A systematic review of the neural bases of psychotherapy for anxiety and related disorders

Brain imaging studies over two decades have delineated the neural circuitry of anxiety and related disorders, particularly regions involved in fear processing and in obsessive-compulsive symptoms. The neural circuitry of fear processing involves the amygdala, anterior cingulate, and insular cortex, while cortico-striatal-thalamic circuitry plays a key role in obsessive-compulsive disorder. More recently, neuroimaging studies have examined how psychotherapy for anxiety and related disorders impacts on these neural circuits. Here we conduct a systematic review of the findings of such work, which yielded 19 functional magnetic resonance imaging studies examining the neural bases of cognitive-behavioral therapy (CBT) in 509 patients with anxiety and related disorders. We conclude that, although each of these related disorders is mediated by somewhat different neural circuitry, CBT may act in a similar way to increase prefrontal control of subcortical structures. These findings are consistent with an emphasis in cognitive-affective neuroscience on the potential therapeutic value of enhancing emotional regulation in various psychiatric conditions.     

Functional neuroimaging studies of the effects of psychotherapy

It has been long established that psychological interventions can markedly alter patients'' thinking patterns, beliefs, attitudes, emotional states, and behaviors. Little was known about the neural mechanisms mediating such alterations before the advent of functional neuroimaging techniques. Since the turn of the new millenium, several functional neuroimaging studies have been conducted to tackle this important issue. Some of these studies have explored the neural impact of various forms of psychotherapy in individuals with major depressive disorder. Other neuroimaging studies have investigated the effects of psychological interventions for anxiety disorders. I review these studies in the present article, and discuss the putative neural mechanisms of change in psychotherapy. The findings of these studies suggest that mental and behavioral changes occurring during psychotherapeutic interventions can lead to a normalization of functional brain activity at a global level.     

Cognitive behavioral therapy in anxiety disorders: current state of the evidence

A plethora of studies have examined the efficacy and effectiveness of cognitive-behavioral therapy (CBT) for adult anxiety disorders. In recent years, several meta-analyses have been conducted to quantitatively review the evidence of CBT for anxiety disorders, each using different inclusion criteria for studies, such as use of control conditions or type of study environment. This review aims to summarize and to discuss the current state of the evidence regarding CBT treatment for panic disorder, generalized anxiety disorder, social anxiety disorder, obsessive-compulsive disorder, and post-traumatic stress disorder. Overall, CBT demonstrates both efficacy in randomized controlled trials and effectiveness in naturalistic settings in the treatment of adult anxiety disorders. However, due to methodological issues, the magnitude of effect is currently difficult to estimate. In conclusion, CBT appears to be both efficacious and effective in the treatment of anxiety disorders, but more high-quality studies are needed to better estimate the magnitude of the effect.     

Sleep and anxiety disorders

Sleep disturbances-particularly insomnia - are highly prevalent in anxiety disorders and complaints such as insomnia or nightmares have even been incorporated in some anxiety disorder definitions, such as generalized anxiety disorder and posttraumatic stress disorder. In the first part of this review, the relationship between sleep and anxiety is discussed in terms of adaptive response to stress. Recent studies suggested that the corticotropin-releasing hormone system and the locus ceruleus-autonomic nervous system may play major roles in the arousal response to stress. It has been suggested that these systems may be particularly vulnerable to prolonged or repeated stress, further leading to a dysfunctional arousal state and pathological anxiety states, Polysomnographic studies documented limited alteration of sleep in anxiety disorders. There is some indication for alteration in sleep maintenance in generalized anxiety disorder and for both sleep initiation and maintenance in panic disorder; no clear picture emerges for obsessive-compulsive disorder or posttraumatic stress disorder. Finally, an unequivocal sleep architecture profile that could specifically relate to a particular anxiety disorder could not be evidenced; in contrast, conflicting results are often found for the same disorder. Discrepancies between studies could have been related to illness severity, diagnostic comorbidity, and duration of illness. A brief treatment approach for each anxiety disorder is also suggested with a special focus on sleep.     

Cognitive-behavioral therapy for anxiety disorders: an update on the empirical evidence

A large amount of research has accumulated on the efficacy and effectiveness of cognitive-behavioral therapy (CBT) for anxiety disorders including posttraumatic stress disorder, obsessive-compulsive disorder, panic disorder, generalized anxiety disorder, social anxiety disorder, and specific phobia. The purpose of the current article is to provide an overview of two of the most commonly used CBT methods used to treat anxiety disorders (exposure and cognitive therapy) and to summarize and discuss the current empirical research regarding the usefulness of these techniques for each anxiety disorder. Additionally, we discuss the difficulties that arise when comparing active CBT treatments, and we suggest directions for future research. Overall, CBT appears to be both efficacious and effective in the treatment of anxiety disorders, but dismantling studies are needed to determine which specific treatment components lead to beneficial outcomes and which patients are most likely to benefit from these treatment components.     

