Claustrophobia is the fear of having no escape and being in closed or small spaces or rooms. It is typically classified as an anxiety disorder and often results in panic attack, and can be the result of many situations or stimuli, including elevators crowded to capacity, windowless rooms, and even tight-necked clothing. The onset of claustrophobia has been attributed to many factors, including a reduction in the size of the amygdala, classical conditioning, or a genetic predisposition to fear small spaces. One study indicates that anywhere from 5–7% of the world population is affected by severe claustrophobia, but only a small percentage of these people receive some kind of treatment for the disorder. The term claustrophobia comes from Latin claustrum “a shut in place” and Greek , phóbos, “fear”.