Relative to healthy controls, people who experience panic attacks

A) have been demonstrated to display chronic muscle tension.
B) have been described as sympathetic restrictors because of their consistently low sympathetic nervous system activity.
C) have extremely high levels of the neurotransmitter dopamine.
D) have extremely low levels of the neurotransmitter dopamine.
E) take longer to unlearn a conditioned fear response.

People who experience panic attacks have been shown to take longer to unlearn a conditioned fear response compared to healthy controls. Chronic muscle tension (A) has been associated with generalized anxiety disorder, but not panic disorder specifically. People with panic disorder actually tend to have higher levels of sympathetic nervous system activity (B) during panic attacks. The role of dopamine (C and D) in panic disorder is not clear, with some studies suggesting either high or low levels of the neurotransmitter.