The amygdala (uh-MIG-duh-luh) structure in the brain may have a function in modulating the fear response. People with an overactive amygdala may have a heightened fear reaction, creating uneasiness in social situations. Also called the anxiety center of the brain, this part of the limbic system is involved in regulating emotions such as anger, fear, and anxiety.
People who suffer from generalized anxiety disorder have an overactive amygdala. These individuals may experience chronic worry about possible dangers in their lives and perform risk-assessment behaviors to calm themselves down when they feel anxious.
In contrast, people with selective avoidance disorder have underactive amygdalae. They may avoid social interactions that might cause them stress because they don't want to face their fears.
Individuals with post-traumatic stress disorder (PTSD) have hyperactive amygdalae. They may have problems falling asleep or staying asleep due to increased awareness of danger. They may also have exaggerated reactions to stressful events related to their trauma. For example, someone who was abused as a child may have trouble coping with school stressors like exams or peer pressure and act out in abusive ways like hitting others or using drugs/alcohol to self-medicate.
People with phobias have abnormal responses to certain objects or situations that trigger a fear reaction.
Scientists believed that inappropriate dread and anxiety in persons with anxiety disorders were produced by an overactive amygdala—a simple cause with a simple consequence. However, we now understand that anxiety is the consequence of ongoing communication across a number of distinct brain regions—a fear network. Anxiety disorders are characterized by excessive fear, avoidance of feared situations, and negative beliefs about the world and oneself. These symptoms can be explained by several different neurobiological mechanisms that have been identified. The main mechanism responsible for the symptoms of anxiety disorders is hyperactivity of the amygdala--the part of the brain that controls emotion and behavior through signals to and from other parts of the brain.
Anxiety can also be caused by damage or dysfunction within any one of a number of areas of the brain, including the prefrontal cortex, hippocampus, and corpus callosum. This type of anxiety is often referred to as "neurological" or "organic." Psychological factors such as stress, trauma, or past experiences can also trigger or exacerbate neurological anxiety disorders.
The most common form of psychological anxiety is known as "generalized anxiety disorder" (GAD). People with GAD experience intense anxiety or worry that interferes with their daily life activities for more than six months. They may also feel physically ill with stomach cramps, diarrhea, or insomnia. GAD can be very difficult to treat, but with proper therapy many people are able to control it.
The amygdala regulates our fear response, but it also plays an important role in a variety of other cognitive activities. As a result, amygdala injury can result in major difficulties such as poor decision-making and impaired emotional memory. Studies have shown that people with damage to the amygdala cannot learn from past mistakes, which makes them prone to repeat the same bad behavior over and over again.
Ample evidence suggests that the amygdala is critically involved in anxiety disorders like generalized anxiety disorder, social anxiety disorder, and specific phobias. It has been found that people with these conditions have larger amygdalae than normal individuals. In addition, research shows that people with anxiety disorders may have problems regulating their emotions, which could also be caused by abnormalities in the amygdala.
Studies have also shown that people with smaller amygdalae tend to make better decisions and show greater persistence in trying new strategies for solving problems than those with larger amygdalae. This indicates that healthy amygdala function is necessary for good decision-making skills and risk management behaviors.
Damage to the amygdala due to disease or trauma can lead to severe anxiety symptoms. People with this type of injury often have trouble deciding what kind of danger is real and what's not, which can put them at risk of suffering from panic attacks.
The amygdala is a component of the limbic system that is hypothesized to play a function in emotion and behavior. It is most recognized for its role in fear processing, albeit as we will see, this is an oversimplified view of amygdala function. The amygdala also plays a role in other functions including socialization, memory, attention, judgment, desire, happiness, sadness, anger, risk taking, love, reproduction, and more.
Ample evidence suggests that the amygdala is important for normal emotional development. Children who suffer damage to their amygdalae before puberty are able to communicate their needs and desires, but lack the ability to feel pleasure or pain from positive or negative events. They can learn new behaviors and achieve goals, but they experience life's challenges without feeling any emotions at all. Young children with damaged amygdalae are not diagnosed with autism or other developmental disorders, because they do not show any abnormal behaviors. However, by adolescence, most patients with amygdala damage develop severe depression or anxiety disorders.
In adulthood, damage to the amygdala can lead to impaired judgment and behavioral changes associated with psychosis. Patients with damage to the amygdala may appear calm, but they are actually unaware of what is going on around them. They may act inappropriately given the situation and fail to recognize friends or family members.