Depression 35 (diurnal variation with symptoms generally worse in the morning, early morning awakening and diminished appetite), and motor features (marked psychomotor retardation or agitation). The dis- tinctions drawn in the DSM-IV and the majority of reports in the literature support the notion that melancholic depression is best viewed as a distinct subtype. Atypical features include mood reactiv- ity (capacity to be cheered up when presented with positive events), increased appetite or weight gain, hypersomnia, leaden paralysis (a feeling of heaviness in the limbs), and a long-standing pattern of extreme sensitivity to perceived interpersonal rejection. There is some evidence to suggest that these depressive subtypes may have different underlying causes and, more clearly, differential responses to treatment. Dysthymia is characterized by a chronically depressed mood that occurs for most of the day, more days than not, for at least 2 years. In children, the mood may be irritable rather than depressed and the required minimum duration is only 1 year. During periods of depressed mood, patients must have at least two of the following symptoms present: poor appetite or overeating, insomnia or hypersom- nia, low energy or fatigue, low self-esteem, poor concentration or difficulty making decisions, and feelings of hopelessness. The point prevalence of dythymic disorder is approx 3% and the lifetime prevalence approx 6%. Dysthymic disorder often has an early onset and a chronic course. DIFFERENTIAL DIAGNOSIS The differential diagnosis of depressive disorders includes other primary psychiatric disorders such as bipolar spectrum disorders (I, II, and III, etc., cyclothymic disorder) or adjustment disorder with depressed mood, cognitive disorders such as Alzheimer’s disease that may initially be characterized by social withdrawal and apathy, bereavement, and metabolic problems such as vitamin B 12 deficiency or hypothyroidism. COGNITIVE DEFICITS IN DEPRESSION MDD may be associated with cognitive deficits sometimes referred to as “pseudodementia” or the “dementia syndrome of depression” (6–8). Subjective complaints of altered cognition may include a decreased ability to concentrate and memory impairment and be accompanied by impaired perfor- mance on objective testing. Such bedside cognitive examination, or more formal neuropsychological testing, when combined with other clinical information, can help with the diagnosis. In most depressed Table 1 Symptom Overview for a Major Depressive Episode Other Atypical Domain DSM-IV symptoms symptoms Melancholic features features Emotional 1) Depressed mood Anxiety Mood not reactive Mood reactive 2) Interest/pleasure Irritability Mood distinct quality (“core” symptoms: at least one must be present) Vegetative 1) Weight loss/gain ↓ Libido Weight loss Weight gain 2) Insomnia/hypersomnia Early morning awakening Hypersomnia 3) Fatigue/loss of energy Diurnal variation (morning worse) Ideational 1) Worthlessness/guilt Hopelessness Guilt Rejection 2) Suicidal ideation Helplessness sensitivity Cognitive Concentration/indecisiveness (text) Motor Psychomotor retardation/agitation Retardation/agitation Leaden paralysis patients, objective cognitive performance is intact, or is limited solely by effort and motivation, as further evidenced by inconsistent effort or responses of exasperated, uncaring, or hopeless “I don’t know” statements rather than incorrect responses. However, a substantial proportion of depressed patients, particularly those of older age or with more severe depression (e.g., with melancholic fea- tures) demonstrate objective cognitive deficits beyond those caused by inadequate effort. Whereas a wide range of deficits have been described over the years, often with mixed or conflicting findings, overall the pattern of cognitive impairment in depression suggests a functional disconnection between subcortical structures and the frontal lobes. Particular emphasis has been placed on prefrontal and cin- gulate cortical regions. Depressed patients may have impairments in attention, mental processing speed, spontaneous verbal elaboration, memory retrieval, and executive functions including planning, sequencing, organizing, and abstracting. There is some evidence to suggest that white matter lesions may play a role in the vulnerability of some elderly patients to develop cognitive impairment during depressive episodes (9). As well, an asso- ciation between white matter lesions and executive dysfunction has been noted. In addition to cognitive deficits as part of depressive illness, depressive symptoms may co-exist with dementias owing to neurodegenerative diseases. The precise nature of this co-existence remains to be determined. Although there is some evidence to suggest that depression may cause or contribute to dementia, there is substantial evidence to support the notion that depression may be an early man- ifestation of dementing illnesses such as Alzheimer’s disease. Particularly in elderly persons and in those for whom detailed history is not available it may be difficult to determine whether