Fear of Unknown Underlies Many Anxiety Disorders

Many types of anxiety disorders such as panic disorder, social anxiety disorder and specific phobias, share a common underlying feature: increased sensitivity to uncertain threat, or fear of the unknown, according to a new study at the University of Illinois at Chicago (UIC).

Uncertain threat is unpredictable in its timing, intensity, frequency, or duration and triggers a generalized feeling of angst and hypervigilance.

“It’s what we call anticipatory anxiety,” said Dr. Stephanie Gorka, research assistant professor of psychiatry and a clinical psychologist at the UIC College of Medicine. “It could be something like not knowing exactly when your doctor will call with test results.”

When a person is hypersensitive to uncertain threat, they can spend the entire day anxious and concerned that something bad could happen, Gorka said. Panic disorder is one example — patients are constantly anxious over the fact that they could have a panic attack at any moment, she said.

Predictable threat, on the other hand, produces a definitive fight-or-flight response that has a clear trigger, like a hungry bear coming at you, and it goes away once the threat has resolved.

“We classify so many different mood and anxiety disorders, and each has its own set of guidelines for treatment, but if we spend time treating their shared characteristics, we might make better progress,” said Dr. K. Luan Phan, professor of psychiatry and director of the mood and anxiety disorders research program and senior author on the study.

“Knowing that sensitivity to uncertain threat underlies all of the fear-based anxiety disorders also suggests that drugs that help specifically target this sensitivity could be used or developed to treat these disorders.”

Prior research by Gorka and her colleagues suggests that heightened sensitivity to uncertain threat may be an important factor that fuels most fear-based internalizing psychopathologies. However, most research in this area focuses solely on panic disorder, so its role in the other fear-based disorders — particularly social anxiety disorder and specific phobias — remains unclear.

For the study, the researchers evaluated data from participants who underwent a startle task in two different experiments. In total, 25 participants had major depressive disorder; 29 had generalized anxiety disorder; 41 had social anxiety disorder; and 24 had a specific phobia.

Forty-one control subjects had no current or prior diagnoses of psychopathology. All participants were between the ages of 18 and 65.

The researchers measured the participants’ eye-blink responses to predictable and unpredictable mild electric shocks to the wrist. To elicit blinking during the shock-task, the participants heard short, acoustic tones via headphones.

“No matter who you are or what your mental health status, you are going to blink in response to the tone,” Gorka said. “It’s a natural reflex, so everyone does it, without exception.”

The findings show that participants with social anxiety disorder or a specific phobia blinked much more strongly during the unpredictable shocks, compared to participants without a mental health diagnosis or to participants with major depressive disorder or generalized anxiety disorder.

The new findings could help steer treatment of these disorders away from diagnosis-based therapies to treating their common characteristics.

“We may, one day, open up clinics that focus on treating the underlying common neurobiology of the patient’s symptoms instead of individual diagnoses,” Gorka said.

“A treatment, or set of treatments, focused on sensitivity to uncertain threat could result in a more impactful and efficient way of treating a variety of anxiety disorders and symptoms.”

The findings are published in the Journal of Abnormal Psychology.

Source: University of Illinois at Chicago