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Biology 202
2000 First Web Report
On Serendip

The Neurobiology of Anxiety Disorders: A Preliminary Investigation

Diana C. Applegate

When I first began my research for this paper, I was primarily interested in learning more about the role of serotonin in the treatment of anxiety disorders. While I did discover that serotonin is important, especially when it comes to understanding the latest drugs being prescribed by doctors to combat anxiety symptoms, I also learned that researchers are pursuing a number of other "leads" in investigating the neurobiology of anxiety disorders. There has been evidence suggesting that a particular gene, or genes, may be associated with the development of anxiety disorders (1). In addition, the circuitry of the amygdala, an area of the brain that regulates fear responses, is now being studied (2). First, I will briefly summarize my findings regarding serotonin, and then I will offer my own personal reaction. I will focus my response around Social Anxiety Disorder, one of a number of anxiety disorders that are diagnosed and treated today.

Anxiety disorders are the most common mental illnesses in America, affecting approximately 19 million adults (3). Although everyone experiences mild symptoms of anxiety at some point in their lives, those who suffer from an anxiety disorder have chronic and intense bouts of panic. They may fear or dread common social situations such as being out in public with a group of friends (4), or experience full-blown panic attacks (5) that make it impossible to go grocery shopping or to get to work in the morning. If untreated, anxiety disorders can severely impact the quality of one's life, and symptoms may grow even worse over time. There are several types of anxiety disorders, including Panic Disorder, Obsessive-Compulsive Disorder, Post-Tramautic Stress Disorder, Social Anxiety Disorder, and Generalized Anxiety Disorder. Each has its own distinct features, but the physiological and psychological symptoms associated with them are quite similar.

Serotonin (6), or 5-Hydroxytryptamine, is a neurotransmitter involved with a number of important human behaviors, including appetite control, mood, sleep, and memory (7). Serotonin-producing neurons extend from the raphe nuclei in the brain stem to many different regions of the central nervous system, including the amygdala. It is now believed that people with anxiety disorders may have a serotonin deficiency, or else the available serotonin in the patient's body isn't being used as efficiently as it should be. This belief is strengthened by the success of SSRI (Selective Serotonin Reuptake Inhibitors) medications like Prozac, Paxil, and Luvox in treating those with anxiety symptoms (8). These drugs increase the amount of available serotonin in the body by blocking presynaptic reuptake transporters from drawing serotonin out of the synaptic cleft.

All of the research currently being done to improve the treatment of anxiety disorders is based on the premise that brain equals behavior, or, more specifically, that changes in the neurochemistry of the brain will bring about desired changes in behavior, such as the alleviation of anxiety symptoms. Although the discoveries being made are highly beneficial to those who suffer from anxiety disorders, and are significantly improving their quality of life, the use of medications in treating anxiety patients is not without controversy. For example, SmithKline Beecham, the drug company that manufactures Paxil, an SSRI approved by the FDA to effectively treat Social Anxiety, recently launched an "educational campaign" centered around this disorder (9). Ostensibly, the countless commercials and magazine advertisements describing Social Anxiety Disorder will promote awareness and encourage those who are suffering to seek help. However, SmithKline Beecham is also running this campaign in hopes that more doctors will now prescribe Paxil so they may reap the financial rewards.

As so-called "brain mapping" continues in anxiety disorder research, and in other areas of study, drug companies will, undoubtedly, be waiting in the wings. It is crucial that those suffering with anxiety disorders seek help, either through medication or therapy, since the symptoms they experience are chronic, extreme, and dangerous. What concerns me is the possibility that the general public might seek to fine tune their behavior in the future, when the availability of such drugs may become rampant. For example, will traits like shyness or an introverted personality be viewed as needing correction, or will we accept the differences between us that account for human diversity, and not abuse our newfound knowledge about the neurobiology of the brain?

WWW Sources

1)"Some Forms of Anxiety may be Genetic", from Reuters Health, June 14, 2000, found on

2)"Anxiety Disorders Treatment Target: Amygdala Circuitry", from the National Institute of Mental Health, December 1998

3)Anxiety Disorders, from the National Institute of Mental Health, 2000

4)"Millions Grapple with Social Anxiety", from U.S. News and World Report, cover story 6/21/99

5)"The Causes of Anxiety and Panic Attacks", from the Anxiety Panic internet resource

6)Serotonin, from Department of Psychology, California State University

7)"The Physiology of Panic Disorder, Part II", from Panic/Anxiety Disorders on

8)"Drug May Help in Rx, Education of Panic Disorder", from The Medical Post, January 29, 1996, found on Internet Mental Health

9)Paxil, from SmithKline Beecham

Other Resources

1)The Neurobiology of Childhood Emotion: Anxiety, from The American Psychoanalyst, Vol. 32, No. 2

2)The Neurobiology of Depression, from Scientific American, June 1998

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