cognitive deficits are due to depression alone or to a separate neurodegenerative disease process. Depressed patients often experience significant distress related to cognitive impairment and/or complain of cog- nitive impairment out of proportion to actual deficits. They may be more apt to have a history of pre- vious depressive episodes and their current symptoms may have a more abrupt or subacute onset. Whereas motivational deficits can be associated with both depression and dementia, appetite distur- bances and somatic complaints are more typical of depression. Depressed patients rarely experience the nocturnal worsening of cognitive functions (“sundowning”) often seen in neurodegenerative dementias. The presence of prominent sadness or ideational symptoms (e.g., hopelessness, worth- lessness, guilt, suicidality) suggests the likelihood of depression, but does not by itself distinguish whether the depression exists alone or co-morbid with a dementing disease. CO-MORBIDITY Depression is associated with substantial psychiatric co-morbidity including substance use disor- ders, personality disorders, primary anxiety disorders, eating disorders, as well as co-morbidity with medical and neurological illnesses (e.g., stroke, heart disease, Parkinson’s disease [10]). NEUROBIOLOGY Depression is generally viewed as idiopathic and multifactorial. There appears to be a complex inter- play of environmental stressors and individual diathesis toward symptomatic expression. Depression appears to be polygenic, although some family pedigrees may be traceable to a single locus. The con- cordance for depression in monzygotic twins is about 50%. MDD is 1.5–3 times more common among first-degree biological relatives of persons with this disorder than among the general population. In the past, the leading theories of depression pathophysiology were relatively simplistic and sug- gested that deficiencies in one or more neurotransmitter systems were responsible for the condition. The main neurotransmitters invoked in the pathophysiology of depression include serotonin, norepi- nephrine, and (to a lesser degree) dopamine, with extensive literature supporting the notion that altered function in these aminergic systems is associated with the depressed state (11). There is also ample lit- erature on the altered function of the hypothalmic–pituitary axis (e.g., abnormal dexamethasone sup- pression test, blunted thyroid-stimulating hormone response to thyrotropin-releasing hormone), the 36 Richard and Lyness immune system, neuropeptides, amino acids, and reproductive hormones. There is also a great deal of literature from “naturally occurring” lesions such as stroke, disease models, and neuroimaging studies devoted to brain localization. Newer functional imaging techniques, results of deep brain stim- ulation procedures, and sophisticated models of neural circuitry suggest that the prefrontal cortex, anterior cingulate cortex, and basal ganglia may have important roles in the pathogenesis of depression (12). More recently, researchers have proposed that genetic factors and life stress contribute not only to neurochemical alterations in depression, but also to impairments of cellular plasticity and resilience. Furthermore, it has become clear that depression is not localized to dysfunction of a single brain struc- ture or system, but rather that there are disturbances in underlying neural circuits involving multiple brain regions and systems. This has led to drug development research targeting neurotrophic path- ways, glucocorticoid signaling, phosphodiesterase activity, and glutamatergic activity. Perhaps sur- prisingly, the advances in molecular biology have only strengthened the notion that life experiences have a crucial impact on the development and course of depressive illnesses. Available data reinforce the concept of plasticity and suggests that experience contributes to the pathophysiology of depres- sion and may influence response to treatment (11,13,14). PSYCHOLOGICAL AND PSYCHOSOCIAL FACTORS It is important to recognize that considerable empirical evidence supports the role of a number of psychological and psychosocial factors in the pathogenesis of depression. As with neurobiological fac- tors, it remains unclear which are truly causal or part of the disease process, and which are merely manifestations—epiphenomena—of depression. However, as discussed here, psychosocial interven- tions have clearly demonstrated efficacy for depression, and are important sole or co-treatments for many patients with depression. Cognitive psychology perspectives focus on patterns of negativistic, distorted thinking (about the self, the future, and/or the environment) that confer risk for depression, and which become accentu- ated during acutely depressed states. Psychodynamic perspectives emphasize the roles of self-esteem regulation (as, e.g., in the narcissistic patient faced with rejections or other narcissistic injuries), failed defense and coping mechanisms, and the processing of losses. Indeed, early life stressors, particularly losses such as deaths of parents or