Biological Explanations of Anxiety Disorders
The human body is an amazing and very complex organism. The intricacies of our bodies, and especially our brains, are presumed to be involved in the origins and maintenance of anxiety disorders. As mentioned, biological factors (or vulnerabilities) usually have to be in place for an anxiety disorder to manifest. Because of advancements in genetic research, we now know that many diseases and disorders have a genetic component. Therefore, it should come as no surprise that psychiatric disorders are believed to have a genetic component as well.
With respect to anxiety disorders, genetic predisposition has been implicated in Panic Disorder, Phobias, and Obsessive-Compulsive Disorder as these disorders have familial links (meaning family members having the same disorder, occurring more often than random chance). However, the research has not yet identified the precise nature of this link.
In addition, temperamental differences, observable at birth, appear to be a function of genetics. Some babies are much more sensitive to stimulation and stress than are other babies. These differences remain as the child matures. People born with these extra-sensitive temperaments are thought to be at greater risk for developing anxiety disorders later in life because their nervous system is more easily aroused. You may recall that normal anxiety is distinguished from pathological anxiety by the intensity, frequency, and duration of symptoms. Therefore, people with these extra-sensitive temperaments are prone to experience greater intensity, frequency, and duration of anxiety symptoms, than people with less-sensitive temperaments; thus, they are more likely to experience pathological levels of anxiety. In a related way, certain personality characteristics are thought to have a genetic component.
One such characteristic is called neuroticism. Neuroticism refers to a person's emotional stability. Neuroticism is best thought of as a personality characteristic that reflects a tendency toward negatively interpreting environmental cues, and a greater degree of reactivity to those cues. For example, a person with high neuroticism is likely to interpret a single poor test score as an indication of their looming and certain failure, and will be highly anxious and unable to concentrate during their next exam. Contrast this to a person with low neuroticism who is likely to be disappointed in their poor test score, but will be determined to study harder for their next exam. Simply stated, people with high neuroticism appear to be more sensitive to stress, and stress seems to impact them in a greater way. Subsequently, high neuroticism places individuals at greater risk for the development and/or exacerbation of anxiety disorders. Moreover, chronic negative reactions to stress may actually lead to further changes in brain chemistry, thus further strengthening a person's preexisting biological vulnerability.
Genetics certainly account for some of the biological differences between people, but our biological make-up also accounts for the similarities among people. One such similarity is the human response to fear called the fight-or-flight response. This is an adaptive response that serves to protect people from danger.
The human body is thought to consist of 10 inter-related systems. More than half of these 10 complex systems are involved in the production of anxious and fearful symptoms: the nervous system (which includes the brain), the cardiovascular system, the respiratory system, the digestive system, the excretory system, and the endocrine system. These six systems are responsible for the physiological, electrical, and chemical changes that cause and affect the manifestation of anxiety symptoms. Explanations of these various systems can become quite complicated. Our goal is to highlight the areas that we find most important to help you better understand the origins of anxiety symptoms.