Biological Explanations of Anxiety Disorders
At birth, there are observable temperamental differences. These differences 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. People with these extra-sensitive temperaments are prone to experience greater intensity, frequency, and duration of anxiety symptoms, than people with less-sensitive temperaments. Therefore, 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 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. As a result, they will become highly anxious and unable to concentrate during their next exam. Contrast this to a person with low neuroticism. Such a person is likely to be disappointed in their poor test score. Rather than discourage them, it serves to motivate them to study more for their next exam. Simply stated, people with high neuroticism appear to be more sensitive to stress, and stress seems to affect 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. These changes further strengthen 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. This response is known as the fight-or-flight response. This adaptive response 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:
1. The nervous system (which includes the brain);
2. The cardiovascular system;
3. The respiratory system;
4. The digestive system;
5. The excretory system;
6. 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 are most important for understanding the origins of anxiety symptoms.