other important figures, increase the risk for developing depres- sion later in childhood or in adulthood. Current stressful life events or circumstances also play impor- tant roles for many patients—particularly so-called “exit” events, which include not only interpersonal losses and separations but also symbolic or actual bodily losses such as those produced by many neu- rological diseases. Couples, families, and other social support/social network factors may protect against or contribute to the development of depression, depending on the quantity, frequency, and qual- itative nature of these relationships. Cultural factors often play important roles in the presentation of depression, and may strongly influence attitudes and behaviors determining help seeking or accep- tance of treatment options. COURSE AND PROGNOSIS Symptoms of major depression usually develop over days to weeks. The major depressive episode may be preceded by a prodromal period lasting for weeks to months that includes anxiety and mild depressive symptoms. Untreated, most major depressive episodes in the community are associated with spontaneous and complete remission in about 6 months, although the spontaneous remission rate in clinical populations is much lower. In naturalistically followed clinical populations, as many as 20% of depressed patients may have persistent major depressive syndrome for months or years (“chronic”), whereas an additional one-third or more may have some improvement followed by persistent “subsyndromal” symptoms (“partial remission”). Even after achieving full remission, the lifetime risk for at least one recurrent episode is more than 50%. Individuals who have had two Depression 37 episodes have a 70% chance of having a third, and individuals experiencing three or more have a 90% probability of suffering another recurrent depressive episode (15). Kraepelin first emphasized that the long-term nature of affective illness is characterized by episode recurrence and that there is a general tendency for the evolution and progression of symptoms (16). Research supporting the progressive nature of depressive disorders includes the following: depressive episodes increase in severity and treatment refractoriness over time, there is cycle acceleration (i.e., shorter well intervals between episodes) and whereas mood disorder episodes are often initially pre- cipitated by psychosocial stressors, after a sufficient number of episodes they begin to emerge autonomously. It is often presumed by clinicians (the authors included) that treatment to reduce the number, severity, or duration of recurrent episodes will reduce the likelihood of subsequent worsen- ing of depression course, although it must be admitted that direct empirical evidence to support this notion is modest. Similarly, clinical experience long has suggested that early intervention improves acute outcomes; it is paramount to teach patients about the risk of recurrence, need for early inter- vention, and thus the need to recognize early warning symptoms of a recurrence. Proposed neurobiological models for the progressive nature of depression have included kindling, sensitization, and alterations in downstream second-messenger systems involved in neurotransmis- sion and neurotrophism (13). It has been suggested that the actions of these second-messenger sys- tems may ultimately result in neuronal loss or alterations in neuronal sprouting and connectivity. In support of this notion are postmortem and neuroimaging studies demonstrating atrophy of various brain areas (hippocampus, frontal/cingulate cortex, basal ganglia). There is also evidence to suggest that mood stabilizers and antidepressants have effects on neuronal trophic factors. TREATMENT OVERVIEW There are several approaches to the treatment of depression and available modalities include psy- chotherapy, pharmacotherapy, electroconvulsive therapy (ECT) as well as several other less commonly used techniques (e.g., transient magnetic stimulation, light therapy). When considering the results of depression treatment studies, it is important to note that the placebo response rate in depression is fairly high (approx 30–40%). The presence of melancholia and/or psychosis may require pharmacological intervention (17). The treatment of depression can be divided into the acute phase (until patient is well), continua- tion phase (6 to 12 months after achieving remission) and maintenance (indefinite for those with two to three or more episodes or particularly destructive episodes). Treatments (AHCPR Guidelines—from Depression in Primary Care www.ahrq.gov clinical prac- tice guideline archive [18]) include the following: 1. Maintain high index of suspicion/evaluate risk factors 2. Detect depressive symptoms with clinical interview 3. Diagnose the mood disorder by history/interview (MSE) 4. Evaluate with complete medical history/physical examination 5. Identify and treat known causes of a mood disorder 6. Re-evaluate for mood disorder 7. Develop a treatment plan with the patient 8. Select an acute phase treatment 9. If medication is chosen, select