In Anxiety disorders the most prominent features are anxiety and avoidance which are irrational or impair functioning.

Noradrenergic model. This model suggests that the autonomic nervous system of anxious patients is hypersensitive and overreacts to various stimuli. The locus ceruleus may have a role in regulating anxiety, as it activates norepinephrine release and stimulates the sympathetic and parasympathetic nervous systems.