Cognitive behavioral group therapy for anxiety: recent developments

Anxiety disorders occur frequently, and can have a negative impact on the quality of people''s lives. They often begin at an early age and can have some serious consequences. This article is an overview of the recent studies concerning group cognitive-behavioral interventions for anxiety disorders. In the last few years, anxiety disorder prevention for children and adolescents has become an important focus of research work. Group prevention programs are based on standard cognitive behavioral therapy (CBT) strategies and are aimed at preventing anxiety disorders as early as possible. Numerous cognitive behavioral group therapies for children as well as adults have been well studied. There are many CBT protocols that have been developed for treating specific anxiety disorders. Now, specialized CBT programs are available for individuals who suffer from different anxiety disorders, enabling them to be treated together in groups.     

NMDA receptors and fear extinction: implications for cognitive behavioral therapy

Based primarily on studies that employ Pavlovian fear conditioning, extinction of conditioned fear has been found to be mediated by N-methyi-D-aspartate (NMDA) receptors in the amygdala and medial prefrontal cortex. This led to the discovery that an NMDA partial agonist, D-cycloserine, could facilitate fear extinction when given systemically or locally into the amygdala. Because many forms of cognitive behavioral therapy depend on fear extinction, this led to the successful use of D-cycloserine as an adjunct to psychotherapy in patients with so-called simple phobias (fear of heights), social phobia, obsessive-compulsive behavior, and panic disorder. Data in support of these conclusions are reviewed, along with some of the possible limitations of D-cycloserine as an adjunct to psychotherapy.     

Current research in child and adolescent bipolar disorder

Although recently more research has considered children with bipolar disorder than in the past, much controversy still surrounds the validity of the diagnosis. Furthermore, questions remain as to whether or not childhood expressions of bipolarity are continuous with adult manifestations of the illness. In order to advance current knowledge of bipolar disorders in children, researchers have begun to conduct phenomenological, longitudinal, treatment, and neuroimaging studies in youths who exhibit symptoms of bipolar illness, as well as offspring of parents with bipolar disorders. Regardless of the differences between research groups regarding how bipolar disorder in children is defined, it is agreed that pediatric bipolarity is a serious and pernicious illness. With early intervention during the period of time in which youths are exhibiting subsyndromal symptoms of pediatric bipolarity, it appears that the progression of the illness to the more malignant manifestation of the disorder may be avoided. This paper will review what is currently known and what still is left to learn about clinically salient topics that pertain to bipolar disorder in children and adolescents.     

Biological predictors of pharmacological therapy in anxiety disorders

At least one third of patients with anxiety disorders do not adequately respond to available pharmacological treatment. The reason that some patients with anxiety disorders respond well, but others not, to the same classes of medication is not yet fully understood. It is suggested that several biological factors may influence treatment mechanisms in anxiety and therefore could be identified as possible biomarkers predicting treatment response. In this review, we look at current evidence exploring different types of treatment predictors, including neuroimaging, genetic factors, and blood-related measures, which could open up novel perspectives in clinical management of patients with anxiety disorders.     

Cognitive neuroscience and brain imaging in bipolar disorder

Bipolar disorder is characterized by a combination of state-related changes in psychological function that are restricted to illness episodes, coupled with trait-related changes that persist through periods of remission, irrespective of symptom status. This article reviews studies that have investigated the brain systems involved in these state- and trait-related changes, using two techniques: (i) indirect measures of neurocognitive function, and (ii) direct neuroimaging measures of brain function during performance of a cognitive task. Studies of neurocognitive function in bipolar disorder indicate deficits in three core domains: attention, executive function, and emotional processing. Functional imaging studies implicate pathophysiology in distributed neural circuitry that includes the prefrontal and anterior cingulate cortices, as well as subcortical limbic structures including the amygdala and the ventral striatum. Whilst there have been clear advances in our understanding of brain changes in bipolar disorder, there are limited data in bipolar depression, and there is limited understanding of the influence of clinical variables including medication status, illness severity, and specific symptom dimensions.     

