Acute Stress Disorder (ASD)  -  A category of mental disorders defined by the DSM- IV as a reaction occurring within four weeks following a traumatic event and which is characterized by dissociative symptoms, avoidance, reexperiencing, and marked anxiety or arousal.

Agoraphobia  -  An irrational or abnormal fear of being in a situation where escape might be difficult. Literally meaning "fear of the marketplace," this disorder is sometimes described as fear of open or public places.

Anxiety  -  An emotional response that is out of proportion with any genuine threat in the environment. In addition, anxiety, instead of being directed towards a current stimulus, is usually associated with the anticipation of a future problem.

Anxiety Disorders  -  The class of mental disorders, including generalized anxiety disorder, panic disorder, obsessive-compulsive disorder, phobias, acute stress disorder, and posttraumatic stress disorder, in which fear or anxiety is the most prominent symptom.

Anxious Apprehension  -  A term coined by the psychologist David Barlow which is used to describe a maladaptive type of anxiety that consists of a focus on negative emotions, perceptions of lack of control, and a constant state of self-preoccupation.

Attention  -  A process wherein mental activity is focused along a specific track, regardless of whether this track consists of inner memories and knowledge or is centered around an external stimulus.

Avoidance  -  An important component of the definition of a phobia, avoidance is characterized by evasion of the anxiety-inducing or feared stimuli, even if it entails utilizing extreme or irrational methods.

Benzodiazepines (Antianxiety Drugs)  -  A group of drugs, such as diazepam (Valium) and alprazolam (Xanax), which show an affinity for receptor sites normally associated with the neurotransmitter gamma-aminobutyric acid (GABA). Minor tranquilizers, or benzodiazepines, which have a potent hypnotic, sedative, and anxiolytic (anxiety relieving) action, inhibit the activity of the GABA neurons. Side effects of these drugs (which are subdivided into two categories based on their rate of absorption and elimination from the body) include sedation, followed by mild cognitive and psychomotor impairments, and more seriously, the possibility of addiction.

Cingulum  -  A marked fiber bundle passing longitudinally in the white matter in the cingulate gyrus (a structure found on the medial surface of the cerebral hemispheres) and extending from the region of the anterior perforated substance back over the dorsal surface of the corpus callosum (the bridge of nervous tissue that connects the right and left hemispheres of the brain). More importantly, it contains association fibers connecting various gyri with the frontal cortex, and the various subdivisions within the gyri.

Clark's Cognitive Model of Panic Disorder  -  A theory proposed by David Clark that hypothesizes a possible psychological basis of panic disorders. According to Clark, panic disorders result from a gross misinterpretation of bodily sensations. Regardless of whether or not the trigger stimulus is an external or internal stimulus, the panic attack is associated with a cognitive misinterpretation of a biological reaction.

Compulsion  -  Repetitive, ritualistic behavior or mental acts that a person, although he/she realizes that the act is senseless or irrational, feels driven to perform either because it reduces stress or prevents some dreaded outcome.

Control Group  -  In an experimental design, the group of participants who are not manipulated. This means that the control group, unlike the experimental group, which receives an active treatment, does not receive any form of treatment or may be given a placebo treatment.

Displacement  -  A type of defense mechanism wherein unconscious and unacceptable feelings, wishes, or actions are transferred from one person or object to another that is less threatening, and therefore more acceptable.

Evolutionary Preparedness  -  A theory proposing that certain mechanisms and experiences of learning are based on, and in fact may depend on, the existence of "prepared," or biologically predetermined, associations between stimuli.

Exposure Habituation  -  A type of non-pharmacological treatment of anxiety disorders wherein individuals are exposed to the anxiety inducing stimuli, but then they allow the anxiety to pass and to let the body return to a normal, calmer state without engaging in any anxiety-reducing acts. In this type of intervention, the procedure is attempting to break the negative reinforcement paradigm, by allowing the fight/flight response to simply pass.

Fear  -  An unpleasant emotional reaction experienced in the face of real, immediate danger. Fear usually builds quickly in intensity and helps to organize the body's responses to possible external threats.

Fight-or-Flight Response  -  A series of psychophysiological reactions, such as increased heart rate and shortness of breath, that prepare the body to take action against possible threats or dangers in the environment.

Generalized Anxiety Disorder  -  One of the anxiety disorders characterized by severe, excessive, prolonged, and uncontrollable worry about a number of events or activities, but is not consistently associated in the individual's mind with any particular object or event in the environment or any specific life experience. Symptoms of arousal are also associated with this disorder.

