Specific Phobia Phenomenology and Subtypes
DSM-IV defines five main types of specific phobia: animal, natu-ral environment, blood-injection-injury, situational and other. These types were introduced on the basis of a series of reports showing that specific phobia types tend to differ on a variety of dimensions including age at onset, sex composition, patterns of covariation among phobias, focus of apprehension, timing and predictability of the phobic response, and type of physiological reaction during exposure to the phobic situation.
Although anxiety about physical sensations and the occur-rence of panic is a feature typically associated with panic disorder, several studies have shown that panic-focused and symptom-fo-cused apprehensions are not unique to panic disorder and agora-phobia. Individuals with specific phobias tend to report anxiety about the sensations (e.g., racing heart, breathlessness, dizziness) typically associated with their fear. Also, there is evidence that in addition to fearing danger from the phobic object (e.g., a plane crash, being bitten by a dog) many individuals with specific pho-bias fear danger as a result of their reaction in the phobic situation (e.g., having a panic attack, losing control, being embarrassed). Also, the few relevant studies that have been conducted suggest that there may be differences in sensation-focused apprehension across specific phobia types.
Data are converging to indicate that individuals with pho-bias from the situational (e.g., claustrophobia) and blood-injury-injection types may be especially internally focused on their fear. Whereas individuals with situational phobias tend to fear the possible consequences of panic, those with blood-injury-injec-tion phobias seem uniquely concerned about sensations that indi-cate that fainting is imminent (e.g., lightheadedness, hot flashes). Delayed and unpredictable panic attacks may be more character-istic of situational phobias than of other phobia types, consistent with the argument that situational phobias share more features with agoraphobia than do other specific phobia types.
Perhaps the most consistent difference among specific phobia types is the tendency for individuals with blood-injury-injection phobias to report a history of fainting in the phobic situ-ation. Although all phobia types are associated with panic attacks in the phobic situation, only patients with blood and injection pho-bias report fainting. The different responses experienced in dif-ferent phobias have been explained from an evolutionary perspec-tive. As mentioned earlier, the typical phobic responses of fear and panic are adaptive in that the increased arousal facilitates escape. In contrast, the most adaptive response during serious injury may be a drop in blood pressure to prevent excessive bleeding. It has been suggested that this response is mediated by an overactive sinoaortic baroreflex that is triggered by heightened arousal in situations involving blood or needles. Of course, in people with blood and injection phobias, the response is excessive and unwar-ranted, as there is typically no danger of excessive blood loss.