The age of onset is most commonly in childhood for simple phobias, the late teens for social phobias and the mid-20's for agoraphobia. Phobias in general appear to be more common in females than males although social phobia seems to be fairly evenly divided. Causes The cause of the various phobia disorders is still under considerable dispute. Traditionally, psychologists have believed that phobias are the result of experiencing a traumatic event in the presence of a specific situation or object. However, recent research has suggested that this is likely to be the case for only a certain proportion of phobic cases, especially cases of simple phobia and some social phobias such as fear of eating, drinking, or writing in front of others.
Some social phobias appear to be worsenings of life-long behaviors and personality factors.
The immediate cause of agoraphobic fear and avoidance involves an unexpected panic attack. The agoraphobic then begins to fear the occurrence of another such attack and avoids those situations which they believe may cause or worsen any future attack. The reasons why an individual may begin to associate certain situations with panic attacks are not yet known. In addition, the cause of the initial panic attack is only just beginning to be systematically investigated. Some factors which might be responsible for causing the first panic attack include life stressors, earlier experience with loss of control, a tendency to breathe too fast, or fluctuations in brain chemicals.