type, drug, and dose 10. Evaluate treatment response 11. Proceed to continuation phase treatment 12. Evaluate the need for maintenance treatment 13. Seek consultation if needed Nonpsychiatrists should consider referring the patient to a psychiatrist when the depression is severe (suicidality, psychosis), occurring in the context of another psychiatric illness (bipolar, schizoaffec- 38 Richard and Lyness tive, personality disorder, anxiety disorder), complicated by medical co-morbidity that complicates the diagnosis or management, or when it appears to be refractory to treatment. PSYCHOTHERAPY There are several types of focused and time-limited psychotherapies used to treat depres- sion. Specific psychotherapies may have a 70–80% response. These include cognitive (correct cognitive distortions), interpersonal, (role transitions, grief, interpersonal conflicts, or deficits) and problem solving (identify, prioritize, solve). Psychotherapy may play an important role in the long-term treatment of recurrent depression and is particularly useful for those with obvious stres- sors, interpersonal difficulties, or low social support, or those who “can’t” or won’t take medications. Adjunctive psychosocial treatments may include couples or family therapy, socialization programs, psychiatric programs (day treatment, partial hospitals, inpatient), or change in residential setting or care level. ELECTROCONVULSIVE THERAPY ECT involves the use of electrical stimulation to induce a seizure in controlled and modified cir- cumstances (anesthesia, muscle relaxation). ECT is remarkably safe and effective (80–90%) and is especially useful for severe, psychotic, or treatment-refractory depression. PHARMACOTHERAPY The main antidepressant drug classes in common use include the selective serotonin reuptake inhibitors (SSRIs), serotonin and norepinephrine reuptake inhibitors (SNRIs), tricyclic antidepressants (TCAs), monoamine oxidase (MAO) inhibitors, and other atypical agents (e.g., bupropion). An overview of these agents is provided in Table 2. Several principles should be adhered to when using antidepressant medications. The patient should be seen every 1–2 weeks during the acute phase of treatment to re-educate, support, and monitor adher- ence, side effects, and treatment response. The maximum response may take 6 weeks or more but usu- ally one sees the beginnings of a response in 1–2 weeks. If there is no response at all in 2−3 weeks, one should reassess the diagnosis and patient compliance. At this point, one can consider switching drugs (within class vs change class), pharmacological augmentation (i.e., addition of medications that are not powerful antidepressants when used as monotherapy, such as lithium, triiodothyronine, psy- chostimulants such as methylphenidate), or combination pharmacotherapy (i.e., two antidepressants from different drug classes, such as an SSRI plus a TCA, or bupropion plus mirtazapine). When deciding which antidepressant to start, one should consider the side-effect profile, the his- tory of response or nonresponse to a particular drug or class of drugs in the patient or patient’s family, potential drug interactions, the presence of co-morbid psychiatric or medical conditions, and the age of the patient. Often with older patients, one must increase the dose slowly, although ultimate target doses may be similar to those in younger patients (“start low and go slow but go all the way”). Recent controversy about suicidality emerging with antidepressant treatment has received considerable atten- tion in the lay media, particularly regarding children. Although data are conflicting and not fully avail- able for review, at this time it is far from clear that antidepressant medications cause suicidal behavior in adults, and benefit-risk considerations favor treatment of diagnosable depression, although prudent clinical monitoring and patient-family education about suicidality are warranted. One needs to be aware of a potential withdrawal syndrome when discontinuing the SSRIs (and paroxetine in particular). Withdrawal symptoms include dizziness, nausea, headache, tingling, fatigue, and irritability. Most symptoms are mild and short-lived and require no therapy. If symptoms occur, they generally occur a few days after stopping the medication and get better within a week. The grad- ual tapering of the study medication makes these symptoms less likely to occur. Depression 39 REFERENCES 1. Charney DS, Reynolds CF 3rd, Lewis L, et al. Depression and bipolar support alliance. Depression and bipolar support alliance consensus statement on the unmet needs in diagnosis and treatment of mood disorders in late life. Arch Gen Psychiatry 2003;60:664–672. 2. Lebowitz BD, Pearson JL, Schneider LS, et al. Diagnosis and treatment of depression in late life. Consensus statement update. JAMA 1997;278:1186–1190. 3. Lyness JM, Bruce ML, Koenig HG, et al. Depression and medical illness in late life: report of a symposium. J Am Geriatr Soc 1996;44:198–203. 4. McDonald WM, Richard IH, DeLong MR. Prevalence, etiology, and treatment of depression in Parkinson’s disease. Biol Psychiatry 2003;54:363–375. 