Development of anxiety disorders depends on a person’s biochemistry, environment, history, and psychological profile.A person with anxiety is biologically vulnerable to stress and is thus more susceptible to environmental stimuli than others.

Changes in the amygdala portion of the brain (also known as the ‘fear center’) is the focus of research with regards to anxiety.The amygdala regulates memory, as well as fear and other emotions.It also starts a chain reaction that produces physical responses to stressful events, such as increases in heart rate and blood pressure. Some research indicates that for the person with an anxiety disorder, the amygdala is very sensitive to unfamiliar situations and responds aggressively.This explains why a person with an anxiety disorder may experience phenomena such as heart palpitations, hyperventilating, and sweating during times that other people may find uneventful.

Imaging studies have found that those with post-traumatic stress disorder (PTSD), a type of anxiety triggered by a traumatic even, have lower hippocampus volume.The hippocampus is a region of the brain that deals with emotion and memory storage.

Several studies seem to point at the imbalance of certain neurotransmitters as a contributor to anxiety disorders.Specifically, focus has been made on the neurotransmitters GABA, serotonin, dopamine, and epinephrine.

DOPAMINE

The dopamine neurotransmitter is produced in several parts of the brain.It also acts as a neurohormone released by the hypothalamus. Dopamine has multiple functions, ranging from sleep and mood to voluntary movement.Drugs that reduce the activity of dopamine have been shown to negatively affect motivation and the ability to experience pleasure.People with social anxiety disorder have been shown to have low receptor-binding levels for a certain type of this neurotransmitter.The effect is similar to having not enough dopamine in the brain.

SERATONIN

With obsessive-compulsive disorder (OCD), there are abnormalities in a specific pathway of nerves.This pathway of nerves may also be related to the secretion and absorption of serotonin, which is a major player in OCD.Serotonin is a neurotransmitter that influences sleep, appetite, and metabolism.

Changes in serotonin and dopamine have also been observed in those with social anxiety disorder.Serotonin levels are believed to be altered in cases of anxiety by the Corticotropin-releasing factor (CRF), another neurotransmitter

EPINEPHRINE

Epinephrine, also known as adrenaline, is a highly potent hormone that has a critical role in “fight or flight” response.It is secreted by the adrenal glands when danger or an emergency is perceived.Epinephrine secretion can be triggered by environmental conditions such as high noise and bright light.

Epinephrine works by boosting the supply of oxygen and sugar to the brain and muscles.It also shuts or slows down non-emergency bodily functions such as digestion.Epinephrine can raise heart rate and blood sugar as well as constrict arterioles of skin and GI tract and dilate arterioles of skeletal muscles.

High epinephrine levels lead to palpitations, anxiety, headaches, hypertension, tremors, and other physiological reactions.

Norepinephrine is a neurotransmitter and a precursor of epinephrine.Its effects are similar to that of epinephrine.

GABA

GABA is a neurotransmitter in the brain that stops neurons from firing and prevents nerves from over-firing.A reigning theory is that GAD occurs when GABA cannot bind well to receptor cells or when there are too few GABA receptors.Thus the neurons fire excessively causing the person not to receive ‘stop’ messages frequently enough.The result is a person who is excessively worried or upset, a qualifying anxiety symptom

GENETICS

Nearly half of people with panic disorder or generalized anxiety have close relatives with the disorder.The chances of inheriting a phobia are between one in four and one in three.There may also be defective genes that regulate neurotransmitters such as serotonin that can explain the heredity of this problem.

Neurotransmitters greatly affect our mood and mental health.