Nonpharmacological treatments for anxiety disorders

An evidence-based review of nonpharmacological treatments for anxiety disorders is presented. The vast majority of the controlled research is devoted to cognitive behavior therapy (CBT) and shows its efficiency and effectiveness in all the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) anxiety disorders in meta-analyses. Relaxation, psychoanalytic therapies, Rogerian nondirective therapy, hypnotherapy and supportive therapy were examined in a few controlled studies, which preclude any definite conclusion about their effectiveness in specific phobias, agoraphobia, panic disorder, obsessive-compulsive disorder (OCD), and posttraumatic stress disorder (PTSD), CBT was clearly better than psychoanalytic therapy in generalized anxiety disorder (GAD) and performance anxiety Psychological debriefing for PTSD appeared detrimental to the patients in one high-quality meta-analysis. Uncontrolled studies of psychosurgery techniques for intractable OCD demonstrated a limited success and detrimental side effects. The same was true for sympathectomy in ereutophobia. Transcranial neurostimulation for OCD is under preliminary study. The theoretical and practical problems of CBT dissemination are discussed.     

A lifespan view of anxiety disorders

Neurodevelopmental changes over the lifespan, from childhood through adulthood into old age, have important implications for the onset, presentation, course, and treatment of anxiety disorders. This article presents data on anxiety disorders as they appear in older adults, as compared with earlier in life. In this article, we focus on aging-related changes in the epidemiology, presentation, and treatment of anxiety disorders. Also, this article describes some of the gaps and limitations in our understanding and suggests research directions that may elucidate the mechanisms of anxiety disorder development later in life. Finally we describe optimal management of anxiety disorders across the lifespan, in "eight simple steps" for practitioners.     

Anxiety disorder

We reviewed recent advances in biological studies of anxiety disorders. The most important achievement was the discovery of the neural circuits of fear in the 1990s by using an animal model in which conditioned fear was induced. In the 2000s, this discovery led to further elucidation of neurotransmitters involved in fear and the precise neuronal mechanism of fear conditioning, thereby improving the understanding of neuroimaging findings of patients with anxiety disorders. The amygdala is a central region that is associated with the generation of fear, and its inactivation diminishes fear. In humans, amygdala activation has been consistently reported in anxiety disorders, indicating that hyperactivation of the amygdala is involved in the pathogenesis of anxiety disorders. Serotonin plays a key role in the treatment of anxiety disorders, and selective serotonin reuptake inhibitors (SSRIs) are currently regarded the first-line drugs used as anxiolytics. From animal studies, the mechanism underlying the anxiolytic effect of SSRIs is hypothesized as follows: SSRIs inhibit the neuronal activities of the amygdala, and this inhibition decreases the level of fear and anxiety. Animal studies of fear conditioning have proposed new treatment strategies for anxiety disorders: D-cycloserine, propranolol, and reactivation-extinction procedure. Among them, D-cycloserine, which is used as an adjunct to psychotherapy to facilitate extinction of fear, has been investigated in several randomized controlled trials, and its efficacies for several anxiety disorders have been established.     

The epidemiology of anxiety disorders: a review

Epidemiological studies show that anxiety disorders are highly prevalent and an important cause of functional impairment; they constitute the most frequent menial disorders in the community. Phobias are the most common with the highest rates for simple phobia and agoraphobia. Panic disorder (PD) and obsessive-compulsive disorder (OCD) are less frequent (2% lifetime prevalence), and there are discordant results for social phobia (SP) (2%-16%) and generalized anxiety disorder (GAD) (3%-30%). These studies underline the importance of an accurate definition of disorders using unambiguous diagnostic and assessment criteria. The boundaries between anxiety disorders are often ill defined and cases may vary widely according to the definition applied. Simple phobia, agoraphobia, and GAD are more common in vmrnen, while there is no gender différence for SP, PD, and OCD, Anxiety disorders are more common in separated, divorced, and widowed subjects; their prevalence is highest in subjects aged 25 to 44 years and lowest in subjects aged >65 years. The age of onset of the different types of anxiety disorders varies widely: phobic disorders begin early in life, whereas PD occurs in young adulthood. Clinical - rather than epidemiological - studies have examined risk factors such as life events, childhood experiences, and familial factors. Anxiety disorders have a chronic and persistent course, and are frequently comorbid with other anxiety disorders, depressive disorders, and substance abuse. Anxiety disorders most frequently precede depressive disorders or substance abuse, Comorbid diagnoses may influence risk factors like functional impairment and quality of life. It remains unclear whether certain anxiety disorders (eg, PD) are risk factors for suicide. The comorbidity of anxiety disorders has important implications for assessment and treatment and the risk factors should be explored. The etiology, natural history, and outcome of these disorders need to be further addressed in epidemiological studies.     

