Glutamatergic systems and anxiety

Abstract

Anxiety is a normal emotion experienced by humans and other mammalian species. However, anxiety also exists in pathological forms, and anxiety disorders are the most prevalent of psychiatric disorders. Prevalence rates vary with the diagnostic tools used to estimate them, and with study design, but the most extensive studies suggest that within the United States, 15.7 million people are affected yearly and 30 million at some point in their lives (1). In a US study, 6% of men and 13% of women had suffered from an anxiety disorder in the previous 6 mo (2). According to current classi-cation in the Diagnostic and Statistical Manual (DSM-IV) (3) major anxiety disorders include phobias, obsessive-compulsive disorder (OCD), posttraumatic stress disorder (PTSD), and generalized anxiety. Although the speci-c symptomatology and etiology of these disorders varies, as does the recommended psychotherapeutic and pharmacological treatment, all of these disorders are characterized by at least three core clusters of symptoms: autonomic arousal, avoidance, and cognitive disturbance. Arousal of the autonomic nervous system involves sympathetic activation with associated tachycardia, sweating, shortness of breath, dry mouth, and other concomitants of preparation for a "-ght-or-ight" response to a real or perceived threat. Avoidance involves physical or psychological distancing from threatening environments or events. Anxietyrelated cognitive disturbance focuses on thoughts and feelings about the perceived threat and includes such symptoms as intrusive thoughts (as in OCD and PTSD), dif-culty concentrating, vigilance, and excessive worry. Although there are similarities in core symptomatology across anxiety disorders, and with normal anxiety, there are also differences in the symptoms of each individual disorder. Accompanying the core symptoms of arousal, avoidance, and cognitive disturbance present in generalized anxiety and fear are alterations in the neurochemical environment within the brain, and many workers in the eld would argue that what distinguishes "normal" anxiety from the anxiety disorders is that the latter reect a neurobiological disorder of the central nervous system (CNS). © 2005 Humana Press.