Out-Of-The-Blue Panic Attacks Aren't Without Warning: Body Sends Signals for Hour Before

http://www.sciencedaily.com/releases/2011/07/110727122651.htm

ScienceDaily (July 29, 2011) — Panic attacks that seem to strike sufferers out-of-the-blue are not without warning after all, according to new research.

A study based on 24-hour monitoring of panic sufferers while they went about their daily activities captured panic attacks as they happened and discovered waves of significant physiological instability for at least 60 minutes before patients' awareness of the panic attacks, said psychologist Alicia E. Meuret at Southern Methodist University in Dallas.

In a rare study in which patients were monitored around-the-clock, portable recorders captured changes in respiration, heart rate and other bodily functions, said Meuret, lead researcher on the study.

The new findings suggest sufferers of panic attacks may be highly sensitive to -- but unaware of -- an accumulating pattern of subtle physiological instabilities that occur before an attack, Meuret said. Monitoring data also showed patients were hyperventilating on a chronic basis.

"The results were just amazing," Meuret said. "We found that in this hour preceding naturally occurring panic attacks, there was a lot of physiological instability. These significant physiological instabilities were not present during other times when the patient wasn't about to have a panic attack."

It is notable that patients reported the attacks as unexpected, lacking awareness of either the coming attack or their changing physiology.

"The changes don't seem to enter the patient's awareness," Meuret said. "What they report is what happens at the end of the 60 minutes -- that they're having an out-of-the blue panic attack with a lot of intense physical sensations. We had expected the majority of the physiological activation would occur during and following the onset of the panic attack. But what we actually found was very little additional physiological change at that time."

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People with panic disorder probably won't be surprised by the results, Meuret said.

By definition, the majority of the 13 symptoms of panic attack are physiological: shortness of breath, heart racing, dizziness, chest pain, sweating, hot flashes, trembling, choking, nausea and numbness. Only three are psychological: feeling of unreality, fear of losing control and fear of dying.

"Most patients obviously feel that there must be something going on physically," Meuret said. "They worry they're having a heart attack, suffocating or going to pass out. Our data doesn't indicate there's something inherently wrong with them physically, neither when they are at rest nor during panic. The fluctuations that we discovered are not extreme; they are subtle. But they seem to build up and may result in a notion that something catastrophic is going on."

Notably, the researchers found that patients' carbon dioxide, or C02, levels were in an abnormally low range, indicating the patients were chronically hyperventilating. These levels rose significantly shortly before panic onset and correlated with reports of anxiety, fear of dying and chest pain.

"It has been speculated, but never verified with data recordings in daily life, that increases in CO2 cause feelings of suffocation and can be panic triggers," Meuret said.

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