Epidemiology of anxiety disorders in the 21st century

Anxiety disorders, including panic disorder with or without agoraphobia, generalized anxiety disorder, social anxiety disorder, specific phobias, and separation anxiety disorder, are the most prevalent mental disorders and are associated with immense health care costs and a high burden of disease. According to large population-based surveys, up to 33.7% of the population are affected by an anxiety disorder during their lifetime. Substantial underrecognition and undertreatment of these disorders have been demonstrated. There is no evidence that the prevalence rates of anxiety disorders have changed in the past years. In cross-cultural comparisons, prevalence rates are highly variable. It is more likely that this heterogeneity is due to differences in methodology than to cultural influences. Anxiety disorders follow a chronic course; however, there is a natural decrease in prevalence rates with older age. Anxiety disorders are highly comorbid with other anxiety disorders and other mental disorders.     

Pharmacotherapy of anxiety disorders: a critical review

Given the enormous contribution of anxiety disorders to the burden of disease, it is key to optimize their prevention and treatment. In this critical review we assess advances in the pharmacotherapy of anxiety disorders, as well as remaining challenges, in recent decades, the field has seen rigorous clinical trial methods to quantify the efficacy and safety of serendipitously discovered agents, more focused development of medications with selective mechanisms of action, and the gradual translation of insights from laboratory research into proof-of-principle clinical trials. On the positive side, a considerable database of studies shows efficacy and relative tolerability of the selective serotonin reuptake inhibitors in the major anxiety disorders, and secondary analyses of such datasets have informed questions such as optimal definition of response and remission, optimal dose and duration, and comparative efficacy of different agents. Significant challenges in the field include barriers to appropriate diagnosis and treatment of anxiety disorders, failure of a significant proportion of patients to respond to first-line pharmacotherapy agents, and a limited database of efficacy or effectiveness studies to guide treatment in such cases.     

Animal models for screening anxiolytic-like drugs: a perspective

Contemporary biological psychiatry uses experimental animal models to increase our understanding of affective disorder pathogenesis. Modern anxiolytic drug discovery mainly targets specific pathways and molecular determinants within a single phenotypic domain. However, greater understanding of the mechanisms of action is possible through animal models. Primarily developed with rats, animal models in anxiety have been adapted with mixed success for mice, easy-to-use mammals with better genetic possibilities than rats. In this review, we focus on the three most common animal models of anxiety in mice used in the screening of anxiolytics. Both conditioned and unconditioned models are described, in order to represent all types of animal models of anxiety. Behavioral studies require careful attention to variable parameters linked to environment, handling, or paradigms; this is also discussed. Finally, we focus on the consequences of re-exposure to the apparatus. Test-retest procedures can provide new answers, but should be intensively studied in order to revalidate the entire paradigm as an animal model of anxiety.     

Neural systems underlying approach and avoidance in anxiety disorders

Approach-avoidance conflict is an important psychological concept that has been used extensively to better understand cognition and emotion. This review focuses on neural systems involved in approach, avoidance, and conflict decision making, and how these systems overlap with implicated neural substrates of anxiety disorders. In particular, the role of amygdala, insula, ventral striatal, and prefrontal regions are discussed with respect to approach and avoidance behaviors. Three specific hypotheses underlying the dysfunction in anxiety disorders are proposed, including: (i) over-representation of avoidance valuation related to limbic overactivation; (ii) under- or over-representation of approach valuation related to attenuated or exaggerated striatal activation respectively; and (iii) insufficient integration and arbitration of approach and avoidance valuations related to attenuated orbitofrontal cortex activation. These dysfunctions can be examined experimentally using versions of existing decision-making paradigms, but may also require new translational and innovative approaches to probe approach-avoidance conflict and related neural systems in anxiety disorders.     

Anxiety and DSM-5

The DSM-5 process, and the publication of DSM-5 in 2013, have had a considerable impact on the classification of anxiety disorders. Major changes included the reorganization of the chapter structure, individual groupings of disorders within each chapter from a life span viewpoint, and the use of specifiers. The DSM-5 chapter on anxiety disorders does not include obsessive-compulsive disorder or post-traumatic stress disorder. The chapter itself now reflects a developmental approach. The text of each disorder has been enhanced with short sections on development and course, risk and prognostic factors, etc. It is expected that the reformulation of anxiety disorders in DSM-5 will lead to greater precision in a variety of ways, as illustrated in the papers in this issue of Dialogues in Clinical Neuroscience. In summary, these changes in the way we classify anxiety disorders reflect our best view on the clinical empirical data and should prove useful in the assessment of specific anxiety disorders.