Acrophobia, derived from the Greek: ákron, meaning “peak, summit, edge”, is an intense, irrational fear of heights. This is a somewhat common fear; between 2 and 5 percent of the general population suffer from a fear of heights, and twice the number of sufferers are female.

Like most phobias, Acrophobia is generally attributed to a traumatic incident involving heights; however, recent studies have questioned this theory, due to the prevalence of this phobia. Some studies have suggested that fear of falling is an inborn or non-associative fear – an adaptation to a world where falling presents a danger. Many mammals, including humans and domestic animals have an intrinsic instinct to avoid heights – a survival instinct.

Experiments using visual cliffs or plexiglass panes have proven that a majority of mammals show some hesitation when venturing onto a glass floor with the illusion of a few feet of emptiness below it. Most people experience a small degree of fear when exposed to heights, but an extreme fear which interferes with daily activities such as climbing stairs or being on a high floor of a building can be debilitating.  Sufferers can experience panic attacks in these situations and become too agitated to get themselves down safely.

A dysfunction in maintaining balance could be a possible contributing factor to Acrophobia. Most sufferers instinctively do not trust their sense of balance, but some actually might have a physical dysfunction maintaining balance, making the fear well-founded.

The human balance system is complex, integrating several areas of the brain and inner ear and their interaction with visual cues to establish position and motion. In normal people an increase of height causes visual cues to recede and balance becomes poorer. However, the average person responds by shifting reliance to the other branches of their equilibrium system (brain and inner ear). A person with Acrophobia could potentially have an inadequately functioning equilibrium system which leaves them continuing to rely on visual cues, overloading their visual cortex and causing fear. If this is the case, exposure therapy may be an unwise course of treatment. In some cases, exposure therapy may be prudent. There have also been a number of promising studies using virtual reality as a treatment option.

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