The National Institute of Mental Health estimates 8.1 percent of adults in any year have a specific phobia, whether it's snakes, spider, flying, heights, fear of open spaces or something else. That is actually almost as high as depression and is nearly eight times more than autism. There may be common mechanisms for this, particularly related to the activity of the amygdala, the brain's emotional governor.
Three categories of phobias:
Commonly thought of as fear of leaving the house, agoraphobia is an anxiety disorder in which sufferes avoid places that they fear might cause them to have a panic attack, such as crowded or enclosed spaces.
People with social phobia feel afraid, anxious and self-conscious in everyday interactions with other people, causing them to avoid social situations.
Fear of a specific object, animal or situation, such as flying.