When people with panic disorder experience a stressful life event, they don’t immediately get hit by a panic attack. Instead, their panic symptoms escalate over time, according to a study by Brown University researchers and published in the Journal of Affective Disorders.

According to Brown press materials, for the study, 418 adults with panic disorder were asked detailed, standardized questions about their anxiety levels and about major life events.

Researchers found that after stressful personal and work-related events, participants’ anxiety symptoms—which would normally fluctuate in intensity—gradually but steadily rose for at least three months afterward.

Interestingly, stressful events in seven other categories, such as “deaths” and “crime/legal,” had no measurable impact on anxiety symptoms. In addition, panic symptoms also didn’t appear to increase before predictably stressful events, such as an upcoming divorce.

But even when events don’t immediately cause a panic attack, it’s important that patients, their family members and psychiatrists remain vigilant, said Martin Keller, MD, a professor of psychiatry and human behavior at Brown University, and lead study author.

To avoid panic disorders getting worse, Keller said, you have to watch for these slowly increasing symptoms.

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