5. American Psychiatric Association (DSM-IV Task Force). Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition. Washington DC: Amer Psychiatric Pub; 1994. 6. Caine ED. The neuropsychology of depression: the pseudodementia syndrome. In: Grant I and Adams KM, eds. Neuropsychological Assessment of Neuropsychiatric Disorders. New York: Oxford University Press; 1986. 7. Post F. Dementia, depression, and pseudodementia. In: Benson DR, Blumer D, eds. Psychiatric Aspects of Neurologic Disease. New York: Grune & Stratton;1975. 8. Richard IH. Cognitive impairment in depression. In: Kurlan R, ed. Secondary Dementias. New York: Marcel Dekker; in press. 9. Kramer-Ginsberg E, Greenwald BS, Krishnan KRR, et al. Neuropsychological functioning and MRI signal hyperinten- sities in geriatric depression. Am J Psychiatry 1999;156:438–444. 10. Williamson GM, Shaffer DR, Parmelee PA. Physical Illness and Depression in Older Adults: A Handbook of Theory, Research, and Practice. New York: Kluwer Academic/Plenum; 2000. 11. Duman RS. The neurochemistry of mood disorders: preclinical studies. In: Charney DS, Nestler EJ, Bunney BS, eds. Neurobiology of Mental Illness. New York: Oxford University Press; 1999:333–347. 12. Sheline YI. Neuroimaging studies of mood disorder effects on the brain. Biol Psychiatry 2003;54:338–352. 40 Richard and Lyness Table 2 Overview of Antidepressant Medications Agent Mechanism Comments Citalopram SSRI Sexual dysfunction, few drug interactions Escitalopram SSRI Sexual dysfunction, few drug interactions Sertraline SSRI Sexual dysfunction, few drug interactions, ± stimulating Paroxetine SSRI Sexual dysfunction, anticholinergic effects Fluvoxamine SSRI Sexual dysfunction, marketed for OCD Fluoxetine SSRI Sexual dysfunction, stimulating, long half-life Venlafaxine SNRI SSRI at ↓ dosages, SNRI at ↑ dosages, Must be titrated, can ↑ blood pressure (clinically significant hypertension uncommon) Mirtazapine NE/5HT antagonist Weight gain, sedation (often decreases at higher dosages) Bupropion Atypical (NE/DA) Not anxiolytic, stimulating, no sexual dysfunction Nefazodone SSRI/5HT antagonist Sedation, no sexual dysfunction, titration/BID dosing, hepatic toxicity, recently removed from US market Trazodone SSRI/5HT antagonist Primarily used to treat insomnia Nortriptyline TCAs (SNRIs) Proven efficacy in severe, melancholic, psychotic Desipramine depression, EKGs in older patients; relatively (and others) contraindicated in CAD (pro-arrhythmogenicity, risk of sudden death) Phenelzine MAOIs Save for psychiatric specialists, potentially lethal drug and Tranylcypromine dietary interactions, require tyramine-free diet Isocarboxazid SSRI, selective serotonin reuptake inhibitor; SNRI, serotonin and norepinephrine reuptake inihibitor; NE, norepi- nephrine; DA, dopamine; BID, twice a day; TCA, tricyclic antidepressant; EKG, electrocardiograph; CAD, coronary artery disease; MAOI, monoamine oxidase inhibitor. 13. Post RM, Weiss SRB. Neurobiological models of recurrence in mood disorders. In: Charney DS, Nestler EJ, Bunney BS, eds. Neurobiology of Mental Illness. New York: Oxford University Press; 1999:365–384. 14. Vaidya VA, Duman RS. Depression-emerging insights from neurobiology. Br Med Bull 2001;57:61–79. 15. Maj M, Veltro F, Pirozzi R, Lobrace S, Magliano L. Pattern of occurrence of illness after recovery from an episode of major depression: a prospective study. Am J Psychiatry 1992;149:795–800. 16. Kraepelin E. Manic-depressive insanity and paranoia.Edinburgh: E & S Livingstone; 1921. 17. Stahl SM. Essential Psychopharmacology: Neuroscientific Basis and Practical Applications, Second Edition. Cambridge: Cambridge University Press; 2000. 18. AHCPR Guidelines. Depression in Primary Care. Available at www.ahrq.gov clinical practice guideline archive. Depression 41 43 5 Anxiety Disorders Julie Loebach Wetherell, Ariel J. Lang, and Murray B. Stein INTRODUCTION The psychiatric disorders that are designated as anxiety disorders include the specific diagnoses of panic disorder with and without agoraphobia, agoraphobia without history of panic disorder, spe- cific phobia, social phobia, obsessive-compulsive disorder (OCD), posttraumatic stress disorder (PTSD), acute stress disorder, generalized anxiety disorder (GAD), anxiety disorder due to a general medical condition, substance-induced anxiety disorder, and anxiety disorder not otherwise specified (NOS) (1,2). An additional diagnosis, separation anxiety disorder, is reserved for children. This chap- ter is organized to include general information about the epidemiology, phenomenology, biology, and development of anxiety in adults, followed by disorder-specific information about epidemiology, signs and symptoms, diagnosis and differential diagnosis, familial and genetic influences, course and prognosis, and pharmacological and behavioral treatment. The chapter concludes with a discussion of the possible effects of anxiety on patients seen by neurologists. EPIDEMIOLOGY OF ANXIETY Anxiety disorders overall are the most common type of psychiatric disorder in adults, with