and duration of affective experiences, it is important to examine the extent to which affective experiences of depressed youth differ on these dimensions from those of healthy youth.

METHODS

The affective behavior and experience of adolescents with major depressive disorder (MDD; n = 75) were compared to a demographically matched cohort of healthy adolescents (n = 77). Both samples were recruited from community high schools. A multi-source (parents and adolescent), multi-method (interviews, behavioral observations, questionnaires) assessment strategy was used to examine positive and negative affects.

RESULTS

Depressed youth had significantly longer durations, higher frequency, and greater intensity when experiencing angry and dysphoric affects and shorter durations and less frequency of happy affect when compared to healthy youth. The most consistent, cross-method results were evident for duration of affect.

CONCLUSIONS

Clinically depressed adolescents experienced disturbances in affective functioning that were evident in the occurrence, intensity, and duration of affect. Notably, the disturbances were apparent in both positive and negative affects.

A proposal for a dimensional classification system based on the shared features of the DSM-IV anxiety and mood disorders: implications for assessment and treatment

A wealth of evidence attests to the extensive current and lifetime diagnostic comorbidity of the Diagnostic and Statistical Manual of Mental Disorders (4th ed., DSM-IV) anxiety and mood disorders. Research has shown that the considerable cross-sectional covariation of DSM-IV emotional disorders is accounted for by common higher order dimensions such as neuroticism/behavioral inhibition (N/BI) and low positive affect/behavioral activation. Longitudinal studies indicate that the temporal covariation of these disorders can be explained by changes in N/BI and, in some cases, initial levels of N/BI are predictive of the temporal course of emotional disorders. The marked phenotypal overlap of the DSM-IV anxiety and mood disorders is a frequent source of diagnostic unreliability (e.g., temporal overlap in the shared features of generalized anxiety disorder and mood disorders, situation specificity of panic attacks in panic disorder and specific phobia). Although extant dimensional proposals may address some drawbacks associated with the DSM nosology (e.g., inadequate assessment of individual differences in disorder severity), these proposals do not reconcile key problems in current classification, such as modest reliability and high comorbidity. This article considers an alternative approach that emphasizes empirically supported common dimensions of emotional disorders over disorder-specific criteria sets. Selection and assessment of these dimensions are discussed along with how these methods could be implemented to promote more reliable and valid diagnosis, prognosis, and treatment planning. For instance, the advantages of this system are discussed in context of transdiagnostic treatment protocols that are efficaciously applied to a variety of disorders by targeting their shared features.

Two-Mode Models of Self-Regulation as a Tool for Conceptualizing Effects of the Serotonin System in Normal Behavior and Diverse Disorders

The serotonin system is a collection of neural pathways whose overall level of functioning (from low to high) relates to diverse kinds of psychological and behavioral variability. Individual differences in serotonergic function are important both in personality and in vulnerability to psychological disorders. These disorders range widely-from impulsive aggression to depression. One way to understand such diverse reflections of differences in serotonergic function is by viewing serotonergic function through the lens of two-mode (or dual-process) models of self-regulation. Such theories posit a lower-order system that responds quickly to associative cues of the moment and a higher-order system that responds reflectively and planfully. Low serotonergic function appears to enhance influence of the lower-order system. This often yields impulsive reactivity. Why, then, does low serotonergic function also relate to depression, which is characterized by lethargy and unresponsiveness? The answer must be that ascendance of the lower system interacts with other factors. One hypothesis is that low serotonergic function plus high sensitivity to incentives yields vulnerability to impulsive approach, whereas low serotonergic function plus low incentive sensitivity yields vulnerability to depression. Conceptualizing serotonergic function this way helps integrate information pertaining to very different disorders into a coherent picture.

Social subordination and polymorphisms in the gene encoding the serotonin transporter enhance estradiol inhibition of luteinizing hormone secretion in female rhesus monkeys

Psychosocial factors, particularly social stress, may compromise reproduction. However, some individuals may be more susceptible to socially induced infertility. The present study used group-housed, adult, ovariectomized rhesus monkeys to test the hypothesis that exposure to psychosocial stress, imposed by social subordination, would enhance estradiol (E2)-negative feedback inhibition of LH. Because polymorphisms in the gene encoding the serotonin transporter (SLC6A4) may contribute to individual differences in response to adverse environments, we determined whether subordinate females with the short-promoter-length allele (s-variant) would show greater suppression of LH. Subordinate females, particularly those with the s-variant SLC6A4 genotype, received significantly higher rates of noncontact aggression from more dominant cage mates and had consistently lower body weights. Serum LH was not influenced by social status in the absence of E2. In contrast, subordinate females were hypersensitive to E2-negative feedback inhibition of LH. Furthermore, serum LH in subordinate females with s-variant SLC6A4 genotype was maximally suppressed by Day 4 of treatment, whereas nadir concentrations were not reached until later in treatment in other females. Finally, pharmacological elevation of serum cortisol potentiated E2-negative feedback inhibition in all females. The current data suggest that infertility induced by psychosocial stressors may be mediated by hypersensitivity to E2-negative feedback and that polymorphisms in the SLC6A4 gene may contribute to differences in reproductive compromise in response to chronic stress.

Mechanisms underlying aggressive and hostile behavior in amphetamine users

PURPOSE OF REVIEW

To review current evidence linking amphetamine use with aggression and to consider possible factors that might underlie this association.

RECENT FINDINGS

Although evidence that amphetamine use is related to increased levels of aggression continues to grow, the underlying processes or mechanisms remain somewhat elusive. In this review, three possible underlying factors are considered. Neurotoxic, pharmacological effects of amphetamine on the dopaminergic and serotonergic systems are related to aggressive, hostile behavior in both animal and human studies. Of particular interest is the converging evidence that amphetamine use is related to impairment in executive functions (including self-control) that are regulated by the prefrontal cortex. Taken together, these findings suggest that amphetamine users may have an impaired capacity to control or inhibit aggressive impulses. Furthermore, high levels of impulsivity related to amphetamine use may also play a role. Finally, amphetamine use is associated with increased positive symptoms of psychosis, particularly paranoia, that contribute to a perception of the environment as a hostile, threatening place.

SUMMARY

Taken separately, each of these factors may lead to an increase in aggression with increased use of amphetamine, but their interactive or synergistic effects may be particularly problematic.

Tendencies Toward Mania and Tendencies Toward Depression Have Distinct Motivational, Affective, and Cognitive Correlates

Debate has emerged in the literature on mania, with some evidence suggesting that tendencies toward mania relate to negative emotional and cognitive styles, and other evidence suggesting that tendencies toward mania relate to positive emotional and cognitive styles. An initial study examined how tendencies toward mania (as measured by the Hypomanic Personality Scale) and tendencies toward depression (as measured by the Inventory to Diagnose Depression-Lifetime version) were related to diverse measures pertaining to incentive and threat motivations, negative and positive emotionality, and cognitive responses to emotion, among 238 undergraduates. Tendencies toward mania related to a self-reported pattern of reacting intensely to positive stimuli, both cognitively and emotionally, as well as lower sensitivity to threatening stimuli and less restraint over impulses. In contrast, tendencies toward depression related to a pattern of reacting more strongly to negative stimuli emotionally and cognitively, as well as deficits in the ability to savor positive affect. This pattern was re-confirmed in a second sample of 394 undergraduates, who completed many of the same measures plus a measure of current mood symptoms. This second sample confirmed that the pattern was not mood-state dependent. Implications for future research and clinical work are discussed, including an intriguing conceptual parallel in the distinct sets of correlates of depressive versus manic tendencies.