Published online by Cambridge University Press: 18 September 2015
One of the theories on the biology of panic disorder which received much attention is the locus coeruleus hypothesis. This hypothesis states that there exists an episodic overactivity of noradrenergic systems in panic disorder. Experiments with yohimbine form the cornerstone of this theory, and additional supporting evidence is provided by challenge studies with isoproterenol and treatment studies with clonidine. These studies are critically reviewed and it is argued that based upon the studies with yohimbine one cannot conclude that there is a specific noradrenergic abnormality in panic disorder, since yohimbine also affects dopaminergic and serotoninergic neurons in the brain.
In an alternative theory on the relationship between noradrenaline and anxiety it is postulated that increases in anxiety, irrespective of the diagnostic category, are related to increases in locus coeruleus activity.