Excerpts from The Panic Attack, Anxiety & Phobia Solutions Handbook
by Muriel MacFarlene, R.N., M.A

Who Gets Panic Disorders?

Genetics
Panic disorder appears to run in families. One study has shown that if one twin in a genetically identical pair has panic disorder, it is likely that the other twin will also suffer from the disorder. Fraternal, or non-identical, twin pairs do not show this high degree of "concordance" with respect to panic disorder. Thus it appears that genetic factors, in combination with environmental factors, may be responsible for vulnerability to this condition.

At the National Institute for Mental Health scientists have been studying families in which several individuals have panic disorder. The aim of these studies is to identify the specific gene or genes involved in the condition. Should such genes be identified this could lead to even more new approaches for diagnosing and treating panic disorder.

The Biological Component

The human body has an extremely elaborate and efficient communication network. This network includes the central nervous system (the brain and the spinal cord) and the peripheral nervous system (the remaining network of nerves). The central nervous system operates by billions of electrical impulses traveling along its pathways, carrying sensory input from our senses (hearing, sight, touch, smell) to the brain and relaying instructions from the brain back to the body, telling it how to respond to that information.

The basic working unit of the central nervous system is the neuron, a specialized cell with the ability to generate and transmit electrical impulses. Chains of neurons form the pathways along which impulses travel on their way to the appropriate regions of the brain. Impulses from the ear travel along the auditory nerve to the superior temporal lobe of the brain where they are translated into sound. Impulses from the eye travel along the optic nerve to the occipital lobe of the brain where they are transmitted into visual images. Exactly how this translation takes place is a mystery, but brain chemicals called neurotransmitters are involved in the translation.

Neurotransmitters regulate the transmission of impulses between neurons. One kind of neurotransmitter acts as a "stop" signal, blocking the transmission of an impulse, and others act as a "go" signal, telling the impulses that they can cross to the next neuron.

These chemical neurotransmitters have a role in every iota of sensory input to the brain. They have a role in every brain activity, including sleep, pleasure, pain, all thought transmission, emotions and the responses to emotions.

Certain areas of the brain have been pinpointed as having to do with a variety of emotional responses. For example, the locus ceruleus is known to be associated with fear responses and this brain area contains an abundance of noradrenergic neurotransmitters.

Norepinephrine, also known as noradrenaline, is produced by the adrenal gland after it gets a message from the brain to do so. This is the chemical that stimulates the heart muscle, accelerates the heart rate, and increases cardiac output. An increase in messages to the adrenals to increase their adrenergic production will also have as a result the raising of anxiety levels, along with the increased heart rate. Experiments in which drugs were given to stimulate the transmitters to increase their flow increased anxiety. Drugs that inhibit the flow decreased anxiety.

Various researchers believe the flaw lies in the chemistry of the brain itself. Their studies indicate that overly sensitive chemoreceptors may be at fault. Panic disorder may be associated with increased activity in the hippocampus and the locus ceruleus, as these portions of the brain monitor all external and internal stimuli and control the brain's responses to them. If neurotransmitters send a message that there is danger, the brain will respond with the appropriate chemicals, sending them throughout the body so that each nerve fiber will do its part in preparing the body to either run or defend itself. It has been well documented that panic disorder patients have increased activity in the adrenergic system, which we have already learned regulates such physiological functions as heart rate and temperature.

Individuals who are prone to panic attacks often have elevated levels of lactic acid in their bloodstreams.

Researchers at the Washington University School of Medicine believe that this is the physiological basis for panic disorder. Positron emission tomography of patients with the disorder illustrate that there is an unequal flow of blood to the parahippocampal gyrus, a region of the brain that is thought to medicate anxiety. These researchers believe that the blood-brain barrier may be slightly defective in these patients, allowing substances such as lactate to reach the brain, thus inducing an attack.

Another group of studies at the NIMH suggests that people with panic disorder may have abnormalities in their benzodiazepine receptors, brain components that react with anxiety-reducing substances within the brain.

In conducting this research, scientists can use several different techniques to provoke panic attacks in individuals who have documented panic disorder, uncomplicated with a medical condition that exhibits some of the similar symptoms. The best known method to provoke panic attacks is an intravenous administration of sodium lactate, the same chemical that normally builds up in the muscles during heavy exercise.

