Most cases of agoraphobia develop as a complication of panic disorder.
Agoraphobia can sometimes develop if a person has a panic attack in a specific situation or environment.
They begin to worry so much about having another panic attack that they feel the symptoms of a panic attack returning when they're in a similar situation or environment.
This causes the person to avoid that particular situation or environment.
As with many mental health conditions, the exact cause of panic disorder isn't fully understood.
However, most experts think a combination of biological and psychological factors may be involved.
There are a number of theories about the type of biological factors that may be involved with panic disorders. These are outlined below.
One theory is panic disorder is closely associated with your body's natural "fight or flight" reflex – its way of protecting you from stressful and dangerous situations.
Anxiety and fear cause your body to release hormones, such as adrenaline, and your breathing and heart rate are increased. This is your body's natural way of preparing itself for a dangerous or stressful situation.
In people with panic disorder, it's thought the fight or flight reflex may be triggered wrongly, resulting in a panic attack.
Another theory is an imbalance in levels of neurotransmitters in the brain can affect mood and behaviour. This can lead to a heightened stress response in certain situations, triggering the feelings of panic.
The "fear network" theory suggests the brains of people with panic disorders may be wired differently from most people.
There may be a malfunction in parts of the brain known to generate both the emotion of fear and the corresponding physical effect fear can bring. They may be generating strong emotions of fear that trigger a panic attack.
Links have been found between panic disorders and spatial awareness. Spatial awareness is the ability to judge where you are in relation to other objects and people.
Some people with panic disorder have a weakened balance system and awareness of space. This can cause them to feel overwhelmed and disorientated in crowded places, triggering a panic attack.
Psychological factors that increase your risk of developing agoraphobia include:
Occasionally, a person can develop symptoms of agoraphobia even though they don't have a history of panic disorder or panic attacks.
This type of agoraphobia can be triggered by a number of different irrational fears (phobias), such as the fear of: