While it might seem intuitive that major life stressors would immediately result in panic attacks in people with panic disorder, a new study speaks to the contrary. The research team found that after stressful events, whether predictable or not, panic patients had steady, slow increases in symptoms, rather than a quick spike.

The participants’ symptoms increased gradually over time, following the event. But there was no sudden spike in panic symptoms around the time of the event itself.

Panic disorder is a form of anxiety disorder, in which patients experience panic or anxiety "attacks" and often live in intense fear of these episodes. During attacks, patients may feel chest pain, palpitations, dizziness, nausea, and have an impression of impending doom, that they are about to die, or are going crazy.

In the new study, the team followed over 400 people enrolled in the Harvard/Brown Anxiety Research Program, who suffered from panic disorder or panic disorder with agoraphobia (which is a phobia of social situations in which patients fear there is no "escape"). The patients’ panic symptoms were tracked for 12 weeks before and 12 weeks after a major life event, like divorce, job loss, death of a spouse or mate, or a health problem. The participants were interviewed regularly to determine the severity of their symptoms.

After analyzing the data, the team found that for life events related to work (like a layoff or demotion) or to family and friends (like a serious family argument or fallout with a family member), the participants’ symptoms increased gradually over time, following the event. But there was no sudden spike in panic symptoms around the time of the event itself.

Lead author Ethan Moitra said in the Brown University news release that he and his colleagues "definitely expected the symptoms to get worse over time, but we also thought the symptoms would get worse right away."

There were no changes in symptoms, immediate or long term, linked to the other life event categories like deaths or legal problems.

The findings are particularly surprising since panic disorder onset has been linked to stressful life events in the past, said Moitra, who adds that the connection may be explained by the tendency of people with panic disorder to sense upcoming hyperventilation in response to stress, which could trigger a panic attack after a major stressor. On the other hand, panic attack episodes can also happen seemingly out of the blue, with no stressful trigger. More research will need to be devoted to understanding the triggers and mechanisms involved in panic disorder, so more effective treatment methods may be developed.

Moitra is a postdoctoral researcher at Brown University, and published the study in the June 11, 2011 issue of the Journal of Affective Disorders.