a 12-month prevalence of 13.1 to 18.7% and a lifetime prevalence of more than 25% (3,4). Mood dis- orders, by contrast, have a 12-month prevalence of 7.1 to 11.1% (3). Prevalence rates for anxiety disorders peak in young adulthood (age 25 to 34) and decrease thereafter; they are 1.5 to 2 times higher in women than in men (4). Anxiety disorders are highly chronic and are often co-morbid with mood disorders, other anxiety disorders, and substance use disorders (3). PHENOMENOLOGY OF ANXIETY In general, anxiety and its disorders are characterized by subjective feelings of apprehension or fear and by somatic sensations characteristic of autonomic arousal such as increased heart and respi- ration rate, shortness of breath, dizziness, perspiration, flushing or pallor, dry mouth, pupillary dilata- tion, chest tightness, gastrointestinal distress, and incontinence (3). Other physical symptoms of anxiety may include muscle tension, restlessness, hypervigilance or exaggerated startle response, sleep disturbance, and fatigue. These physiological changes, mediated by the autonomic nervous system, all serve in some way to prepare the organism to respond to threat or danger or result from such prepa- ration. For example, perspiration cools the body during flight or defensive fighting; it also makes the skin more slippery to facilitate escape from a predator. A distinction is often made between state anx- iety—transient levels of apprehension, fear, and physiological reactions to perceived threat—and trait From: Current Clinical Neurology: Psychiatry for Neurologists Edited by: D.V. Jeste and J.H. Friedman © Humana Press Inc., Totowa, NJ anxiety—anxiety proneness—which is related to the personality trait neuroticism (5). Trait anxiety may represent a vulnerability factor for the development of anxiety disorders. Anxiety-related cognitions often involve an exaggerated sense of risk or danger and diminished sense of ability to cope (6). Anxiety sensitivity describes individual differences in fear of the physi- cal, psychological, and social manifestations of anxiety and may represent another risk factor for the development of anxiety disorders, particularly panic disorder with or without agoraphobia and PTSD (7). Anxiety is often associated with threatening interpretations of ambiguous or even neutral situa- tions. The evidence for an anxiety-related explicit memory bias for threatening events is mixed, with evidence for explicit memory bias in panic disorder, PTSD, and OCD, but not in social phobia or GAD (8). Evidence is strong for the existence of implicit memory bias across disorders. Evidence is also strong for an attentional bias for threat cues, which operates at a preconscious level and appears to be a cause rather than a consequence of anxiety (9). This bias may lead to distractibility and often results in poorer task performance at high levels of anxiety. In general, the relationship between anxiety and performance follows an inverse U-shaped curve, with highest levels of performance achieved at an intermediate level of anxiety. Behavioral concomitants of anxiety typically involve escape or avoidance, which can include actu- ally leaving or avoiding a feared object or situation, immobilization, procrastination, distraction, or self-medication with drugs or alcohol. Worry, a verbal process consisting of a chain of thoughts about actual or possible current or future dangers, may also serve as an avoidance mechanism by reducing aversive autonomic sensations associated with anxiety-provoking imagery (10). Rituals, safety objects, or safety behaviors such as checking or seeking reassurance may be used as protection from harm. BIOLOGY OF ANXIETY Both the central and peripheral nervous systems are involved in anxiety. The brain structure most often implicated in anxiety and its disorders is the amygdala, which is believed to be the site of fear recognition, memory acquisition, and response. The amygdala receives input from the thalamus and the cortex and projects to the periaqueductal gray, lateral hypothalamus, periventricular hypothala- mus, and the reticulopontis caudalis, which control the freezing, blood pressure, stress hormone, and startle reflex responses, respectively (11). Other important central nervous system (CNS) structures include the locus coeruleus, which regulates arousal and attention; the hippocampus, which encodes contextual information involved in emotional memories; and the prefrontal cortex, which can inhibit or modify responses to anxiety-provoking stimuli (12). Gray has proposed another model of the anatomical correlates of anxiety. In this model, a behav- ioral inhibition system (BIS) (13) consisting of the septal area, hippocampus, and the Papez circuit, includes cortical and cholinergic inputs to the septo-hippocampal system, dopaminergic inputs to the prefrontal cortex, and noradrenergic input to the hypothalamus and the locus coeruleus. The BIS sup- presses behavior and redirects attention to relevant stimuli after receiving signals of novelty, nonre- ward, or punishment. Anxiety is believed to be caused by a BIS that is overly reactive to novelty or punishment. In contrast, the behavioral approach system involving the medial forebrain bundle responds to signals of nonpunishment and rewards by facilitating approach. A third system, the fight- flight system, organized by the central periaqueductal gray, the medial hypothalamus, and the amyg- dala, responds to punishment, pain, and the omission of expected reward by facilitating defensive aggression or escape. The BIS model is broadly consistent with Peter Lang’s bioinformational theory of emotion, which holds that emotions, including anxiety, consist of stimulus (context), response (action tendencies), and meaning structures stored in memory (14). Action tendencies include an appetitive system (similar to the behavioral approach system) and a defensive system (similar to the BIS and the fight-flight system). Evidence from the laboratory of Richard Davidson suggests that some aspects of these sys- tems may be localized in the left and right anterior frontal cortex, respectively (15). 44 Wetherell et al. Anxiety Disorders 45 Neurotransmitters involved in anxiety include the γ-aminobutyric acid (GABA), noradrenergic, serotonergic and dopaminergic systems, glutamate, and the corticotropin-releasing hormone pathway (12). GABA, the principal inhibitory neurotransmitter, acts by opening neuronal chloride channels, leading to hyperpolarization that decreases the responsiveness of the nerve cell. The noradrenergic system is closely related to the activity of the locus coeruleus, which increases arousal and enhances the signal-to-noise ratio for detecting relevant environmental events. Depletion of serotonin is believed to increase response to punishment, impulsivity, and anxiety. Based on preclinical studies (including brain lesioning, genetic knockout techniques, and pharmacological probes), different serotonin recep- tors are believed to have different roles in the development and maintenance of anxiety: based on brain lesioning, genetic knockout, and pharmacological probe studies, activation of the 5HT 1a receptor presynaptically reduces anxiety-related behaviors, whereas activation of the postsynaptic 5HT 1a recep- tor and the 5HT 1b , 5HT 1c , 5HT 2a , 5HT 2c and 5HT 3 receptors increases anxiety-related behaviors. Serotonin also affects anxiety indirectly by altering noradrenergic and dopaminergic release, by sta- bilizing arousal through its effect on the locus coeruleus, and by attenuating prefrontal cortical activ- ity. Although stress causes the release of dopamine in the prefrontal cortex, this release is not necessarily associated with anxiety. Rather, the dopaminergic system may serve to increase motiva- tion and acquire coping responses. Glutamate, an excitatory neurotransmitter, is important for the acquisition of memories and the acquisition and extinction of conditioned emotional responses. One of the more exciting new developments in the treatment of anxiety disorders involves the use of N-methyl- D-aspartate (NMDA), a glutamate agonist that has been shown to facilitate extinction of fear- related behaviors, as an adjunct to exposure therapy (16). Finally, corticotropin-releasing hormone stimulates the release of adrenocorticotropic hormone and activates the hypothalamic–pituitary– adrenal axis, which produces many of the physiological sensations associated with anxiety. Endocrine changes reported to be associated with anxiety include increased release of epinephrine and norepinephrine, cortisol, growth hormone, and prolactin, as well as decreased testosterone in men (12), although none of these has been consistently replicated across studies. Chronic anxiety is asso- ciated with diminished autonomic variability, probably caused by lower levels of parasympathetic ner- vous system activity, which leads to attenuated but longer lasting responses. This diminished autonomic variability appears to represent a vulnerability factor for chronic anxiety and perhaps for cardiovas- cular disease as well. Although anxiety is characterized by physiological responses, these changes are often nonspecific or subtle enough to preclude reliable psychophysiological assessment of anxiety. Thus, there are at present no “laboratory tests” to aid in the diagnosis of anxiety disorders. DEVELOPMENT OF ANXIETY Estimated heritability of anxiety disorders is 30 to 40%, lower than for schizophrenia or bipolar disorder (17). Genes that have been associated with specific anxiety disorders are discussed below. Research by Jerome Kagan and colleagues has led to the identification of a temperament, “behavioral inhibition” (BI), that is found in 10 to 15% of infants and children and appears to be related to the subsequent onset of anxiety disorders, particularly social phobia (18). Infants and children with BI react to novel situations with behavioral restraint and physiological differences such as high and stable heart rate, increased salivary cortisol and urinary catecholamines, pupillary dilation, and laryngeal muscle tension. These findings have led to the hypothesis that BI, which is likely genetically medi- ated, is related to a low threshold for arousal in the amygdala and hypothalamus. PANIC DISORDER Epidemiology Almost 13% of the adult population experiences panic attacks (19). Twelve-month and lifetime prevalence rates of panic disorder in the National Comorbidity Survey (NCS), an epidemiological study [...]