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 panic attack returning when they're in a similar situation or environment.

This causes the person to avoid that particular situation or environment.

Panic disorder

As with many mental health conditions, the exact cause of panic disorder isn't fully understood.

However, most experts think that a combination of biological and psychological factors may be involved.

Biological factors

A number of theories about what type of biological factors may be involved with panic disorders are outlined below:

‘Fight or flight’ reflex

One theory is that 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 adrenalin, 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 that the fight or flight reflex may be triggered wrongly, resulting in a panic attack.

Neurotransmitters

Another theory is that there is an imbalance in levels of neurotransmitters in the brain which can affect mood and behaviour. This can lead to a heightened stress response in certain situations, triggering the feelings of panic.

The fear network

The "fear network" theory suggests that 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.

Spatial awareness

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

Psychological factors that increase your risk of developing agoraphobia include: 

• a traumatic childhood experience, such as the death of a parent or being sexually abused
• experiencing a stressful event, such as bereavement, divorce or losing your job 
• a previous history of mental illnesses, such as depression, anorexia nervosa or bulimia
• alcohol misuse or drug misuse
• being in an unhappy relationship, or in a relationship where your partner is very controlling