What Are Anxiety Disorders?
Anxiety disorder is generally defined as a chronic condition that causes an excessive, persistent sense of apprehension along with physical symptoms of sweating, palpitations and stressful feelings. However, anxiety disorders are not all alike, and the National Institutes of Mental Health has described five major types of anxiety disorder. Each type is based on the specific effects of anxiety that someone experiences:
- Generalized Anxiety Disorder (GAD)
- Obsessive-Compulsive Disorder (OCD)
- Panic Disorder
- Post-Traumatic Stress Disorder (PTSD)
- Social Phobia (also known as Social Anxiety Disorder)
Each category can be further classified based on the signs and symptoms that someone experiences. There is also a sixth category that involves specific phobias, such as a fear of heights or needles.
Causes of Anxiety Disorder
A large amount of evidence shows that anxiety disorders are caused by a combination of biological and environmental factors. Environmental factors include psychological vulnerabilities, such as beliefs, patterns of thought and how we “choose” to respond to stressful situations.
The role of biology in anxiety is incredibly complex, and there is much that is not yet understood. However, it is clear that biological factors (including a person’s genetics and physiology) are major contributors to the development of anxiety disorders.
In recent years, a number of studies have looked at gene expression levels in people with generalized anxiety disorders. Neuroimaging studies have looked to evaluate how the brain responds to stressful events in people with an anxiety disorder. Most of these studies have found significant differences between people with an anxiety disorder and people without one.
Researchers are also studying the effects of genetic and environmental factors in twins. A recent twin study found that anxiety is influenced by genetics but that environmental factors also make a significant contribution. In other words, even if someone inherits genes that increase the risk of developing an anxiety disorder, they may never actually develop one.
One theory about environmental factors involves how young people respond to stress. Because the brain develops during adolescence, the brain of a child may develop differently due to trauma. Some neuroimaging studies have supported this hypothesis. In one neuroimaging study, people with panic disorder were found to have larger amygdalas (the part of the brain that responds to stress and fear) than other people.