19.03.1 Fear, Anxiety and Anxiety Disorders

Fear and anxiety are adaptive responses to aversive stimuli (eg: danger, pain, noxious conditions) that facilitate survival. Fear represents an immediate, often innate, response to threatening stimuli, but can also be learnt (conditioned) so that specific stimuli are predicted to be associated with danger, pain or harm. Anxiety is a state of anticipation of danger, elicited by less specific cues, and is learnt. It is characterized by vigilance, physiological autonomic arousal and subjective distress. Normal fear and anxiety behaviours include avoidance, escape or defense.

Anxiety disorders arise when: normal fearful or anxious behaviours become exaggerated or prolonged, or occur in the absence of any real threat; anticipation of a feared event or object becomes distressing; or increased salience is given to usually innocuous stimuli so that they come to be perceived as threatening. Precipitating factors may be external (e.g. situation, object) or internal (such as catastrophic cognitions or rationalizations, recall of stressful experiences, or physiological autonomic arousal). DSM-IV-TR categorises anxiety disorders into a number of subtypes, including social phobia, specific phobias, panic disorder, obsessive-compulsive disorder, post-traumatic stress disorder, and generalized anxiety disorder. Each of these has unique features, however the common characteristics include somatic (motor tension, trembling, palpitations, restlessness, sleep disturbances), emotional (distress, fear and anxiety) and cognitive (hypervigilance, derealization, negative self-evaluation) features. For clinical diagnosis according to DSM-IV-TR, the anxiety must interfere significantly with social and occupational functioning, or this interference causes significant distress.