Insecure Attachment  -  In the field of developmental psychology, a term used to describe infants who display either avoidant or anxious behavior towards their caregiver (too attached or not attached enough).

Isolation  -  A defense mechanism, a process wherein a memory or an idea is separated from its emotional component.

Modeling Coping  -  A social learning technique similar to modeling mastery, wherein an approach to anxiety-inducing stimuli is presented without the expression of anxious symptoms. In this exposure-by-proxy procedure, however, the dimension of coping mechanisms, such as deep-breathing exercises and relaxation techniques, is also introduced.

Modeling Mastery  -  A social learning technique wherein an approach to anxiety-inducing stimuli, without the expression of anxious symptoms, is presented. This exposure-by- proxy procedure, therefore, breaks the pattern of negative reinforcement by showing that nothing bad is prevented by anxiety responses.

Negative Reinforcement  -  In operant conditioning, the process which occurs when the cessation or decrease of a stimulus, such as anxiety, increases the likelihood of that behavior being repeated (a compulsive act, for instance). In other words, negative reinforcement is the condition in which a particular response results in the removal of a negative reinforcer.

Obsession  -  Recurrent, persistent thoughts, images, or impulses that are experienced as intrusive and which the individual cannot stop from occurring. The individual realizes that these unwanted and generally unpleasant cognitive events, which usually lead to an increase in subjective anxiety, are a product of their own mind.

Obsessive-Compulsive Disorder (OCD)  -  A disorder characterized by a repeated, disturbing, irrational mental act that increases levels of anxiety and can then only be alleviated (temporarily) by performing some repetitive action or ritualistic behavior.

Panic Attack  -  A major characteristic of panic disorders, panic attacks are a sudden, overwhelming experience of terror or fright, which is much more focused than anxiety.

Panic Disorder  -  A psychosomatic disorder characterized by a preoccupation with pain, but differentiated from somatoform disorders in that panic disorder consists of an inherent psychological component. Panic disorder is characterized by the presence of attacks that seemingly come out of nowhere and are not precipitated by the threat of some external stimulus. For one month following the attack, one of these symptoms must be experienced for the individual to meet the diagnostic criteria of panic disorder: there must be implications of the panic attack; persistent concern of having another attack; and a significant change in behavior in response to the attack.

Perception of Control  -  A social theory proposing that individuals who believe that they have power and control over the events that occur in their lives and in the environment are generally less vulnerable to developing certain types of disorders, such as anxiety disorders.

Phobia  -  A persistent or irrational fear that is associated with the presence or anticipation of a specific object or situation.

Positron Emission Tomography (PET)  -  A visual display of brain activity that is based upon the uptake and distribution of a radioactive form of oxygen into active areas of the brain.

Posttraumatic Stress Disorder (PTSD)  -  A psychological disorder that is directly and explicitly associated with the experience of a particular traumatic incident or set of incidents and that is characterized by recurring symptoms of numbing, reexperiencing, and hyperarousal following exposure to some traumatic stressor. In addition, in contrast to ASD, PTSD usually lasts longer and has a delayed onset.

Psychosomatic  -  Pertaining to the influence of the mind or of higher cognitive functions of the brain, such as emotions, fears, and desires, upon the functions of the body, especially in relation to diseases or bodily disorders. The term "psychosomatic disorder," therefore, describes a physical disease that is a product both of the psyche and of the body.

Reaction Formation  -  A type of defense mechanism wherein the mind turns a painful, unacceptable, or frightening thought or wish into its safer opposite.

Repression  -  A type of defense mechanism wherein the mind prevents anxiety-provoking or threatening thoughts from becoming conscious.

Retrospective Studies  -  A study based on the individual's recollections about past experiences. These types of studies are often criticized for their lack of reliability and validity.

Self-Fulfilling Prophecy  -  A process by which the expectation or belief of a certain outcome, whether initially true or false, may conform or affect behavior and performance in such a manner that it creates the reality. (Also called the Pygmalion Effect.)

Social Phobia  -  Any type of phobia, such as fear of public speaking, wherein the basic fear is of being placed in a social situation that would require scrutiny or evaluation by other people.

Specific Phobia  -  Any phobia characterized by fear of a well-defined category of objects, such as snakes or environmental situations (excluding other people).

Tourette's Syndrome  -  A rare disorder characterized by repeated motor and verbal tics.

Trichotillomania  -  A compulsion to pull out one's own hair.

Undoing  -  A defense mechanism through which an individual reacts to an psychologically unacceptable event by unconsciously attempting to reverse the act by doing its opposite, usually repetitiously, to relieve anxiety.