... Treatments That Work, Second Edition New York: Oxford University Press; 20 02: 301–336 30 Barlow DH, Gorman JM, Shear MK, Woods SW Cognitive-behavioral therapy, imipramine, or their combination for panic disorder: a randomized controlled trial JAMA 20 00 ;28 3 :25 29 25 36 31 Doyle A, Pollack MH Long-term management of panic disorder J Clin Psychiatry 20 04;65 :24 28 32 Skre I, Onstad S, Torgersen S, Philos DR, Lygren... adenosine 2A receptor and panic disorder Neuropsychopharmacology 20 04 ;29 :558–565 25 Rothe C, Gutknecht L, Freitag C, et al Association of a functional -1 019C>G 5-HT1A receptor gene polymorphism with panic disorder with agoraphobia Int J Neuropsychopharmacol 20 04;7:1–4 26 Woo JM, Yoon KS, Yu BH Catechol O-methyl-transferase genetic polymorphism in panic disorder Am J Psychiatry 20 02; 159:1785–1787 27 Yonkers... advances in diagnostic technology—of neurologists Two more recent reports from Queen Square showed rates of re-diagnosis as organic disease of 15% and 5% at follow-up (20 ,21 ) A Dutch study found a rate of false-positive diagnosis of Conversion Disorder of 12% (22 ), and a Scottish study found only one re-diagnosis in 48 patients at long-term follow-up (23 ) Accounting for the differences among these studies... susceptibility to panic disorder–anxiety sensitivity (22 ) Specific genes that, in preliminary studies, appear to be associated with panic disorder, particularly panic disorder with agoraphobia, include the catecholamine-O-methyltransferase gene on chromosome 22 q11 .2, the adenosine 2A receptor, and the 5-HT1A receptor gene polymorphism on chromosome 5q 12. 3 (23 26 ) Course and Prognosis Onset of panic disorder... DISORDER Epidemiology Twelve-month and lifetime prevalence rates of GAD are estimated at 3.1 and 5.1%, respectively (4) Rates for men are 2 ( 1 2- month) and 3.6% (lifetime), whereas rates for women are 4.3 ( 1 2- month) and 6.6% (lifetime) The best estimate for 1 2- month prevalence of GAD is 3.4% (3) GAD is often co-morbid with mood disorders, other anxiety disorders, substance-related disorders, and general... disorder J Clin Psychopharmacol 20 03 ;23 :24 0 24 9 67 Pande AC, Crockatt JG, Feltner DE, et al Pregabalin in generalized anxiety disorder: a placebo-controlled trial Am J Psychiatry 20 03;160:533–540 68 Rosenthal M Tiagabine for the treatment of generalized anxiety disorder: a randomized, open-label, clinical trial with paroxetine as a positive control J Clin Psychiatry 20 03;64: 124 5– 124 9 69 Welden S, Yesavage... Psychol Med 20 03;33:879–885 22 Stein MB, Jang KL, Livesley WJ Heritability of anxiety sensitivity: a twin study Am J Psychiatry 1999;156 :24 6 25 1 23 Domschke K, Freitag CM, Kuhlenbäumer G, et al Association of the functional V158M catechol-O-methyl-transferase polymorphism with panic disorder in women Int J Neuropsychopharm 20 04;7:1–6 24 Hamilton SP, Slager SL, De Leon AB, et al Evidence for the genetic... recommendations for the longterm treatment of social phobia CNS Spectr, 20 03;8(Suppl 1):40– 52 38 Huppert JD, Roth DA, Foa EB Cognitive-behavioral treatment of social phobia: new advances Curr Psychiatry Rep 20 03;5 :28 9 29 6 39 Snider LA, Swedo SE Pediatric obsessive-compulsive disorder JAMA 20 00 ;28 4:3104–3106 40 Nestadt G, Lan T, Samuels J, et al Complex segregation analysis provides compelling evidence for a... of the brain-derived neurotrophic factor (BDNF) gene are strongly associated with obsessive-compulsive disorder Am J Hum Genet 20 03;73:370–376 43 Meira-Lima I, Shavitt RG, Miguita K, et al Association analysis of the catechol-o-methyltransferase (COMT), serotonin transporter (5-HTT) and serotonin 2A receptor (5HT2A) gene polymorphisms with obsessive-compulsive disorder Genes Brain Behav 20 04;3:75–79... stress disorder: a double-blind, placebo-controlled study Am J Psychiatry 20 04;161:515– 524 56 Sherman JL Effects of psychotherapeutic treatments for PTSD: a meta-analysis of controlled clinical trials J Trauma Stress 1998;1:413–435 57 Van Etten ML, Taylor S Comparative efficacy of treatments for post-traumatic stress disorder: a metaanalysis Clin Psychol Psychother 1998;5: 126 –144 58 Bryant RA Acute . 11.3%, respectively (4). Rates for men are 4.4 ( 1 2- month) and 6.7% (lifetime), whereas rates for women are 13 .2 ( 1 2- month) and 15.7% (lifetime). The best estimate for 1 2- month prevalence based on. catecholamine-O-methyltransferase gene on chromosome 22 q11 .2, the adenosine 2A receptor, and the 5-HT1A receptor gene polymorphism on chromosome 5q 12. 3 (23 26 ). Course and Prognosis Onset of panic disorder. DISORDER Epidemiology Twelve-month and lifetime prevalence rates of GAD are estimated at 3.1 and 5.1%, respectively (4). Rates for men are 2 ( 1 2- month) and 3.6% (lifetime), whereas rates for women are 4.3 ( 1 2- month) and