Dr. Donald Klein, professor of psychiatry at Columbia University, believes panic attacks may be a result of a defect in the way the brain warns against suffocation. The human brain's warning system fires whenever the amount of carbon dioxide in the blood becomes too high, a sign of oxygen deprivation. In some people, an overly sensitive system fires a false alarm that then sets off a cascade of events which culminate in a panic attack. Hyperventilation and breathing air with a higher-than-usual level of carbon dioxide can also trigger attacks in people with panic disorder.

Other substances that have been shown to trigger panic attacks in susceptible people include caffeine (generally 5 or more cups of coffee are required).

Because such provocations generally do NOT trigger panic attacks in people who do not have the disorder, scientists have inferred that individuals who have panic disorder are somehow biologically different from people who do not.

It probably isn't important which of these biological factors are at the physiological root of panic disorder. It is sufficient to know that in some individuals such an overly reactive brain chemistry is sending out a false alarm. The message the body is sending probably isn't accurate, and just this knowledge, that there may be some biological basis for the disorder, should be comforting to many.

In addition, it is also true that when people prone to panic attacks are told in advance about the sensations these provocations with sodium lactate and carbon dioxide will cause, they are much less likely to panic. This suggests also that there is a strong psychological component, as well as the biological one, in panic disorder.

Many people experience triggering events such as periods of high stress at work. Some develop panic disorder and agoraphobia, others do not. What separates those who do develop the anxiety/panic cycle from those who do not seems to be the personality traits. People with high anxiety personality traits are more likely to exaggerate the meaning of the initial symptoms, begin to watch their bodies carefully, worry about what the symptoms mean and what might happen if they cannot be controlled. In essence, anxiety becomes a kind of “black cloud” hanging over their heads. They run from any sign of the black cloud on the horizon. Unfortunately, most of the symptoms they are running away from are quite normal. The key to the development of the anxiety/panic cycle is what the individual believes about the external factors that are impacting them.

Results of Animal Studies

NIMH-sponsored researchers are studying anxiety in animals in an effort to find clues to the underlying causes of anxiety. One series of studies involved an inbred line of pointer dogs that exhibited extreme, abnormal fearfulness when approached by humans or that startled excessively by loud noises. In contrast with normal pointers, these nervous dogs have been found to react more strongly to caffeine and to have brain tissue that is richer in receptors for adenosine, a naturally occurring sedative that normally exerts a calming effect within the brain. Further study of these animals is expected to reveal how a genetic predisposition toward anxiety is expressed in their brains.

Other animal studies involve macaque monkeys. Some of these animals exhibit anxiety when given an infusion of lactate, much like people with panic disorder. Other macaques do not exhibit this response. Scientists conducting these studies are attempting to determine how the brains of the responsive and non-responsive monkeys differ. Hopefully, this research should provide additional information concerning the causes of panic disorder.

In addition, research with rats is exploring the effects of various medications on the parts of the brain involved in anxiety.

Further, scientists funded by NIMH are investigating the basic thought processes and emotions that come into play during a panic attack and those that contribute to the development and persistence of agoraphobia. These studies on the cognitive factors in panic disorders will evaluate the impact of various therapies to determine if some variants are more effective and for which individuals. The research program will also explore the effects of interpersonal stress such as marital conflict on the disorder.

The Role of Diet

It seems silly to think that diet could be a contributing factor in creating panic attacks but if we think that all bodily chemistry is the result of chemical interactions within cells, then it seems apparent that these chemicals must come from somewhere. Just as gasoline fuels an automobile, food fuels the body.

Dr. Michael Lesser, a psychiatrist who specializes in nutritional medicine says,"Ninety-two percent of the patients who come to see me with symptoms such as anxiety, fatigue, palpitations, fears, trembling - all the symptoms of panic disorder and phobia - had abnormal blood sugar test results. I firmly believe that abnormalities in blood sugar have a direct physiological correlation to the symptoms."

Dr. Lesser always administers a five or six hour glucose tolerance test to all patients exhibiting such symptoms and suggests that all physicians who see patients with these symptoms do the same. If you have not had such a test, you should have one before you look any further for the reasons for your mental distress.