Many physiological researchers suspect a chemical imbalance in the brain to be one of the main anxiety disorder causes.

Any emotions, feelings and actions are transmitted to the brain as electrical impulses from one nerve cell (neuron) to receptor of another nerve cell. Chemicals in the brain such as serotonin, dopamine, norepinephrine help to facilitate communication between neurons. Those chemicals called neurotransmitters help to regulate our mood. If there is a failure in this process and one of the receptors gets blocked, neurotransmitter is unable to send electrical impulse further. This can interfere with the amount of the neurotransmitters in the brain and create imbalance in its biochemistry.

Chemical imbalance in the brain can be also caused by a shift in the way almond-shaped area in the brain called "amygdala" responds to the brain signals. Amygdala is an "alarm system" that plays a large role in processing emotions, development of memories as well as in our defensive behavior. When danger is perceived, amygdala begins to set off a number of reactions that will help to defend the body and get extra oxygen to major muscle groups. Those reactions include rapid heart rate and breathing, sweating, hot and cold flashes and so on.

There is evidence that genetics can play an important role in developing anxiety. About 25% of people who are pre-disposed to serotonin and dopamine imbalance have a family history of anxiety disorders.

Other causes of anxiety attack can be environmental factors as well as personality traits. Sometimes upsetting events like death of a loved one, divorce, financial difficulties or unemployment can put a person under more stress that he/ she can cope with, which leads to anxiety. Such personality traits like low self-esteem, pessimism, shyness and poor coping skills combined with environmental factors may affect development of anxiety disorder or depression.

Anxiety disorder may also develop as a result of traumatic event, such as car accident, terrorism, physical or emotional abuse and natural cataclysms. In this case painful memories, nightmares, scary thoughts and anniversaries of the event can trigger anxiety attacks and outbursts of anger. Anxiety attacks usually

Some health conditions like heart disease, diabetes, neurological disease, sleep disorders, tumors, endocrine disorders, asthma and infections can mimic anxiety symptoms or cause anxiety.

Certain over-the-counter medications (such as decongestants), ADHD and high blood pressure medications, illegal drugs (marijuana, cocaine, heroin), weight loss products, alcohol, nicotine and energy boosters containing a large amount of caffeine may cause anxiety and for they reason should be avoided.

Herbal remedies are known to help coping with anxiety, but they can also trigger it. For example, such herbs as Ephedra and Ma huang are proved to stimulate anxiety attack.

Most psychotherapists agree that chronic anxiety disorders are related to both human anatomy and psychology. The various complex factors and anxiety risk factors can interact with the impact to one another.